gustafsson

explanation blue bibcodes open ADS page with paths to full text

Author name code: gustafsson
ADS astronomy entries on 2022-09-14
author:"Gustafsson, Bengt"

---------------------------------------------------------
Title: Chemical Tracing and the Origin of Carbon in the Galactic Disk
Authors: Gustafsson, Bengt
2022Univ....8..409G Altcode:
A basic problem in studies of the evolution of chemical elements in
galaxies is the uncertainties in the yields of elements produced by
different types of stars. The possibilities of tracing the sites
producing chemical elements and corresponding yields in stellar
populations by studying ratios of abundances in stars of different ages
and metallicities, with an approach with minimal assumptions concerning
the yields, is explored by means of simple models of Galactic chemical
evolution. Elemental abundances of carbon and oxygen, obtained by
recent observations of samples of solar-type stars with estimated
ages in the thin disk of the Galaxy, are analysed. Constraints on the
yields from winds of intermediate-mass stars and of hot massive stars,
including core-collapse supernovae, are derived. It is found that a
dominating contribution of carbon from massive stars is most probable,
although stars in the mass interval of two to three solar masses
may have provided some amounts of carbon in the Sun. The results are
consistent with those obtained by using theoretical yields and more
elaborate models of Galactic evolution. The uncertainties as regards
the mixing of stellar populations due to migration of stars in the
Galactic disk may be important for the conclusions. Variations in the
star formation rates, lack of chemical homogeneity in the Galactic gas,
the inflow of gas from the intergalactic space and possible variations
in the Initial mass function may also limit conclusions about the sites
and their yields. Very accurate abundance ratios and the determination
of stellar ages provide further important constraints on the yields.

---------------------------------------------------------
Title: Iron-Phosphorus Feedbacks Drive Multidecadal Oscillations in
Baltic Sea Hypoxia
Authors: Jilbert, Tom; Gustafsson, Bo G.; Veldhuijzen, Simon; Reed,
Daniel C.; van Helmond, Niels A. G. M.; Hermans, Martijn; Slomp,
Caroline P.
2021GeoRL..4895908J Altcode:
Hypoxia has occurred intermittently in the Baltic Sea since the
establishment of brackish-water conditions at ∼8,000 years B.P.,
principally as recurrent hypoxic events during the Holocene Thermal
Maximum (HTM) and the Medieval Climate Anomaly (MCA). Sedimentary
phosphorus release has been implicated as a key driver of these events,
but previous paleoenvironmental reconstructions have lacked the sampling
resolution to investigate feedbacks in past iron-phosphorus cycling on
short timescales. Here we employ Laser Ablation (LA)-ICP-MS scanning of
sediment cores to generate ultra-high resolution geochemical records of
past hypoxic events. We show that in-phase multidecadal oscillations
in hypoxia intensity and iron-phosphorus cycling occurred throughout
these events. Using a box model, we demonstrate that such oscillations
were likely driven by instabilities in the dynamics of iron-phosphorus
cycling under preindustrial phosphorus loads, and modulated by external
climate forcing. Oscillatory behavior could complicate the recovery
from hypoxia during future trajectories of external loading reductions.

---------------------------------------------------------
Title: Impact of natural re-oxygenation on the sediment dynamics of
manganese, iron and phosphorus in a euxinic Baltic Sea basin
Authors: Hermans, Martijn; Lenstra, Wytze K.; van Helmond, Niels
A. G. M.; Behrends, Thilo; Egger, Matthias; Séguret, Marie J. M.;
Gustafsson, Erik; Gustafsson, Bo G.; Slomp, Caroline P.
2019GeCoA.246..174H Altcode:
The Baltic Sea is characterized by the largest area of hypoxic
(oxygen (O2) &lt; 2 mg L-1) bottom waters in
the world's ocean induced by human activities. Natural ventilation
of these O2-depleted waters largely depends on episodic
Major Baltic Inflows from the adjacent North Sea. In 2014 and 2015,
two such inflows led to a strong rise in O2 and decline in
phosphate (HPO42-) in waters below 125 m depth in
the Eastern Gotland Basin. This provided the opportunity to assess the
impact of such re-oxygenation events on the cycles of manganese (Mn),
iron (Fe) and phosphorus (P) in the sediment for the first time. We
demonstrate that the re-oxygenation induced the activity of sulphur
(S)-oxidising bacteria, known as Beggiatoaceae in the surface sediment
where a thin oxic and suboxic layer developed. At the two deepest sites,
strong enrichments of total Mn and to a lesser extent Fe oxides and
P were observed in this surface layer. A combination of sequential
sediment extractions and synchrotron-based X-ray spectroscopy revealed
evidence for the abundant presence of P-bearing rhodochrosite and Mn(II)
phosphates. In contrast to what is typically assumed, the formation
of Fe oxides in the surface sediment was limited. We attribute this
lack of Fe oxide formation to the high flux of reductants, such as
sulphide, from deeper sediments which allows Fe(II) in the form of FeS
to be preserved and restricts the penetration of O2 into the
sediment. We estimate that enhanced P sequestration in surface sediments
accounts for only ∼5% of water column HPO42-
removal in the Eastern Gotland Basin linked to the recent inflows. The
remaining HPO42- was transported to adjacent areas
in the Baltic Sea. Our results highlight that the benthic O2
demand arising from the accumulation of organic-rich sediments over
several decades, the legacy of hypoxia, has major implications for
the biogeochemical response of euxinic basins to re-oxygenation. In
particular, P sequestration in the sediment in association with Fe
oxides is limited. This implies that artificial ventilation projects
that aim at removing water column HPO42- and
thereby improving water quality in the Baltic Sea will likely not have
the desired effect.

---------------------------------------------------------
Title: Dust cleansing of star-forming gas. II. Did late accretion
flows change the chemical composition of the solar atmosphere?
Authors: Gustafsson, Bengt
2018A&A...620A..53G Altcode: 2018arXiv180902361G
 Aims: The possibility that the chemical composition of the
solar atmosphere has been affected by radiative dust cleansing of late
and weak accretion flows by the proto-sun itself is explored. Methods: Estimates, using semi-analytical methods and numerical
simulations of the motion of dust grains in a collapsing non-magnetic
and non-rotating gas sphere with a central light source are made in
order to model possible dust-cleansing effects. Results: Our
calculations indicate that the amount of cleansed material may well be
consistent with the abundance differences observed for the Sun when
compared with solar-like stars and with the relations found between
these differences and the condensation temperature of the element. Conclusions: It seems quite possible that the proposed mechanism
produced the significant abundance effects observed for the Sun,
provided that late and relatively weak accretion did occur. The effects
of cleansing may, however, be affected by outflows from the Sun, the
existence and dynamics of magnetic fields and of the accretion disk,
and the possible presence and location of the early Sun in a rich
stellar cluster.

---------------------------------------------------------
Title: High-precision stellar abundances of the elements: methods
and applications
Authors: Nissen, Poul Erik; Gustafsson, Bengt
2018A&ARv..26....6N Altcode: 2018arXiv181006535N
Efficient spectrographs at large telescopes have made it possible
to obtain high-resolution spectra of stars with high signal-to-noise
ratio and advances in model atmosphere analyses have enabled estimates
of high-precision differential abundances of the elements from these
spectra, i.e. with errors in the range 0.01-0.03 dex for F, G, and K
stars. Methods to determine such high-precision abundances together
with precise values of effective temperatures and surface gravities
from equivalent widths of spectral lines or by spectrum synthesis
techniques are outlined, and effects on abundance determinations from
using a 3D non-LTE analysis instead of a classical 1D LTE analysis
are considered. The determination of high-precision stellar abundances
of the elements has led to the discovery of unexpected phenomena and
relations with important bearings on the astrophysics of galaxies,
stars, and planets, i.e. (i) Existence of discrete stellar populations
within each of the main Galactic components (disk, halo, and bulge)
providing new constraints on models for the formation of the Milky
Way. (ii) Differences in the relation between abundances and elemental
condensation temperature for the Sun and solar twins suggesting
dust-cleansing effects in proto-planetary disks and/or engulfment of
planets by stars; (iii) Differences in chemical composition between
binary star components and between members of open or globular clusters
showing that star- and cluster-formation processes are more complicated
than previously thought; (iv) Tight relations between some abundance
ratios and age for solar-like stars providing new constraints on
nucleosynthesis and Galactic chemical evolution models as well as the
composition of terrestrial exoplanets. We conclude that if stellar
abundances with precisions of 0.01-0.03 dex can be achieved in studies
of more distant stars and stars on the giant and supergiant branches,
many more interesting future applications, of great relevance to stellar
and galaxy evolution, are probable. Hence, in planning abundance
surveys, it is important to carefully balance the need for large
samples of stars against the spectral resolution and signal-to-noise
ratio needed to obtain high-precision abundances. Furthermore, it is
an advantage to work differentially on stars with similar atmospheric
parameters, because then a simple 1D LTE analysis of stellar spectra
may be sufficient. However, when determining high-precision absolute
abundances or differential abundance between stars having more widely
different parameters, e.g. metal-poor stars compared to the Sun or
giants to dwarfs, then 3D non-LTE effects must be taken into account.

---------------------------------------------------------
Title: Dust cleansing of star-forming gas. I. Has radiation from
bright stars affected the chemical composition of the Sun and M 67?
Authors: Gustafsson, Bengt
2018A&A...616A..91G Altcode: 2018arXiv180500547G
 Aims: We explore the possibility that solar chemical composition,
as well as the similar composition of the rich open cluster M 67,
have been affected by dust cleansing of the presolar or precluster
cloud due to the radiative forces from bright early-type stars in
its neighbourhood. Methods: We estimate possible cleansing
effects using semi-analytical methods, which are essentially based on
momentum conservation. Results: Our calculations indicate that
the amounts of cleansed neutral gas are limited to a relatively thin
shell surrounding the H II region around the early-type stars. 
Conclusions: It seems possible that the proposed mechanism acting in
individual giant molecular clouds may produce significant abundance
effects for masses corresponding to single stars or small groups of
stars. The effects of cleansing are, however, severely constrained
by the thinness of the cleansed shell of gas and by turbulence in the
cloud. This is why the mechanism can hardly be important in cleansing
masses corresponding to rich clusters, such as the mass of the original
M 67.

---------------------------------------------------------
Title: The destruction of an Oort Cloud in a rich stellar cluster
Authors: Nordlander, T.; Rickman, H.; Gustafsson, B.
2017A&A...603A.112N Altcode: 2017arXiv170403341N
Context. It is possible that the formation of the Oort Cloud dates
back to the earliest epochs of solar system history. At that time,
the Sun was almost certainly a member of the stellar cluster where
it was born. Since the solar birth cluster is likely to have been
massive (103-104ℳ⊙), and therefore
long-lived, an issue concerns the survival of such a primordial Oort
Cloud. Aims: We have investigated this issue by simulating
the orbital evolution of Oort Cloud comets for several hundred Myr,
assuming the Sun to start its life as a typical member of such a massive
cluster. Methods: We have devised a synthetic representation of
the relevant dynamics, where the cluster potential is represented by
a King model, and about 20 close encounters with individual cluster
stars are selected and integrated based on the solar orbit and the
cluster structure. Thousands of individual simulations are made,
each including 3000 comets with orbits with three different initial
semi-major axes. Results: Practically the entire initial Oort
Cloud is found to be lost for our choice of semi-major axes (5000-20 000
au), independent of the cluster mass, although the chance of survival
is better for the smaller cluster, since in a certain fraction of the
simulations the Sun orbits at relatively safe distances from the dense
cluster centre. Conclusions: For the range of birth cluster
sizes that we investigate, a primordial Oort Cloud will likely survive
only as a small inner core with semi-major axes ≲3000 au. Such a
population of comets would be inert to orbital diffusion into an outer
halo and subsequent injection into observable orbits. Some mechanism
is therefore needed to accomplish this transfer, in case the Oort Cloud
is primordial and the birth cluster did not have a low mass. From this
point of view, our results lend some support to a delayed formation of
the Oort Cloud, that occurred after the Sun had left its birth cluster.

---------------------------------------------------------
Title: A grid of MARCS model atmospheres for late-type stars. II. S
stars and their properties
Authors: Van Eck, Sophie; Neyskens, Pieter; Jorissen, Alain; Plez,
Bertrand; Edvardsson, Bengt; Eriksson, Kjell; Gustafsson, Bengt;
Jørgensen, Uffe Gråe; Nordlund, Åke
2017A&A...601A..10V Altcode:
S-type stars are late-type giants whose atmospheres are enriched in
carbon and s-process elements because of either extrinsic pollution
by a binary companion or intrinsic nucleosynthesis and dredge-up on
the thermally-pulsing asymptotic giant branch. A grid of MARCS model
atmospheres has been computed for S stars, covering the range 2700 ≤
Teff(K) ≤ 4000, 0.50 ≤ C/O ≤ 0.99, 0 ≤ log g ≤ 5,
[Fe/H] = 0., -0.5 dex, and [s/Fe] = 0, 1, and 2 dex (where the latter
quantity refers to the global overabundance of s-process elements). The
MARCS models make use of a new ZrO line list. Synthetic spectra
computed from these models are used to derive photometric indices in
the Johnson and Geneva systems, as well as TiO and ZrO band strengths. A
method is proposed to select the model best matching any given S star,
a non-trivial operation since the grid contains more than 3500 models
covering a five-dimensional parameter space. The method is based on
the comparison between observed and synthetic photometric indices and
spectral band strengths, and has been applied on a vast subsample of
the Henize sample of S stars. Our results confirm the old claim by
Piccirillo (1980, MNRAS, 190, 441) that ZrO bands in warm S stars
(Teff&gt;3200 K) are not caused by the C/O ratio being
close to unity, as traditionally believed, but rather by some Zr
overabundance. The TiO and ZrO band strengths, combined with V-K and
J-K photometric indices, are used to select Teff, C/O, [Fe/H]
and [s/Fe]. The Geneva U-B1 and B2-V1
indices (or any equivalent) are good at selecting the gravity. The
defining spectral features of dwarf S stars are outlined, but none is
found among the Henize S stars. More generally, it is found that, at
Teff = 3200 K, a change of C/O from 0.5 to 0.99 has a strong
impact on V-K (2 mag). Conversely, a range of 2 mag in V-K corresponds
to a 200 K shift along the (Teff, V-K) relationship
(for a fixed C/O value). Hence, the use of a (Teff, V-K)
calibration established for M stars will yield large errors for S stars,
so that a specific calibration must be used, as provided in the present
paper. Using the atmospheric parameters derived by our method for the
sample of Henize S stars, we show that the extrinsic-intrinsic dichotomy
among S stars reveals itself very clearly as a bimodal distribution in
the effective temperatures. Moreover, the increase of s-process element
abundances with increasing C/O ratios and decreasing temperatures is
apparent among intrinsic stars, confirming theoretical expectations. Based on observations carried out at the European Southern Observatory
(ESO, La Silla, Chile; program 58.E-0942), on the Swiss 70 cm telescope
(La Silla, Chile) and on the Mercator telescope (La Palma, Spain).The
MARCS S star model atmospheres will be archived on the MARCS website:
<A href="http://marcs.astro.uu.se">http://marcs.astro.uu.se</A>Full
Tables 2 and 3 are only available at the CDS via anonymous ftp to
<A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
(<A href="http://130.79.128.5">http://130.79.128.5</A>) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/601/A10">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/601/A10</A>

---------------------------------------------------------
Title: Sun-like stars unlike the Sun: Clues for chemical anomaliesof
cool stars
Authors: Adibekyan, V.; Delgado-Mena, E.; Feltzing, S.; González
Hernández, J. I.; Hinkel, N. R.; Korn, A. J.; Asplund, M.; Beck,
P. G.; Deal, M.; Gustafsson, B.; Honda, S.; Lind, K.; Nissen, P. E.;
Spina, L.
2017AN....338..442A Altcode: 2017arXiv170105737A
We present a summary of the splinter session "Sun-like stars unlike
the Sun" that was held on June 9, 2016, as part of the Cool Stars
19 conference (Uppsala, Sweden), in which the main limitations
(in the theory and observations) in the derivation of very precise
stellar parameters and chemical abundances of Sun-like stars were
discussed. The most important and most debated processes that can
produce chemical peculiarities in solar-type stars were outlined and
discussed. Finally, in an open discussion between all the participants,
we tried to identify new pathways and prospects toward future solutions
of the currently open questions.

---------------------------------------------------------
Title: VizieR Online Data Catalog: A grid of MARCS model atmospheres
for S stars (Van Eck+, 2017)
Authors: van Eck, S.; Neyskens, P.; Jorissen, A.; Plez, B.; Edvardsson,
B.; Eriksson, K.; Gustafsson, B.; Jorgensen, U. G.; Nordlund, A.
2017yCat..36010010V Altcode:
Johnson and Geneva (G) photometric indices and band indices measured
on the observed Henize S stars. (3 data files).

---------------------------------------------------------
Title: 67P/C-G inner coma dust properties from 2.2 au inbound to
2.0 au outbound to the Sun
Authors: Della Corte, V.; Rotundi, A.; Fulle, M.; Ivanovski, S.; Green,
S. F.; Rietmeijer, F. J. M.; Colangeli, L.; Palumbo, P.; Sordini, R.;
Ferrari, M.; Accolla, M.; Zakharov, V.; Mazzotta Epifani, E.; Weissman,
P.; Gruen, E.; Lopez-Moreno, J. J.; Rodriguez, J.; Bussoletti, E.;
Crifo, J. F.; Esposito, F.; Lamy, P. L.; McDonnell, J. A. M.; Mennella,
V.; Molina, A.; Morales, R.; Moreno, F.; Palomba, E.; Perrin, J. M.;
Rodrigo, R.; Zarnecki, J. C.; Cosi, M.; Giovane, F.; Gustafson, B.;
Ortiz, J. L.; Jeronimo, J. M.; Leese, M. R.; Herranz, M.; Liuzzi,
V.; Lopez-Jimenez, A. C.
2016MNRAS.462S.210D Altcode: 2016MNRAS.tmp.1514D
GIADA (Grain Impact Analyzer and Dust Accumulator) on-board the
Rosetta space probe is designed to measure the momentum, mass and
speed of individual dust particles escaping the nucleus of comet
67P/Churyumov-Gerasimenko (hereafter 67P). From 2014 August to
2016 June, Rosetta escorted comet 67P during its journey around
the Sun. Here, we focus on GIADA data taken between 2015 January
and 2016 February which included 67P's perihelion passage. To better
understand cometary activity and more specifically the presence of dust
structures in cometary comae, we mapped the spatial distribution of dust
density in 67P's coma. In this manner, we could track the evolution of
high-density regions of coma dust and their connections with nucleus
illumination conditions, namely tracking 67P's seasons. We also studied
the link between dust particle speeds and their masses with respect to
heliocentric distance, I.e. the level of cometary activity. This allowed
us to derive a global and a local correlation of the dust particles'
speed distribution with respect to the H2O production rate.

---------------------------------------------------------
Title: VizieR Online Data Catalog: Kepler-10 chemical composition
(Liu+, 2016)
Authors: Liu, F.; Yong, D.; Asplund, M.; Ramirez, I.; Melendez,
J.; Gustafsson, B.; Howes, L. M.; Roederer, I. U.; Lambert, D. L.;
Bensby, T.
2016yCat..74562636L Altcode:
We obtained high resolution and high SNR spectra with the
Canada-France-Hawaii Telescope (CFHT), the Hobby-Eberly Telescope (HET)
and the Magellan Clay Telescope. We observed Kepler-10 with the
Echelle SpectroPolarimetric Device for the Observation of Stars at
the CFHT during 2013 June. The spectral revolving power is 68000 and
the spectral range is 3800-8900Å. We also observed Kepler-10
with the High Resolution Spectrograph (HRS) on the HET at McDonald
Observatory during 2011 May. A total integration time of 6.8h was
needed to achieve SNR&gt;350 per pixel. The spectrum has a spectral
resolving power of 60000 and covers 4100-7800Å, with a gap of about
100Å around 6000Å. (4 data files).

---------------------------------------------------------
Title: Gravitational Scattering In The Galactic Disk And The Old
High-Altitude Open Clusters
Authors: Gustafsson, Bengt
2016diga.confE..37G Altcode:
By means of numerical simulations we have investigated the possibility
that the observed heating of the Thin Disk and the existence of old
high-altitude open clusters are both the result of gravitational
scattering by GMCs and other inhomogeneities in the Galactic
potential. We find consistency between model results and observations,
but the results are very dependent on the structure adopted for the
GMCs and their surroundings.

---------------------------------------------------------
Title: Gravitational scattering of stars and clusters and the heating
of the Galactic disk
Authors: Gustafsson, Bengt; Church, Ross P.; Davies, Melvyn B.;
Rickman, Hans
2016A&A...593A..85G Altcode: 2016arXiv160502965G
Context. Could the velocity spread, increasing with time, in the
Galactic disk be explained as a result of gravitational interactions
of stars with giant molecular clouds (GMCs) and spiral arms? Do the
old open clusters high above the Galactic plane provide clues to this
question? Aims: We explore the effects on stellar orbits of
scattering by inhomogeneities in the Galactic potential due to GMCs,
spiral arms and the Galactic bar, and whether high-altitude clusters
could have formed in orbits closer to the Galactic plane and later
been scattered. Methods: Simulations of test-particle motions
are performed in a realistic Galactic potential. The effects of the
internal structure of GMCs are explored. The destruction of clusters
in GMC collisions is treated in detail with N-body simulations of the
clusters. Results: The observed velocity dispersions of stars
as a function of time are well reproduced. The GMC structure is found
to be significant, but adequate models produce considerable scattering
effects. The fraction of simulated massive old open clusters, scattered
into orbits with |z| &gt; 400 pc, is typically 0.5%, in agreement with
the observed number of high-altitude clusters and consistent with the
present formation rate of massive open clusters. Conclusions:
The heating of the thin Galactic disk is well explained by gravitational
scattering by GMCs and spiral arms, if the local correlation between the
GMC mass and the corresponding voids in the gas is not very strong. Our
results suggest that the high-altitude metal-rich clusters were formed
in orbits close to the Galactic plane and later scattered to higher
orbits. It is possible, though not very probable, that the Sun formed
in such a cluster before scattering occurred.

---------------------------------------------------------
Title: Evolution of the Dust Size Distribution of Comet
67P/Churyumov-Gerasimenko from 2.2 au to Perihelion
Authors: Fulle, M.; Marzari, F.; Della Corte, V.; Fornasier, S.;
Sierks, H.; Rotundi, A.; Barbieri, C.; Lamy, P. L.; Rodrigo, R.;
Koschny, D.; Rickman, H.; Keller, H. U.; López-Moreno, J. J.;
Accolla, M.; Agarwal, J.; A'Hearn, M. F.; Altobelli, N.; Barucci,
M. A.; Bertaux, J. -L.; Bertini, I.; Bodewits, D.; Bussoletti, E.;
Colangeli, L.; Cosi, M.; Cremonese, G.; Crifo, J. -F.; Da Deppo,
V.; Davidsson, B.; Debei, S.; De Cecco, M.; Esposito, F.; Ferrari,
M.; Giovane, F.; Gustafson, B.; Green, S. F.; Groussin, O.; Grün,
E.; Gutierrez, P.; Güttler, C.; Herranz, M. L.; Hviid, S. F.; Ip,
W.; Ivanovski, S. L.; Jerónimo, J. M.; Jorda, L.; Knollenberg, J.;
Kramm, R.; Kührt, E.; Küppers, M.; Lara, L.; Lazzarin, M.; Leese,
M. R.; López-Jiménez, A. C.; Lucarelli, F.; Mazzotta Epifani, E.;
McDonnell, J. A. M.; Mennella, V.; Molina, A.; Morales, R.; Moreno,
F.; Mottola, S.; Naletto, G.; Oklay, N.; Ortiz, J. L.; Palomba, E.;
Palumbo, P.; Perrin, J. -M.; Rietmeijer, F. J. M.; Rodríguez, J.;
Sordini, R.; Thomas, N.; Tubiana, C.; Vincent, J. -B.; Weissman, P.;
Wenzel, K. -P.; Zakharov, V.; Zarnecki, J. C.
2016ApJ...821...19F Altcode:
The Rosetta probe, orbiting Jupiter-family comet
67P/Churyumov-Gerasimenko, has been detecting individual dust particles
of mass larger than 10-10 kg by means of the GIADA dust
collector and the OSIRIS Wide Angle Camera and Narrow Angle Camera
since 2014 August and will continue until 2016 September. Detections
of single dust particles allow us to estimate the anisotropic dust flux
from 67P, infer the dust loss rate and size distribution at the surface
of the sunlit nucleus, and see whether the dust size distribution of
67P evolves in time. The velocity of the Rosetta orbiter, relative
to 67P, is much lower than the dust velocity measured by GIADA, thus
dust counts when GIADA is nadir-pointing will directly provide the
dust flux. In OSIRIS observations, the dust flux is derived from the
measurement of the dust space density close to the spacecraft. Under
the assumption of radial expansion of the dust, observations in the
nadir direction provide the distance of the particles by measuring
their trail length, with a parallax baseline determined by the motion
of the spacecraft. The dust size distribution at sizes &gt;1 mm
observed by OSIRIS is consistent with a differential power index of
-4, which was derived from models of 67P’s trail. At sizes &lt;1 mm,
the size distribution observed by GIADA shows a strong time evolution,
with a differential power index drifting from -2 beyond 2 au to -3.7
at perihelion, in agreement with the evolution derived from coma and
tail models based on ground-based data. The refractory-to-water mass
ratio of the nucleus is close to six during the entire inbound orbit
and at perihelion.

---------------------------------------------------------
Title: Division G Commission 36: Theory of Stellar Atmospheres
Authors: Puls, Joachim; Hubeny, Ivan; Asplund, Martin; Allard, France;
Allende Prieto, Carlos; Ayres, Thomas R.; Carlsson, Mats; Gustafsson,
Bengt; Kudritzki, Rolf-Peter; Ryabchikova, Tatiana A.
2016IAUTA..29..453P Altcode:
Different from previous triennial reports, this report covers the
activities of IAU Commission 36 `Theory of Stellar Atmospheres'
over the past six years†, and will be the last report from the
`old' Commission 36. After the General Assembly in Honolulu (August
2015), a new Commission `Stellar and Planetary Atmospheres' (C.G5,
under Division G, `Stars and Stellar Physics') has come into life,
and will continue our work devoted to the outer envelopes of stars,
as well as extend it to the atmospheres of planets (see Sect. 4).

---------------------------------------------------------
Title: The detailed chemical composition of the terrestrial planet
host Kepler-10
Authors: Liu, F.; Yong, D.; Asplund, M.; Ramírez, I.; Meléndez,
J.; Gustafsson, B.; Howes, L. M.; Roederer, I. U.; Lambert, D. L.;
Bensby, T.
2016MNRAS.456.2636L Altcode: 2015arXiv151109287L
Chemical abundance studies of the Sun and solar twins have demonstrated
that the solar composition of refractory elements is depleted when
compared to volatile elements, which could be due to the formation
of terrestrial planets. In order to further examine this scenario, we
conducted a line-by-line differential chemical abundance analysis of the
terrestrial planet host Kepler-10 and 14 of its stellar twins. Stellar
parameters and elemental abundances of Kepler-10 and its stellar twins
were obtained with very high precision using a strictly differential
analysis of high quality Canada-France-Hawaii Telescope, Hobby-Eberly
Telescope and Magellan spectra. When compared to the majority of
thick disc twins, Kepler-10 shows a depletion in the refractory
elements relative to the volatile elements, which could be due to
the formation of terrestrial planets in the Kepler-10 system. The
average abundance pattern corresponds to ∼13 Earth masses, while
the two known planets in Kepler-10 system have a combined ∼20 Earth
masses. For two of the eight thick disc twins, however, no depletion
patterns are found. Although our results demonstrate that several
factors [e.g. planet signature, stellar age, stellar birth location and
Galactic chemical evolution (GCE)] could lead to or affect abundance
trends with condensation temperature, we find that the trends give
further support for the planetary signature hypothesis.

---------------------------------------------------------
Title: Shelf-to-basin iron shuttling enhances vivianite formation
in deep Baltic Sea sediments
Authors: Reed, Daniel C.; Gustafsson, Bo G.; Slomp, Caroline P.
2016E&PSL.434..241R Altcode:
Coastal hypoxia is a growing and persistent problem largely attributable
to enhanced terrestrial nutrient (i.e., nitrogen and phosphorus)
loading. Recent studies suggest phosphorus removal through burial of
iron (II) phosphates, putatively vivianite, plays an important role in
nutrient cycling in the Baltic Sea - the world's largest anthropogenic
dead zone - yet the dynamics of iron (II) phosphate formation are poorly
constrained. To address this, a reactive-transport model was used to
reconstruct the diagenetic and depositional history of sediments in
the Fårö basin, a deep anoxic and sulphidic region of the Baltic Sea
where iron (II) phosphates have been observed. Simulations demonstrate
that transport of iron from shelf sediments to deep basins enhances
vivianite formation while sulphide concentrations are low, but that
pyrite forms preferentially over vivianite when sulphate reduction
intensifies due to elevated organic loading. Episodic reoxygenation
events, associated with major inflows of oxic waters, encourage
the retention of iron oxyhydroxides and iron-bound phosphorus in
sediments, increasing vivianite precipitation as a result. Results
suggest that artificial reoxygenation of the Baltic Sea bottom waters
could sequester up to 3% of the annual external phosphorus loads as
iron (II) phosphates, but this is negligible when compared to potential
internal phosphorus loads due to dissolution of iron oxyhydroxides when
low oxygen conditions prevail. Thus, enhancing vivianite formation
through artificial reoxygenation of deep waters is not a viable
engineering solution to eutrophication in the Baltic Sea. Finally,
simulations suggest that regions with limited sulphate reduction and
hypoxic intervals, such as eutrophic estuaries, could act as important
phosphorus sinks by sequestering vivianite. This could potentially
alleviate eutrophication in shelf and slope environments.

---------------------------------------------------------
Title: Coma dust environment observed by GIADA during the Perihelion
of 67P/Churyumov-Gerasimenko.
Authors: Rotundi, A.; Della Corte, V.; Fulle, M.; Ferrari, M.;
Ivanovski, S. L.; Sordini, R.; Mazzotta Epifani, E.; Palumbo, P.;
Colangeli, L.; Lopez-Moreno, J. J.; Rodriguez, J.; Zakharov, V.;
Bussoletti, E.; Crifo, J. F.; Esposito, F.; Green, S.; Gruen, E.;
Lamy, P. L.; McDonnell, T.; Mennella, V.; Molina, A.; Moreno, F.;
Ortiz, J. L.; Palomba, E.; Perrin, J. M.; Rodrigo, R.; Weissman,
P. R.; Zarnecki, J.; Cosi, M.; Giovane, F.; Gustafson, B.; Herranz,
M.; Jeronimo, J. M.; Leese, M.; Lopez-Jimenez, A.; Morales, R.
2015AGUFM.P33E..05R Altcode:
GIADA (Grain Impact Analyzer and Dust Accumulator) is an in-situ
instrument mounted onboard Rosetta monitoring the dust environment of
comet 67P/Churyumov-Gerasimenko. GIADA is composed of 3 sub-systems: 1)
the Grain Detection System, based on particle detection through light
scattering; 2) the Impact Sensor, giving momentum measurement; 3) the
Micro-Balances System, constituted of 5 quartz crystal microbalances,
giving cumulative deposited dust. The combination of the measurements
performed by these 3 subsystems provides: the number, the mass,
the momentum and the speed distribution of dust particles emitted
from the comet nucleus. We will present the coma dust environment as
observed by GIADA during the perihelion phase of the Rosetta space
mission. Despite the large distance from the nucleus, more than 200 km,
GIADA was able to detect temporal and spatial variation of dust density
distribution. Specific high dust spatial density sectors of the coma
have been identified and their evolution during the perihelion phase
was studied. Acknowledgements. GIADA was built by a consortium led
by the Univ. Napoli "Parthenope" &amp; INAF- Oss. Astr. Capodimonte,
IT, in collaboration with the Inst. de Astrofisica de Andalucia,
ES, Selex-ES s.p.a. and SENER. GIADA is presently managed &amp;
operated by Ist. di Astrofisica e Planetologia Spaziali-INAF,
IT. GIADA was funded and managed by the Agenzia Spaziale Italiana,
IT, with a support of the Spanish Ministry of Education and Science
MEC, ES. GIADA was developped from a PI proposal supported by the
University of Kent; sci. &amp; tech. contribution given by CISAS,
IT, Lab. d'Astr. Spat., FR, and Institutions from UK, IT, FR, DE and
USA. We thank the RSGS/ESAC, RMOC/ESOC &amp; Rosetta Project/ESTEC for
their outstanding work. Science support provided by NASA through the US
Rosetta Project managed by JPL/California Institute of Technology. GIADA
calibrated data will be available through the ESA's PSA web site.

---------------------------------------------------------
Title: GIADA: shining a light on the monitoring of the comet dust
production from the nucleus of 67P/Churyumov-Gerasimenko
Authors: Della Corte, V.; Rotundi, A.; Fulle, M.; Gruen, E.;
Weissman, P.; Sordini, R.; Ferrari, M.; Ivanovski, S.; Lucarelli,
F.; Accolla, M.; Zakharov, V.; Mazzotta Epifani, E.; Lopez-Moreno,
J. J.; Rodriguez, J.; Colangeli, L.; Palumbo, P.; Bussoletti, E.;
Crifo, J. F.; Esposito, F.; Green, S. F.; Lamy, P. L.; McDonnell,
J. A. M.; Mennella, V.; Molina, A.; Morales, R.; Moreno, F.; Ortiz,
J. L.; Palomba, E.; Perrin, J. M.; Rietmeijer, F. J. M.; Rodrigo, R.;
Zarnecki, J. C.; Cosi, M.; Giovane, F.; Gustafson, B.; Herranz, M. L.;
Jeronimo, J. M.; Leese, M. R.; Lopez-Jimenez, A. C.; Altobelli, N.
2015A&A...583A..13D Altcode:
Context. During the period between 15 September 2014 and 4 February
2015, the Rosetta spacecraft accomplished the circular orbit phase
around the nucleus of comet 67P/Churyumov-Gerasimenko (67P). The Grain
Impact Analyzer and Dust Accumulator (GIADA) onboard Rosetta monitored
the 67P coma dust environment for the entire period. Aims: We
aim to describe the dust spatial distribution in the coma of comet 67P
by means of in situ measurements. We determine dynamical and physical
properties of cometary dust particles to support the study of the
production process and dust environment modification. Methods:
We analyzed GIADA data with respect to the observation geometry and
heliocentric distance to describe the coma dust spatial distribution
of 67P, to monitor its activity, and to retrieve information on active
areas present on its nucleus. We combined GIADA detection information
with calibration activity to distinguish different types of particles
that populate the coma of 67P: compact particles and fluffy porous
aggregates. By means of particle dynamical parameters measured by
GIADA, we studied the dust acceleration region. Results: GIADA
was able to distinguish different types of particles populating the
coma of 67P: compact particles and fluffy porous aggregates. Most of
the compact particle detections occurred at latitudes and longitudes
where the spacecraft was in view of the comet's neck region of the
nucleus, the so-called Hapi region. This resulted in an oscillation
of the compact particle abundance with respect to the spacecraft
position and a global increase as the comet moved from 3.36 to 2.43
AU heliocentric distance. The speed of these particles, having masses
from 10-10 to 10-7 kg, ranged from 0.3 to 12.2 m
s-1. The variation of particle mass and speed distribution
with respect to the distance from the nucleus gave indications of the
dust acceleration region. The influence of solar radiation pressure on
micron and submicron particles was studied. The integrated dust mass
flux collected from the Sun direction, that is, particles reflected by
solar radiation pressure, was three times higher than the flux coming
directly from the comet nucleus. The awakening 67P comet shows a strong
dust flux anisotropy, confirming what was suggested by on-ground dust
coma observations performed in 2008.

---------------------------------------------------------
Title: Gaia FGK benchmark stars: Effective temperatures and surface
gravities
Authors: Heiter, U.; Jofré, P.; Gustafsson, B.; Korn, A. J.; Soubiran,
C.; Thévenin, F.
2015A&A...582A..49H Altcode: 2015arXiv150606095H
Context. In the era of large Galactic stellar surveys, carefully
calibrating and validating the data sets has become an important and
integral part of the data analysis. Moreover, new generations of stellar
atmosphere models and spectral line formation computations need to
be subjected to benchmark tests to assess any progress in predicting
stellar properties. Aims: We focus on cool stars and aim at
establishing a sample of 34 Gaia FGK benchmark stars with a range
of different metallicities. The goal was to determine the effective
temperature and the surface gravity independently of spectroscopy
and atmospheric models as far as possible. Most of the selected stars
have been subjected to frequent spectroscopic investigations in the
past, and almost all of them have previously been used as reference,
calibration, or test objects. Methods: Fundamental determinations
of Teff and log g were obtained in a systematic way from
a compilation of angular diameter measurements and bolometric fluxes
and from a homogeneous mass determination based on stellar evolution
models. The derived parameters were compared to recent spectroscopic and
photometric determinations and to gravity estimates based on seismic
data. Results: Most of the adopted diameter measurements have
formal uncertainties around 1%, which translate into uncertainties in
effective temperature of 0.5%. The measurements of bolometric flux seem
to be accurate to 5% or better, which contributes about 1% or less to
the uncertainties in effective temperature. The comparisons of parameter
determinations with the literature in general show good agreements with
a few exceptions, most notably for the coolest stars and for metal-poor
stars. Conclusions: The sample consists of 29 FGK-type stars and
5 M giants. Among the FGK stars, 21 have reliable parameters suitable
for testing, validation, or calibration purposes. For four stars,
future adjustments of the fundamental Teff are required,
and for five stars the log g determination needs to be improved. Future
extensions of the sample of Gaia FGK benchmark stars are required
to fill gaps in parameter space, and we include a list of suggested
candidates.

---------------------------------------------------------
Title: New H-band Stellar Spectral Libraries for the SDSS-III/APOGEE
Survey
Authors: Zamora, O.; García-Hernández, D. A.; Allende Prieto, C.;
Carrera, R.; Koesterke, L.; Edvardsson, B.; Castelli, F.; Plez,
B.; Bizyaev, D.; Cunha, K.; García Pérez, A. E.; Gustafsson,
B.; Holtzman, J. A.; Lawler, J. E.; Majewski, S. R.; Manchado, A.;
Mészáros, Sz.; Shane, N.; Shetrone, M.; Smith, V. V.; Zasowski, G.
2015AJ....149..181Z Altcode: 2015arXiv150205237Z
The Sloan Digital Sky Survey-III (SDSS-III) Apache Point Observatory
Galactic Evolution Experiment (APOGEE) has obtained high-resolution
(R ∼ 22,500), high signal-to-noise ratio (\gt 100) spectra in
the H-band (∼1.5-1.7 μm) for about 146,000 stars in the Milky Way
galaxy. We have computed spectral libraries with effective temperature
({{T}eff}) ranging from 3500 to 8000 K for the automated
chemical analysis of the survey data. The libraries, used to derive
stellar parameters and abundances from the APOGEE spectra in the
SDSS-III data release 12 (DR12), are based on ATLAS9 model atmospheres
and the ASSɛT spectral synthesis code. We present a second set of
libraries based on MARCS model atmospheres and the spectral synthesis
code Turbospectrum. The ATLAS9/ASSɛT ({{T}eff} = 3500-8000
K) and MARCS/Turbospectrum ({{T}eff} = 3500-5500 K) grids
cover a wide range of metallicity (-2.5 ≤slant [M/H] ≤slant +0.5
dex), surface gravity (0 ≤ log g ≤slant 5 dex), microturbulence
(0.5 ≤slant ξ ≤slant 8 km s-1), carbon (-1 ≤slant
[C/M] ≤slant +1 dex), nitrogen (-1 ≤slant [N/M] ≤slant +1 dex),
and α-element (-1 ≤slant [α/M] ≤slant +1 dex) variations,
having thus seven dimensions. We compare the ATLAS9/ASSɛT and
MARCS/Turbospectrum libraries and apply both of them to the analysis
of the observed H-band spectra of the Sun and the K2 giant Arcturus,
as well as to a selected sample of well-known giant stars observed at
very high resolution. The new APOGEE libraries are publicly available
and can be employed for chemical studies in the H-band using other
high-resolution spectrographs.

---------------------------------------------------------
Title: Dust Measurements in the Coma of Comet
67P/Churyumov-Gerasimenko Inbound to the Sun Between 3.7 and 3.4 AU
Authors: Fulle, M.; Della Corte, V.; Rotundi, A.; Accolla, M.;
Ferrari, M.; Ivanovski, S.; Lucarelli, F.; Sordini, R.; Zakharov, V.;
Mazzotta Epifani, E.; Lopez-Moreno, J. J.; Rodriguez, J.; Colangeli,
L.; Palumbo, P.; Bussoletti, E.; Crifo, J.; Esposito, F.; Green,
S. F.; Gruen, E.; Lamy, P. L.; McDonnell, J. A. M.; Mennella, V.;
Molina, A.; Morales, R.; Moreno, F.; Ortiz, J. L.; Palomba, E.;
Perrin, J.; Rodrigo, R.; Weissman, P.; Zarnecki, J. C.; Cosi, M.;
Giovane, F.; Gustafson, B.; Herranz, M. L.; Jeronimo, J. M.; Leese,
M. R.; Lopez-Jimenez, A. C.; Altobelli, N.; Sierks, H.; Agarwal, J.;
Bertini, I.; Fornasier, S.; Gutierrez, P. J.; Lara, L.; Guettler, C.;
Marzari, F.; Oaklay, N.; Snodgrass, C.; Tubiana, C.; Vincenzo, J. B.
2015LPI....46.2420F Altcode: 2015LPICo1832.2420F
GIADA and OSIRIS dust data, combined with data from MIRO and ROSINA
instruments onboard Rosetta, from 3.7 to 3.4 AU inbound provide a
dust/gas ratio of 4 ± 2.

---------------------------------------------------------
Title: Density and Charge of Pristine Fluffy Particles from Comet
67P/Churyumov-Gerasimenko
Authors: Fulle, M.; Della Corte, V.; Rotundi, A.; Weissman, P.; Juhasz,
A.; Szego, K.; Sordini, R.; Ferrari, M.; Ivanovski, S.; Lucarelli,
F.; Accolla, M.; Merouane, S.; Zakharov, V.; Mazzotta Epifani, E.;
López-Moreno, J. J.; Rodríguez, J.; Colangeli, L.; Palumbo, P.;
Grün, E.; Hilchenbach, M.; Bussoletti, E.; Esposito, F.; Green,
S. F.; Lamy, P. L.; McDonnell, J. A. M.; Mennella, V.; Molina, A.;
Morales, R.; Moreno, F.; Ortiz, J. L.; Palomba, E.; Rodrigo, R.;
Zarnecki, J. C.; Cosi, M.; Giovane, F.; Gustafson, B.; Herranz, M. L.;
Jerónimo, J. M.; Leese, M. R.; López-Jiménez, A. C.; Altobelli, N.
2015ApJ...802L..12F Altcode:
The Grain Impact Analyzer and Dust Accumulator (GIADA) instrument on
board ESA’s Rosetta mission is constraining the origin of the dust
particles detected within the coma of comet 67 P/Churyumov-Gerasimenko
(67P). The collected particles belong to two families: (i) compact
particles (ranging in size from 0.03 to 1 mm), witnessing the presence
of materials that underwent processing within the solar nebula and (ii)
fluffy aggregates (ranging in size from 0.2 to 2.5 mm) of sub-micron
grains that may be a record of a primitive component, probably linked to
interstellar dust. The dynamics of the fluffy aggregates constrain their
equivalent bulk density to \lt 1 kg m-3. These aggregates
are charged, fragmented, and decelerated by the spacecraft negative
potential and enter GIADA in showers of fragments at speeds \lt 1
m s-1. The density of such optically thick aggregates
is consistent with the low bulk density of the nucleus. The mass
contribution of the fluffy aggregates to the refractory component of
the nucleus is negligible and their coma brightness contribution is
less than 15%.

---------------------------------------------------------
Title: Dust measurements in the coma of comet
67P/Churyumov-Gerasimenko inbound to the Sun
Authors: Rotundi, Alessandra; Sierks, Holger; Della Corte, Vincenzo;
Fulle, Marco; Gutierrez, Pedro J.; Lara, Luisa; Barbieri, Cesare;
Lamy, Philippe L.; Rodrigo, Rafael; Koschny, Detlef; Rickman, Hans;
Keller, Horst Uwe; López-Moreno, José J.; Accolla, Mario; Agarwal,
Jessica; A'Hearn, Michael F.; Altobelli, Nicolas; Angrilli, Francesco;
Barucci, M. Antonietta; Bertaux, Jean-Loup; Bertini, Ivano; Bodewits,
Dennis; Bussoletti, Ezio; Colangeli, Luigi; Cosi, Massimo; Cremonese,
Gabriele; Crifo, Jean-Francois; Da Deppo, Vania; Davidsson, Björn;
Debei, Stefano; De Cecco, Mariolino; Esposito, Francesca; Ferrari,
Marco; Fornasier, Sonia; Giovane, Frank; Gustafson, Bo; Green,
Simon F.; Groussin, Olivier; Grün, Eberhard; Güttler, Carsten;
Herranz, Miguel L.; Hviid, Stubbe F.; Ip, Wing; Ivanovski, Stavro;
Jerónimo, José M.; Jorda, Laurent; Knollenberg, Joerg; Kramm, Rainer;
Kührt, Ekkehard; Küppers, Michael; Lazzarin, Monica; Leese, Mark R.;
López-Jiménez, Antonio C.; Lucarelli, Francesca; Lowry, Stephen C.;
Marzari, Francesco; Epifani, Elena Mazzotta; McDonnell, J. Anthony M.;
Mennella, Vito; Michalik, Harald; Molina, Antonio; Morales, Rafael;
Moreno, Fernando; Mottola, Stefano; Naletto, Giampiero; Oklay,
Nilda; Ortiz, José L.; Palomba, Ernesto; Palumbo, Pasquale; Perrin,
Jean-Marie; Rodríguez, Julio; Sabau, Lola; Snodgrass, Colin; Sordini,
Roberto; Thomas, Nicolas; Tubiana, Cecilia; Vincent, Jean-Baptiste;
Weissman, Paul; Wenzel, Klaus-Peter; Zakharov, Vladimir; Zarnecki,
John C.
2015Sci...347a3905R Altcode: 2015Sci...347.3905R
Critical measurements for understanding accretion and the dust/gas
ratio in the solar nebula, where planets were forming 4.5 billion
years ago, are being obtained by the GIADA (Grain Impact Analyser
and Dust Accumulator) experiment on the European Space Agency’s
Rosetta spacecraft orbiting comet 67P/Churyumov-Gerasimenko. Between
3.6 and 3.4 astronomical units inbound, GIADA and OSIRIS (Optical,
Spectroscopic, and Infrared Remote Imaging System) detected 35
outflowing grains of mass 10-10 to 10-7 kilograms,
and 48 grains of mass 10-5 to 10-2 kilograms,
respectively. Combined with gas data from the MIRO (Microwave Instrument
for the Rosetta Orbiter) and ROSINA (Rosetta Orbiter Spectrometer for
Ion and Neutral Analysis) instruments, we find a dust/gas mass ratio
of 4 ± 2 averaged over the sunlit nucleus surface. A cloud of larger
grains also encircles the nucleus in bound orbits from the previous
perihelion. The largest orbiting clumps are meter-sized, confirming
the dust/gas ratio of 3 inferred at perihelion from models of dust
comae and trails.

---------------------------------------------------------
Title: HIRES: the high resolution spectrograph for the E-ELT
Authors: Zerbi, F. M.; Bouchy, F.; Fynbo, J.; Maiolino, R.; Piskunov,
N.; Rebolo Lopez, R.; Santos, N.; Strassmeier, K.; Udry, S.; Vanzi,
L.; Riva, M.; Basden, A.; Boisse, I.; Bonfils, X.; Buscher, D.; Cabral,
A.; Dimarcantonio, P.; Di Varano, I.; Henry, D.; Monteiro, M.; Morris,
T.; Murray, G.; Oliva, Ernesto; Parry, I.; Pepe, F.; Quirrenbach, A.;
Rasilla, J. L.; Rees, P.; Stempels, E.; Valenziano, L.; Wells, M.;
Wildi, F.; Origlia, L.; Allende Prieto, C.; Chiavassa, A.; Cristiani,
S.; Figueira, P.; Gustafsson, B.; Hatzes, A.; Haehnelt, M.; Heng,
K.; Israelian, G.; Kochukhov, O.; Lovis, C.; Marconi, A.; Martins,
C. J. A. P.; Noterdaeme, P.; Petitjean, P.; Puzia, T.; Queloz, D.;
Reiners, A.; Zoccali, M.
2014SPIE.9147E..23Z Altcode:
The current instrumentation plan for the E-ELT foresees a High
Resolution Spectrograph conventionally indicated as HIRES. Shaped
on the study of extra-solar planet atmospheres, Pop-III stars and
fundamental physical constants, HIRES is intended to embed observing
modes at high-resolution (up to R=150000) and large spectral range
(from the blue limit to the K band) useful for a large suite of science
cases that can exclusively be tackled by the E-ELT. We present in
this paper the solution for HIRES envisaged by the "HIRES initiative",
the international collaboration established in 2013 to pursue a HIRES
on E-ELT.

---------------------------------------------------------
Title: Benchmark stars for cross-calibration of Galactic stellar
surveys
Authors: Heiter, U.; Jofré, P.; Gustafsson, B.; Thévenin, F.; Korn,
A.; Soubiran, C.; Blanco-Cuaresma, S.
2014EAS....67..375H Altcode:
Various Galactic stellar spectroscopic surveys are currently underway,
and each is expected to achieve high internal accuracy in terms of
stellar parameters and abundances. A number of questions related to
the formation and evolution of the Galaxy may be addressed based
on samples of stars observed within each survey. In addition,
complementary samples of stars may be constructed by combining
data from different surveys. The Gaia FGK Benchmark Stars provide
the necessary link to bring the quantities measured from different
spectra with different methods onto the same scale. We selected
28 FGK stars and 5 M giants with available angular diameter θ,
bolometric flux Fbol, and distance. We used the fundamental
relation Teff ∝ F/θ0.5 to determine a
reference effective temperature. We used the fundamental relation
g ∝ M/R2, where M is the mass and R the radius, to
determine a reference surface gravity. A homogeneous analysis of a
high resolution and high signal-to-noise spectral library provides a
reference metallicity (Blanco-Cuaresma et al. 2014A&amp;A...566A..98B,
Jofré et al. 2014A&amp;A...564A.133J). These stars serve as a reference
for testing and homogenizing large stellar surveys such as the Gaia
mission and the Gaia-ESO public spectroscopic survey and for improving
models of FGK-star atmospheres. A detailed discussion of the fundamental
Teff and logg values will be presented in Heiter et al. (to
be submitted).

---------------------------------------------------------
Title: Early Grain Detections in the Coma of Comet
67P/Churyumov-Gerasimenko
Authors: Rotundi, A.; Della Corte, V.; Fulle, M.; Accolla, M.;
Ferrari, M.; Ivanovski, S.; Lucarelli, F.; Sordini, R.; Zakharov, V.;
Mazzotta Epifani, E.; Lopez-Moreno, J. J.; Rodriguez, J.; Colangeli,
L.; Palumbo, P.; Crifo, J. C.; Bussoletti, E.; Esposito, F.; Green, S.;
Grün, E.; Lamy, P. L.; McDonnell, J. A. M.; Mennella, V.; Molina, A.;
Morales, R.; Moreno, F.; Ortiz, J. L.; Palomba, E.; Perrin, J. -M.;
Rietmeijer, F. J. M.; Rodrigo, R.; Weissman, P. R.; Zarnecki, J. C.;
Cosi, M.; Giovane, F.; Gustafson, B.; Herranz, M. L.; Jeronimo, J. M.;
Leese, M. R.; Lopez-Jimenez, A.; Altobelli, N.
2014EPSC....9..868R Altcode:
The GIADA (Grain Impact Analyser and Dust Accumulator) instrument aboard
the Rosetta spacecraft at comet 67P/Churyumov-Gerasimenko (67P/C-G)
measures dust grain number, mass, momentum and velocity [1,2]. GIADA
is composed of three sub-systems: the Grain Detection System (GDS),
detecting dust grains based on light scattering; an Impact Sensor
(IS), providing momentum measurements from the impact on a plate
connected to five piezoelectric sensors; and the MicroBalances System
(MBS), made up of five Quartz Crystal Microbalances (QCMs), to yield
cumulative deposited dust mass through the shift in resonance frequency.

---------------------------------------------------------
Title: Abundances and possible diffusion of elements in M 67 stars
Authors: Önehag, Anna; Gustafsson, Bengt; Korn, Andreas
2014A&A...562A.102O Altcode: 2013arXiv1310.6297O
Context. The rich open cluster M 67 is known to have a chemical
composition close to solar and an age of about 3.5-4.8 Gyr. It offers
an important opportunity to check and develop our understanding of
the physics and the evolution of solar-type stars. Aims: We
present a spectroscopic study at high resolution, R ≈ 50 000, of
14 stars located on the main sequence, at the turn-off point, and on
the early subgiant branch in the cluster in order to investigate its
detailed chemical composition, for comparison with the Sun and solar
twins in the solar neighbourhood, and to explore selective atomic
diffusion of chemical elements as predicted by stellar-structure
theory. Methods: We have obtained VLT/FLAMES-UVES spectra
and analysed these strictly differentially in order to explore
chemical-abundance similarities and differences between the M
67 stars and the Sun and among the M 67 stars themselves. 
Results: Individual abundances of 19 different chemical elements
are obtained for the stars. They are found to agree very well with
solar abundances, with abundance ratios closer to solar than those
of most solar twins in the solar neighbourhood. An exception is Li,
which shows considerable scatter among the cluster stars. There is a
tendency for the cluster-star abundances to be more depleted than the
abundances in the field stars in correlation with the condensation
temperature of the elements, a tendency also found earlier for the
Sun. Moreover, the heavy-element abundances are found to be reduced
in the hotter stars and dwarfs by typically ≤0.05 dex, as compared
to the abundances of the subgiants. Conclusions: The results
support the hypothesis that the gas of the proto-cluster was depleted
by formation and cleansing of dust before the stars formed. They
also add support to the proposal that the Sun was formed in a dense
stellar environment. Moreover, the observed minor reductions of
heavy elements, relative to our standard star M 67-1194 and the
subgiants, in the atmospheres of dwarfs and turn-off point stars
seem to suggest that diffusion processes are at work in these stars,
although the evidence is not compelling. Based on theoretical models,
the diffusion-corrected initial metallicity of M 67 is estimated to be
[Fe/H] = +0.06. Appendix A is available in electronic form at <A
href="http://www.aanda.org/10.1051/0004-6361/201322663/olm">http://www.aanda.org</A>

---------------------------------------------------------
Title: Model Stellar Spectral Libraries for Analysis of the SDSS-III
Apache Point Observatory Galactic Evolution Experiment (APOGEE)
Authors: Allende-Prieto, Carlos; Koesterke, L.; Shetrone, M. D.;
Zamora, O.; Ruffoni, M. P.; Smith, V. V.; Cunha, K. M.; Lawler,
J. E.; Pickering, J. C.; Nave, G.; Garcia Perez, A.; Bizyaev, D.;
Edvardsson, B.; Gustafsson, B.; Plez, B.; Castelli, F.; Majewski,
S. R.; Schiavon, R. P.; Meszaros, Sz.; de Vicente, A.
2014AAS...22344005A Altcode:
The Apache Point Observatory Galactic Evolution Experiment (APOGEE)
is obtaining high resolution ( 22,500), high signal-to-noise (&gt;
100) spectra in the 1510-1690 nm spectral region for 100,000 cool,
predominantly post-main sequence stars. To ascertain the stellar
atmospheric parameters and measure chemical abundances for the numerous
chemical elements with line transitions in this wavelength region, the
APOGEE Atmospheric Parameters and Chemical Abundances Pipeline (ASPCAP)
relies on an optimization algorithm that identifies the best-fitting
model for each of the observed APOGEE spectra. The fitting algorithm
speeds up the model evaluation by interpolation in pre-computed grids of
synthetic spectra that have been compressed using Principal Component
Analysis. Here we describe the main model grids used in ASPCAP for
the tenth data release of the Sloan Digital Sky Survey (SDSS DR10),
how they were calculated. We also provide a description of ongoing
and planned upgrades.

---------------------------------------------------------
Title: A Community Science Case for E-ELT HIRES
Authors: Maiolino, R.; Haehnelt, M.; Murphy, M. T.; Queloz, D.;
Origlia, L.; Alcala, J.; Alibert, Y.; Amado, P. J.; Allende Prieto, C.;
Ammler-von Eiff, M.; Asplund, M.; Barstow, M.; Becker, G.; Bonfils, X.;
Bouchy, F.; Bragaglia, A.; Burleigh, M. R.; Chiavassa, A.; Cimatti,
D. A.; Cirasuolo, M.; Cristiani, S.; D'Odorico, V.; Dravins, D.;
Emsellem, E.; Farihi, J.; Figueira, P.; Fynbo, J.; Gansicke, B. T.;
Gillon, M.; Gustafsson, B.; Hill, V.; Israelyan, G.; Korn, A.; Larsen,
S.; De Laverny, P.; Liske, J.; Lovis, C.; Marconi, A.; Martins, C.;
Molaro, P.; Nisini, B.; Oliva, E.; Petitjean, P.; Pettini, M.; Recio
Blanco, A.; Rebolo, R.; Reiners, A.; Rodriguez-Lopez, C.; Ryde, N.;
Santos, N. C.; Savaglio, S.; Snellen, I.; Strassmeier, K.; Tanvir, N.;
Testi, L.; Tolstoy, E.; Triaud, A.; Vanzi, L.; Viel, M.; Volonteri, M.
2013arXiv1310.3163M Altcode:
Building on the experience of the high-resolution community with the
suite of VLT high-resolution spectrographs, which has been tremendously
successful, we outline here the (science) case for a high-fidelity,
high-resolution spectrograph with wide wavelength coverage at the
E-ELT. Flagship science drivers include: the study of exo-planetary
atmospheres with the prospect of the detection of signatures of life
on rocky planets; the chemical composition of planetary debris on the
surface of white dwarfs; the spectroscopic study of protoplanetary and
proto-stellar disks; the extension of Galactic archaeology to the Local
Group and beyond; spectroscopic studies of the evolution of galaxies
with samples that, unlike now, are no longer restricted to strongly
star forming and/or very massive galaxies; the unraveling of the
complex roles of stellar and AGN feedback; the study of the chemical
signatures imprinted by population III stars on the IGM during the
epoch of reionization; the exciting possibility of paradigm-changing
contributions to fundamental physics. The requirements of these science
cases can be met by a stable instrument with a spectral resolution
of R~100,000 and broad, simultaneous spectral coverage extending
from 370nm to 2500nm. Most science cases do not require spatially
resolved information, and can be pursued in seeing-limited mode,
although some of them would benefit by the E-ELT diffraction limited
resolution. Some multiplexing would also be beneficial for some of
the science cases. (Abridged)

---------------------------------------------------------
Title: New ATLAS9 and MARCS Model Atmosphere Grids for the Apache
Point Observatory Galactic Evolution Experiment (APOGEE)
Authors: Mészáros, Sz.; Allende Prieto, C.; Edvardsson, B.; Castelli,
F.; García Pérez, A. E.; Gustafsson, B.; Majewski, S. R.; Plez,
B.; Schiavon, R.; Shetrone, M.; de Vicente, A.
2012AJ....144..120M Altcode: 2012arXiv1208.1916M
We present a new grid of model photospheres for the SDSS-III/APOGEE
survey of stellar populations of the Galaxy, calculated using the
ATLAS9 and MARCS codes. New opacity distribution functions were
generated to calculate ATLAS9 model photospheres. MARCS models were
calculated based on opacity sampling techniques. The metallicity
([M/H]) spans from -5 to 1.5 for ATLAS and -2.5 to 0.5 for MARCS
models. There are three main differences with respect to previous
ATLAS9 model grids: a new corrected H2O line list, a wide
range of carbon ([C/M]) and α element [α/M] variations, and solar
reference abundances from Asplund et al. The added range of varying
carbon and α-element abundances also extends the previously calculated
MARCS model grids. Altogether, 1980 chemical compositions were used for
the ATLAS9 grid and 175 for the MARCS grid. Over 808,000 ATLAS9 models
were computed spanning temperatures from 3500 K to 30,000 K and log g
from 0 to 5, where larger temperatures only have high gravities. The
MARCS models span from 3500 K to 5500 K, and log g from 0 to 5. All
model atmospheres are publicly available online.

---------------------------------------------------------
Title: Obituaries: Roger A Bell: 1935-2012
Authors: Gustafsson, Bengt
2012A&G....53e..38G Altcode:
Fellow of the RAS, stellar spectroscopist who pioneered the calculation
of synthetic spectra and their diverse applications.

---------------------------------------------------------
Title: M-dwarf metallicities. A high-resolution spectroscopic study
in the near infrared
Authors: Önehag, A.; Heiter, U.; Gustafsson, B.; Piskunov, N.; Plez,
B.; Reiners, A.
2012A&A...542A..33O Altcode: 2011arXiv1112.0141O
Context. The relatively wide spread in the derived metallicities
([Fe/H]) of M dwarfs shows that various approaches have not yet
converged to consistency. The presence of strong molecular features
and incomplete line lists for the corresponding molecules have made
determining the metallicity of M dwarfs difficult. Furthermore, the
faint M dwarfs require long exposure times for the signal-to-noise
ratio needed for a detailed spectroscopic abundance analysis. 
Aims: We present a high-resolution (R ~ 50 000) spectroscopic study
of a sample of eight single M dwarfs and three wide-binary systems
observed in the infrared J band. Methods: The absence of large
molecular contributions allows for a precise continuum placement. We
derived metallicities based on the best fit of synthetic spectra to
the observed spectra. To verify the accuracy of the applied atmospheric
models and test our synthetic spectrum approach, three binary systems
with a K-dwarf primary and an M-dwarf companion were observed and
analysed along with the single M dwarfs. Results: We obtain
good agreement between the metallicities derived for the primaries and
secondaries of our test binaries, thereby confirming the reliability
of our method of analysing M dwarfs. Our metallicities agree well
with some earlier determinations, and deviate from others. 
Conclusions: We conclude that spectroscopic abundance analysis in the J
band is a reliable method for establishing the metallicity scale for M
dwarfs. We recommend its application to a larger sample covering lower,
as well as higher, metallicities. Further prospects for the method
include abundance determinations for individual elements. Based
on data obtained at ESO-VLT, Paranal Observatory, Chile, Program ID
082.D-0838(A) and 084.D-1042(A).Table 2 is available in electronic form
at <A href="http://www.aanda.org">http://www.aanda.org</A>Electronic
version of the spectra is only available at CDS via
anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/542/A33">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/542/A33</A>

---------------------------------------------------------
Title: VizieR Online Data Catalog: 3 M dwarfs near-infrared spectra
(Onehag+, 2012)
Authors: Onehag, A.; Heiter, U.; Gustafsson, B.; Piskunov, N.; Plez,
B.; Reiners, A.
2012yCat..35420033O Altcode: 2012yCat..35429033O
The observations were carried out in service mode with the infrared
spectrometer CRIRES at ESO-VLT. In total 14 targets were observed
during periods 82 (1st of October 2008 to 31st of March 2009) and 84
(1st of October 2009 to 31st of March 2010). (4 data files).

---------------------------------------------------------
Title: The Gaia-ESO Public Spectroscopic Survey
Authors: Gilmore, G.; Randich, S.; Asplund, M.; Binney, J.; Bonifacio,
P.; Drew, J.; Feltzing, S.; Ferguson, A.; Jeffries, R.; Micela, G.;
Negueruela, I.; Prusti, T.; Rix, H. -W.; Vallenari, A.; Alfaro, E.;
Allende-Prieto, C.; Babusiaux, C.; Bensby, T.; Blomme, R.; Bragaglia,
A.; Flaccomio, E.; François, P.; Irwin, M.; Koposov, S.; Korn, A.;
Lanzafame, A.; Pancino, E.; Paunzen, E.; Recio-Blanco, A.; Sacco,
G.; Smiljanic, R.; Van Eck, S.; Walton, N.; Aden, D.; Aerts, C.;
Affer, L.; Alcala, J. -M.; Altavilla, G.; Alves, J.; Antoja, T.;
Arenou, F.; Argiroffi, C.; Asensio Ramos, A.; Bailer-Jones, C.;
Balaguer-Nunez, L.; Bayo, A.; Barbuy, B.; Barisevicius, G.; Barrado
y Navascues, D.; Battistini, C.; Bellas Velidis, I.; Bellazzini, M.;
Belokurov, V.; Bergemann, M.; Bertelli, G.; Biazzo, K.; Bienayme, O.;
Bland-Hawthorn, J.; Boeche, C.; Bonito, S.; Boudreault, S.; Bouvier,
J.; Brandao, I.; Brown, A.; de Bruijne, J.; Burleigh, M.; Caballero,
J.; Caffau, E.; Calura, F.; Capuzzo-Dolcetta, R.; Caramazza, M.;
Carraro, G.; Casagrande, L.; Casewell, S.; Chapman, S.; Chiappini,
C.; Chorniy, Y.; Christlieb, N.; Cignoni, M.; Cocozza, G.; Colless,
M.; Collet, R.; Collins, M.; Correnti, M.; Covino, E.; Crnojevic,
D.; Cropper, M.; Cunha, M.; Damiani, F.; David, M.; Delgado, A.;
Duffau, S.; Edvardsson, B.; Eldridge, J.; Enke, H.; Eriksson, K.;
Evans, N. W.; Eyer, L.; Famaey, B.; Fellhauer, M.; Ferreras, I.;
Figueras, F.; Fiorentino, G.; Flynn, C.; Folha, D.; Franciosini,
E.; Frasca, A.; Freeman, K.; Fremat, Y.; Friel, E.; Gaensicke, B.;
Gameiro, J.; Garzon, F.; Geier, S.; Geisler, D.; Gerhard, O.; Gibson,
B.; Gomboc, A.; Gomez, A.; Gonzalez-Fernandez, C.; Gonzalez Hernandez,
J.; Gosset, E.; Grebel, E.; Greimel, R.; Groenewegen, M.; Grundahl,
F.; Guarcello, M.; Gustafsson, B.; Hadrava, P.; Hatzidimitriou, D.;
Hambly, N.; Hammersley, P.; Hansen, C.; Haywood, M.; Heber, U.; Heiter,
U.; Held, E.; Helmi, A.; Hensler, G.; Herrero, A.; Hill, V.; Hodgkin,
S.; Huelamo, N.; Huxor, A.; Ibata, R.; Jackson, R.; de Jong, R.;
Jonker, P.; Jordan, S.; Jordi, C.; Jorissen, A.; Katz, D.; Kawata,
D.; Keller, S.; Kharchenko, N.; Klement, R.; Klutsch, A.; Knude,
J.; Koch, A.; Kochukhov, O.; Kontizas, M.; Koubsky, P.; Lallement,
R.; de Laverny, P.; van Leeuwen, F.; Lemasle, B.; Lewis, G.; Lind,
K.; Lindstrom, H. P. E.; Lobel, A.; Lopez Santiago, J.; Lucas, P.;
Ludwig, H.; Lueftinger, T.; Magrini, L.; Maiz Apellaniz, J.; Maldonado,
J.; Marconi, G.; Marino, A.; Martayan, C.; Martinez-Valpuesta, I.;
Matijevic, G.; McMahon, R.; Messina, S.; Meyer, M.; Miglio, A.;
Mikolaitis, S.; Minchev, I.; Minniti, D.; Moitinho, A.; Momany, Y.;
Monaco, L.; Montalto, M.; Monteiro, M. J.; Monier, R.; Montes, D.;
Mora, A.; Moraux, E.; Morel, T.; Mowlavi, N.; Mucciarelli, A.; Munari,
U.; Napiwotzki, R.; Nardetto, N.; Naylor, T.; Naze, Y.; Nelemans, G.;
Okamoto, S.; Ortolani, S.; Pace, G.; Palla, F.; Palous, J.; Parker, R.;
Penarrubia, J.; Pillitteri, I.; Piotto, G.; Posbic, H.; Prisinzano,
L.; Puzeras, E.; Quirrenbach, A.; Ragaini, S.; Read, J.; Read, M.;
Reyle, C.; De Ridder, J.; Robichon, N.; Robin, A.; Roeser, S.; Romano,
D.; Royer, F.; Ruchti, G.; Ruzicka, A.; Ryan, S.; Ryde, N.; Santos,
N.; Sanz Forcada, J.; Sarro Baro, L. M.; Sbordone, L.; Schilbach, E.;
Schmeja, S.; Schnurr, O.; Schoenrich, R.; Scholz, R. -D.; Seabroke, G.;
Sharma, S.; De Silva, G.; Smith, M.; Solano, E.; Sordo, R.; Soubiran,
C.; Sousa, S.; Spagna, A.; Steffen, M.; Steinmetz, M.; Stelzer, B.;
Stempels, E.; Tabernero, H.; Tautvaisiene, G.; Thevenin, F.; Torra,
J.; Tosi, M.; Tolstoy, E.; Turon, C.; Walker, M.; Wambsganss, J.;
Worley, C.; Venn, K.; Vink, J.; Wyse, R.; Zaggia, S.; Zeilinger, W.;
Zoccali, M.; Zorec, J.; Zucker, D.; Zwitter, T.; Gaia-ESO Survey Team
2012Msngr.147...25G Altcode:
The Gaia-ESO Public Spectroscopic Survey has begun and will obtain high
quality spectroscopy of some 100000 Milky Way stars, in the field and
in open clusters, down to magnitude 19, systematically covering all the
major components of the Milky Way. This survey will provide the first
homogeneous overview of the distributions of kinematics and chemical
element abundances in the Galaxy. The motivation, organisation and
implementation of the Gaia-ESO Survey are described, emphasising the
complementarity with the ESA Gaia mission. Spectra from the very first
observing run of the survey are presented.

---------------------------------------------------------
Title: Hypoxia in future climates: A model ensemble study for the
Baltic Sea
Authors: Meier, H. E. M.; Andersson, H. C.; Eilola, K.; Gustafsson,
B. G.; Kuznetsov, I.; Müller-Karulis, B.; Neumann, T.; Savchuk, O. P.
2011GeoRL..3824608M Altcode:
Using an ensemble of coupled physical-biogeochemical models driven
with regionalized data from global climate simulations we are able to
quantify the influence of changing climate upon oxygen conditions in
one of the numerous coastal seas (the Baltic Sea) that suffers worldwide
from eutrophication and from expanding hypoxic zones. Applying various
nutrient load scenarios we show that under the impact of warming climate
hypoxic and anoxic areas will very likely increase or at best only
slightly decrease (in case of optimistic nutrient load reductions)
compared to present conditions, regardless of the used global model
and climate scenario. The projected decreased oxygen concentrations
are caused by (1) enlarged nutrient loads due to increased runoff, (2)
reduced oxygen flux from the atmosphere to the ocean due to increased
temperature, and (3) intensified internal nutrient cycling. In future
climate a similar expansion of hypoxia as projected for the Baltic
Sea can be expected also for other coastal oceans worldwide.

---------------------------------------------------------
Title: A grid of S stars MARCS model atmospheres
Authors: Van Eck, Sophie; Neyskens, Pieter; Plez, Bertrand; Jorissen,
Alain; Edvardsson, Bengt; Eriksson, Kjell; Gustafsson, Bengt; Gråe
Jørgensen, Uffe; Nordlund, Åke
2011JPhCS.328a2009V Altcode:
S stars are cool stars of temperatures similar to those of M giants,
but their atmospheres are enriched in carbon and s-process elements
because of either extrinsic pollution by a binary companion or intrinsic
nucleosynthesis and dredge-up on the thermally-pulsing AGB. Despite
numerous attempts to link phenomenological spectral classification
criteria to physical parameters (Teff, gravity, C/O, [s/Fe],
[Fe/H]), the parameter space of S stars is poorly known and this has
prevented accurate abundance analysis of S stars until now. Here we
present a large grid of S-star model atmospheres. ZrO and TiO band
strength indices as well as VJHKL photometry are needed to disentangle
the effective temperature, C/O and [s/Fe]. The stellar parameters
derived on the basis of low-resolution spectra and photometry are
shown to be fairly accurate when compared to high-resolution data
of the same stars. The C/O ratio of S stars is found to be between
the solar value (0.5) and 0.99, and not 1 as often claimed in the
literature. Consistently with stellar evolution expectations, the C/O
ratio increases as the effective temperature decreases.

---------------------------------------------------------
Title: Analysis of old very metal rich stars in the solar
neighbourhood
Authors: Trevisan, M.; Barbuy, B.; Eriksson, K.; Gustafsson, B.;
Grenon, M.; Pompéia, L.
2011A&A...535A..42T Altcode: 2011arXiv1109.6304T
Context. A sample of mostly old metal-rich dwarf and turn-off stars with
high eccentricity and low maximum height above the Galactic plane has
been identified. From their kinematics, it was suggested that the inner
disk is their most probable birthplace. Their chemical imprints may
therefore reveal important information about the formation and evolution
of the still poorly understood inner disk. Aims: To probe the
formation history of these stellar populations, a detailed analysis
of a sample of very metal-rich stars is carried out. We derive the
metallicities, abundances of α elements, ages, and Galactic orbits. Methods: The analysis of 71 metal-rich stars is based on optical
high-resolution échelle spectra obtained with the FEROS spectrograph
at the ESO 1.52-m Telescope at La Silla, Chile. The metallicities
and abundances of C, O, Mg, Si, Ca, and Ti were derived based on LTE
detailed analysis, employing the MARCS model atmospheres. 
Results: We confirm the high metallicity of these stars reaching
up to [Fe i/H] = 0.58, and the sample of metal-rich dwarfs can be
kinematically subclassified in samples of thick disk, thin disk, and
intermediate stellar populations. All sample stars show solar α-Fe
ratios, and most of them are old and still quite metal rich. The orbits
suggest that the thin disk, thick disk and intermediate populations
were formed at Galactocentric distances of ~8 kpc, ~6 kpc, and ~7 kpc,
respectively. The mean maximum height of the thick disk subsample of
Zmax ~ 380 pc, is lower than for typical thick disk stars. A
comparison of α-element abundances of the sample stars with bulge stars
shows that the oxygen is compatible with a bulge or inner thick disk
origin. Our results suggest that models of radial mixing and dynamical
effects of the bar and bar/spiral arms might explain the presence
of these old metal-rich dwarf stars in the solar neighbourhood. Observations collected at the European Southern Observatory, La
Silla, Chile.Full Tables A.1 to A.4 are only available at the CDS
via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via <A
href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/535/A42">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/535/A42</A>

---------------------------------------------------------
Title: Is the solar spectrum latitude-dependent?. An investigation
with SST/TRIPPEL
Authors: Kiselman, D.; Pereira, T. M. D.; Gustafsson, B.; Asplund,
M.; Meléndez, J.; Langhans, K.
2011A&A...535A..14K Altcode: 2011arXiv1108.4527K
Context. In studies of the solar spectrum compared to spectra of solar
twin stars, it has been found that the chemical composition of the Sun
seems to depart systematically from those of the twins. One possible
explanation could be that the effect is caused by the special aspect
angle of the Sun when observed from Earth compared with the aspect
angles of the twins. This means that a latitude dependence of the
solar spectrum, even with the heliocentric angle constant, could
lead to the observed effects. Aims: We explore a possible
variation in the strength of certain spectral lines that are used
in the comparisons between the composition of the Sun and the twins
at loci on the solar disk with different latitudes but at constant
heliocentric angle. Methods: We use the TRIPPEL spectrograph at
the Swedish 1-m Solar Telescope on La Palma to record spectra in five
spectral regions to compare different locations on the solar disk at
a heliocentric angle of 45°. Equivalent widths and other parameters
are measured for fifteen different lines representing nine atomic
species. Spectra acquired at different times are used in averaging the
line parameters for each line and observing position. Results:
The relative variations in equivalent widths at the equator and at
solar latitude ~45° are found to be less than 1.5% for all spectral
lines studied. Translated into elemental abundances as they would be
measured from a terrestrial and a hypothetical pole-on observer, the
difference is estimated to be within 0.005 dex in all cases. 
Conclusions: It is very unlikely that latitude effects could cause the
reported abundance difference between the Sun and the solar twins. The
accuracy obtainable in measurements of small differences in spectral
line strengths between different solar disk positions is very high,
and can be exploited in studies of, e.g. weak magnetic fields or
effects of solar activity on atmospheric structure.

---------------------------------------------------------
Title: VizieR Online Data Catalog: Metal rich stars in solar
neighbourhood (Trevisan+, 2011)
Authors: Trevisan, M.; Barbuy, B.; Eriksson, K.; Gustafsson, B.;
Grenon, M.; Pompeia, L.
2011yCat..35350042T Altcode: 2011yCat..35359042T
Spectroscopic stellar parameters and abundances of C, O, Mg, Si, Ca, Ti
and Ni for 71 stars. U, V, W velocities and orbital parameters derived
using the GRINTON integrator (Carraro et al. 2002MNRAS.332..705C,
Bedin et al. 2006A&amp;A...460L..27B). Atomic data for Fe I, Fe II,
Si I, Ca I, and Ti I lines. (7 data files).

---------------------------------------------------------
Title: A Grid of MARCS Model Atmospheres for S Stars
Authors: van Eck, S.; Neyskens, P.; Plez, B.; Jorissen, A.; Edvardsson,
B.; Eriksson, K.; Gustafsson, B.; Jørgensen, U. G.; Nordlund, Å.
2011ASPC..445...71V Altcode: 2010arXiv1011.2092V
S-type stars are late-type giants whose atmospheres are enriched in
carbon and s-process elements because of either extrinsic pollution by
a binary companion or intrinsic nucleosynthesis and dredge-up on the
thermally-pulsing AGB. A large grid of S-star model atmospheres has
been computed covering the range 2700 ≤ Teff(K) ≤ 4000
with 0.5 ≤ C/O ≤ 0.99. ZrO and TiO band strength indices as well
as VJHKL photometry are needed to disentangle Teff, C/O and
[s/Fe]. A “best-model finding tool” has been developed using a set
of well-chosen indices and checked against photometry as well as low-
and high-resolution spectroscopy. It is found that applying M-star
model atmospheres (i.e., with a solar C/O ratio) to S stars can lead
to errors in Teff up to 400 K. We constrain the parameter
space occupied by the S stars of the vast Henize sample in terms of
Teff, [C/O] and [s/Fe].

---------------------------------------------------------
Title: Detached Shells of Dust and Gas around Carbon Stars
Authors: Maercker, M.; Olofsson, H.; Eriksson, K.; Gustafsson, B.;
Schöier, F. L.
2011ASPC..445..345M Altcode:
We present observations of dust-scattered light of the carbon stars
U Ant, R Scl, and U Cam taken with the EFOSC2 camera on the ESO 3.6-m
telescope and the ACS on the Hubble Space Telescope. The observations
show the detached shells around these stars in unprecedented detail,
revealing a distinctively clumpy structure in the HST images of R Scl,
and a separation of the dust and gas in the ground-based data for
U Ant. This allows us to investigate the detached shells and their
origin with exceptional precision.

---------------------------------------------------------
Title: Sulphur abundances in halo giants from the [S I] line at 1082
nm and the [S I] triplet around 1045 nm
Authors: Jönsson, H.; Ryde, N.; Nissen, P. E.; Collet, R.; Eriksson,
K.; Asplund, M.; Gustafsson, B.
2011A&A...530A.144J Altcode: 2011arXiv1104.2148J
Context. It is still debated whether or not the Galactic chemical
evolution of sulphur in the halo follows the flat trend with [Fe/H]
that is ascribed to the result of explosive nucleosynthesis in type
II SNe. It has been suggested that the disagreement between different
investigations of sulphur abundances in halo stars might be owing
to problems with the diagnostics used, that a new production source
of sulphur might be needed in the early Universe, like hypernovae, or
that the deposition of supernova ejecta into the interstellar medium is
time-delayed. Aims: The aim of this study is to try to clarify
this situation by measuring the sulphur abundance in a sample of halo
giants using two diagnostics: the S i triplet around 1045 nm and the
[S i] line at 1082 nm. The latter of the two is not believed to be
sensitive to non-LTE effects. We can thereby minimize the uncertainties
in the diagnostic used and estimate the usefulness of the triplet for
the sulphur determination in halo K giants. We will also be able to
compare our sulphur abundance differences from the two diagnostics
with the expected non-LTE effects in the 1045 nm triplet previously
calculated by others. Methods: High-resolution near-infrared
spectra of ten K giants were recorded using the spectrometer CRIRES
mounted at VLT. Two standard settings were used, one covering the S i
triplet and one covering the [S i] line. The sulphur abundances were
individually determined with equivalent widths and synthetic spectra
for the two diagnostics using tailored 1D model atmospheres and relying
on non-LTE corrections from the litterature. Effects of convective
inhomogeneities in the stellar atmospheres are investigated. 
Results: The sulphur abundances derived from both the [S i] line and the
non-LTE corrected 1045 nm triplet favor a flat trend for the evolution
of sulphur. In contrast to some previous studies, we saw no "high"
values of [S/Fe] in our sample. Conclusions: We corroborate
the flat trend in the [S/Fe] vs. [Fe/H] plot for halo stars found in
some previous studies but do not find a scatter or a rise in [S/Fe]
as obtained in other works. We find the sulphur abundances deduced
from the non-LTE corrected triplet to be somewhat lower than the
abundances from the [S i] line, possibly indicating too large non-LTE
corrections. Considering 3D modeling, however, they might instead
be too small. Moreover, we show that the [S i] line can be used as
a sulphur diagnostic down to [Fe/H] ~ -2.3 in giants. Based on
observations collected at the European Southern Observatory, Chile
(ESO program 080.D-0675(A)).

---------------------------------------------------------
Title: M67-1194, an unusually Sun-like solar twin in M67
Authors: Önehag, A.; Korn, A.; Gustafsson, B.; Stempels, E.;
Vandenberg, D. A.
2011A&A...528A..85O Altcode: 2010arXiv1009.4579O
Context. The rich open cluster M67 is known to have a chemical
composition close to solar, and an age around 4 Gyr. It thus offers
the opportunity to check our understanding of the physics and the
evolution of solar-type stars in a cluster environment. Aims:
We present the first spectroscopic study at high resolution, R ≈
50 000, of the potentially best solar twin, M67-1194, identified
among solar-like stars in M67. Methods: G dwarfs in M67 (d
≈ 900 pc) are relatively faint (V ≈ 15), which makes detailed
spectroscopic studies time-consuming. Based on a pre-selection of
solar-twin candidates performed at medium resolution by Pasquini et
al. (2008, A&amp;A, 489, 677), we explore the chemical-abundance
similarities and differences between M67-1194 and the Sun, using
VLT/FLAMES-UVES. Working with a solar twin in the framework of a
differential analysis, we minimize systematic model errors in the
abundance analysis compared to previous studies which utilized more
evolved stars to determine the metallicity of M67. The differential
approach yields precise and accurate chemical abundances for M67, which
enhances the possibility to use this object in studies of the potential
peculiarity, or normality, of the Sun. Results: We find M67-1194
to have stellar parameters indistinguishable from the solar values, with
the exception of the overall metallicity which is slightly super-solar
([Fe/H] = 0.023 ± 0.015). An age determination based on evolutionary
tracks yields 4.2 ± 1.6 Gyr. Most surprisingly, we find the chemical
abundance pattern to closely resemble the solar one, in contrast to
most known solar twins in the solar neighbourhood. Conclusions:
We confirm the solar-twin nature of M67-1194, the first solar twin
known to belong to a stellar association. This fact allows us to put
some constraints on the physical reasons for the seemingly systematic
departure of M67-1194 and the Sun from most known solar twins regarding
chemical composition. We find that radiative dust cleansing by nearby
luminous stars may be the explanation for the peculiar composition
of both the Sun and M67-1194, but alternative explanations are also
possible. The chemical similarity between the Sun and M67-1194 also
suggests that the Sun once formed in a cluster like M67. Based
on data obtained at ESO-VLT, Paranal Observatory, Chile, Program ID
082.D-0726(A).Appendix A is only available in electronic form at <A
href="http://www.aanda.org">http://www.aanda.org</A>

---------------------------------------------------------
Title: Astrophysics: Unexpected warm water
Authors: Gustafsson, Bengt
2010Natur.467...35G Altcode:
The detection of water vapour in a carbon star has challenged the
understanding of ageing stars. The discovery that such water can be
warm shows that our knowledge of these objects is still rudimentary.

---------------------------------------------------------
Title: The solar, exoplanet and cosmological lithium problems
Authors: Meléndez, J.; Ramírez, I.; Casagrande, L.; Asplund, M.;
Gustafsson, B.; Yong, D.; Do Nascimento, J. D.; Castro, M.; Bazot, M.
2010Ap&SS.328..193M Altcode: 2009Ap&SS.tmp..221M; 2009arXiv0910.5845M
We review three Li problems. First, the Li problem in the Sun, for which
some previous studies have argued that it may be Li-poor compared to
other Suns. Second, we discuss the Li problem in planet hosting stars,
which are claimed to be Li-poor when compared to field stars. Third,
we discuss the cosmological Li problem, i.e. the discrepancy between
the Li abundance in metal-poor stars (Spite plateau stars) and the
predictions from standard Big Bang Nucleosynthesis. In all three cases
we find that the “problems” are naturally explained by non-standard
mixing in stars.

---------------------------------------------------------
Title: SIMPLE: a high-resolution near-infrared spectrometer for
the E-ELT
Authors: Origlia, Livia; Oliva, Ernesto; Maiolino, Roberto; Gustafsson,
Bengt; Piskunov, Nikolai; Kochucov, Oleg; Vanzi, Leonardo; Minniti,
Dante; Zoccali, Manuela; Hatzes, Artie; Guenther, Eike
2010SPIE.7735E..2BO Altcode: 2010SPIE.7735E..78O
SIMPLE is an optimized near IR echelle spectrograph for the E-ELT
assisted by adaptive optics. It delivers a complete 0.84-2.5μm spectrum
in one exposure with resolution up to R=130,000, nearly diffraction
limited pixel scale and limiting magnitudes down to JHK~20. Its most
prominent science cases include the study of the intergalactic medium
in the early Universe (z&gt;6) and of the atmospheres of exo-planet
transiting nearby low mass stars.

---------------------------------------------------------
Title: The chemical composition of solar-type stars in comparison
with that of the Sun
Authors: Gustafsson, Bengt; Meléndez, Jorge; Asplund, Martin;
Yong, David
2010Ap&SS.328..185G Altcode: 2010Ap&SS.tmp...36G
The question whether the solar chemical composition is typical for
solar-type stars is analysed by comparing the Sun with different stellar
samples, including a sample of stars with very similar parameters,
solar twins. Although typical in terms of overall metallicity for
stars of solar age and galactic orbit, the solar atmosphere is found to
have abundances, as compared with solar twins, that indicate that its
gas has once been affected by dust formation and dust separation. It
is concluded that this may be related to the formation of the solar
planetary system and its special properties.

---------------------------------------------------------
Title: Ulysses Dust Detection System V3.1
Authors: Gruen, E.; Krueger, H.; Landgraf, M.; Altobelli, N.; Anweiler,
B.; Baguhl, M.; Dermott, S. F.; Dikarev, V.; Divine, N.; Fechtig,
H.; Graps, A. L.; Gustafson, B. A.; Hamilton, D. P.; Hanner, M. S.;
Horanyi, M.; Kissel, J.; Lindblad, B. -A.; Linkert, D.; Linkert, G.;
Mann, I.; McDonnell, J. A. M.; Morfill, G. E.; Polanskey, C.; Riemann,
R.; Schwehm, G.; Siddique, N.; Srama, R.; Staubach, P.; Zook, H. A.
2010PDSS..140.....G Altcode:
This data set contains the data from the Ulysses dust detector system
(UDDS) from start of mission through the end of mission, 1990-2007. (As
the dust detector was turned off after Nov. 30, 2007, this is the
last date for which UDDS data is recorded.) Included are the dust
impact data, noise data, laboratory calibration data, and location
and orientation of the spacecraft and instrument.

---------------------------------------------------------
Title: Three years of Ulysses dust data: 2005 to 2007
Authors: Krüger, H.; Dikarev, V.; Anweiler, B.; Dermott, S. F.;
Graps, A. L.; Grün, E.; Gustafson, B. A.; Hamilton, D. P.; Hanner,
M. S.; Horányi, M.; Kissel, J.; Linkert, D.; Linkert, G.; Mann,
I.; McDonnell, J. A. M.; Morfill, G. E.; Polanskey, C.; Schwehm, G.;
Srama, R.
2010P&SS...58..951K Altcode: 2009arXiv0908.1279K
The Ulysses spacecraft has been orbiting the Sun on a highly inclined
ellipse ( i=79∘, perihelion distance 1.3 AU, aphelion
distance 5.4 AU) since it encountered Jupiter in February 1992. Since
then it has made almost three revolutions about the Sun. Here we
report on the final three years of data taken by the on-board dust
detector. During this time, the dust detector recorded 609 dust impacts
of particles with masses 10-16g⩽m⩽10-7g,
bringing the mission total to 6719 dust data sets. The impact rate
varied from a low value of 0.3 per day at high ecliptic latitudes to
1.5 per day in the inner solar system. The impact direction of the
majority of impacts between 2005 and 2007 is compatible with particles
of interstellar origin; the rest are most likely interplanetary
particles. We compare the interstellar dust measurements from
2005/2006 with the data obtained during earlier periods (1993/1994)
and (1999/2000) when Ulysses was traversing the same spatial region
at southern ecliptic latitudes but the solar cycle was at a different
phase. During these three intervals the impact rate of interstellar
grains varied by more than a factor of two. Furthermore, in the two
earlier periods the grain impact direction was in agreement with the
flow direction of the interstellar helium while in 2005/2006 we observed
a shift in the approach direction of the grains by approximately
30∘ away from the ecliptic plane. The reason for this
shift remains unclear but may be connected with the configuration of
the interplanetary magnetic field during solar maximum. We also find
that the dust measurements are in agreement with the interplanetary
flux model of Staubach et al. (1997) which was developed to fit a
5-year span of Ulysses data.

---------------------------------------------------------
Title: Galileo dust data from the jovian system: 2000 to 2003
Authors: Krüger, H.; Bindschadler, D.; Dermott, S. F.; Graps, A. L.;
Grün, E.; Gustafson, B. A.; Hamilton, D. P.; Hanner, M. S.; Horányi,
M.; Kissel, J.; Linkert, D.; Linkert, G.; Mann, I.; McDonnell,
J. A. M.; Moissl, R.; Morfill, G. E.; Polanskey, C.; Roy, M.; Schwehm,
G.; Srama, R.
2010P&SS...58..965K Altcode: 2009arXiv0908.1051K
The Galileo spacecraft was the first man-made satellite of Jupiter,
orbiting the planet between December 1995 and September 2003. The
spacecraft was equipped with a highly sensitive dust detector that
monitored the jovian dust environment between approximately 2 and 370
RJ (jovian radius RJ=71 492 km). The Galileo
dust detector was a twin of the one flying on board the Ulysses
spacecraft. This is the tenth in a series of papers dedicated to
presenting Galileo and Ulysses dust data. Here we present data from
the Galileo dust instrument for the period January 2000 to September
2003 until Galileo was destroyed in a planned impact with Jupiter. The
previous Galileo dust data set contains data of 2883 particles detected
during Galileo's interplanetary cruise and 12 978 particles detected
in the jovian system between 1996 and 1999. In this paper we report
on the data of additional 5389 particles measured between 2000 and
the end of the mission in 2003. The majority of the 21 250 particles
for which the full set of measured impact parameters (impact time,
impact direction, charge rise times, charge amplitudes, etc.) was
transmitted to Earth were tiny grains (about 10 nm in radius), most of
them originating from Jupiter's innermost Galilean moon Io. They were
detected throughout the jovian system and the impact rates frequently
exceeded 10 min -1. Surprisingly large impact rates up to 100
min -1 occurred in August/September 2000 when Galileo was far
away (≈280RJ) from Jupiter, implying dust ejection rates in
excess of 100 kg s -1. This peak in dust emission appears to
coincide with strong changes in the release of neutral gas from the Io
torus. Strong variability in the Io dust flux was measured on timescales
of days to weeks, indicating large variations in the dust release
from Io or the Io torus or both on such short timescales. Galileo has
detected a large number of bigger micron-sized particles mostly in the
region between the Galilean moons. A surprisingly large number of such
bigger grains was measured in March 2003 within a four-day interval
when Galileo was outside Jupiter's magnetosphere at approximately
350 RJ jovicentric distance. Two passages of Jupiter's
gossamer rings in 2002 and 2003 provided the first actual comparison
of in-situ dust data from a planetary ring with the results inferred
from inverting optical images. Strong electronics degradation of the
dust instrument due to the harsh radiation environment of Jupiter led
to increased calibration uncertainties of the dust data.

---------------------------------------------------------
Title: Galileo Dust Detection System V4.1
Authors: Krueger, H.; Gruen, E.; Baguhl, M.; Bindschadler, D.; Dermott,
S.; Divine, N.; Fechtig, H.; Graps, A.; Gustafson, B.; Hamilton, D.;
Hanner, M.; Horanyi, M.; Kissel, J.; Lindblad, B. -A.; Linkert, D.;
Linkert, G.; McDonnell, J. A. M.; Mann, I.; Moissl, R.; Morfill, G.;
Polanskey, C.; Schwehm, G.; Riemann, R.; Siddique, N.; Srama, R.;
Staubach, P.; Zook, H.
2010PDSS..139.....K Altcode:
This data set contains the data from the Galileo dust detector system
(GDDS) from start of mission through the end of mission. Included
are the dust impact data, noise data, laboratory calibration data,
and location and orientation of the spacecraft and instrument.

---------------------------------------------------------
Title: High-resolution HST/ACS images of detached shells around
carbon stars
Authors: Olofsson, H.; Maercker, M.; Eriksson, K.; Gustafsson, B.;
Schöier, F.
2010A&A...515A..27O Altcode: 2010arXiv1003.0362O
Context. Overall spherically symmetric, geometrically thin gas and dust
shells have been found around a handful of asymptotic giant branch (AGB)
carbon stars. Their dynamical ages lie in the range of 103
to 104 years. A tentative explanation for their existence is
that they have formed as a consequence of mass-loss-rate modulations
during a He-shell flash. Aims: The detached shells carry
information on their formation process, as well as on the small-scale
structure of the circumstellar medium around AGB stars due to the
absence of significant line-of-sight confusion. Methods: The
youngest detached shells, those around the carbon stars R Scl and U
Cam, are studied here in great detail in scattered stellar light with
the Advanced Survey Camera on the Hubble Space Telescope. Quantitative
results are derived assuming optically thin dust scattering. 
Results: The detached dust shells around R Scl and U Cam are found to
be consistent with an overall spherical symmetry. They have radii of
19.2 arcsec (corresponding to a linear size of 8 × 1016
cm) and 7.7 arcsec (5 × 1016 cm), widths of 1.2 arcsec
(5 × 1015 cm) and 0.6 arcsec (4 × 1015 cm),
and dust masses of 3 × 10-6 and 3 × 10-7 M_⊙,
respectively. The dynamical ages of the R Scl and U Cam shells are
estimated to be 1700 and 700 yr, respectively, and the shell widths
correspond to time scales of 100 and 50 yr, respectively. Small-scale
structure in the form of less than arcsec-sized clumps is clearly
seen in the images of the R Scl shell. Average clump dust masses are
estimated to be about 2 × 10-9 M_⊙. Comparisons with CO
line interferometer data show that the dust and gas shells coincide
spatially, within the errors (≤1´´ for U Cam and ≈2´´ for
R Scl). Conclusions: The results are consistent with the
interpretation of geometrically thin gas and dust shells formed by
a mass-loss eruption during a He-shell flash, and where interaction
with a previous wind plays a role as well. The mass loss responsible
for the shells must have been remarkably isotropic, and, if wind
interaction plays a role, this also applies to the mass loss prior
to the eruption. Clumpy structure is present in the R Scl shell,
possibly as a consequence of the mass loss itself, but more likely
as a consequence of instabilities in the expanding shell. Based
on observations with the NASA/ESA Hubble Space Telescope, obtained at
the Space Telescope Science Insitute, which is operated by the AURA,
Inc., under NASA contract NAS5-26555.

---------------------------------------------------------
Title: Division III: Planetary Systems Science
Authors: Bowell, Edward L. G.; Meech, Karen J.; Williams, Iwan P.;
Boss, Alan; Courtin, Régis; Gustafson, Bo Å. S.; Levasseur-Regourd,
Anny-Chantal; Mayor, Michel; Spurný, Pavel; Watanabe, Jun-ichi;
Consolmagno, Guy J.; Fernández, Julio A.; Huebner, Walter F.; Marov,
Mikhail Ya.; Schulz, Rita M.; Valsecchi, Giovanni B.; Witt, Adolf N.
2010IAUTB..27..158B Altcode:
The meeting was opened by Ted Bowell, president, at 11 am. The 2006
Division III meetings were reviewed by Guy Consolmagno, secretary;
as the minutes of those meetings have already been published, they
were assumed to be approved.

---------------------------------------------------------
Title: Commission 36: Theory of Stellar Atmospheres
Authors: Asplund, Martin; Puls, Joachim; Landstreet, John; Allende
Prieto, Carlos; Ayres, Thomas; Berdyugina, Svetlana; Gustafsson,
Bengt; Hubeny, Ivan; Ludwig, Hans Günter; Mashonkina, Lyudmila;
Randich, Sofia
2010IAUTB..27..197A Altcode:
The members of the Commission 36 Organizing Committee attending the IAU
General Assembly in Rio de Janeiro met for a business session on August
7. Both members from the previous (2006-2009) and the new (2009-2012)
Organizing Committee partook in the discussions. Past president John
Landstreet described the work he had done over the past three years
in terms of supporting proposed conferences on the topic. He has
also spent significant amount of time establishing an updated mailing
list of all &gt;350 members of the commission, which is unfortunately
not provided automatically by the IAU. Such a list is critical for a
rapid dissemination of information to the commission members and for
a correct and smooth running of elections of IAU officials. Everyone
present thanked John effusively for all of his hard work over the past
three years to stimulate a high level of activity within the discipline.

---------------------------------------------------------
Title: Lithium abundances in Bulge-like SMR stars
Authors: Barbuy, Beatriz; Trevisan, M.; Gustafsson, B.; Eriksson,
K.; Grenon, M.; Pompéia, L.
2010IAUS..268..325B Altcode:
We analyze a sample of 21 super-metal-rich (SMR) stars, using
high-resolution échelle spectra obtained with the FEROS Spectrograph
at the 1.5m ESO telescope. The metallicities are in the range 0.15 &lt;
[Fe/H] &lt; 0.5, 3 of them in common with Pompéia et al. (2002). Geneva
photometry, astrometric data from Hipparcos, and radial velocities
from CORAVEL are available for these stars. The peculiar kinematics
suggests the thin disk close to the bulge as the probable birthplace
of these stars (Grenon 1999). From Hipparcos data, it appears that
the turnoff of this population indicates an age of 10-11 Gyr (Grenon
1999). Detailed analysis of the sample stars is carried out. Lithium
abundances of these stars were derived, and their behaviour with
effective temperature is shown.

---------------------------------------------------------
Title: FEROS Abundance Analysis of 21 Bulgelike SMR Stars
Authors: Trevisan, Marina; Barbuy, Beatriz; Grenon, M.; Gustafsson,
B.; Pompéia, L.
2010IAUS..265..382T Altcode:
We analyze a sample of 21 super-metal-rich (SMR) stars, using
high-resolution échelle spectra obtained with the Fiber-fed Extended
Range Optical Spectrograph at the 1.5m ESO telescope. The metallicities
are in the range 0.07 ≤ [Fe/H] ≤ 0.45, 3 of them in common with
Pompéia et al. (2009). Geneva photometry, astrometric data from
Hipparcos, and radial velocities from CORAVEL are available for these
stars. The peculiar kinematics suggests the thin disk close to the bulge
as the probable birthplace of these stars (Grenon 1999). From Hipparcos
data, it appears that the turnoff of this population indicates an age
of 10-11 Gyr (Grenon 1999). Detailed analysis of the sample stars is
carried out, and atmospheric parameters are derived from spectroscopic
and photometric determinations. Oxygen abundances of these stars are
derived, and [O/Fe] overabundances up to +0.35 are found.

---------------------------------------------------------
Title: Are “realistic” model atmospheres realistic enough?
Authors: Gustafsson, Bengt
2010IAUS..265..187G Altcode:
During the latest decades the number of papers on stellar chemical
abundances has increased dramatically. This is basically reflecting the
very great achievements in telescope- and spectrometer-construction
technology. The analysis of the resulting stellar spectra, however,
is still not up to the standard that is offered by the observational
methods. Recent significant advances in the analysis methods (i.e.,
in constructing model atmospheres and model spectra to compare with
the observed ones) is reviewed with the emphasis on the application
to abundance analysis of late-type stars. It is found that the
very considerable progress that have been made beyond mixing-length
convection and LTE is a major break-through for physically consistent
modeling. Still, however, further steps must be taken, in particular
for the cooler stars, before the situation is fully satisifactory.

---------------------------------------------------------
Title: Unprecedented accurate abundances: signatures of other Earths?
Authors: Meléndez, Jorge; Asplund, Martin; Gustafsson, Bengt; Yong,
David; Ramírez, Iván
2010IAUS..265..412M Altcode: 2009arXiv0910.0875M
For more than 140 years the chemical composition of our Sun has
been considered typical of solar-type stars. Our highly differential
elemental abundance analysis of unprecedented accuracy (~0.01 dex)
of the Sun relative to solar twins, shows that the Sun has a peculiar
chemical composition with a ≈20% depletion of refractory elements
relative to the volatile elements in comparison with solar twins. The
abundance differences correlate strongly with the condensation
temperatures of the elements. A similar study of solar analogs from
planet surveys shows that this peculiarity also holds in comparisons
with solar analogs known to have close-in giant planets while the
majority of solar analogs without detected giant planets show the solar
abundance pattern. The peculiarities in the solar chemical composition
can be explained as signatures of the formation of terrestrial planets
like our own Earth.

---------------------------------------------------------
Title: The detached dust and gas shells around the carbon star
U Antliae
Authors: Maercker, M.; Olofsson, H.; Eriksson, K.; Gustafsson, B.;
Schöier, F. L.
2010A&A...511A..37M Altcode: 2009arXiv0912.2673M
Context. Geometrically thin, detached shells of gas have been found
around a handful of carbon stars. The current knowledge on these shells
is mostly based on CO radio line data. However, imaging in scattered
stellar light adds important new information as well as allows studies
of the dust shells. Aims: Previous observations of scattered
stellar light in the circumstellar medium around the carbon star U
Ant were taken through filters centred on the resonance lines of K
and Na. These observations could not separate the scattering by dust
and atoms. The aim of this paper is to remedy this situation. 
Methods: We have obtained polarization data on stellar light scattered
in the circumstellar medium around U Ant through filters which contain
no strong lines, making it possible to differentiate between the two
scattering agents. Kinematic, as well as spatial, information on the
gas shells were obtained through high-resolution echelle spectrograph
observations of the KI and NaD lines. Results: We confirm the
existence of two detached shells around U Ant. The inner shell (at a
radius of ≈43´´ and a width of ≈2´´) consists mainly of gas,
while the outer shell (at a radius of ≈50´´ and a width of ≈7´´)
appears to consist exclusively of dust. Both shells appear to have
an over-all spherical geometry. The gas shell mass is estimated to
be 2 × 10-3~M⊙, while the mass of the dust
shell is estimated to be 5 × 10-5~M⊙. The
derived expansion velocity, from the KI and NaD lines, of the gas
shell, 19.5 km s-1, agrees with that obtained from CO radio
line data. The inferred shell age is 2700 years. There is structure,
e.g. in the form of arcs, inside the gas shell, but it is not clear
whether these are due to additional shells. Conclusions: Our
results support the hypothesis that the observed geometrically thin,
detached shells around carbon stars are the results of brief periods
of intense mass loss, probably associated with thermal pulses, and
subsequent wind-wind interactions. The separation into a gas and a dust
shell, with different widths, is most likely the effect of different
dynamical evolutions of the two media after their ejection.

---------------------------------------------------------
Title: Phosphorus recycling and burial in Baltic Sea sediments with
contrasting redox conditions
Authors: Mort, Haydon P.; Slomp, Caroline P.; Gustafsson, Bo G.;
Andersen, Thorbjørn J.
2010GeCoA..74.1350M Altcode:
In this study, redox-dependent phosphorus (P) recycling and burial at 6
sites in the Baltic Sea is investigated using a combination of porewater
and sediment analyses and sediment age dating ( 210Pb and
137Cs). We focus on sites in the Kattegat, Danish Straits
and Baltic Proper where present-day bottom water redox conditions range
from fully oxygenated and seasonally hypoxic to almost permanently
anoxic and sulfidic. Strong surface enrichments of Fe-oxide bound P
are observed at oxic and seasonally hypoxic sites but not in the anoxic
basins. Reductive dissolution of Fe-oxides and release of the associated
P supports higher sediment-water exchange of PO 4 at hypoxic
sites (up to ∼800 μmol P m -2 d -1) than in
the anoxic basins. This confirms that Fe-bound P in surface sediments
in the Baltic acts as a major internal source of P during seasonal
hypoxia, as suggested previously from water column studies. Most burial
of P takes place as organic P. We find no evidence for significant
authigenic Ca-P formation or biogenic Ca-P burial. The lack of major
inorganic P burial sinks makes the Baltic Sea very sensitive to the
feedback loop between increased hypoxia, enhanced regeneration of P
and increased primary productivity. Historical records of bottom water
oxygen at two sites (Bornholm, Northern Gotland) show a decline over
the past century and are accompanied by a rise in values for typical
sediment proxies for anoxia (total sulfur, molybdenum and organic C/P
ratios). While sediment reactive P concentrations in anoxic basins are
equal to or higher than at oxic sites, burial rates of P at hypoxic and
anoxic sites are up to 20 times lower because of lower sedimentation
rates. Nevertheless, burial of reactive P in both hypoxic and anoxic
areas is significant because of their large surface area and should
be accounted for in budgets and models for the Baltic Sea.

---------------------------------------------------------
Title: Chemical abundances of 11 bulge stars from high-resolution,
near-IR spectra
Authors: Ryde, N.; Gustafsson, B.; Edvardsson, B.; Meléndez, J.;
Alves-Brito, A.; Asplund, M.; Barbuy, B.; Hill, V.; Käufl, H. U.;
Minniti, D.; Ortolani, S.; Renzini, A.; Zoccali, M.
2010A&A...509A..20R Altcode: 2009arXiv0910.0448R
Context. It is debated whether the Milky Way bulge has characteristics
more similar to those of a classical bulge than those of a
pseudobulge. Detailed abundance studies of bulge stars are important
when investigating the origin, history, and classification of the
bulge. These studies provide constraints on the star-formation
history, initial mass function, and differences between stellar
populations. Not many similar studies have been completed because
of the large distance and high variable visual extinction along the
line-of-sight towards the bulge. Therefore, near-IR investigations
can provide superior results. Aims: To investigate the origin
of the bulge and study its chemical abundances determined from
near-IR spectra for bulge giants that have already been investigated
with optical spectra. The optical spectra also provide the stellar
parameters that are very important to the present study. In particular,
the important CNO elements are determined more accurately in the
near-IR. Oxygen and other α elements are important for investigating
the star-formation history. The C and N abundances are important for
determining the evolutionary stage of the giants and the origin of C
in the bulge. Methods: High-resolution, near-infrared spectra
in the H band were recorded using the CRIRES spectrometer mounted on
the Very Large Telescope. The CNO abundances are determined from the
numerous molecular lines in the wavelength range observed. Abundances
of the α elements Si, S, and Ti are also determined from the near-IR
spectra. Results: The abundance ratios [O/Fe], [Si/Fe], and
[S/Fe] are enhanced to metallicities of at least [Fe/H] = -0.3, after
which they decline. This suggests that the Milky Way bulge experienced a
rapid and early burst of star formation similar to that of a classical
bulge. However, a similarity between the bulge trend and the trend of
the local thick disk seems to be present. This similarity suggests that
the bulge could have had a pseudobulge origin. The C and N abundances
suggest that our giants are first-ascent red-giants or clump stars,
and that the measured oxygen abundances are those with which the
stars were born. Our [C/Fe] trend does not show any increase with
[Fe/H], which is expected if W-R stars contributed substantially to
the C abundances. No “cosmic scatter” can be traced around our
observed abundance trends: the measured scatter is expected, given the
observational uncertainties. Based on observations collected at
the European Southern Observatory, Chile (ESO program 079.B-0338(A)).

---------------------------------------------------------
Title: The Peculiar Solar Composition and Its Possible Relation to
Planet Formation
Authors: Meléndez, J.; Asplund, M.; Gustafsson, B.; Yong, D.
2009ApJ...704L..66M Altcode: 2009arXiv0909.2299M
We have conducted a differential elemental abundance analysis of
unprecedented accuracy (~0.01 dex) of the Sun relative to 11 solar twins
from the Hipparcos catalog and 10 solar analogs from planet searches. We
find that the Sun shows a characteristic signature with a ≈20%
depletion of refractory elements relative to the volatile elements in
comparison with the solar twins. The abundance differences correlate
strongly with the condensation temperatures of the elements. This
peculiarity also holds in comparisons with solar analogs known to have
close-in giant planets while the majority of solar analogs found not
to have such giant planets in radial velocity monitoring show the solar
abundance pattern. We discuss various explanations for this peculiarity,
including the possibility that the differences in abundance patterns
are related to the formation of planetary systems like our own, in
particular to the existence of terrestrial planets.

---------------------------------------------------------
Title: Assessing the role of the Bothnian Sea phosphorus burial sink
Authors: Mort, Haydon P.; Slomp, Caroline P.; Gustafsson, Bo G.
2009GeCAS..73R.908M Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Calibration of Strömgren uvby-Hβ photometry for late-type
stars - a model atmosphere approach
Authors: Önehag, A.; Gustafsson, B.; Eriksson, K.; Edvardsson, B.
2009A&A...498..527O Altcode: 2009A&A...498..527A
Context: The use of model atmospheres for deriving stellar fundamental
parameters, such as T_eff, log g, and [Fe/H], will increase as we find
and explore extreme stellar populations where empirical calibrations
are not yet available. Moreover, calibrations for upcoming large
satellite missions of new spectrophotometric indices, similar to the
uvby-Hβ system, will be needed. Aims: We aim to test the power
of theoretical calibrations based on a new generation of MARCS models
by comparisons with observational photomteric data. Methods: We
calculated synthetic uvby-Hβ colour indices from synthetic spectra. A
sample of 367 field stars, as well as stars in globular clusters, is
used for a direct comparison of the synthetic indices versus empirical
data and for scrutinizing the possibilities of theoretical calibrations
for temperature, metallicity, and gravity. Results: We show that
the temperature sensitivity of the synthetic (b-y) colour is very close
to its empirical counterpart, whereas the temperature scale based upon
Hβ shows a slight offset. The theoretical metallicity sensitivity of
the m1 index (and for G-type stars its combination with c_1)
is somewhat higher than the empirical one, based upon spectroscopic
determinations. The gravity sensitivity of the synthetic c1
index shows satisfactory behaviour when compared to obervations of F
stars. For stars cooler than the sun, a deviation is significant in the
c1-(b-y) diagram. The theoretical calibrations of (b-y),
(v-y), and c1 seem to work well for Pop II stars and lead
to effective temperatures for globular cluster stars supporting recent
claims that atomic diffusion occurs in stars near the turnoff point of
NGC 6397. Conclusions: Synthetic colours of stellar atmospheres
can indeed be used, in many cases, to derive reliable fundamental
stellar parameters. The deviations seen when compared to observational
data could be due to incomplete linelists but are possibly also due
to the effects of assuming plane-parallell or spherical geometry and
LTE. Model colours are only available in electronic form at the
CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/498/527

---------------------------------------------------------
Title: Bengt Strömgren's Approach to the Galaxy
Authors: Gustafsson, Bengt
2009IAUS..254....3G Altcode:
The contributions of Bengt Strömgren to the exploration and
understanding of the Galactic Disk are sketched. The question what we
can learn from his systematic approach is discussed.

---------------------------------------------------------
Title: VizieR Online Data Catalog: Calibration of Stromgren phot. for
late-type stars (Onehag+, 2009)
Authors: Onehag, A.; Gustafsson, B.; Eriksson, K.; Edvardsson, B.
2009yCat..34980527O Altcode:
The file "stellar.dat" contains coordinates (J2000) and identifiers
of the comparison stars. Furthermore the stellar parameters: effective
temperature (Teff), logarithmic surface gravity (logg), and metallicity
with respect to the sun ([Fe/H]) are listed. The reddening corrected
Stromgren indices c1 and m1 and the reddening corrected Stromgren
(b-y) colours are listed together with the Crawford/Mander H-beta
indices. The file "model.dat" contains data calculated from the
MARCS models. The following model parameters are listed: effective
temperature (Teff), logarithmic surface gravity (logg), and metallicity
with respect to the sun ([Fe/H]). Synthetic Stromgren indices c1 and
m1 and synthetic Stromgren (b-y) colours are listed together with the
synthetic Crawford/Mander H-beta indices. (2 data files).

---------------------------------------------------------
Title: Abundances in bulge stars from high-resolution, near-IR
spectra. I. The CNO elements observed during the science verification
of CRIRES at VLT
Authors: Ryde, N.; Edvardsson, B.; Gustafsson, B.; Eriksson, K.;
Käufl, H. U.; Siebenmorgen, R.; Smette, A.
2009A&A...496..701R Altcode: 2009arXiv0902.2124R
Context: The formation and evolution of the Milky Way bulge is not yet
well understood and its classification is ambiguous. Constraints can,
however, be obtained by studying the abundances of key elements in
bulge stars. Aims: The aim of this study is to determine the
chemical evolution of C, N, O, and a few other elements in stars in
the Galactic bulge, and to discuss the sensitivities of the derived
abundances from molecular lines. Methods: High-resolution,
near-infrared spectra in the H band were recorded using the CRIRES
spectrometer on the Very Large Telescope. Due to the high and variable
visual extinction in the line-of-sight towards the bulge, an analysis
in the near-IR is preferred. The C, N, and O abundances can all be
determined simultaneously from the numerous molecular lines in the
wavelength range observed. Results: The three giant stars in
Baade's window presented here are the first bulge stars observed
with CRIRES during its science verification observations. We have
especially determined the C, N, and O abundances, with uncertainties
of less than 0.20 dex, from CO, CN, and OH lines. Since the systematic
uncertainties in the derived C, N, and O abundances due to uncertainties
in the stellar fundamental parameters, notably T_eff, are significant,
a detailed discussion of the sensitivities of the derived abundances
is included. We find good agreement between near-IR and optically
determined O, Ti, Fe, and Si abundances. Two of our stars show a solar
[C+N/Fe], suggesting that these giants have experienced the first
dredge-up and that the oxygen abundance should reflect the original
abundance of the giants. The two giants fit into the picture, in which
there is no significant difference between the oxygen abundance in bulge
and thick-disk stars. Our determination of the sulphur abundances is the
first for bulge stars. The high [S/Fe] values for all the stars indicate
a high star-formation rate in an early phase of the bulge evolution. Based on observations collected at the European Southern Observatory,
Chile (ESO Programme 60.A-9058A). Table [see full text] is only
available in electronic from at http://www.aanda.org

---------------------------------------------------------
Title: Magnetic fields in M dwarf stars from high-resolution infrared
spectra
Authors: Kochukhov, O.; Heiter, U.; Piskunov, N.; Ryde, N.; Gustafsson,
B.; Bagnulo, S.; Plez, B.
2009AIPC.1094..124K Altcode: 2009csss...15..124K
Magnetic fields play a central role in the atmospheric properties
and variability of active M dwarfs. Information on the strength and
structure of magnetic fields in these objects is vital for understanding
dynamo mechanisms and magnetically-driven activity of low-mass stars,
and for constraining theories of star formation and evolution. We have
initiated the first systematic high-resolution survey of magnetically
sensitive infrared spectral lines in M dwarf stars using the CRIRES
instrument at the ESO VLT. We have completed observations for a sample
of 35 active and inactive M dwarfs. Here we report first results of our
project, demonstrating a clear detection of magnetic splitting of lines
in the spectra of several M dwarfs. We assess diagnostic potential of
different Zeeman-sensitive lines in the observed spectral region and
apply spectrum synthesis modelling to infer magnetic field properties
of selected M dwarfs.

---------------------------------------------------------
Title: Division III: Planetary Systems Sciences
Authors: Bowell, Edward L. G.; Meech, Karen J.; Williams, Iwan P.;
Boss, Alan P.; Consolmagno, Guy J.; Courtin, Régis; Fernández,
Julio A.; Gustafson, Bo Å. S.; Huebner, Walter F.; Levasseur-Regourd,
Anny-Chantal; Marov, Mikhail Ya.; Mayor, Michel; Schulz, Rita M.;
Spurný, Pavel; Valsecchi, Giovanni B.; Watanabe, Jun-ichi; Williams,
Iwan P.; Witt, Adolf N.
2009IAUTA..27..149B Altcode:
Division III's activities focus on a broad range of astronomical
research on bodies in the solar system (excluding the Sun), on
extrasolar planets, and on the search for life in the Universe.

---------------------------------------------------------
Title: Commission 21: Light of the Night Sky
Authors: Witt, Adolf N.; Murthy, Jayant; Gustafson, Bo Å. S.;
Baggaley, W. Jack; Dwek, Eli; Levasseur-Regourd, Anny-Chantal; Mann,
Ingrid; Mattila, Kalevi; Watanabe, Jun-ichi
2009IAUTA..27..171W Altcode:
Commission 21 consists of IAU members and consultants with expertise
and interest in the study of the light of the night sky and its various
diffuse components, at all accessible electromagnetic frequencies. In
cosmic distance scales, the subjects of Commission 21 range from
airglow and tropospheric scattering in Earth's atmosphere, through
zodiacal light in the solar system, including thermal emission from
interplanetary dust, integrated starlight in the Milky Way galaxy,
diffuse galactic light due to dust scattering in the galactic diffuse
interstellar medium, thermal emissions from interstellar dust and
free free emission from ionized interstellar gas, to various diffuse
extragalactic background sources, including the cosmologically important
cosmic microwave background (CMB). Observations of the diffuse night
sky brightness at any frequency typically include signals from several
of these sources, and it has been the historic mandate of Commission
21 to foster the necessary collaboration of experts from the different
astronomical sub-disciplines involved.

---------------------------------------------------------
Title: An attempt to summarize and conclude
Authors: Gustafsson, B.
2008PhST..133a4041G Altcode:
Some points are made on contributions to the Symposium A Stellar
Journey in Uppsala, June 2008. Conclusions are drawn concerning the
present status of the stellar-atmosphere research, and a wish list is
presented for its further development.

---------------------------------------------------------
Title: A new sample of extremely/ultra metal-poor stars
Authors: García Pérez, A. E.; Christlieb, N.; Ryan, S. G.; Beers,
T. C.; Aoki, W.; Asplund, M.; Barklem, P. S.; Bessell, M. S.; Eriksson,
K.; Frebel, A.; Gustafsson, B.; Korn, A. J.; Nordström, B.; Norris,
J. E.
2008PhST..133a4036G Altcode:
A sample of 30 very metal-poor stars from the Hamburg-European
Southern Observatory (ESO) objective-prism survey have been observed
at high spectral resolution at the Very Large Telescope (VLT) using the
Ultraviolet and Visual Echelle Spectrograph (UVES). Two of the observed
stars are very interesting not only because of their very low iron
content, approximately four orders of magnitude lower than the solar
value, but also because we detected the neutral lithium resonance line
at 670.8 nm. Hydrogen lines suggest that the two observed stars have
effective temperatures around 6000 6250 K and according to isochrones,
they are either on the main sequence or on the subgiant branch, in
which case they would probably be the most metal-poor dwarfs or warm
subgiants with lithium detections known. These detections would allow
to determine more accurately the slope of the trend of the lithium
abundance with [Fe/H] than was possible with samples of unevolved
stars restricted to higher metallicities.

---------------------------------------------------------
Title: A grid of MARCS model atmospheres for late-type
stars. I. Methods and general properties
Authors: Gustafsson, B.; Edvardsson, B.; Eriksson, K.; Jørgensen,
U. G.; Nordlund, Å.; Plez, B.
2008A&A...486..951G Altcode: 2008arXiv0805.0554G
Context: In analyses of stellar spectra and colours, and for the
analysis of integrated light from galaxies, a homogeneous grid
of model atmospheres of late-type stars and corresponding flux
spectra is needed. Aims: We construct an extensive grid of
spherically-symmetric models (supplemented with plane-parallel ones
for the highest surface gravities), built on up-to-date atomic and
molecular data, and make it available for public use. Methods:
The most recent version of the MARCS program is used. Results:
We present a grid of about 104 model atmospheres for stars
with 2500 K ≤ T_eff ≤ 8000 K, -1 ≤ log g = log (GM/R^2) ≤ 5
(cgs) with various masses and radii, -5 ≤ [Me/H] ≤ +1, with [
α/Fe] = 0.0 and 0.4 and different choices of C and N abundances. This
includes “CN-cycled” models with C/N = 4.07 (solar), 1.5 and 0.5,
C/O ranging from 0.09 to (normally) 5.0 to also represent stars of
spectral types R, S and N, and with 1.0 ≤ ξt ≤ 5 km
s-1. We also list thermodynamic quantities (T, P_g, P_e, ρ,
partial pressures of molecules, etc.) and provide them on the World Wide
Web, as well as calculated fluxes in approximately 108 000 wavelength
points. Underlying assumptions in addition to 1D stratification
(spherical or plane-parallel) include hydrostatic equilibrium,
mixing-length convection and local thermodynamic equilibrium. We
discuss a number of general properties of the models, in particular
in relation to the effects of changing abundances, of blanketing, and
of sphericity. We illustrate positive and negative feedbacks between
sphericity and molecular blanketing. We compare the models with those of
other available grids and find excellent agreement with plane-parallel
models of Castelli &amp; Kurucz (if convection is treated consistently)
within the overlapping parameter range. Although there are considerable
departures from the spherically-symmetric NextGen models, the agreement
with more recent PHOENIX models is gratifying. Conclusions: The
models of the grid show considerable regularities, but some interesting
departures from general patterns occur for the coolest models due
to the molecular opacities. We have tested a number of approximate
“rules of thumb” concerning effects of blanketing and sphericity
and often found them to be astonishingly accurate. Some interesting
new phenomena have been discovered and explored, such as the intricate
coupling between blanketing and sphericity, and the strong effects of
carbon enhancement on metal-poor models. We give further details of
line absorption data for molecules, as well as details of models and
comparisons with observations in subsequent papers.

---------------------------------------------------------
Title: Is the Sun unique as a star—and if so, why?
Authors: Gustafsson, B.
2008PhST..130a4036G Altcode:
The question whether the Sun is peculiar as compared with other stars
in its neigbourhood is revisited. It is concluded that although the
Sun is rather normal from many points of view, it departs in several
respects from most stars of similar age and galactic orbit. Thus,
it is more massive, and the amplitude of the micro-variability of
the Sun at visual wavelengths seems unusually small. It also departs
from most stars in being a single star, and it may have an unusual
planetary system. There are some tentative indications that its
chemical composition departs from those of most solar-type stars of
similar age. This is discussed and the departures are found not to be
significant. I discuss here to what extent these peculiarities may be
understood in terms of it being a planet host.

---------------------------------------------------------
Title: INTRODUCTION: Nobel Symposium 135: Physics of Planetary Systems
(18 22 June 2007, Lidingö, Stockholm, Sweden)
Authors: Piskunov, Nikolai; Rickman, Hans; Gustafsson, Bengt
2008PhST..130a1001P Altcode:
Since the discovery of the first planet, orbiting a sun-like star
outside of our solar system, astronomy has changed dramatically. This
event inspired a wide spectrum of activities not just in observational
astronomy but in all fields related to planets from star formation to
astrobiology. The discovery itself was the result of long and systematic
work on perfecting measuring techniques and collecting data. Once the
required level of precision was reached news about extrasolar planets
started to appear frequently not just in scientific journals but also in
the general media. Although fast progress is quite obvious in many
areas related to planetary sciences for this Nobel symposium, dedicated
to the Physics of Planetary Systems, we selected five topics where a
number of particularly important breakthroughs happened in the last
decade. These are: detection of exoplanets planet birthplaces:
observations and modelling planet formation evolution of planetary
systems planet characterization. We dedicated a full session,
consisting of a few review talks and a joint discussion, to each of
these topics. The format was a success, but what made this meeting
so remarkable was the quality of the talks. We are very thankful to
the world leading scientists for coming to Lidingö and making this
symposium a truly memorable event. This book contains most of their
contributions for you to enjoy. We are very thankful to the Nobel
Foundation for generous sponsorship which made this symposium possible.

---------------------------------------------------------
Title: Phosphorus burial in Baltic Sea sediments with contrasting
redox conditions
Authors: Mort, Haydon P.; Slomp, Caroline P.; Gustafsson, Bo G.
2008GeCAS..72R.654M Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Science cases, wavelength ranges, and strategies for ELTs:
some remarks and conclusions
Authors: Gustafsson, Bengt
2008SPIE.6986E..0MG Altcode: 2008SPIE.6986E..22G
Discussions at the Symposium ELTs: Which wavelengths? in Lund in
December 2007 are summarized and in particular comments are made on
the relation between the optimization of the presently planned ELTs,
and their corresponding background science cases. The division of
labour between the ELTs and the JWST is commented on. The need for
an ELT (and/or a future Space Telescope) for the optical wavelength
region is stressed. Possible strategies for pursuing the ELT projects
are commented on.

---------------------------------------------------------
Title: On the Use of Blanketed Atmospheres as Boundary Conditions
for Stellar Evolutionary Models
Authors: VandenBerg, Don A.; Edvardsson, Bengt; Eriksson, Kjell;
Gustafsson, Bengt
2008ApJ...675..746V Altcode: 2007arXiv0708.1188V
Stellar models have been computed for stars having [ Fe/H ]
= 0.0 (assuming both the Grevesse &amp; Sauval and Asplund et
al. heavy-element mixtures) and -2.0 to determine the effects on the
predicted Teff scale of using boundary conditions derived
from the latest MARCS model atmospheres. The latter were fitted in a
fully consistent way to the interior models at the photosphere and at
τ = 100: the resultant evolutionary sequences on the H-R diagram were
found to be nearly independent of the chosen fitting point. Tracks
were also computed in which the pressure at T = Teff was
obtained by integrating the hydrostatic equation together with either
the classical gray T(τ , Teff) relation or that derived by
Krishna Swamy from an empirical solar atmosphere. Due to the effects
of differences in the solar-calibrated values of the mixing-length
parameter, αMLT, very similar tracks were obtained for the
different treatments of the atmosphere, except at solar abundances,
where the models based on the Krishna Swamy T(τ , Teff)
relationship predicted ~150 K hotter giant branches than the others,
in good agreement with the inferred temperatures of giants in the open
cluster M67 from recent (V - K) -Teff relations. Tracks that
used new “scaled solar, differentially corrected” MARCS atmospheres
were found to agree well with those that employed the Krishna Swamy
T(τ , Teff) relationship, independently of the assumed
metal abundance. (Gray atmospheres are quite different from MARCS
models.) Fits of isochrones for [ Fe/H ] = - 2.0 to the CMD of the
globular cluster M68, as well as the possibility that αMLT
varies with stellar parameters, are also discussed.

---------------------------------------------------------
Title: Hercules-stream stars and the metal-rich thick disk
Authors: Bensby, T.; Oey, M. S.; Feltzing, S.; Gustafsson, B.
2008mru..conf...62B Altcode: 2006astro.ph.10754B
Using the MIKE spectrograph, mounted on the 6.5 m Magellan/Clay
telescope at the Las Campanas observatory in Chile, we have obtained
high-resolution spectra for 60 F and G dwarf stars, all likely members
of a density enhancement in the local velocity distribution, referred
to as the Hercules stream. Comparing with an existing sample of 102
thin and thick disk stars we have used space velocities, detailed
elemental abundances, and stellar ages to trace the origin of the
Hercules stream. We find that the Hercules stream stars show a wide
spread in stellar ages, metallicities, and element abundances. However,
the spreads are not random but separate the Hercules stream into the
abundance and age trends as outlined by either the thin disk or the
thick disk. We hence claim that the major part of the Hercules stream
actually are thin and thick disk stars. These diverse properties of
the Hercules stream point toward a dynamical origin, probably caused
by the Galactic bar. However, we can at the moment not entirely rule
out that the Hercules stream could be the remnants of a relatively
recent merger event.

---------------------------------------------------------
Title: M 67: a constraint on Z_⊙ and/or on diffusive processes in
stellar interiors.
Authors: VandenBerg, D. A.; Gustafsson, B.; Edvardsson, B.; Eriksson,
K.; Ferguson, J. W.
2008MmSAI..79..759V Altcode:
The mass of the lowest mass star that has a convective core throughout
the main-sequence phase is predicted to be a fairly sensitive function
of Z (especially the CNO abundances). The ∼ 4 Gyr open cluster M 67
thus provides a constraint on Z_⊙ (and the solar metals mix) because
(i) it has the same metallicity as the Sun according to high-resolution
spectroscopy, and (ii) its turnoff stars have masses just above this
lower mass limit. While isochrones computed for Z = 0.0165, assuming
the Grevesse &amp; Sauval (1998) heavy-element mixture, are able to
reproduce the M 67 color-magnitude diagram satisfactorily, those for the
solar abundances derived by M. Asplund et al. (implying Z_⊙ = 0.0125)
do not predict a gap near the turnoff where one is observed. These
results suggest either that there is a problem with the solar metal
abundances derived by Asplund et al. or that the neglect of diffusive
processes in the present models is responsible for this difficulty. If
the latter is the correct explanation, then M 67 provides an important
constraint on the rates of diffusive processes in the deep interiors
of stars.

---------------------------------------------------------
Title: Commission 21: Light of the Night Sky
Authors: Gustafson, Bo A. S.; Witt, Adolf N.; Lamy, Philippe; Dwek,
Eli; Lamy, Philippe; Henry, Richard C.; Mann, Ingrid
2007IAUTB..26..138G Altcode:
Applications have been received from Dr. Peter Wheatley (proposed by
UK), Prof. Harald Schuh (proposed by Austria), and Dr. Busaba Kramer
(proposed by Thailand). All applications were endorsed, with the caveat
that Dr. Kramer's application needs to be endorsed by at least one
of the other commissions since she has not a publication record in
our field.

---------------------------------------------------------
Title: Atomic Diffusion and Mixing in Old Stars. I. Very Large
Telescope FLAMES-UVES Observations of Stars in NGC 6397
Authors: Korn, A. J.; Grundahl, F.; Richard, O.; Mashonkina, L.;
Barklem, P. S.; Collet, R.; Gustafsson, B.; Piskunov, N.
2007ApJ...671..402K Altcode: 2007arXiv0709.0639K
We present a homogeneous photometric and spectroscopic analysis of
18 stars along the evolutionary sequence of the metal-poor globular
cluster NGC 6397 ([Fe/H]~-2), from the main-sequence turnoff point to
red giants below the bump. The spectroscopic stellar parameters, in
particular stellar parameter differences between groups of stars, are
in good agreement with broadband and Strömgren photometry calibrated
on the infrared flux method. The spectroscopic abundance analysis
reveals, for the first time, systematic trends of iron abundance
with evolutionary stage. Iron is found to be 30% less abundant in the
turnoff point stars than in the red giants. An abundance difference
in lithium is seen between the turnoff point and warm subgiant
stars. The impact of potential systematic errors on these abundance
trends (stellar parameters, the hydrostatic and LTE approximations)
is quantitatively evaluated and found not to alter our conclusions
significantly. Trends for various elements (Li, Mg, Ca, Ti, and Fe)
are compared with stellar structure models including the effects of
atomic diffusion and radiative acceleration. Such models are found
to describe the observed element-specific trends well, if extra
(turbulent) mixing just below the convection zone is introduced. It
is concluded that atomic diffusion and turbulent mixing are largely
responsible for the subprimordial stellar lithium abundances of warm
halo stars. Other consequences of atomic diffusion in old metal-poor
stars are also discussed. Based on observations carried out at
the European Southern Observatory (ESO), Paranal, Chile, under program
ID 075.D-0125(A).

---------------------------------------------------------
Title: Towards a Satisfactory Understanding of AGB-Star Atmospheres?
Authors: Gustafsson, B.
2007ASPC..378...60G Altcode:
The understanding and the modelling of the atmospheres of AGB stars
are discussed and found to be unsatisfactory for most purposes. A
number of developments and possible actions to improve this situation
are considered.

---------------------------------------------------------
Title: Carbon Stars in the Bulge -- or Beyond It?
Authors: Wahlin, R.; Eriksson, K.; Gustafsson, B. >; Ryde, N.;
Westerlund, B.; Lambert, D. L.
2007ASPC..378..410W Altcode:
The carbon stars in the direction of the Bulge were recently proposed
to belong to the Sagittarius system which, with its lower metallicity,
would more easily produce carbon stars. The compositions of the carbon
stars might be used to distinguish between true members of the Bulge and
members of the Sagittarius stream seen through the Bulge. We present
oxygen abundances for a sample of carbon stars in the Sagittarius
dwarf galaxy including its tidal stream, and towards the galactic
Bulge. The abundances were determined from infrared spectra obtained
with the ISAAC spectrometer on VLT (R=1500). We find that the oxygen
abundances of the Bulge carbon stars are compatible with membership
of the Sagittarius stream, but we also discuss possible scenarios that
might explain their abundances if they were true Bulge members.

---------------------------------------------------------
Title: A Constraint on Zsolar from Fits of Isochrones to
the Color-Magnitude Diagram of M67
Authors: VandenBerg, Don A.; Gustafsson, Bengt; Edvardsson, Bengt;
Eriksson, Kjell; Ferguson, Jason
2007ApJ...666L.105V Altcode: 2007arXiv0708.1172V
The mass at which a transition is made between stars that have radiative
or convective cores throughout the core H burning phase is a fairly
sensitive function of Z (particularly, the CNO abundances). As a
consequence, the ~4 Gyr, open cluster M67 provides a constraint on
Zsolar (and the solar heavy-element mixture) because (1)
high-resolution spectroscopy indicates that this system has virtually
the same metal abundances as the Sun, and (2) its turnoff stars have
masses just above the lower limit for sustained core convection on
the main sequence. In this study, evolutionary tracks and isochrones
using the latest MARCS model atmospheres as boundary conditions have
been computed for 0.6-1.4 Msolar on the assumption of a
metals mix (implying Zsolar~0.0125) based on the solar
abundances derived by M. Asplund and collaborators using 3D model
atmospheres. These calculations do not predict a turnoff gap where one
is observed in M67. No such difficulty is found if the analysis uses
isochrones for Zsolar=0.0165, assuming the Grevesse and
Sauval mix of heavy elements. Our findings, like the inferences from
helioseismology, indicate a problem with the abundances of Asplund
and collaborators. However, it is possible that low-Z models with
diffusive processes taken into account will be less problematic.

---------------------------------------------------------
Title: A First Study of Giant Stars in the Galactic Bulge based on
Crires spectra
Authors: Ryde, N.; Edvardsson, B.; Gustafsson, B.; Käufl, H. -U.
2007IAUS..241..260R Altcode: 2007astro.ph..1916R
We present our on-going work on the determination of elemental
abundances of giants in the Galactic Bulge by means of infrared
spectroscopy. We show a preliminarily reduced spectrum and a
synthetic spectrum fit of the Bulge giant Arp 4203 recorded with the
near-infrared, high-resolution Crires spectrograph mounted on the VLT
during its science verification run in August 2006. Abundances derived
from this spectrum are discussed.

---------------------------------------------------------
Title: On Stellar Models with Blanketed Atmospheres as Boundary
Conditions
Authors: Vandenberg, Don A.; Edvardsson, Bengt; Eriksson, Kjell;
Gustafsson, Bengt; Ferguson, Jason W.
2007IAUS..241...23V Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Libraries of synthetic stellar spectra - or are we building
palaces upon sand?
Authors: Gustafsson, Bengt; Heiter, Ulrike; Edvardsson, Bengt
2007IAUS..241...47G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Chemical Abundances in Metal-Rich Bulge-like Stars
Authors: Pompéia, L.; Barbuy, B.; Grenon, M.; Gustafsson, B.
2007IAUS..241...78P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Exploring the Near-Infrared at High Spatial and Spectral
Resolution: First Results from CRIRES Science Verification
Authors: Siebenmorgen, Ralf; Smette, Alain; Käufl, Hans Ulrich;
Seifahrt, Andreas; Uttenthaler, Stefan; Bik, Arjan; Casali, Mark;
Hubrig, Swetlana; Jung, Yves; Kerber, Florian; Melnick, Jorge;
Moorwood, Alan; Pirard, Jean-François; Sana, Hugues; Valenti,
Elena; Tacconi-Garman, Lowell; Hilker, Michael; Primas, Francesca;
Amado, Pedro J.; Carmona, Andrés; van Dishoeck, Ewine F.; Foellmi,
Cédric; Goto, Miwa; Gredel, Roland; Günther, Eike; Gustafsson,
Bengt; Kurtz, Don; Lidman, Christopher; Linz, Hendrik; Martins,
Fabrice; Menten, Karl; Moutou, Claire; Nissen, Poul E.; Nürnberger,
Dieter; Reiners, Ansgar
2007Msngr.128...17S Altcode:
The VLT cryogenic high-resolution infrared echelle spectrograph CRIRES
offers high spatial, spectral and temporal resolution spectroscopy
from 1 to 5 μm. Highlights from among the 29 pilot studies of the
CRIRES science verification (SV) runs are summarised.

---------------------------------------------------------
Title: The Origin of the Hercules Stream
Authors: Oey, M. S.; Bensby, T.; Feltzing, S.; Gustafsson, B.
2007AAS...210.8503O Altcode: 2007BAAS...39..194O
We find that the Hercules Stream appears to have a dynamical origin
within our own Galaxy. Our measurements of [Mg/Fe] and [Ba/Fe] in 60
Hercules Stream stars show a range of one-tenth solar to super-solar
metallicity; across this range, the data are consistent with the
abundance patterns of these elements in the Galactic thick and thin
disks. Thus, our results favor a dynamical origin, perhaps induced by
the Galactic bar, rather than an extragalactic merger origin, for the
Hercules Stream.

---------------------------------------------------------
Title: Working Group on Definition of Planet
Authors: Williams, Iwan P.; Bowell, Edward L. G.; Tedesco, Edward;
Consolmagno, Guy J.; Valsecchi, Giovanni B.; Gustafson, Bo Å.;
Mann, Ingrid; Meech, Karen J.; A'Hearn, Michael F.; Boss, Alan P.;
Cruikshank, Dale P.; Levasseur-Regourd, Anny-Chantal; Marov, Mikhail;
Morrison, David; Tinney, Chris; Marsden, Brian; Stern, Alan; Ticha,
Jana; Askness, Kaare
2007IAUTA..26..189W Altcode:
The Working Group was formed at the request of the Board of DivisionIII
and approved by the IAU Executive committee in March 2004. This was in
recognition of the fact that discoveries in the Trans Neptunian region
were repeatedly raising the question of "what is a planet". The task
of the WG was to investigate the options available and give indications
of the level of support and opposition for each if more than one option
was emerging.

---------------------------------------------------------
Title: Commission 21: Light of the Night Sky
Authors: Gustafson, Bo Å. S.; Witt, Adolf N.; Dwek, E.; Lamy, P.;
Henry, R.; Mann, I.
2007IAUTA..26..161G Altcode:
Commission 21, one of IAU's smallest commissions, consists of some
hundred members and consultants working to understand and describe the
light of the night sky with emphasis on the diffuse components. Many
more work on these topics without being members of the commission. Light
is here defined in its broader sense of electromagnetic radiation of
any frequency. The diffuse components of the light of the night sky
encompass a variety of physical phenomena over the full range of cosmic
distance scales and include scattered light, thermal emission, line
emission, and any other emission phenomena producing a diffuse light
source. These attract interest not only as scientific topics of study
in their own right but also as an unwanted foreground or background
against which all other sky phenomena are observed. Commission 21 has
for mandate to promote research and availability of results on issues
related to the diffuse light of the night sky. This document is a report
on activities in this field and is not confined to the activities of its
members, no distinction is made between work carried out by commission
members and non commission members. The report is organized starting
with a summary of the state of broad surveys that provide most of the
observations. The report on developments in the various disciplines
start with the sources closest to the observer known as airglow and
progresses by way of the interplanetary and interstellar mediums to
the increasingly distant integrated starlight, diffuse galactic light
and diffuse emission in other galaxies ending with the extragalactic
background radiation.

---------------------------------------------------------
Title: Disentangling the Hercules Stream
Authors: Bensby, T.; Oey, M. S.; Feltzing, S.; Gustafsson, B.
2007ApJ...655L..89B Altcode: 2006astro.ph.12658B
Using high-resolution spectra of nearby F and G dwarf stars, we have
investigated the detailed abundance and age structure of the Hercules
stream. We find that the stars in the stream have a wide range of
stellar ages, metallicities, and element abundances. By comparing to
existing samples of stars in the solar neighborhood with kinematics
typical of the Galactic thin and thick disks, we find that the
properties of the Hercules stream distinctly separate into the abundance
and age trends of the two disks. Hence, we find it unlikely that the
Hercules stream is a unique Galactic stellar population but rather is
a mixture of thin and thick disk stars. This points toward a dynamical
origin for the Hercules stream, probably caused by the Galactic bar. Based on observations collected with the MIKE spectrograph on the
6.5 m Magellan Clay telescope at the Las Campanas observatory in Chile.

---------------------------------------------------------
Title: Gaia and Metal-Poor Stars
Authors: Gustafsson, B.
2006ASPC..353..387G Altcode:
The expected impact of the Gaia mission on our understanding of
metal-poor stars and the formation of the Galactic halo is discussed. It
is concluded that substantial ground-based efforts will be needed in
order to realise the full potential of the Gaia project with its grand
volume of high-precision astrometric and photometric stellar data.

---------------------------------------------------------
Title: New Abundances for Old Stars - Atomic Diffusion at Work in
NGC 6397
Authors: Korn, A.; Grundahl, F.; Richard, O.; Barklem, P.; Mashonkina,
L.; Collet, R.; Piskunov, N.; Gustafsson, B.
2006Msngr.125....6K Altcode: 2006astro.ph.10077K; 2006Msngr.125...10K
A homogeneous spectroscopic analysis of unevolved and evolved
stars in the metal-poor globular cluster NGC 6397 with FLAMES-UVES
reveals systematic trends of stellar surface abundances that are
likely caused by atomic diffusion. This finding helps to understand,
among other issues, why the lithium abundances of old halo stars are
significantly lower than the abundance found to be produced shortly
after the Big Bang.

---------------------------------------------------------
Title: Galileo dust data from the jovian system: 1997 1999
Authors: Krüger, H.; Bindschadler, D.; Dermott, S. F.; Graps,
A. L.; Grün, E.; Gustafson, B. A.; Hamilton, D. P.; Hanner, M. S.;
Horányi, M.; Kissel, J.; Lindblad, B. A.; Linkert, D.; Linkert, G.;
Mann, I.; McDonnell, J. A. M.; Moissl, R.; Morfill, G. E.; Polanskey,
C.; Schwehm, G.; Srama, R.; Zook, H. A.
2006P&SS...54..879K Altcode:
The dust detector system on board the Galileo spacecraft recorded
dust impacts in circumjovian space during the craft's orbital mission
about Jupiter. This is the eighth in a series of papers dedicated to
presenting Galileo and Ulysses dust data. We present data from the
Galileo dust instrument for the period January 1997-December 1999 when
the spacecraft completed 21 revolutions about Jupiter. In this time
interval data were obtained as high resolution realtime science data or
recorded data during 449 days (representing 41% of the entire period),
or via memory readouts during the remaining times. Because the data
transmission rate of the spacecraft was very low, the complete data
set (i.e. all parameters measured by the instrument during impact of
a dust particle) of only 3% (7625) of all particles detected could be
transmitted to Earth; the other particles were only counted. Together
with the data of 2883 particles detected during Galileo's interplanetary
cruise and 5353 particles detected in the jovian system in 1996,
complete data of 15 861 particles detected by the Galileo dust
instrument from 1989 to 1999 are now available. The majority of the
detected particles were tiny grains (about 10 nm in radius), most of
them originating from Jupiter's innermost Galilean moon Io. They were
detected throughout the jovian system and the highest impact rates
exceeded 100min-1 (C21 orbit; 01 July 1999). With the new
data set the times of onset, cessation and a 180∘ shift in
the impact direction of the grains measured during 19 Galileo orbits
about Jupiter are well reproduced by simulated 9 nm particles charged
up to a potential of +3V, confirming earlier results obtained for only
two Galileo orbits (Horányi, M., Grün, E., Heck, A., 1997. Modeling
the Galileo dust measurements at Jupiter. Geophys. Res. Lett. 24,
2175-2178). Galileo has detected a large number of bigger particles
mostly in the region between the Galilean moons. The average radius
of 370 of these grains measured in the 1996-1999 period is about 2μm
(assuming spherical grains with density 1gcm-3) and the
size distribution rises steeply towards smaller grains. The biggest
detected particles have a radius of about 10μm.

---------------------------------------------------------
Title: A probable stellar solution to the cosmological lithium
discrepancy
Authors: Korn, A. J.; Grundahl, F.; Richard, O.; Barklem, P. S.;
Mashonkina, L.; Collet, R.; Piskunov, N.; Gustafsson, B.
2006Natur.442..657K Altcode: 2006astro.ph..8201K
The measurement of the cosmic microwave background has strongly
constrained the cosmological parameters of the Universe. When the
measured density of baryons (ordinary matter) is combined with
standard Big Bang nucleosynthesis calculations, the amounts of
hydrogen, helium and lithium produced shortly after the Big Bang can
be predicted with unprecedented precision. The predicted primordial
lithium abundance is a factor of two to three higher than the value
measured in the atmospheres of old stars. With estimated errors of 10
to 25%, this cosmological lithium discrepancy seriously challenges
our understanding of stellar physics, Big Bang nucleosynthesis or
both. Certain modifications to nucleosynthesis have been proposed,
but found experimentally not to be viable. Diffusion theory, however,
predicts atmospheric abundances of stars to vary with time, which offers
a possible explanation of the discrepancy. Here we report spectroscopic
observations of stars in the metal-poor globular cluster NGC6397
that reveal trends of atmospheric abundance with evolutionary stage
for various elements. These element-specific trends are reproduced
by stellar-evolution models with diffusion and turbulent mixing. We
thus conclude that diffusion is predominantly responsible for the low
apparent stellar lithium abundance in the atmospheres of old stars by
transporting the lithium deep into the star.

---------------------------------------------------------
Title: Five years of Ulysses dust data: 2000 2004
Authors: Krüger, H.; Altobelli, N.; Anweiler, B.; Dermott, S. F.;
Dikarev, V.; Graps, A. L.; Grün, E.; Gustafson, B. A.; Hamilton,
D. P.; Hanner, M. S.; Horányi, M.; Kissel, J.; Landgraf, M.; Lindblad,
B. A.; Linkert, D.; Linkert, G.; Mann, I.; McDonnell, J. A. M.;
Morfill, G. E.; Polanskey, C.; Schwehm, G.; Srama, R.; Zook, H. A.
2006P&SS...54..932K Altcode:
The Ulysses spacecraft has been orbiting the Sun on a highly inclined
ellipse ( i=79∘, perihelion distance 1.3 AU, aphelion
distance 5.4 AU) since it encountered Jupiter in 1992. Between
January 2000 and December 2004, the spacecraft completed almost an
entire revolution about the Sun, passing through perihelion in May
2001 and aphelion in July 2004. In this five-year period the dust
detector on board recorded 4415 dust impacts. We publish and analyse
the complete data set of both raw and reduced data for particles with
masses 10-16g⩽m⩽10-7g. Together with 1695
dust impacts recorded between launch of Ulysses and the end of 1999
published earlier (Grün, E., Baguhl, M., Divine, N., Fechtig, H.,
Hamilton, D.P, Hanner, M.S., Kissel, J., Lindblad, B.A., Linkert, D.,
Linkert, G., Mann, I., McDonnell, J.A.M., Morfill, G.E., Polanskey,
C., Riemann, R., Schwehm, G.H., Siddique, N., Staubach, P., Zook, H.A.,
1995a. Two years of Ulysses dust data. Planetary Space Sci. 43, 971-999,
Paper III; Krüger, H., Grün, E., Landgraf, M., Baguhl, M., Dermott,
S.F., Fechtig, H., Gustafson, B.A., Hamilton, D.P., Hanner, M.S.,
Horányi, M., Kissel, J., Lindblad, B., Linkert, D., Linkert, G., Mann,
I., McDonnell, J.A.M., Morfill, G.E., Polanskey, C., Schwehm, G.H.,
Srama, R., Zook, H.A., 1995. Three years of Ulysses dust data: 1993
to 1995. Planetary and Space Sci. 47, 363-383, Paper V; Krüger, H.,
Grün, E., Landgraf, M., Dermott, S.F., Fechtig, H., Gustafson, B.A.,
Hamilton, D.P., Hanner, M.S., Horányi, M., Kissel, J., Lindblad, B.,
Linkert, D., Linkert, G., Mann, I., McDonnell, J.A.M., Morfill, G.E.,
Polanskey, C., Schwehm, G.H., Srama, R., Zook, H.A., 2001b. Four years
of Ulysses dust data: 1996 to 1999. Planetary Space Sci. 49, 1303-1324,
Paper VII), a data set of 6110 dust impacts detected with the Ulysses
sensor between October 1990 and December 2004 is now available. The
impact rate measured between 2000 and 2002 was relatively constant
with about 0.3 impacts per day showing a maximum at 1.5 per day around
ecliptic plane crossing in early-2001. The impact direction of the
majority of impacts between 2000 and 2002 is compatible with particles
of interstellar origin, the rest are most likely interplanetary
particles. In 2003 and 2004 dust stream particles originating from the
jovian system dominated the overall impact rate. Twenty-two individual
dust streams were measured between November 2002 and December 2004. The
observed impact rates are compared with models for interplanetary and
interstellar dust. The dust measurements from the entire mission since
Ulysses launch give good agreement with the interplanetary flux model
of Staubach, P., Grün, E., Jehn, R., 1997. The meteoroid environment
near Earth, Adv. Space Res. 19, 301-308.

---------------------------------------------------------
Title: Oxygen abundances in metal-poor subgiants as determined from
[O I], O I and OH lines
Authors: García Pérez, A. E.; Asplund, M.; Primas, F.; Nissen,
P. E.; Gustafsson, B.
2006A&A...451..621G Altcode: 2005astro.ph.12290G
The debate on the oxygen abundances of metal-poor stars has its
origin in contradictory results obtained using different abundance
indicators. To achieve a better understanding of the problem we
have acquired high quality spectra with the Ultraviolet and Visual
Echelle Spectrograph at VLT, with a signal-to-noise of the order of
100 in the near ultraviolet and 500 in the optical and near infrared
wavelength range. Three different oxygen abundance indicators,
OH ultraviolet lines around 310.0 nm, the [O i] line at 630.03 nm
and the O i lines at 777.1-5 nm were observed in the spectra of 13
metal-poor subgiants with -3.0≤[Fe/H]≤-1.5. Oxygen abundances
were obtained from the analysis of these indicators which was carried
out assuming local thermodynamic equilibrium and plane-parallel
model atmospheres. Abundances derived from O i were corrected for
departures from local thermodynamic equilibrium. Stellar parameters
were computed using T_eff-vs.-color calibrations based on the infrared
flux method and Balmer line profiles, Hipparcos parallaxes and Fe II
lines. [O/Fe] values derived from the forbidden line at 630.03 nm are
consistent with an oxygen/iron ratio that varies linearly with [Fe/H] as
[O/Fe]=-0.09(±0.08)[Fe/H]+0.36(±0.15). Values based on the O i triplet
are on average 0.19±0.22 dex(s.d.) higher than the values based on the
forbidden line while the agreement between OH ultraviolet lines and the
forbidden line is much better with a mean difference of the order of
-0.09±0.25 dex(s.d.). In general, our results follow the same trend
as previously published results with the exception of the ones based
on OH ultraviolet lines. In that case our results lie below the values
which gave rise to the oxygen abundance debate for metal-poor stars.

---------------------------------------------------------
Title: The Hamburg/ESO R-process enhanced star survey (HERES). III. HE
0338-3945 and the formation of the r + s stars
Authors: Jonsell, K.; Barklem, P. S.; Gustafsson, B.; Christlieb,
N.; Hill, V.; Beers, T. C.; Holmberg, J.
2006A&A...451..651J Altcode: 2006astro.ph..1476J
We have derived abundances of 33 elements and upper limits for 6
additional elements for the metal-poor ([Fe/H] = -2.42) turn-off star
HE 0338-3945 from high-quality VLT-UVES spectra. The star is heavily
enriched, by about a factor of 100 relative to iron and the Sun, in the
heavy s-elements (Ba, La, ...). It is also heavily enriched in Eu, which
is generally considered an r-element, and in other similar elements. It
is less enriched, by about a factor of 10, in the lighter s-elements
(Sr, Y and Zr). C is also strongly enhanced and, to a somewhat lesser
degree, N and O. These abundance estimates are subject to severe
uncertainties due to NLTE and thermal inhomogeneities which are not
taken into detailed consideration. However, an interesting result,
which is most probably robust in spite of these uncertainties, emerges:
the abundances derived for this star are very similar to those of
other stars with an overall enhancement of all elements beyond the iron
peak. We have defined criteria for this class of stars, r+s stars, and
discuss nine different scenarios to explain their origin. None of these
explanations is found to be entirely convincing. The most plausible
hypotheses involve a binary system in which the primary component goes
through its giant branch and asymptotic giant branch phases and produces
CNO and s-elements which are dumped onto the observed star. Whether
the r-element Eu is produced by supernovae before the star was formed
(perhaps triggering the formation of a low-mass binary), by a companion
as it explodes as a supernova (possibly triggered by mass transfer),
or whether it is possibly produced in a high-neutron-density version
of the s-process is still unclear. Several suggestions are made on
how to clarify this situation.

---------------------------------------------------------
Title: Getting a handle on the origin of the Galactic Bulge
Authors: Lambert, David L.; Ryde, Nils; Hinkle, Kenneth; Smith, Verne
V.; Gustafsson, Bengt; Edvardsson, Bengt; Asplund, Martin; Johansson,
Sveneric; Wahlin, Rurik
2006noao.prop..268L Altcode:
The origin, chemical properties, and evolution history of the
Galactic Bulge remain poorly understood. Abundance ratios of bulge
stars, especially in the [(alpha)/Fe] vs [Fe/H] diagram, serve to
constrain the evolutionary models. Measuring, for instance, a high
(alpha) over-abundance indicates rapid and early star-formation. Thus,
we propose an infrared based study of the (alpha) elements, including
oxygen, of ten stars in two low-extinction windows towards the bulge. We
will also re-investigate the oxygen abundance trends found from optical
spectra of K giants in Baade's window by McWilliam &amp; Rich (2004),
which indicate a surprising cession of oxygen production in the bulge
for metallicities larger than -0.5. The infrared, with lower extinction
and molecular rather than atomic abundance indicators, is a preferred
wavelength region to study abundances in bulge stars.

---------------------------------------------------------
Title: The Chemical Composition of Red Giants, AGB Stars and
Planetary Nebulae
Authors: Gustafsson, Bengt; Wahlin, Rurik
2006IAUS..234..251G Altcode: 2006astro.ph..7218G
The determinations of element abundances in red-giant stars and in
particular in AGB stars are reviewed and the resulting abundances are
compared with those obtained for planetary nebulae in the Galaxy and in
nearby galaxies. The problems, possibilities and implications of such
comparisons when estimating yields from low-mass and intermediate-mass
stars are illustrated and commented on.

---------------------------------------------------------
Title: Carbon stars in local group dwarf galaxies: C and O abundances
Authors: Wahlin, R.; Eriksson, K.; Gustafsson, B.; Hinkle, K. H.;
Lambert, D. L.; Ryde, N.; Westerlund, B.
2006MmSAI..77..955W Altcode: 2006astro.ph..5244W
We present abundances of carbon and oxygen as well as abundance
ratios 12C/13C for a sample of carbon stars
in the LMC, SMC, Carina, Sculptor and Fornax dwarf galaxies. The
overall metallicities in these dwarf galaxies are lower than in the
galactic disc. The observations cover most of the AGB and we discuss
the abundance patterns in different regions along the AGB. The
abundances are determined from infrared spectra obtained with the
ISAAC spectrometer on VLT (R=1500) and the Phoenix Spectrometer on
Gemini South (R=50000). The synthetic spectra used in the analysis
were computed with MARCS model atmospheres. We find that the oxygen
abundance is decreasing with decreasing overall metallicity of the
system while the C/O ratio at a given evolutionary phase is increasing
with decreasing oxygen abundance. Based on observations collected
at the European Southern Observatory, Paranal, Chile (ESO Programme
70.D-0414 &amp; 072.D-0501)

---------------------------------------------------------
Title: Pinning Down Gravitational Settling
Authors: Korn, A. J.; Piskunov, N.; Grundahl, F.; Barklem, P.;
Gustafsson, B.
2006cams.book..294K Altcode: 2006astro.ph..8338K
We analyse high-resolution archival UVES data of turnoff
and subgiant stars in the nearby globular cluster NGC6397
([Fe/H]≈-2). Balmer-profile analyses are performed to derive
reddening-free effective temperatures. Due to the limited S/N and
uncertainties related to blaze removal, we find the data quality
insufficient to exclude the existence of gravitational settling. If
the newly derived effective temperatures are taken as a basis for an
abundance analysis, the photospheric iron (Fe ii) abundance in the
turnoff stars is 0.11 dex lower than in the (well-mixed) subgiants.

---------------------------------------------------------
Title: An investigation of Titan's aerosols using microwave analog
measurements and radiative transfer modeling
Authors: Thomas-Osip, J. E.; Gustafson, B. Å. S.; Kolokolova, L.;
Xu, Y. -L.
2005Icar..179..511T Altcode:
A combination of laboratory experiments, theoretical modeling, and
spacecraft observations is employed to characterize the aerosols in
the atmosphere of Titan. The scattering properties of model aerosols
were measured using the Microwave Analog Light Scattering Facility at
the University of Florida and complemented with theoretical modeling
of single scattering characteristics and radiative transfer in
Titan's atmosphere. This study compares these modeling results with
photopolarimetric observations made over a range of phase angles by
the Pioneer 11 and Voyagers 1 and 2 spacecraft. Important results of
this work include a survey of the scattering properties of different
particle morphologies and compositions necessary to accurately interpret
these observations without introducing non-physical assumptions about
the particles or requiring additional free parameters to the radiative
transfer models. Previous studies use calculation methods which, due to
computing memory and processing time requirements, a priori exclude
much of the parameter space that the microwave analog laboratory
is ideal for exploring. The goal of the present work, to directly
constrain aerosol physical characteristics, is addressed by studying
in a consistent manner how a variety of particle morphologies and
refractive indices affect the polarization and intensity reflected by
Titan's atmosphere. Based on comparisons of model results to spacecraft
observations, many model morphologies are excluded from further
consideration. The most plausible physical particle models suggest
that a combination of Rayleigh-like single particles and aggregates
that are larger than those previously suggested and investigated
[West, R.A., Smith, P.H., 1991. Evidence for aggregate particles in
the atmospheres of Titan and Jupiter. Icarus 90, 330-333; Rannou, P.,
Cabane, M., Botet, R., Chassefière, E., 1997. A new interpretation of
scattered light measurements at Titan's limb. J. Geophys. Res. 102,
10997-11013] provide the best fit to the existing data. Additional
laboratory experiments and more refined modeling awaits the results of
the new rich observational dataset from the Cassini/Huygens encounter
with Titan.

---------------------------------------------------------
Title: Scattering by "Bird's-Nest"-type Material and Large Dust
Aggregates: Microwave Analogue Measurements
Authors: Gustafson, B. Å. S.; Espy, A. J.
2005LPICo1280...65G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Chemical abundances in 43 metal-poor stars
Authors: Jonsell, K.; Edvardsson, B.; Gustafsson, B.; Magain, P.;
Nissen, P. E.; Asplund, M.
2005A&A...440..321J Altcode: 2005astro.ph..5118J
We have derived abundances of O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Fe,
Ni, and Ba for 43 metal-poor field stars in the solar neighbourhood,
most of them subgiants or turn-off-point stars with iron abundances
[Fe/H] ranging from -0.4 to -3.0. About half of this sample has not been
spectroscopically analysed in detail before. Effective temperatures
were estimated from uvby photometry, and surface gravities primarily
from Hipparcos parallaxes. The analysis is differential relative to
the Sun, and was carried out with plane-parallel MARCS models. Various
sources of error are discussed and found to contribute a total error
of about 0.1-0.2 dex for most elements, while relative abundances,
such as [Ca/Fe], are most probably more accurate. For the oxygen
abundances, determined in an NLTE analysis of the 7774 Å triplet
lines, the errors may be somewhat larger. We made a detailed comparison
with similar studies and traced the reasons for the, in most cases,
relatively small differences. Among the results we find that [O/Fe]
possibly increases beyond [Fe/H] = -1.0, though considerably less so
than in results obtained by others from abundances based on OH lines. We
did not trace any tendency toward strong overionization of iron, and
find the excesses, relative to Fe and the Sun, of the α elements Mg,
Si, and Ca to be smaller than those of O. We discuss some indications
that also the abundances of different α elements relative to Fe vary
and the possibility that some of the scatter around the trends in
abundances relative to iron may be real. This may support the idea that
the formation of Halo stars occurred in smaller systems with different
star formation rates. We verify the finding by Gratton et al. (2003b,
A&amp;A, 406, 131) that stars that do not participate in the rotation
of the galactic disk show a lower mean and larger spread in [ α/Fe]
than stars participating in the general rotation. The latter stars also
seem to show some correlation between [ α/Fe] and rotation speed. We
trace some stars with peculiar abundances, among these two Ba stars,
<ASTROBJ>HD 17072</ASTROBJ> and <ASTROBJ>HD 196944</ASTROBJ>, the
second already known to be rich in s elements. Finally we advocate
that a spectroscopic study of a larger sample of halo stars with
well-defined selection criteria is very important, in order to add to
the very considerable efforts that various groups have already made.

---------------------------------------------------------
Title: Light Scattering as a Diagnostic for Asteroid Structure
Authors: Espy, A. J.; Gustafson, B. A. S.
2005DPS....37.1508E Altcode: 2005BAAS...37..640E
With the identification of the Veritas family as the source of the
9.35 degree dust band of the Zodiacal cloud (Nesvory, et. al 2003),
instead of the formerly assigned Eos, we are presented with a new
means to study the Veritas family and its precursor asteroid. When an
asteroid breaks up, the larger pieces remain together on the same orbit
and may reassemble into what is known as a rubble pile. The smaller
(sub-millimeter to micron sized) particles, however, experience a
stronger perturbation from the solar radiation pressure and these
particles migrate to the zodiacal cloud, rather than remaining with
the rubble pile. The light scattering of this corresponding band
of the zodiacal cloud can be studied for information on the dust
particles comprising it, specifically their size and structure, and
thus also their precursor asteroid. Using the unique capability of
the Microwave Scattering Facility (Gustafson 1996), models of these
dust particles are created and the scattering by these particles
is measured, specifically the intensities and polarizations. The
models are based on the currently known data for the Veritas family,
i.e. taxonomic class, tensile strength(calculated from light curves),
break-up epochs (obtained from theoretical orbital integrations),
and albedo dispersion. Our current hypothesis is that the Veritas
precursor was NOT differentiated, but rather it was an aggregate of
interstellar grains like the Bird's Nest model of dust proposed by
Greenberg and Gustafson(1981). The Bird's Nest model represents the
dust as pieces of aggregated nebular dust from which water ice has
sublimated. We expect to find structure in the zodiacal dust on the
scale of the size of the interstellar grains, 0.1-0.7 microns. If,
however, the precursor WAS differentiated then the bulk material in
the dust should appear homogeneous (for full differentiation) or show
struucture on a different size scale (for partial differentiation). We
present here our method and first results.

---------------------------------------------------------
Title: Stochastic chemical enrichment in metal-poor
systems. II. Abundance ratios and scatter
Authors: Karlsson, T.; Gustafsson, B.
2005A&A...436..879K Altcode: 2005astro.ph..4617K
A stochastic model of the chemical enrichment of metal-poor systems
by core collapse supernovae is used to study the scatter in stellar
abundance ratios. Large-scale mixing of the enriched material by
turbulent motions and cloud collisions in the interstellar medium,
and infall of pristine matter are taken into account. The resulting
scatter in abundance ratios, e.g. as functions of the overall
metallicity, is demonstrated to be crucially dependent on the as
yet uncertain supernovae yields. The observed abundance ratios
and their scatters therefore have diagnostic power as regards the
yields. The relatively small star-to-star scatter observed in many
chemical abundance ratios, e.g. by Cayrel et al. (2004) for stars
down to [Fe/H]= -4, is tentatively explained by the averaging of a
large number of contributing supernovae and by the cosmic selection
effects favoring contributions from supernovae in a certain mass range
for the most metal-poor stars. The scatter in observed abundances of
α-elements is understood in terms of observational errors only, while
additional spread in yields or sites of nucleosynthesis may affect
the odd-even elements Na and Al. For the iron-group elements we find
some systematic deviations from observations in abundance ratios,
such as systematically too high predicted Cr/Fe and Cr/Mg ratios,
as well as differences between the different sets of yields, both in
terms of predicted abundance ratios and scatter. The semi-empirical
yields recently suggested by Francois et al. (2004) are found to lead to
scatter in abundance ratios significantly greater than observed, when
applied in the inhomogeneous models. "Spurs", very narrow sequences
in abundance-ratio diagrams, may disclose a single-supernova origin
of the elements of the stars on the sequence. Verification of the
existence of such features, called single supernova sequences (SSSs),
is challenging. This will require samples of several hundred stars
with abundance ratios observed to accuracies of 0.05 dex or better.

---------------------------------------------------------
Title: VizieR Online Data Catalog: Chemical abundances in 43
metal-poor stars (Jonsell+, 2005)
Authors: Jonsell, K.; Edvardsson, B.; Gustafsson, B.; Magain, P.;
Nissen, P. E.; Asplund, M.
2005yCat..34400321J Altcode:
Data from an analysis of 43 metal-poor field stars with iron abundances
[Fe/H] ranging from -0.4 to -3.0dex are presented here. Photometric
data, stellar velocities, masses, fundamental parameters, spectral
classifications and notations of possible binarity are given. Tables
with line data for O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Fe, Ni and
Ba, equivalent widths and resulting abundances are also given. (4
data files).

---------------------------------------------------------
Title: Cool stars in the Gaia photometric system
Authors: Heiter, U.; Piskunov, N.; Gustafsson, B.; Jordi, C.; Carrasco,
J. M.
2005ESASP.560..635H Altcode: 2005csss...13..635H
No abstract at ADS

---------------------------------------------------------
Title: Carbon stars in local group dwarf galaxies: C &amp;
O abundances
Authors: Wahlin, R.; Eriksson, K.; Gustafsson, B.; Hinkle, K. H.;
Lambert, D. L.; Ryde, N.; Westerlund, B.
2005ESASP.560.1017W Altcode: 2005csss...13.1017W
No abstract at ADS

---------------------------------------------------------
Title: Concluding remarks
Authors: Gustafsson, Bengt
2005IAUS..228..603G Altcode:
Attempts are made to summarize some main points and results discussed
at the IAU Symposium No. 228 in Paris, May 2005. It is concluded that,
although the situation in areas pioneered by F. and M. Spite is nowdays
rather complex, some important progress has recently been made, and
more is expected to occur within the next few years if the level of
ambition in the astronomical community is kept at the high level set
by the pioneers.

---------------------------------------------------------
Title: Oxygen abundances in metal-poor subgiants
Authors: García Pérez, A. E.; Asplund, M.; Primas, F.; Nissen,
P. E.; Gustafsson, B.
2005IAUS..228..257G Altcode: 2005IAUS..228..257P
There seems to be no consensus on the [O/Fe] values found in
metal-poor stars nor their trend with metallicity: different
indicators give different results. We present here [O/Fe] derived
from three different oxygen abundance indicators ([OI], OI and OH UV
lines) for a sample of thirteen subgiant stars with metallicities
in the range -3≤[Fe/H]≤-1.5. Oxygen and iron abundances were
determined from the analysis of high S/N spectra acquired with
the UVES spectrograph at VLT. We found good agreement between
[O/Fe] estimates based on OH and the estimates based on [Oi]
(mean difference∼-0.09±0.25(s.d.)), although the scatter is not
insignificant. Unfortunately, good agreement is not reached for
the third indicator (mean difference∼0.19±0.22(s.d.)). Our [OI]
and OH-based estimates do not show a well defined linear trend with
metallicity. Another interesting result is that the abundances based
on molecular lines ([O/Fe]∼0.45) are in general lower than previous
published results for turn-off stars even though a lower solar oxygen
abundance (A(O)=8.74) was assumed.

---------------------------------------------------------
Title: Stochastic chemical enrichment in the early Galaxy
Authors: Karlsson, Torgny; Gustafsson, Bengt
2005IAUS..228..231K Altcode:
A stochastic model of the chemical enrichment of metal-poor systems
by core-collapse supernovae is used to study the scatter in relative
elemental abundances in extremely metal-poor stars. The resulting
scatter in abundance ratios is demonstrated to be crucially dependent
on the as yet uncertain supernovae yields. The relatively small
star-to-star scatter observed in many of these abundance ratios, e.g. by
Cayrel et al. (2004), is tentatively explained by the averaging of a
large number of contributing supernovae and by the cosmic selection
effects favoring contributions from supernovae in a certain mass
range for the most metal-poor stars. "Spurs", very narrow sequences
in abundance-ratio diagrams, may disclose a single-supernova origin
of the elements of the stars on the sequence and would thus be an
indication of an unmixed interstellar medium (ISM). Verification of the
existence of such features, called single supernova sequences (SSSs),
is challenging. This will require samples of several hundred stars
with abundance ratios observed to accuracies of 0.05 dex or better.

---------------------------------------------------------
Title: Phoenix Spectra of Carbon Stars in the LMC
Authors: Wahlin, Rurik; Eriksson, Kjell; Gustafsson, Bengt; Hinkle,
Kenneth; Lambert, David; Ryde, Nils; Westerlund, Bengt
2005hris.conf..439W Altcode:
We present high-resolution, IR-spectra of Carbon stars in the LMC
obtained with the Phoenix spectrometer on the Gemini South 8-meter
telescope. This is part of an ongoing project where CNO abundances
and 12C/13C ratios of Carbon Stars are determined in Local-Group
dwarf galaxies of different metallicities. The spectra obtained so
far cover two 20 cm 1 wide spectral regions in the H and K bands. The
bands contain lines from CN, C2, and CO, with 12C and 13C isotopes, and
several atomic lines. The spectra are analyzed with synthetic spectra
of model atmospheres from the MARCS spherical-model-atmosphere code.

---------------------------------------------------------
Title: The Abundance of Elements in Cool Stars, as Determined from
High-Resolution 1 5 μm Spectroscopy
Authors: Ryde, Nils; Gustafsson, Bengt; Eriksson, Kjell; Wahlin, Rurik
2005hris.conf..365R Altcode: 2004astro.ph..7340R
We review the field of abundance determinations of elements in cool
stars, with special interest paid to determinations based on analyses
of high-resolution, 1 5 μm spectra. We discuss the current status,
problems, and challenges of exploring high-resolution, near-infrared
spectra. In particular, advantages and drawbacks are pointed out. A few
examples of current, chemical-abundance determinations are highlighted
and, finally, we discuss the development and future prospects of
the field.

---------------------------------------------------------
Title: Chemical abundances in 43 metal-poor stars
Authors: Gustafsson, Bengt; Asplund, Martin; Edvardsson, Bengt;
Jonsell, Karin; Magain, Pierre; Nissen, Poul Erik
2005IAUS..228..259G Altcode:
We have derived abundances of O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Fe,
Ni and Ba for 43 metal-poor field stars, mostly stars at the turn-off
point and on the subgiant branch, in the interval {-}3.0{[Fe/H]{. The
analysis is differential relative to the Sun. Oxygen abundances,
with consideration of NLTE effects, were derived from the OI 777.4 nm
triplet lines. We find [O/Fe] to gradually increase with decreasing
[Fe/H], though considerably slower than has earlier been obtained from
OH lines in the UV. A scatter in [O,Mg,Ca,Ti/Fe] at a given [Fe/H] is
found and we argue that this scatter is partly real. The deviations from
the mean trends of abundance ratios vs [Fe/H] are found to correlate
in non-trivial ways for different abundances. Similar trends are found
from results of accurate studies by other groups. This seems to give
further evidence for the hypothesis that the stars once formed in
different subsystems, with different star-formation rates.The paper
is in press in A&amp;A, may be obtained as astro-ph/0505118.

---------------------------------------------------------
Title: Subgiants as probes of galactic chemical evolution
Authors: Thorén, P.; Edvardsson, B.; Gustafsson, B.
2004A&A...425..187T Altcode: 2004astro.ph..7260T
Chemical abundances for 23 candidate subgiant stars have been derived
with the aim at exploring their usefulness for studies of galactic
chemical evolution. High-resolution spectra from ESO CAT-CES and
NOT-SOFIN covered 16 different spectral regions in the visible part
of the spectrum. Some 200 different atomic and molecular spectral
lines have been used for abundance analysis of ∼30 elemental
species. The wings of strong, pressure-broadened metal lines were
used for determination of stellar surface gravities, which have
been compared with gravities derived from HIPPARCOS parallaxes and
isochronic masses. Stellar space velocities have been derived from
HIPPARCOS and Simbad data, and ages and masses were derived with
recent isochrones. Only 12 of the stars turned out to be subgiants,
i.e. on the “horizontal” part of the evolutionary track between the
dwarf- and the giant stages. The abundances derived for the subgiants
correspond closely to those of dwarf stars. With the possible exceptions
of lithium and carbon we find that subgiant stars show no “chemical”
traces of post-main-sequence evolution and that they are therefore very
useful targets for studies of galactic chemical evolution. Based
on observations made at ESO, La Silla. Based on observations made
at NOT, La Palma. Tables 1 and 2 are only available in electronic
form at http://www.edpsciences.org

---------------------------------------------------------
Title: On the Oxygen Abundance of HE 0107-5240
Authors: Bessell, M. S.; Christlieb, N.; Gustafsson, B.
2004ApJ...612L..61B Altcode: 2004astro.ph..1450B
We have determined the oxygen abundance of HE 0107-5240 from UV-OH
lines detected in VLT/UVES spectra. Using a plane-parallel LTE
model atmosphere, we derive [O/Fe]=+2.3, and a similar analysis of
CD -38°245 yields [O/Fe]=+0.9. We estimate systematic errors due to
three-dimensional effects to be on the order of 0.3-0.4 dex. That is,
our derived O abundances are likely overestimates: effects from thermal
inhomogeneities due to convection may require that the abundances
should be reduced by 0.3-0.4 dex or even more. Radial velocity data
for HE 0107-5240 based on high-resolution spectra show that over
a time span of 373 days, the radial velocity was constant at 44.5
km s-1, with a 1 σ scatter of the measurements of 0.5 km
s-1. However, it cannot yet be ruled out that HE 0107-5240 is
a very long period and/or low amplitude binary. These results provide
new constraints on scenarios for the origin of the abundance pattern
of HE 0107-5240. In particular, it seems unlikely that the large
overabundances of CNO have been produced in a medium-mass asymptotic
giant branch star that later evolved into a white dwarf. The oxygen
abundance of HE 0107-5240 is significantly smaller than the prediction
of Umeda &amp; Nomoto from calculated yields of an ~25 Msolar
Population III star exploding as a supernova of low explosion energy
(Eexp=3×1050 ergs) with mixing and fallback. The
scenario of Limongi et al., involving two Population III supernovae,
predicts an oxygen abundance of [O/Fe]=+4.1 for HE 0107-5240, in
strong contradiction to the observed value. In conclusion, none
of the above-mentioned scenarios, in their present realizations,
can satisfactorily explain the abundance pattern of HE 0107-5240. Based on observations collected at the European Southern Observatory,
Paranal, Chile (proposal 70.D-0009).

---------------------------------------------------------
Title: The R Coronae Borealis stars: carbon abundances from forbidden
carbon lines
Authors: Pandey, Gajendra; Lambert, David L.; Rao, N. Kameswara;
Gustafsson, Bengt; Ryde, Nils; Yong, David
2004MNRAS.353..143P Altcode: 2004MNRAS.tmp..228P; 2004astro.ph..5600P
Spectra of several R Coronae Borealis (RCB) stars at maximum light
have been examined for the [CI] 9850- and 8727-Åabsorption lines. The
9850-Åline is variously blended with an FeII and CN lines, but positive
identifications of the [CI] line are made for RCrB and SUTau. The
8727-Åline is detected in the spectrum of the five stars observed
in this wavelength region. Carbon abundances are derived from the
[CI] lines using the model atmospheres and atmospheric parameters
used by Asplund et al. Although the observed strength of a CI
line is constant from cool to hot RCB stars, the strength is lower
than predicted by an amount equivalent to a factor of 4 reduction
of the gf-value of a line. Asplund et al. dubbed this `the carbon
problem' and discussed possible solutions. The [CI] 9850-Åline
seen clearly in RCrB and SUTau confirms the magnitude of the carbon
problem revealed by the CI lines. The [CI] 8727-Åline measured in
five stars shows an enhanced carbon problem. The gf-value required
to fit the observed [CI] 8727-Åline is a factor of 15 less than the
well-determined theoretical gf-value. We suggest that the carbon problem
for all lines may be alleviated to some extent by a chromospheric-like
temperature rise in these stars. The rise far exceeds that predicted
by our non-local thermodynamic equilibrium calculations, and requires
a substantial deposition of mechanical energy.

---------------------------------------------------------
Title: VizieR Online Data Catalog: Chemical abundances of 23 subgiants
&amp; giants (Thoren+, 2004)
Authors: Thoren, P.; Edvardsson, B.; Gustafsson, B.
2004yCat..34250187T Altcode:
Chemical abundances, stellar parameters, and atomic and molecular line
data are given for a study of 23 subgiant and giant stars in the solar
vicinity. With the exception of Li and possibly C we show that subgiant
stars show no "chemical" traces of post-main-sequence evolution and that
they are therefore and because of their simple age dating very useful
targets for studies of galactic chemical evolution. (3 data files).

---------------------------------------------------------
Title: HE 0107-5240, a Chemically Ancient Star. I. A Detailed
Abundance Analysis
Authors: Christlieb, N.; Gustafsson, B.; Korn, A. J.; Barklem, P. S.;
Beers, T. C.; Bessell, M. S.; Karlsson, T.; Mizuno-Wiedner, M.
2004ApJ...603..708C Altcode: 2003astro.ph.11173C
We report on a detailed abundance analysis of HE 0107-5240, a halo giant
with [Fe/H]NLTE=-5.3. This star was discovered in the course
of follow-up medium-resolution spectroscopy of extremely metal-poor
candidates selected from the digitized Hamburg/ESO objective-prism
survey. On the basis of high-resolution VLT/UVES spectra, we derive
abundances for eight elements (C, N, Na, Mg, Ca, Ti, Fe, and Ni)
and upper limits for another 12 elements. A plane-parallel LTE model
atmosphere has been specifically tailored for the chemical composition
of HE 0107-5240. Scenarios of the origin of the abundance pattern
observed in the star are discussed. We argue that HE 0107-5240 is
most likely not a post-asymptotic giant branch star and that the
extremely low abundances of the iron-peak and other elements are
not due to selective dust depletion. The abundance pattern of HE
0107-5240 can be explained by preenrichment from a zero-metallicity
Type II supernova (SN II) of 20-25 Msolar, plus either
self-enrichment with C and N or production of these elements in the
asymptotic giant branch phase of a formerly more massive companion,
which is now a white dwarf. However, significant radial velocity
variations have not been detected within the 52 days covered by our
moderate- and high-resolution spectra. Alternatively, the abundance
pattern can be explained by enrichment of the gas cloud from which
HE 0107-5240 formed by a 25 Msolar first-generation
star exploding as a subluminous SN II, as proposed by Umeda &amp;
Nomoto. We discuss consequences of the existence of HE 0107-5240 for
low-mass star formation in extremely metal-poor environments and for
currently ongoing and future searches for the most metal-poor stars
in the Galaxy. Based on observations collected at the European
Southern Observatory, Paranal, Chile (proposal 268.D-5745).

---------------------------------------------------------
Title: Physical properties of cometary dust from light scattering
and thermal emission
Authors: Kolokolova, L.; Hanner, M. S.; Levasseur-Regourd, A. -Ch.;
Gustafson, B. Å. S.
2004come.book..577K Altcode:
This chapter explores how physical properties of cometary dust (size
distribution, composition, and grain structure) can be obtained from
characteristics of the electromagnetic radiation that the dust scatters
and emits. We summarize results of angular and spectral observations
of brightness and polarization in continuum as well as thermal emission
studies. We review methods to calculate light scattering starting with
solutions to Maxwell's equations as well as approximations and specific
techniques used for the interpretation of cometary data. Laboratory
experiments on light scattering and their results are also reviewed. We
discuss constraints on physical properties of cometary dust based on
the results of theoretical and experimental simulations. At the present,
optical and thermal infrared observations equally support two models of
cometary dust: (1) irregular polydisperse particles with a predominance
of submicrometer particles, or (2) porous aggregates of submicrometer
particles. In both models the dust should contain silicates and some
absorbing material. Comparison with the results obtained by other than
lightscattering methods can provide further constraints.

---------------------------------------------------------
Title: Atmospheres of AGB Stars
Authors: Gustafsson, Bengt; Höfner, Susanne
2004agbs.book..149G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Laboratory Simulations
Authors: Huebner, W. F.; Walker, J.; Gustafson, B.
2004cosp...35.2021H Altcode: 2004cosp.meet.2021H
Geophysical properties of near-Earth objects (NEOs) can best
be studied using radio tomography and seismology. Reflection and
transmission radio tomography is best suited for measuring the complex
electric permittivity of poorly conducting materials to reveal the
internal structure of NEOs. Such NEOs are primarily comet nuclei
and carbonaceous asteroids. Seismic experiments are most suitable
for studying elastic properties of consolidated materials to reveal
material strengths of stony and iron-nickel asteroids. Thus, the two
methods are complementary for investigating comets and asteroids of
all types. Analysis of reflection and transmission radio tomography of
heterogeneous irregular shaped bodies is very difficult. Scattering by
internal and outer boundaries, differences in the refractive indices
of heterogeneous materials, and attenuation by electric conductivity
complicate the analyses. For this reason laboratory simulations with
scaled objects and scaled wavelengths is extremely useful to check
the reliability of inversion techniques of radio signals to arrive
at the interior structure of an NEO. Another approach to obtaining
quantitative information on the composition and structure of an NEO
is through induced seismology. There are two approaches to producing
seismic waves: small explosive charges and impactors. Experimental
work has been performed in the laboratory to examine the impulse
delivered by explosives. Wave travel times can be used to back out basic
material properties and first order structure of an NEO. For example, if
distinct arrival pulses for P and S waves are recorded and the explosive
initiation/impact time and location are known, then it is possible to
determine the elastic properties of bulk and shear modulus. Reflections
in the seismograms allow a determination of material boundaries in an
NEO. Original arrival time is important since Q numbers for stony NEO
material are presumed to be high, as they were on the Moon, and thus
it is expected that there will be extensive ringing and noise. Other
types of NEO materials will have differing seismic characteristics.

---------------------------------------------------------
Title: Nucleosynthesis and future stellar abundance determinations
Authors: Gustafsson, B.
2004EAS....11...21G Altcode:
The most remarkable future possibilities of stellar spectroscopy and
abundance analysis are discussed, and their consequences for the further
understanding of stellar nucleosynthesis are commented on. It is argued
that it will soon be possible to put the exploration of the origin
of the chemical elements and the study of the chemical evolution of
galaxies on a solid empirical ground, through systematic observations
of yields from AGB stars and planetary nebulae, Wolf-Rayet stars
and supernovae, and of well-determined abundance trends in different
stellar populations.

---------------------------------------------------------
Title: Model Atmospheres and Stellar Abundance Analysis
Authors: Gustafsson, Bengt
2004oee..symp..102G Altcode: 2004oee..symp..104G
Model atmospheres have now been used in the analysis of stellar
abundances for more than 50 years. During this period, remarkable
progress has been made in the understanding of the physics of stellar
atmospheres and in their modeling. The advances made in the observation
of stellar spectra are even more remarkable. The question addressed here
is whether comparable progress also can be found in the accuracy of the
resulting abundances. It seems that this is not the case to the extent
one might have expected, and the reasons for this are discussed. A
number of recent developments in model atmosphere construction and
in basic atomic and molecular data may, however, suggest that we are
now approaching a situation with significantly diminished systematic
errors in stellar abundances.

---------------------------------------------------------
Title: Resonant Structure in the Kuiper Disk: An Asymmetric Plutino
Disk
Authors: Holmes, Elizabeth K.; Dermott, Stanley F.; Gustafson, Bo
Å. S.; Grogan, Keith
2003ApJ...597.1211H Altcode:
In order to develop a dynamical model of the Kuiper disk, we run
numerical integrations of particles originating from source bodies
trapped in the 3:2 external mean motion resonance with Neptune to
determine what percentage of particles remain in the resonance
for a variety of particle and source body sizes. The dynamical
evolution of the particles is followed from source to sink with
Poynting-Robertson light drag, solar wind drag, radiation pressure,
the Lorentz force, neutral interstellar gas drag, and the effects of
planetary gravitational perturbations included. We find that the number
of particles in the 3:2 resonance increases with decreasing β (i.e.,
increasing particle size) for the cases in which the initial source
bodies are small (&lt;=10 km in diameter) and that the percentage
of particles in resonance is not significantly changed by either
the addition of the Lorentz force, as long as the potential of the
particles is small (~5 V), or the effect of neutral interstellar gas
drag. The brightness of the entire Kuiper disk is calculated using a
model composed of 500 μm diameter particles and fits well with upper
limits to the Kuiper disk brightness and previous estimates. A disk
with a size-frequency distribution weighted toward large particles,
which are more likely to remain in resonance, may have a stronger,
more easily identifiable resonant signature than a disk composed of
small particles.

---------------------------------------------------------
Title: Development and testing of quartz crystal microbalances for
missions to measure particle fluxes from minor solar system bodies
Authors: Stephens, J.; Gustafson, B.; Waldemarsson, K.
2003EAEJA.....4478S Altcode:
An instrument is being developed to measure the mass flux and size
distribution of particles striking a spacecraft operating in the
vicinity of airless minor solar system bodies including asteroids,
small moons, and comets. We are developing and testing quartz crystal
microbalances (QCMs) with robust particle capture coatings coupled with
advanced oscillator electronics. The instrument is an extension the QCMs
that are part of the Grain Impact Analyzer and Dust Accumulator (GIADA)
instrument that will be carried aboard the European Space Agency (ESA)
Rosetta Spacecraft. Particle capture coatings are required that will
survive the interplanetary environment for long periods. The coatings
should provide effective particle capture and coupling to a QCM to
allow mass measurements during rendezvous encounters. We are using thin
aerogel layers for particle capture since aerogel consists of a very
low density (99% void volume) web of rigidly connected, sub-micron
silica fibers. Sophisticated oscillator circuits are required to
oscillate a QCM with a thick particle capture coating. Previously
we reported on measurements of the electro-mechanical properties of
thick (100 micrometer) layers of aerogel bonded to QCMs. In this work
we report the results of firing small (100-500 micrometer) grains
at aerogel-coated QCMs using a light gas gun at the University of
Florida. The efficiency of particle capture by the aerogel layer as
a function of particle size, velocity, and material composition was
measured. The results will help guide the design of a second generation
of aerosol capture coatings for QCMs.

---------------------------------------------------------
Title: ISO-SWS calibration and the accurate modelling of cool-star
atmospheres. III. A0 to G2 stars
Authors: Decin, L.; Vandenbussche, B.; Waelkens, K.; Eriksson, C.;
Gustafsson, B.; Plez, B.; Sauval, A. J.
2003A&A...400..695D Altcode: 2002astro.ph..7636D
Vega, Sirius, beta Leo, alpha Car and alpha Cen A belong to a
sample of twenty stellar sources used for the calibration of
the detectors of the Short-Wavelength Spectrometer on board the
Infrared Space Observatory (ISO-SWS). While general problems with
the calibration and with the theoretical modelling of these stars
are reported in {Decin} et al. (\cite{Decin2000b}), each of these
stars is discussed individually in this paper. As demonstrated in
{Decin} et al. (\cite{Decin2000b}), it is not possible to deduce the
effective temperature, the gravity and the chemical composition from
the ISO-SWS spectra of these stars. But since ISO-SWS is absolutely
calibrated, the angular diameter (thetad ) of these
stellar sources can be deduced from their ISO-SWS spectra, which
consequently yields the stellar radius (R), the gravity-inferred mass
(Mg) and the luminosity (L) for these stars. For Vega,
we obtained thetad = 3.35 +/- 0.20 mas, R = 2.79 +/-
0.17 Rsun, Mg = 2.54 +/- 1.21 Msun
and L = 61 +/- 9 Lsun; for Sirius thetad =
6.17 +/- 0.38 mas, R = 1.75 +/- 0.11 Rsun, Mg
= 2.22 +/- 1.06 Msun and L = 29 +/- 6 Lsun;
for beta Leo thetad = 1.47 +/- 0.09 mas, R = 1.75 +/-
0.11 Rsun, Mg = 1.78 +/- 0.46 Msun
and L = 15 +/- 2 Lsun; for alpha Car thetad =
7.22 +/- 0.42 mas, R = 74.39 +/- 5.76 Rsun, Mg
= 12.80+24.95-6.35 Msun and L = 14573
+/- 2268 Lsun and for alpha Cen A thetad = 8.80
+/- 0.51 mas, R = 1.27 +/- 0.08 Rsun, Mg = 1.35
+/- 0.22 Msun and L = 1.7 +/- 0.2 Lsun. These
deduced parameters are confronted with other published values and the
goodness-of-fit between observed ISO-SWS data and the corresponding
synthetic spectrum is discussed. Based on observations with ISO,
an ESA project with instruments funded by ESA Member States (especially
the PI countries France, Germany, The Netherlands and the UK) and with
the participation of ISAS and NASA.}\fnmsep\thanks{Appendices A and
B are only available in electronic form at http://www.edpsciences.org}

---------------------------------------------------------
Title: ISO-SWS calibration and the accurate modelling of cool-star
atmospheres. IV. G9 to M2 stars
Authors: Decin, L.; Vandenbussche, B.; Waelkens, C.; Decin, G.;
Eriksson, K.; Gustafsson, B.; Plez, B.; Sauval, A. J.
2003A&A...400..709D Altcode: 2002astro.ph..7653D
A detailed spectroscopic study of 11 giants with spectral type
from G9 to M2 is presented. The 2.38-4.08 mu m wavelength-range of
band 1 of ISO-SWS (Short-Wavelength Spectrometers on board of the
Infrared Space Observatory) in which many different molecules -
with their own dependence on each of the stellar parameters - are
absorbing, enables us to estimate the effective temperature, the
gravity, the microturbulence, the metallicity, the CNO-abundances,
the 12C/13C-ratio and the angular diameter from
the ISO-SWS data. Using the Hipparcos' parallax, the radius, luminosity
and gravity-inferred mass are derived. The stellar parameters obtained
are in good agreement with other published values, though also some
discrepancies with values deduced by other authors are noted. For a
few stars (delta Dra, xi Dra, alpha Tuc, H Sco and alpha Cet) some
parameters - e.g. the CNO-abundances - are derived for the first
time. By examining the correspondence between different ISO-SWS
observations of the same object and between the ISO-SWS data and
the corresponding synthetic spectrum, it is shown that the relative
accuracy of ISO-SWS in band 1 (2.38-4.08 mu m) is better than 2%
for these high-flux sources. The high level of correspondence between
observations and theoretical predictions, together with a confrontation
of the estimated Teff (ISO) value with Teff values
derived from colours - which demonstrates the consistency between V-K,
BCK, Teff and thetad derived from
optical or IR data - proves that both the used MARCS models to derive
the stellar quantities and the flux calibration of the ISO-SWS detectors
have reached a high level of reliability. Based on observations
with ISO, an ESA project with instruments funded by ESA Member States
(especially the PI countries France, Germany, The Netherlands and the
UK) and with the participation of ISAS and NASA. Appendices A-D
are only available in electronic form at http://www.edpsciences.org

---------------------------------------------------------
Title: ISO-SWS calibration and the accurate modelling of cool-star
atmospheres. II. General results
Authors: Decin, L.; Vandenbussche, B.; Waelkens, C.; Eriksson, K.;
Gustafsson, B.; Plez, B.; Sauval, A. J.; Hinkle, K.
2003A&A...400..679D Altcode: 2002astro.ph..7621D
The fine calibration of the ISO-SWS detectors (Infrared Space
Observatory - Short Wavelength Spectrometer) has proven to be a delicate
problem. We therefore present a detailed spectroscopic study in the
2.38-12 mu m wavelength range of a sample of 16 A0-M2 stars used for
the calibration of ISO-SWS. By investigating the discrepancies between
the ISO-SWS data of these sources, the theoretical predictions of their
spectra, the high-resolution FTS-KP (Kitt Peak) spectrum of alpha Boo
and the solar FTS-ATMOS (Atmospheric Trace Molecule Spectroscopy)
spectrum, both calibration problems and problems in computing the
theoretical models and the synthetic spectra are revealed. The
underlying reasons for these problems are sought for and the impact
on the further calibration of ISO-SWS and on the theoretical modelling
is discussed extensively. Based on observations with ISO, an ESA
project with instruments funded by ESA Member States (especially the
PI countries France, Germany, The Netherlands and the UK) and with
the participation of ISAS and NASA. Appendix is only available
in electronic form at http://www.edpsciences.org

---------------------------------------------------------
Title: Imaging polarimetry of stellar light scattered in detached
shells around the carbon stars R Scl and U Ant
Authors: González Delgado, D.; Olofsson, H.; Schwarz, H. E.; Eriksson,
K.; Gustafsson, B.; Gledhill, T.
2003A&A...399.1021G Altcode:
Imaging polarimetry has been used to study the extended, detached
circumstellar shells around the bright carbon stars <ASTROBJ>R
Scl</ASTROBJ> and <ASTROBJ>U Ant</ASTROBJ>. The observations were
done in two narrow band filters centred on the resonance lines of
neutral K and Na, but much broader than the expected line widths. The
polarimetric data reveal brightness distributions, in both cases,
which are in perfect agreement with previous observations of scattered
light obtained through direct imaging techniques. The total intensity
images towards <ASTROBJ>R Scl</ASTROBJ> outline, in both filters,
circular disk-like distributions out to a radius of ~21arcsec , where
the intensity drops sharply. The polarised intensity images reveal,
however, that the scattering occurs in a geometrically thin shell. The
degree of polarisation reaches values of ~35% in both filters. The
imaging polarimetry observations of <ASTROBJ>U Ant</ASTROBJ> reveal a
somewhat more complex structure, where the existence of several shells
can be discerned. The polarised scattered light comes from a component,
at a radius of ~50arcsec from the star, which lies outside the region
where the bulk of the light is scattered. The latter comes from a
dominating shell at ~43arcsec , which coincides spatially with the
detached gas shell inferred from CO radio line data, and there may be
another two shells inside this. The polarisation degree reaches ~50%
in the outer component. We model, with a code based on the Monte Carlo
method, the scattered emission under the assumption of dust scattering,
using the observed polarised brightness distributions as constraints. In
the case of <ASTROBJ>R Scl</ASTROBJ> we found that the polarised, as
well as the total, light distributions can be explained by scattering
in a 2arcsec wide shell of radius 20arcsec containing a dust mass of
~2*E-6 Msun. This dust shell is also responsible
for the thermal dust emission measured by IRAS. There is room, up to 30%
of the total scattered flux, for other scattering agents. Comparison
with CO radio line data shows that this dust shell probably lies outside
the detached CO gas shell. In the case of <ASTROBJ>U Ant</ASTROBJ> the
modelling explains the outer component in terms of a 5arcsec wide shell
at a radius of about 52arcsec with a dust mass of ~4*E-6
Msun. This is also the dust shell responsible for the
emission measured by IRAS. However, the bulk of the scattered light
cannot in this case be due to scattering by dust. In accordance
with a discussion in a previous paper we attribute the remaining,
unpolarised, scattering to the KI and Na D resonance lines. In both
cases we found evidence that a dust shell has separated from the rest
of the circumstellar medium. This may be due to gas-grain drift,
or to hydrodynamical effects, which may also explain the complex
multiple-shell structure seen towards <ASTROBJ>U Ant</ASTROBJ>. The
model results are very dependent on the grain size distribution,
and the observational data can only be reconciled with a very steep
decline in grain size. Based on observations using the 3.6 m
telescope of the European Southern Observatory, La Silla, Chile.

---------------------------------------------------------
Title: Carbon Stars in the Local Group -- Detailed Abundance Analysis
of Carbon Stars in the LMC
Authors: Lambert, David L.; Eriksson, Kjell; Gustafsson, Bengt;
Hinkle, Kenneth H.; Ryde, Nils; Wahlin, Rurik; Westerlund, Bengt
2003noao.prop..265L Altcode:
Using the Phoenix on Gemini we propose to observe a sample of carbon
stars in the LMC in four different wavelength regions at high spectral
resolution and with high S/N. The spectra will provide CO, CN, and
C_2 and atomic lines from which elemental and isotopic C, N, and O
abundances and metal abundances will be derived by an approach similar
to that previously used for Galactic field carbon stars (Lambert et
al. 1986). We will then be able to calibrate lower resolution spectra
of carbon stars in other Local Group galaxies. The observational study
of carbon stars is a key to understanding late evolutionary stages
and nucleosynthesis of low mass stars.

---------------------------------------------------------
Title: Integrated Study of the Physical Characteristics of Primitive
Solar System Bodies
Authors: Kolokolova, L.; Gustafson, B. A. S.; Lara, L. M.; Licandro,
J.; Tozzi, G. P.
2003RMxAC..16...94K Altcode:
Primitive bodies (comets, Centaurs, trans-Neptunian objects, etc.) are
the best-preserved remnants of the Solar Nebula. Their composition and
structure harbor clues to the origin of solar and exosolar planets
and the evolution of protoplanetary disks. The capabilities of the
Gran Telescopio Canarias (GTC) and its instrumentation provide us a
unique opportunity to accomplish an integrated study of the physical
properties of these remote small bodies.

---------------------------------------------------------
Title: A Grid of Model Atmospheres for Cool Stars
Authors: Gustafsson, B.; Edvardsson, B.; Eriksson, K.; Mizuno-Wiedner,
M.; Jørgensen, U. G.; Plez, B.
2003ASPC..288..331G Altcode: 2003sam..conf..331G
An extensive grid of spherically symmetric model atmospheres of stars
with 1. 2500 K ≤ Teff ≤ 8000 K, 2. -1.0 ≤ log g
(= log GM/R2) ≤ 5.0 (cgs units), 3. different combinations
of M and R, 4. -5 ≤ [A/H] ≤ 1, and 5. a number of CNO abundance
combinations is being constructed with an updated version of the
MARCS program. Special efforts are made to reach accuracy and
completeness in opacity data. Opacity sampling is used with 10,000
and (for a minority of models) 90,000 wavelength points. Synthetic
spectra are also provided. We shall show how these classical
models may be used to illustrate important physical properties of cool
star atmospheres.

---------------------------------------------------------
Title: The Current Status in the Modelling of Stellar Atmospheres
Authors: Gustafsson, B.
2003IAUS..210....3G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: A New MARCS Grid
Authors: Gustafsson, B.; Edvardsson, B.; Eriksson, K.; Jørgensen,
U. G.; Mizuno-Wiedner, M.; Plez, B.
2003IAUS..210P..A4G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The virtue of looking in another direction
Authors: Gustafsson, Bengt
2003UppOR..59....1G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Atmospheres of AGB Stars
Authors: Gustafsson, Bengt; Höfner, Susanne
2003agbs.conf..149G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: A MARCS Grid of S-Type Star Atmospheres
Authors: Plez, B.; van Eck, S.; Jorissen, A.; Edvardsson, B.; Eriksson,
K.; Gustafsson, B.
2003IAUS..210P..A2P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Dynamical evolution of dust particles in the Kuiper disk
Authors: Holmes, Elizabeth K.; Dermott, Stanley F.; Gustafson, Bo A. S.
2002ESASP.500...43H Altcode: 2002acm..conf...43H
A Kuiper belt disk will have a resonant structure, arising because
a subset of Kuiper belt objects, the Plutinos, are in the 3:2 mean
motion resonance with Neptune. We run numerical integrations of
particles originating from Plutinos to determine what percentage of
particles remain in the resonance for a variety of particle and source
body sizes. The dynamical evolution of the particles is followed
from source to sink with Poynting-Robertson light drag, solar wind
drag, radiation pressure, the Lorentz force, neutral interstellar
gas drag, and the effects of planetary gravitational perturbations
included. The percentage of particles in the 3:2 resonance increases
with decreasing β for the cases where the source bodies are small
(≤10 km), and is not significantly changed by either the addition
of neutral interstellar gas drag or the Lorentz force, as long as the
potential of the particles is small (U≍5 V).

---------------------------------------------------------
Title: A stellar relic from the early Milky Way
Authors: Christlieb, N.; Bessell, M. S.; Beers, T. C.; Gustafsson, B.;
Korn, A.; Barklem, P. S.; Karlsson, T.; Mizuno-Wiedner, M.; Rossi, S.
2002Natur.419..904C Altcode: 2002astro.ph.11274C
The chemical composition of the most metal-deficient stars largely
reflects the composition of the gas from which they formed. These
old stars provide crucial clues to the star formation history and the
synthesis of chemical elements in the early Universe. They are the local
relics of epochs otherwise observable only at very high redshifts; if
totally metal-free (`population III') stars could be found, this would
allow the direct study of the pristine gas from the Big Bang. Earlier
searches for such stars found none with an iron abundance less than
1/10,000 that of the Sun, leading to the suggestion that low-mass
stars could form from clouds above a critical iron abundance. Here we
report the discovery of a low-mass star with an iron abundance as low
as 1/200,000 of the solar value. This discovery suggests that population
III stars could still exist-that is, that the first generation of stars
also contained long-lived low-mass objects. The previous failure to
find them may be an observational selection effect.

---------------------------------------------------------
Title: Electromagnetic and Light Scattering by Nonspherical Particle
Authors: Gustafson, Bo Åke Sture; Kolokolova, Ludmilla; Videen, Gorden
2002elsn.conf.....G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Dust in Interplanetary Space
Authors: Gustafson, B. Å. S.
2002AAS...200.6602G Altcode: 2002BAAS...34Q.754G
I will critically review the main results on dust in interplanetary
space and its diversity based on deep space probing. The dust impact
rate on the Ulysses and Galileo dust detectors can be discerned
as depending on the changing viewing geometry of the detector as
the spacecraft spins and moves along its orbit. This reveals the
existence of dynamically separate populations, evidence for these
will be presented and interpretations in terms of the progenitors
will be discussed. The decreasing flux with increasing size or mass in
combination with typical detector areas of the order of one square meter
means that the smallest grains in the micron and submicron range are
sampled while statistically very little or no information is obtained
on larger grains. The next step will be the study of larger grains and
their retrieval for analysis in the laboratory. I will address plans
for a large cosmic dust collector in Earth orbit to bring back grains
of tens of microns to Earth for laboratory studies.

---------------------------------------------------------
Title: Erratum: Chemical abundance patterns - fingerprints of
nucleosynthesis in the first stars
Authors: Karlsson, T.; Gustafsson, B.
2002A&A...386..884K Altcode:
Figures 17 and 18 on page 478 were misprinted. The metallicity of
the stars, measured by [Fe/H], was wrongly indicated and one star
was missing. The corrected figures are shown below. No conclusions
are altered.

---------------------------------------------------------
Title: Planetary aerosol monitor/interplanetary dust analyser
Authors: Gustafson, B. Å. S.; Giovane, F.; Waldemarsson, T.;
Kolokolova, L.; Xu, Yu. -I.; McKisson, J.
2002dsso.conf..195G Altcode: 2002IAUCo.181..195G
No abstract at ADS

---------------------------------------------------------
Title: Light scattering by flakes
Authors: Waldemarsson, K. W. T.; Gustafson, B. Å. S.
2002dsso.conf..320W Altcode: 2002IAUCo.181..320W
No abstract at ADS

---------------------------------------------------------
Title: Evolution of cometary grains from studies of comet images
Authors: Kolokolova, L.; Gustafson, B. Å. S.; Jockers, K.;
Lichtenberg, G.
2002dsso.conf..269K Altcode: 2002IAUCo.181..269K
No abstract at ADS

---------------------------------------------------------
Title: Chemical abundance patterns - fingerprints of nucleosynthesis
in the first stars
Authors: Karlsson, T.; Gustafsson, B.
2001A&A...379..461K Altcode: 2001astro.ph..9010K
The interstellar medium of low-metallicity systems undergoing star
formation will show chemical abundance inhomogeneities due to supernova
events enriching the medium on a local scale. If the star formation
time-scale is shorter than the time-scale of mixing of the interstellar
matter, the inhomogeneities are reflected in the surface abundances of
low-mass stars and thereby detailed information on the nucleosynthesis
in the first generations of supernovae is preserved. Characteristic
patterns and substructures are therefore expected to be found, apart
from the large scatter behaviour, in the distributions of stars when
displayed in diagrams relating different element abundance ratios. These
patterns emerge from specific variations with progenitor stellar mass
of the supernova yields and it is demonstrated that the patterns
are insensitive to the initial mass function (IMF) even though the
relative density of stars within the patterns may vary. An analytical
theory of the formation of patterns is presented and it is shown that
from a statistical point of view the abundance ratios can trace the
different nucleosynthesis sites even when mixing of the interstellar
medium occurs. Using these results, it should be possible to empirically
determine supernova yields from the information on relative abundance
ratios of a large, homogeneous sample of extremely metal-poor Galactic
halo stars.

---------------------------------------------------------
Title: One year of Galileo dust data from the Jovian system: 1996
Authors: Krüger, H.; Grün, E.; Graps, A.; Bindschadler, D.; Dermott,
S.; Fechtig, H.; Gustafson, B. A.; Hamilton, D. P.; Hanner, M. S.;
Horányi, M.; Kissel, J.; Lindblad, B. A.; Linkert, D.; Linkert, G.;
Mann, I.; McDonnell, J. A. M.; Morfill, G. E.; Polanskey, C.; Schwehm,
G.; Srama, R.; Zook, H. A.
2001P&SS...49.1285K Altcode: 2001astro.ph..7052K
The dust detector system onboard Galileo has recoding dust impacts in
circumjovian space since the spacecraft was injected into a bound orbit
about Jupiter in December 1995. This is the sixth in a series of papers
dedicated to presenting Galileo and Ulysses dust data. We present data
from the Galileo dust instrument for the period January to December
1996 when the spacecraft completed four orbits about Jupiter (G1, G2,
C3 and E4). Data were obtained as high-resolution realtime science
data or recorded data during a time period of 100 days, or via memory
read-outs during the remaining times. Because the data transmission
rate of the spacecraft is very low, the complete data set (i.e. all
parameters measured by the instrument during impact of a dust particle)
for only 2% (5353) of all particles detected could be transmitted to
Earth; the other particles were only counted. Together with the data
for 2883 particles detected during Galileo's interplanetary cruise
and published earlier, complete data of 8236 particles detected by
the Galileo dust instrument from 1989 to 1996 are now available. The
majority of particles detected are tiny grains (about 10 nm in radius)
originating from Jupiter's innermost Galilean moon Io. These grains
have been detected throughout the Jovian system and the highest impact
rates exceeded 100 min-1. A small number of grains has been
detected in the close vicinity of the Galilean moons Europa, Ganymede
and Callisto which belong to impact-generated dust clouds formed by
(mostly submicrometer sized) ejecta from the surfaces of the moons
(Krüger et al., 1999e. Nature 399, 558). Impacts of submicrometer
to micrometer sized grains have been detected throughout the Jovian
system and especially in the region between the Galilean moons.

---------------------------------------------------------
Title: Systematic Study of the Light Scattering by Aggregates Using
Microwave Analog Experiments and Multifactor Analysis
Authors: Kolokolova, L.; Gustafson, B. A. S.
2001DPS....33.6202K Altcode: 2001BAAS...33.1154K
The unique microwave-analog-to-light-scattering facility at
the University of Florida was used to survey light scattering
characteristics of aggregated particles. Microwave analog
experiments are the fastest and most flexible means to simulate
light scattering by complex cosmic dust particles. This remains
true although powerful computer codes to calculate light scattering
by irregular and inhomogeneous particles have been developed in
recent years. Aggregates of a variety of physical characteristics
(number and size of constituent particles, packing factor) were
built and the scattering was measured at a variety of orientations
(to simulate random orientation) and across a range of wavelengths
(to study spectral properties). To satisfy the requirements of the
statistical multi-factor analysis, known as 2k factorial
design, each of three characteristics of an aggregate (number and size
of particles, aggregate packing factor) could take two fixed values. In
each new experiment only one characteristic differed from those in
the previous experiment. Thus, eight (23) aggregates of
all possible combinations of two values of three parameters were
studied. The values of the characteristics were: 1000 and 5000
for the number of particles in the aggregates; the particle size
corresponded to 0.25 and 0.5 micron; the packing factor (the ratio
of the total volume of the particles to the volume of the aggregate)
was 10 and 50%. The angular and spectral dependencies of intensity and
polarization were obtained for these aggregates. The subjects of the
statistical analysis were color, polarization and polarimetric color
around the scattering angle 90 degree. The statistical analysis showed
that the intensity and polarization are mostly affected by the size of
the constituent particles. The size also determines the shape of the
angular and spectral dependencies and, consequently, the color and
polarimetric color. The packing factor and number of the particles
have less influence on the light-scattering characteristics within
the range studied. NASA supported this work through grants NAG5-8944
and NAG5-6378.

---------------------------------------------------------
Title: The “Planetary Aerosol Monitor/ Interplanetary Dust Analyzer"
Instrument for Comet or Planet Missions.
Authors: Gustafson, B. Å. S.; Giovane, F.; Kolokolova, L.;
Waldemarsson, K. W. T.; Xu, Y. -l.; McKisson, J.
2001DPS....33.5714G Altcode: 2001BAAS...33.1146G
The Laboratory for Astrophysics at the University of Florida
has developed a dust analyzer capable of measuring key particle
physical parameters without causing damage to the dust grains. A
laser illuminates particles passing through an optical system that
measures intensity and polarization of the scattered light at specific
scattering angles. The choice of scattering angles, a sophisticated
light collecting assembly and analysis algorithms allow classification
of the dust particles according to size, shape (equidimensional,
elongated, smooth or angular), composition (dielectric, absorbing, or
metallic) and internal structure (compact or porous). The instrument's
capabilities are illustrated using theoretical simulations, microwave
analogue measurements and tests data obtained using a laboratory
version of the PAM/IDA. We gratefully acknowledge NASA support through
the Planetary Instrument Definition &amp; Development Program, Grant
NAG5-4547.

---------------------------------------------------------
Title: Application of Microwave Analog Measurements to the Modeling
of Titan's Aerosols
Authors: Thomas-Osip, J. E.; Gustafson, B. Å. S.; Kolokolova, L.;
Xu, Y. -l.
2001DPS....33.3804T Altcode: 2001BAAS...33.1109T
A combination of laboratory experiments, theoretical modeling, and
spacecraft in situ observations is employed to characterize the aerosols
in the atmosphere of Titan. The scattering properties of model aerosols
were measured using the Microwave Analog Light Scattering Facility
at the University of Florida and complemented with theoretical
modeling of radiative transfer in Titan's atmosphere. This study
compares these modeling results with photopolarimetric observations
made over a range of phase angles by the Pioneer 11 and Voyagers 1
and 2 spacecraft. Important results of this work include a survey
of the scattering properties of different particle morphologies and
compositions necessary to accurately interpret these observations
without introducing non-physical assumptions about the particles
or requiring additional free parameters to the radiative transfer
models. Previous studies use calculation methods which, due to computing
memory and processing time requirements, a priori exclude many particle
shapes and sizes that the microwave analog laboratory is ideal for
exploring. The goal of the present work, to directly constrain aerosol
physical characteristics, is addressed by studying in a consistent
manner how a variety of aerosol characteristics affect the polarization
and intensity reflected by Titan's atmosphere. Model results for
many particle morphologies do not match the in situ spacecraft
observations. The most plausible physical particle models suggest that
a combination of Rayleigh-like single particles and aggregates that
are larger than those previously suggested and investigated (Rannou
et al. 1997, JGR, 102, 10997; West &amp; Smith 1991, Icarus, 90, 330)
provide the best fit to the existing data. Additional laboratory
experiments and more refined modeling awaits the results of a new
rich observational dataset following the Cassini/Huygens encounter
with Titan in 2004. This work was partially funded by the NASA GSRP.

---------------------------------------------------------
Title: Four years of Ulysses dust data: 1996-1999
Authors: Krüger, H.; Grün, E.; Landgraf, M.; Dermott, S.; Fechtig,
H.; Gustafson, B. A.; Hamilton, D. P.; Hanner, M. S.; Horányi, M.;
Kissel, J.; Lindblad, B. A.; Linkert, D.; Linkert, G.; Mann, I.;
McDonnell, J. A. M.; Morfill, G. E.; Polanskey, C.; Schwehm, G.;
Srama, R.; Zook, H. A.
2001P&SS...49.1303K Altcode: 2001astro.ph..6322K
The Ulysses spacecraft is orbiting the Sun on a highly inclined
ellipse ( i=79°, perihelion distance 1.3 AU, aphelion distance 5.4
AU). Between January 1996 and December 1999 the spacecraft was beyond
3 AU from the Sun and crossed the ecliptic plane at aphelion in May
1998. In this 4-yr period 218 dust impacts were recorded with the dust
detector on board. We publish and analyse the complete data set of
both raw and reduced data for particles with masses 10 -16-
10 -8 g. Together with 1477 dust impacts recorded between
launch of Ulysses and the end of 1995 published earlier (Grün et al.,
Planet. Space Sci. 43 (1995a) 971; Krüger et al., Planet. Space Sci. 47
(1999b) 363), a data set of 1695 dust impacts detected with the Ulysses
sensor between October 1990 and December 1999 is now available. The
impact rate measured between 1996 and 1999 was relatively constant with
about 0.2 impacts per day. The impact direction of the majority of the
impacts is compatible with particles of interstellar origin, the rest
are most likely interplanetary particles. The observed impact rate is
compared with a model for the flux of interstellar dust particles. The
flux of particles several micrometres in size is compared with the
measurements of the dust instruments on board Pioneer 10 and Pioneer 11
beyond 3 AU (Humes, J. Geophys. Res. 85 (1980) 5841). Between 3 and 5
AU, Pioneer results predict that Ulysses should have seen 5 times more
( ∼10 μm sized) particles than actually detected.

---------------------------------------------------------
Title: Imaging of detached shells around the carbon stars <ASTROBJ>R
Scl</ASTROBJ> and <ASTROBJ>U Ant</ASTROBJ> through scattered
stellar light
Authors: González Delgado, D.; Olofsson, H.; Schwarz, H. E.; Eriksson,
K.; Gustafsson, B.
2001A&A...372..885G Altcode: 2001astro.ph..4140G; 2001astro.ph..4140D
We present the first optical images of scattered light from large,
detached gas/dust shells around two carbon stars, <ASTROBJ>R
Scl</ASTROBJ> and <ASTROBJ>U Ant</ASTROBJ>, obtained in narrow band
filters centred on the resonance lines of neutral K and Na, and in
a Ström}gren b filter (only <ASTROBJ>U Ant</ASTROBJ>). They confirm
results obtained in CO radio line observations, but also reveal new
and interesting structures. Towards <ASTROBJ>R Scl</ASTROBJ> the
scattering appears optically thick in both the K and Na filters, and
both images outline almost perfectly circular disks with essentially
uniform intensity out to a sharp outer radius of ~21arcsec . These
disks are larger - by about a factor of two - than the radius of the
detached shell which has been marginally resolved in CO radio line
data. In <ASTROBJ>U Ant</ASTROBJ> the scattering in the K filter
appears to be, at least partially, optically thin, and the image is
consistent with scattering in a geometrically thin (~3arcsec ) shell
(radius ~43arcsec ) with an overall spherical symmetry. The size of
this shell agrees very well with that of the detached shell seen in
CO radio line emission. The scattering in the Na filter appears more
optically thick, and the image suggests the presence of at least one,
possibly two, shells inside the 43arcsec shell. There is no evidence
for such a multiple-shell structure in the CO data, but this can be due
to considerably lower masses for these inner shells. Weak scattering
appears also in a shell which is located outside the 43arcsec shell. The
present data do not allow us to conclusively identify the scattering
agent, but we argue that most of the emission in the K and Na filter
images is to due to resonance line scattering, and that there is
also a weaker contribution from dust scattering in the <ASTROBJ>U
Ant</ASTROBJ> data. Awaiting new observational data, our interpretation
must be regarded as tentative. Based on observations using the 3.6 m
telescope of the European Southern Observatory, La Silla, Chile.

---------------------------------------------------------
Title: Color and polarization as indicators of comet dust properties
and evolution in the near-nucleus coma
Authors: Kolokolova, Ludmilla; Jockers, Klaus; Gustafson, Bo Å. S.;
Lichtenberg, Günther
2001JGR...10610113K Altcode:
We present CCD colorimetric and polarimetric observations of comets
Hale-Bopp, Hyakutake, and Tabur and an analysis of their change
in color and polarization with the distance from the nucleus that
may indicate dust evolution in the coma. We concentrate on trends
along the solar-antisolar direction in the innermost coma, where
all three observed comets demonstrate a correlation between color and
polarization. Comparisons to laboratory studies of scattering by complex
dust structures reveal that the observed correlation is most likely
a result of evaporation/destruction of a dark (organic) material. We
study the evolution and properties of the dust in the central coma of
these comets using a tentative model of cometary dust as an ensemble
of core-mantle particles with sublimating mantles. Calculations for a
variety of optical properties, core-mantle mass ratios, and dust size
distributions showed that this model could describe the observed change
in color and polarization in cometary comae when realistic ranges of
input parameters are used. The best fit particles have silicate cores of
radius 0.05-0.2μm with a porous organic-carbon mantle of mantle/core
mass ratio 0.5-1. Within the frames of the model the peculiarity of
the color and polarization for comet Hale-Bopp (both increase with
the distance from the nucleus unlike the decrease observed in comets
Hyakutake and Tabur) can be understood in terms of a compact organic
mantle on the Hale-Bopp dust grains, whereas the Hyakutake and Tabur
dust have more porous mantles. We show how polarimetric color restricts
the range of satisfactory refractive indices of both the core and the
mantle materials.

---------------------------------------------------------
Title: New Searches for R-Process Enhanced Stars
Authors: Christlieb, N.; Beers, T. C.; Hill, V.; Primas, F.; Rhee,
J.; Ryan, S. G.; Bessell, M.; Norris, J. E.; Sneden, C.; Edvardsson,
B.; Gustafsson, B.; Karlsson, T.; Mizuno-Wiedner, M.
2001ASPC..245..298C Altcode: 2001aats.conf..298C
No abstract at ADS

---------------------------------------------------------
Title: Interactions with Electromagnetic Radiation: Theory and
Laboratory Simulations
Authors: Gustafson, Bo A. S.; Greenberg, J. Mayo; Kolokolova, Ludmilla;
Xu, Yu-lin; Stognienko, Ralf
2001indu.book..509G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Interplanetary Dust
Authors: Grün, E.; Gustafson, B. A. S.; Dermott, S.; Fechtig, H.
2001indu.book.....G Altcode: 2001ipd..book.....G
This is a handbook on the physics of interplanetary dust, a topic
of interest not only to astronomers and space scientists but also to
engineers. The following topics are covered in the book: historical
perspectives; cometary dust; near-Earth environment; meteoroids and
meteors; properties of interplanetary dust, information from collected
samples; in situ measurements of cosmic dust; numerical modeling of the
Zodiacal Cloud structure; synthesis of observations; instrumentation;
physical processes; optical properties of interplanetary dust; orbital
evolution of interplanetary dust; circumplanetary dust, observations
and simple physics; interstellar dust and circumstellar dust disks.

---------------------------------------------------------
Title: Images in Scattered Light of Two Carbon Stars (CD-ROM
Directory: contribs/gonzalez)
Authors: González Delgado, D.; Olofsson, H.; Schwarz, H.; Eriksson,
K.; Gustafsson, B.
2001ASPC..223.1219G Altcode: 2001csss...11.1219G
No abstract at ADS

---------------------------------------------------------
Title: How Good Are New Ages for Old Stars?
Authors: Gustafsson, Bengt; Mizuno-Wiedner, Michelle
2001ASPC..245..271G Altcode: 2001aats.conf..271G
No abstract at ADS

---------------------------------------------------------
Title: Are there Dust-Flakes in Cometary Atmospheres?
Authors: Waldemarsson, K. W. T.; Kolokolova, L.; Gustafson, B. A. S.
2000AAS...197.5001W Altcode: 2000BAAS...32.1486W
Recent comet observations show that the inner comae (within 5000 km
from the nucleus) has unusual light scattering features. Particularly,
the color, polarization, and polarimetric color are much different
than in the surrounding cometary atmosphere and cannot be explained
by the light scattering from simple spherical particles. More complex
particle geometries have been proposed. Stephens and Gustafson (1991,
Icarus 94, 209) showed through a laboratory study that thin flakes can
form on surfaces of sublimating dust/ice mixtures. Microwave analog to
light scattering measurements has shown that such flakes can produce
unusual combinations of color, polarization and polarimetric color and
may be inner coma particle candidates. This paper presents the results
of our theoretical modeling of the light scattering by flake-like dust
particles. The modeling is based on our approximate light scattering
solution for a thin plate with arbitrary refractive index. When
the scattering model is compared to microwave test measurements an
overall good agreement is found. We investigate the dependence of the
polarization, color, and polarimetric color on the refractive index and
geometrical dimensions of the flakes. We show how the light scattering
by flakes can explain observational features of inner comae.

---------------------------------------------------------
Title: ISO-SWS calibration and the accurate modelling of cool-star
atmospheres. I. Method
Authors: Decin, L.; Waelkens, C.; Eriksson, K.; Gustafsson, B.; Plez,
B.; Sauval, A. J.; Van Assche, W.; Vandenbussche, B.
2000A&A...364..137D Altcode: 2000astro.ph..8316D
A detailed spectroscopic study of the ISO-SWS data of the red
giant alpha Tau is presented, which enables not only the accurate
determination of the stellar parameters of alpha Tau, but also serves
as a critical review of the ISO-SWS calibration. This study is situated
in a broader context of an iterative process in which both accurate
observations of stellar templates and cool star atmosphere models
are involved to improve the ISO-SWS calibration process as well as the
theoretical modelling of stellar atmospheres. Therefore a sample of cool
stars, covering the whole A0 - M8 spectral classification, has been
observed in order to disentangle calibration problems and problems
in generating the theoretical models and corresponding synthetic
spectrum. By using stellar parameters found in the literature large
discrepancies were seen between the ISO-SWS data and the generated
synthetic spectrum of alpha Tau. A study of the influence of various
stellar parameters on the theoretical models and synthetic spectra,
in conjunction with the Kolmogorov-Smirnov test to evaluate objectively
the goodness-of-fit, enables us to pin down the stellar parameters with
a high accuracy: Teff = 3850 +/- 70 K, log g = 1.50 +/- 0.15,
M = 2.3 +/- 0.8 Msun, z = -0.15 +/- 0.20 dex, xit
= 1.7 +/- 0.3 km s-1, 12C/13C = 10
+/- 1, varepsilon (C) = 8.35 +/- 0.20 dex, varepsilon (N) = 8.35 +/-
0.25 dex, varepsilon (O) = 8.83 +/- 0.15 dex and thetad =
20.77 +/- 0.83 mas. These atmospheric parameters were then compared
with the results provided by other authors using other methods
and/or spectra. Based on observations with ISO, an ESA project with
instruments funded by ESA Member States (especially the PI countries
France, Germany, the Netherlands and the United Kingdom) and with the
participation of ISAS and NASA.

---------------------------------------------------------
Title: Mira's Wind Explored in Scattering Infrared CO Lines
Authors: Ryde, N.; Gustafsson, B.; Eriksson, K.; Hinkle, K. H.
2000ApJ...545..945R Altcode: 2000astro.ph..8235R
We have observed the intermediate regions of the circumstellar
envelope of Mira (ο Ceti) in photospheric light scattered by three
vibration-rotation transitions of the fundamental band of CO, from
low-excited rotational levels of the ground vibrational state, at an
angular distance of β~2”-7" away from the star. The data
were obtained with the Phoenix spectrometer mounted on the 4 m Mayall
telescope at Kitt Peak. The spatial resolution is approximately 0.5"
and seeing limited. Our observations provide absolute fluxes, leading
to an independent new estimate of the mass-loss rate of approximately
3×10-7 Msolar yr-1, as derived from
a simple analytic wind model. We find that the scattered intensity
from the wind of Mira for 2”&lt;~β&lt;~7”
decreases as β-3, which suggests a time constant mass-loss
rate, when averaged over 100 yr, over the past 1200 yr.

---------------------------------------------------------
Title: The Effect of the Lorentz Force on the Resonant Structure of
Dust Particles in the Kuiper Belt
Authors: Holmes, E. K.; Dermott, S. F.; Gustafson, B. A. S.
2000AAS...197.5005H Altcode: 2000BAAS...32.1487H
There is a possible connection between structure in circumstellar disks
and the presence of planets, our own zodiacal cloud being a proven
example. Asymmetries in such a disk could be diagnostic of planets
which would be otherwise undetectable. At least three different types
of asymmetries can serve to indicate bodies orbiting a star in a disk:
(1) a warp in the plane of symmetry of the disk, (2) an offset in the
center of symmetry of the disk with respect to the central star, and
(3) density anomalies in the plane of the disk due to resonant trapping
of dust particles. In the asteroid belt, collisions between asteroids
supply dust particles to the zodiacal cloud. By comparison, it has
been postulated that collisions between Kuiper Belt Objects (KBOs)
could initiate a collisional cascade which would produce a Kuiper dust
disk. A Kuiper Disk would most likely have a resonant structure, with
two concentrations in brightness along the ecliptic longitude. This
large scale structure arises because many of the KBOs, the Plutinos,
are in the 2:3 mean motion resonance with Neptune. By running numerical
integrations of particles in Pluto-like orbits, the resonant structure
of the Kuiper belt can be studied by determining the percentage of
particles trapped in the resonance as a function of their initial
velocity and beta, where β = Frad}/F{grav. The
dynamical evolution of the particles is followed from source to sink
with Poynting Robertson light drag, solar wind drag, radiation pressure,
the Lorentz force, neutral interstellar gas drag, and the effects of
planetary gravitational perturbations included. The integrations are
run with and without the Lorentz force to determine what effect the
Lorentz force has on particles in the Kuiper Belt as a function of
particle size. This research was funded in part by a NASA GSRP grant.

---------------------------------------------------------
Title: The Rare 1932 Dust Trail Encounter of November 17, 2000,
As Observed from Aircraft
Authors: Jenniskens, P.; Gustafson, B. A. S.
2000JIMO...28..209J Altcode:
Both encounters with the 1932 and 1866 dust trails of Comet
55T/Temple-Tuttle on November 17 and 18, 2000, respectively, were
observed with intensified cameras from a twin-engine Cessna-130 aircraft
over southern Florida. Here, preliminary results are presented for the
1932 dust trail encounter, which was most difficult to observe from
the ground. Results are consistent with models that predict strong
Leonid returns in November 2001 and 2002.

---------------------------------------------------------
Title: ISO Impact on Stellar Models and Viceversa
Authors: Decin, L.; Waelkens, C.; Eriksson, K.; Gustafsson, B.; Plez,
B.; Sauval, A. J.; van Assche, W.; Vandenbussche, B.
2000ESASP.456..289D Altcode: 2000astro.ph..8362D; 2000ibp..conf..289D
We present a detailed spectroscopic study of a sample of bright,
mostly cool, stars observed with the Short-Wavelength Spectrometer
(SWS) on board ISO, which enables the accurate determination of the
stellar parameters of the cool giants, but also serves as a critical
review of the ISO-SWS calibration.

---------------------------------------------------------
Title: Gasdynamics of Detached Shells Around Carbon Stars With
Variable Mass Loss
Authors: Myasnikov, A. V.; Belov, N. A.; Gustafsson, B.; Eriksson, K.
2000Ap&SS.274..231M Altcode:
Gasdynamic features of detached shells around carbon stars with
variable mass loss rate are investigated in detail numerically. It
is shown that a shell is unstable and also, 2D perturbations are less
developed that 3D ones. The structure of perturbed flows corresponding
to different evolution scenarios is compared. The results obtained
seem to be promising for interpretation of observations, in particular,
the recently obtained detailed data of TT Cyg.

---------------------------------------------------------
Title: Applicability of effective medium theories to photometric
and polarimetric observations of cosmic dust - A laboratory study
using the microwave analog technique
Authors: Kolokolova, L.; Gustafson, B. A. S.; Bourgeois, M.
2000DPS....32.5603K Altcode: 2000BAAS...32.1107K
The interpretation of optical (photometric, polarimetric,
colorimetric, etc.) observations of dust, whether cometary,
interplanetary, circum-stellar, or planetary aerosols, is hampered
by the complicated structure of the grains that, most likely, include
multi-compositional, aggregated particles. It is a common practice to
use effective medium theories (EMT) to estimate average, "effective"
optical constants of such inhomogeneous materials. A variety of EMTs
were developed for different structures of the medium (aggregated,
fractal, separated inclusions) and for a variety of sizes and shapes
of the inhomogeneities. However, the validity of EMT for astronomical
applications has only been demonstrated for extinction cross-sections
that were checked using the DDA method. This paper compares angular
distribution and wavelength dependence of intensity and polarization
of scattered light obtained from EMT calculations with the results
of microwave analog measurements at the microwave facilities of the
University of Florida. We simulated the light-scattering by organic
grains with silicate inclusions of size parameter x=0.075 (0.04 micron),
0.58 (0.3 micron), and 1.2 (0.6 micron). The conclusion is that all EMTs
(including Maxwell-Garnett, Bruggeman, Looyenga, Stroud and Pan) yield
similar results and work better for the intensity of the scattered
light than for its polarization. The dependency of the intensity on
the scattering angle is in good agreement with the EMTs. However,
calculations overestimate the magnitude of the intensity when the
size of the inclusions and/or their volume fraction in the mixture
increases. We find that the EMTs cannot reproduce the angular dependence
of polarization and yield errors in polarization of around 45-65%
for all sizes and volume fractions of the inclusions. The spectral
gradient of polarization (polarimetric color) calculated using EMTs
also differ from the experiments by the same order. By contrast, the
calculated spectral gradient of intensity (color) is in good agreement
with the experiments. This work was supported by NASA grants NAG5-8944
and NAG5-6378.

---------------------------------------------------------
Title: Growth and Form of Planetary Seedlings: Results from a
Microgravity Aggregation Experiment
Authors: Blum, J.; Wurm, G.; Kempf, S.; Poppe, T.; Klahr, H.; Kozasa,
T.; Rott, M.; Henning, T.; Dorschner, J.; Schräpler, R.; Keller,
H. U.; Markiewicz, W. J.; Mann, I.; Gustafson, B. A.; Giovane,
F.; Neuhaus, D.; Fechtig, H.; Grün, E.; Feuerbacher, B.; Kochan,
H.; Ratke, L.; El Goresy, A.; Morfill, G.; Weidenschilling, S. J.;
Schwehm, G.; Metzler, K.; Ip, W. -H.
2000PhRvL..85.2426B Altcode:
The outcome of the first stage of planetary formation, which is
characterized by ballistic agglomeration of preplanetary dust grains
due to Brownian motion in the free molecular flow regime of the solar
nebula, is still somewhat speculative. We performed a microgravity
experiment flown onboard the space shuttle in which we simulated,
for the first time, the onset of free preplanetary dust accumulation
and revealed the structures and growth rates of the first dust
agglomerates in the young solar system. We find that a thermally
aggregating swarm of dust particles evolves very rapidly and forms
unexpected open-structured agglomerates.

---------------------------------------------------------
Title: The r-Process-enriched Low-Metallicity Giant HD 115444
Authors: Westin, Jenny; Sneden, Christopher; Gustafsson, Bengt; Cowan,
John J.
2000ApJ...530..783W Altcode: 1999astro.ph.10376W
New high-resolution, very high signal-to-noise spectra of
ultra-metal-poor (UMP) giant stars HD 115444 and HD 122563 have
been gathered with the High-Resolution Echelle Spectrometer of
the McDonald Observatory 2.7 m telescope. With these spectra, line
identification and model atmosphere analyses have been conducted,
emphasizing the neutron-capture elements. Twenty elements with
Z&gt;30 have been identified in the spectrum of HD 115444. This star
is known to have overabundances of the neutron-capture elements,
but it has lacked a detailed analysis necessary to compare with
nucleosynthesis predictions. The new study features a line-by-line
differential abundance comparison of HD 115444 with the bright,
well-studied halo giant HD 122563. For HD 115444, the overall
metallicity is [Fe/H]~=-3.0. The abundances of the light and iron-peak
elements generally show the same pattern as other UMP stars (e.g.,
overdeficiencies of manganese and chromium, overabundances of cobalt),
but the differential analysis indicates several nucleosynthesis
signatures that are unique to each star. Synthetic spectrum analyses
reveal substantial overabundances of the heavier neutron-capture
elements (Z&gt;=56 elements barium and beyond) in HD 115444. Thus with
[Eu/Fe]~=+0.9, for example, HD 115444 is a moderate version of the
extremely neutron-capture-rich UMP giant CS 22892-052 ([Fe/H]~=-3.1,
[Eu/Fe]~=+1.7). The abundance pattern of the heavier neutron-capture
elements is consistent with scaled solar system r-process-only
abundances (with little contribution from the s-process). In HD 115444,
[Ba/Eu]=-0.73, while in CS 22892-052 this ratio is -0.79. Thus HD
115444 becomes the second UMP r-process-rich halo giant unambiguously
identified from a very detailed abundance analysis. Abundances of the
lighter neutron-capture elements strontium, yttrium, and zirconium are,
however, nearly identical in HD 115444 and HD 122563. Along with the
heavier neutron-capture elements, the 4019 Å line of Th II has been
detected in HD 115444, yielding log ɛ(Th) = -2.23+/-0.07. Comparing
the observed thorium abundance in HD 115444, along with CS 22892-052,
with other theoretical estimates of the time-zero abundance suggests
an age for both of these UMP stars of 15.6+/-4 Gyr, consistent with
previous radioactive age estimates for CS 22892-052 and other Galactic
and cosmological age determinations.

---------------------------------------------------------
Title: CO Imaging of Late-Type Circumstellar Shells
Authors: Gustafsson, Bengt; Eriksson, Kjell; Lambert, David L.;
Olofsson, Hans; Ryde, Nils; Schoier, Fredrik L.
2000noao.prop..293G Altcode:
Microwave emission lines and optical resonance lines have been used
to image circumstellar shells on the sky. Now it is possible to
image resonance scattering from infrared vibration-rotational carbon
monoxide lines (see Ryde et al. A&amp; A 347, L35, 1999). Infrared CO is
formed closer to the star than microwave CO and provides complementary
information. Infrared CO mapping is especially powerful because many
CO lines of differing excitation are present, allowing the extraction
of excitation temperature and abundance from the measured column
densities. Previous on-star observations have led to the detection
of multiple velocity components in the CO lines, formed in different
parts of the circumstellar shell. We have found in an earlier observing
run with this method that the shell of CO gas around Mira (4 arcsec-10
arcsec from the star) is spherically symmetric and homogeneous. But we
also trace from the data a region close to the star devoid of gas or
at least of CO (Ryde et al. ApJ, soon to be submitted). Each CO line
can be used to image the circumstellar outflow at different stellar
radii. Information on the velocity structure and the development of
clumps in the flow will be extracted. The present proposal focuses on
the study of shells around carbon stars for which we have complementary
mm and optical data. We will furthermore for the first time map detached
shells with this method.

---------------------------------------------------------
Title: Interferometric Molecular Line observations of RW LMi
Authors: Lindqvist, Michael; Lucas, Robert; Olofsson, Hans; Larsen,
Fredrick; Omont, Alain; Eriksson, Kjell; Gustafsson, Bengt
2000IAUS..177..557L Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Microwave Analog to Light-Scattering Measurements
Authors: Gustafson, Bo Å. S.
2000lsnp.book..367G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Tracing the first supernovae in halo dwarf stars
Authors: Karlsson, T.; Gustafsson, B.
2000LIACo..35..237K Altcode: 2000ghgc.conf..237K
No abstract at ADS

---------------------------------------------------------
Title: Commission 21: Light of the Night Sky: (Lumiere du Ciel
Nocturne)
Authors: Bowyer, S.; Lamy, P.; Dwek, E.; Gustafson, B.; Hanner,
M.; Levasseur-Regourd, A. Ch.; Mikhail, J.; Mann, I.; Mukai, T.;
Matsumoto, T.
2000IAUTA..24..152B Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Carbon Stars and Nucleosynthesis in Galaxies
Authors: Gustafsson, Bengt; Ryde, Nils
2000IAUS..177..481G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: VizieR Online Data Catalog: Atmospheric parameters in
metal-poor stars. II (Gratton+, 1999)
Authors: Gratton, R. G.; Carretta, E.; Eriksson, K.; Gustafsson, B.
2000yCat..33500955G Altcode:
We present non-LTE corrections to abundances of Fe, O, Na, and Mg
derived from LTE analyses of F-K stars over a broad range of gravities
and metal abundances; they were obtained using statistical equilibrium
calculations and new model atoms. Line opacity was considered by
means of an empirical procedure where it was attributed to a veil
of weak Fe I lines; in the case of solar-type dwarfs, results were
compared with those obtained using (LTE) mean intensities computed
from OSMARCS models. We think that the empirical procedure produces
better results for metal-poor stars, while mean intensities should
perhaps be preferred for the Sun (where departures from LTE are
anyway not very large). Collisions with both electrons and H I atoms
were considered. Since cross sections for this second mechanism
are very poorly known, we calibrated them empirically by matching
observations of RR Lyrae variables at minimum light (discussed in
Clementini et al., 1995, Cat. ). These stars were selected because
non-LTE effects are expected to be larger in these stars than in
those usually considered in the study of the chemical evolution of the
Galaxy (cool main sequence and red giant branch stars). We found that
different non-LTE mechanisms are important for the different species
and transitions considered; on the whole, our calculations yielded
moderate corrections to LTE abundances for high excitation O lines
in warm dwarfs and giants, Na and Mg lines in giants and supergiants,
and Fe I lines in F-supergiants (where corrections becomes very large
for IR O lines). Non-LTE corrections were found to be negligible in
the other cases studied. (3 data files).

---------------------------------------------------------
Title: A high-resolution study of episodic mass loss from the carbon
star TT Cygni
Authors: Olofsson, H.; Bergman, P.; Lucas, R.; Eriksson, K.;
Gustafsson, B.; Bieging, J. H.
2000A&A...353..583O Altcode:
CO radio line observations with the IRAM Plateau de Bure interferometer
show that the carbon star TT Cyg is surrounded by a large (radius
~ 35arcsec or 2.7x1017 cm), geometrically thin (average
width ~ 2farcs 5 or 1.9x1016 cm) shell of gas, which has a
remarkable overall spherical symmetry (e.g., its radius varies by less
than +/-3%). It expands with a velocity of ~ 12.6 km s-1. The
emitting gas is very evenly distributed in the shell when averaged
over a solid angle of about 0.2 steradians. We estimate a molecular
hydrogen density of ~ 250 cm-3, a gas kinetic temperature
of ~ 100 K, and a mass of ~ 0.007 M_sun for the shell if the medium
is homogeneous. There is no evidence for matter immediately inside
or outside the shell, nor is there any evidence for structure in the
radial direction of the shell brightness distribution (it is essentialy
perfectly fitted with Gaussians). The shell centre is displaced ~
1farcs 7 (position angle ~ -20degr ) with respect to the star. We
favour an interpretation of this displacement in terms of TT Cyg being
a member of a binary system. We put forward several arguments for a
shell medium that consists almost entirely of a large number of small
(la 1arcsec ) clumps (in which case the density required to fit the
observational data is much higher, ~ 104 cm-3,
and the kinetic temperature is considerably lower, la 20 K). TT Cyg is
presently losing mass at a modest rate, ~ 3x10-8 M_sunpyr,
and with a low expansion velocity, ~ 3.8 km s-1. This is
inferred from CO line emission from a region centred on the present
position of the star. The systemic velocity is estimated, from both
the centre and the shell emission, to be -27.3+/-0.1 km s-1
in the LSR system. All quantitative results are obtained assuming
the Hipparcos distance of 510 pc. These data strongly support that TT
Cyg has recently ( ~ 7x103 yr ago) gone through a period
of drastically varying mass loss properties. We discuss briefly two
scenarios: a short period (a few hundred years) of very intense mass
loss (a rate in excess of 10-5 M_sunpyr), and a related
scenario with a more modest mass ejection and where most of the shell
gas is swept-up from a previous, slower stellar wind. It is presently
not possible to favour any of these two scenarios, but we suggest that
in either case it is a coordinated mass ejection that caused the shell
formation. The He-shell flash phenomenon in AGB-stars can provide this
coordination, and it also fits the time scales involved.

---------------------------------------------------------
Title: The R Coronae Borealis stars - atmospheres and abundances
Authors: Asplund, M.; Gustafsson, B.; Lambert, D. L.; Rao, N. K.
2000A&A...353..287A Altcode:
An abundance analysis of the H-deficient and He- and C-rich R Coronae
Borealis (R CrB) stars has been undertaken to examine the ancestry of
the stars. The investigation is based on high-resolution spectra and
line-blanketed H-deficient model atmospheres. The models successfully
reproduce the flux distributions and all spectral features, both
molecular bands and high-excitation transitions, with one important
exception, the C i lines. Since photoionization of C i dominates
the continuous opacity, the line strengths of C i are essentially
independent of the adopted carbon abundance and stellar parameters. All
predicted C i lines are, however, much too strong compared with
observations, with a discrepancy in abundance corresponding to 0.6 dex
with little star-to-star scatter. Various solutions of this “carbon
problem” have been investigated. A possible solution is that classical
model atmospheres are far from adequate descriptions of supergiants such
as the R CrB stars. We can also not exclude completely, however, the
possibility that the gf-values for the C i lines are in error. This is
supported by the fact that the C ii, [C i] and C_2 lines are reproduced
by the models with no apparent complications. In spite of the carbon
problem, various tests suggest that abundance ratios are little affected
by the uncertainties. Judging by chemical composition, the R CrB stars
can be divided into a homogeneous majority group and a diverse minority,
which is characterized by extreme abundance ratios, in particular as
regards Si/Fe and S/Fe. All stars show evidence of H- and He-burning in
different episodes as well as mild s-process enhancements. Four of the
majority members are Li-rich, while overabundances of Na, Al, Si and
S are attributes of all stars. An anti-correlation found between the
H and Fe abundances of H-deficient stars remains unexplained. These
enigmatic stars are believed to be born-again giants, formed either
through a final He-shell flash in a post-AGB star or through a merger
of two white dwarfs. Owing to a lack of theoretical predictions of
the resulting chemical compositions, identification of the majority
and minority groups with the two scenarios is unfortunately only
preliminary. Furthermore, <ASTROBJ>Sakurai's object</ASTROBJ> and
<ASTROBJ>V854 Cen</ASTROBJ> exhibit aspects of both majority and
minority groups, which may suggest that the division into two groups
is too simplistic.

---------------------------------------------------------
Title: Scattered Light from Envelopes around N-type Stars
Authors: Gustafsson, Bengt; Eriksson, Kjell; Kiselman, Dan; Olander,
Nils; Olofsson, Hans; Schwarz, Hugo E.
2000IAUS..177..409G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Dust Dynamics of Transplanetary Disks
Authors: Gustafson, Bo Å. S.
2000IAUJD...4E..11G Altcode:
Forces acting on a given dust particle in Trans-Neptunian space differ
in relative importance from the forces that the same grain would
experience in the inner parts of the solar system. The Lorentz force
due to solar wind interaction can no longer be neglected at Neptune's
distance and is shown to cause dust orbits to precess along the solar
equator. Alternating epochs of nodal recession and advance result from
the change in magnetic field direction with the solar cycles. Secular
perturbations are expected to cause dust structures reminiscent of the
now well-known solar system dust bands in the asteroid belt. While the
asteroid dust bands are induced by gravitational perturbations resulting
primarily from the Jovian planets, the Lorentz-force induced dust
bands that may extend parallel to the solar equator in Trans-Neptunian
space are independent of the existence of any planets. It is therefore
possible that the counterparts of the dust bands in extra solar dust
disks may be mistaken for evidence for one or more planets. Ironically,
the drag from interstellar gas would pump-up orbital eccentricities
and would likely prevent a planet-induced ring from forming in our
solar system at these large heliocentric distances.

---------------------------------------------------------
Title: Oxygen -- abundances and model atmospheres
Authors: Gustafsson, Bengt
2000IAUJD...8E...7G Altcode:
The uncertainties in current determinations of oxygen abundances of Pop
II stars, resulting from systematic errors in models used to represent
the stellar atmospheres, are analysed and discussed. Recommendations
are given for abundance criteria to be selected and for model atmosperes
to be used and developed further.

---------------------------------------------------------
Title: Deflection of the local interstellar dust flow by solar
radiation pressure.
Authors: Landgraf, M.; Augustsson, K.; Grün, E.; Gustafson, B. Å. S.
1999Sci...286.2319L Altcode:
Interstellar dust grains intercepted by the dust detectors on the
Ulysses and Galileo spacecrafts at heliocentric distances from 2 to
4 AU show a deficit of grains with masses from 1×10-17
to 3×10-16kg relative to grains intercepted outside 4
AU. To divert grains out of the 2- to 4-AU region, the solar radiation
pressure must be 1.4 to 1.8 times the force of solar gravity. These
figures are consistent with the optical properties of spherical or
elongated grains that consist of astronomical silicates or organic
refractory material. Pure graphite grains with diameters of 0.2 to
0.4 μm experience a solar radiation pressure force as much as twice
the force of solar gravity.

---------------------------------------------------------
Title: Spectroscopic Observations of Convective Patterns in the
Atmospheres of Metal-poor Stars
Authors: Allende Prieto, Carlos; García López, Ramón J.; Lambert,
David L.; Gustafsson, Bengt
1999ApJ...526..991A Altcode: 1999astro.ph..7046A; 1999astro.ph..7046P
Convective line asymmetries in the optical spectrum of two metal-poor
stars, Gmb 1830 and HD 140283, are compared to those observed for solar
metallicity stars. The line bisectors of the most metal-poor star, the
subgiant HD 140283, show a significantly larger velocity span that the
expectations for a solar-metallicity star of the same spectral type
and luminosity class. The enhanced line asymmetries are interpreted
as the signature of the lower metal content, and therefore opacity,
in the convective photospheric patterns. These findings point out the
importance of the three-dimensional convective velocity fields in the
interpretation of the observed line asymmetries in metal-poor stars and,
in particular, urge caution when deriving isotopic ratios from observed
line shapes and shifts using one-dimensional model atmospheres. The
mean line bisector of the photospheric atomic lines is compared with
those measured for the strong Mg I b1 and b2
features. The upper parts of the bisectors are similar, and-assuming
they overlap-the bottom ends of the stronger lines, which are formed
higher in the atmosphere, go much farther to the red. This is in
agreement with the expected decreasing of the convective blueshifts
in upper atmospheric layers, and is compatible with the high-velocity
redshifts observed in the chromosphere, transition region, and corona
in late-type stars.

---------------------------------------------------------
Title: A Consistency Test of Spectroscopic Gravities for Late-Type
Stars
Authors: Allende Prieto, Carlos; García López, Ramón J.; Lambert,
David L.; Gustafsson, Bengt
1999ApJ...527..879A Altcode: 1999astro.ph..7155P; 1999astro.ph..7155A
Chemical analyses of late-type stars are usually carried out
following the classical recipe: LTE line formation and homogeneous,
plane-parallel, flux-constant, and LTE model atmospheres. We review
different results in the literature that have suggested significant
inconsistencies in the spectroscopic analyses, pointing out the
difficulties in deriving independent estimates of the stellar
fundamental parameters and hence, detecting systematic errors. The
trigonometric parallaxes measured by the Hipparcos mission provide
accurate appraisals of the stellar surface gravity for nearby
stars, which are used here to check the gravities obtained from the
photospheric iron ionization balance. We find an approximate agreement
for stars in the metallicity range -1.0&lt;=[Fe/H]&lt;=0, but the
comparison shows that the differences between the spectroscopic and
trigonometric gravities decrease toward lower metallicities for more
metal-deficient dwarfs (-2.5&lt;=[Fe/H]&lt;=-1.0), which casts a shadow
upon the abundance analyses for extreme metal-poor stars that make use
of the ionization equilibrium to constrain the gravity. The comparison
with the strong-line gravities derived by Edvardsson and Fuhrmann
confirms that this method provide systematically larger gravities than
the ionization balance. The strong-line gravities get closer to the
physical ones for the stars analyzed by Fuhrmann, but they are even
further away than the iron ionization gravities for the stars of lower
gravities in Edvardsson's sample. The confrontation of the deviations
of the iron ionization gravities in metal-poor stars, reported here
with departures from the excitation balance found in the literature,
show that they are likely to be induced by the same physical mechanism.

---------------------------------------------------------
Title: VizieR Online Data Catalog: The R CrB stars (Asplund+, 2000)
Authors: Asplund, M.; Gustafsson, B.; Lambert, D. L.; Rao, N. K.
1999yCat..33530287A Altcode:
Adopted line data, measured equivalent widths and derived elemental
abundances for the individual lines observed in R Coronae Borealis
and Extreme Helium stars. (2 data files).

---------------------------------------------------------
Title: Reply
Authors: Knowles, S.; Meier, R. R.; Gustafson, B. Å. S.; Giovane,
F. J.
1999JGR...10422609K Altcode:
<A href="/journals/ja/ja9910/1999JA900320/0.html">Abstract Available</A>
from <A href="http://www.agu.org">AGU</A>

---------------------------------------------------------
Title: The cosmic dust aggregation experiment CODAG
Authors: Blum, Jürgen; Wurm, Gerhard; Poppe, Torsten; Kempf, Sascha;
Fiethe, Björn; Giel, Michaela; Offterdinger, Peter; Neuhaus, Dietmar;
Rott, Martin; Giovane, Frank; Gustafson, Bo
1999MeScT..10..836B Altcode:
For the simulation of the first stage of preplanetary dust aggregation,
we developed the cosmic dust aggregation experiment (CODAG). With
CODAG, we intend to study the aggregational behaviour of a cloud of
micron-sized dust particles due to Brownian motion of the grains. For
a realistic simulation of the processes in the young solar system,
the dust grains have to be dispersed in a rarefied gas so that mutual
collisions are ballistic. Fast sedimentation of the grains in the
Earth's gravitational field leads to unrealistic collision velocities
and to a rapid loss of particles to the container walls. Therefore,
CODAG was designed to work in a microgravity environment. In this
paper, we present an overview of the experimental design of CODAG
which was recently flown in a Get Away Special container during the
STS-95 mission.

---------------------------------------------------------
Title: Abundances of light elements in metal-poor stars. II. Non-LTE
abundance corrections
Authors: Gratton, R. G.; Carretta, E.; Eriksson, K.; Gustafsson, B.
1999A&A...350..955G Altcode:
We present non-LTE corrections to abundances of Fe, O, Na, and Mg
derived from LTE analyses of F-K stars over a broad range of gravities
and metal abundances; they were obtained using statistical equilibrium
calculations and new model atoms. Line opacity was considered by
means of an empirical procedure where it was attributed to a veil
of weak Fe I lines; in the case of solar-type dwarfs, results were
compared with those obtained using (LTE) mean intensities computed
from OSMARCS models. We think that the empirical procedure produces
better results for metal-poor stars, while mean intensities should
perhaps be preferred for the Sun (where departures from LTE are
anyway not very large). Collisions with both electrons and H I atoms
were considered. Since cross sections for this second mechanism
are very poorly known, we calibrated them empirically by matching
observations of RR Lyrae variables at minimum light (discussed in
Clementini et al. 1995). These stars were selected because non-LTE
effects are expected to be larger in these stars than in those
usually considered in the study of the chemical evolution of the
Galaxy (cool main sequence and red giant branch stars). We found that
different non-LTE mechanisms are important for the different species
and transitions considered; on the whole, our calculations yielded
moderate corrections to LTE abundances for high excitation O lines
in warm dwarfs and giants, Na and Mg lines in giants and supergiants,
and Fe I lines in F-supergiants (where corrections becomes very large
for IR O lines). Non-LTE corrections were found to be negligible in
the other cases studied. The Tables~1 to 12 are available only in
electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr
(130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html

---------------------------------------------------------
Title: ERRATUM: Comparison between Multisphere Light-scattering
Calculations: Rigorous Solution and Discrete Dipole Approximation
Authors: Xu, Yu-lin; Gustafson, Bo Å. S.
1999ApJ...522.1206X Altcode:
In the paper “Comparison between Multisphere Light-scattering
Calculations: Rigorous Solution and Discrete Dipole Approximation”
by Yu-lin Xu and Bo Å. S. Gustafson (ApJ, 513, 894 [1999]), there is a
minor error in the figures concerning the Müller matrix elements. This
error involves Figures 8, 9, 10, 14, 22, 23, and 24, but not Figures 7
and 18. The corrected figures are shown below. The authors thank
Bruce T. Draine for bringing this error to their attention.

---------------------------------------------------------
Title: Experiments for in-situ monitoring of dust environments in
the Solar System
Authors: Colangeli, L.; Bussoletti, E.; Lopez Moreno, J. J.; Epifani,
E.; Esposito, F.; Mennella, V.; Palomba, E.; Palumbo, P.; Rotundi,
A.; Vergara, S.; Jeronimo, J. M.; Lopez-Jimenez, A. C.; Molina, A.;
Morales, R.; Moreno, F.; Olivares, I.; Rodrigo, R.; Rodriguez-Gomez,
J. F.; Ruiz-Falco, A.; Sanchez, J.; McDonnell, J. A. M.; Leese, M.;
Lamy, P.; Perruchot, S.; Crifo, J. F.; Fulle, M.; Perrin, J. M.;
Angrilli, F.; Coradini, A.; Giovane, F.; Gruen, E.; Gustafson, B.;
Maag, C.; Weissman, P. R.
1999DPS....31.2906C Altcode:
"Dust" is present in the Solar System, from planetary surfaces
to comets. The in-situ monitoring of its physical and dynamical
properties is one of the main scientific tasks to be achieved in order
to characterise grains and to correctly understand their role in the
evolution of Solar System bodies. A new generation of methods for
in-situ exploration of dusty environments in the Solar System has been
studied and adopted in different instruments under development or study
for future planetary space missions. Mass flux measurements by quartz
crystal microbalances, optical detection of single grains and momentum
monitoring by piezoelectric transducers are techniques which provide
high sensitivity for grains at relatively low (below some hundreds m/s)
velocities. The GIADA (Grain Impact Analyser and Dust Accumulator)
experiment is part of the payload of the ESA Rosetta orbiter, targeted
to a rendez-vous of 46P/Wirtanen comet. Thanks to GIADA, one of the
prime scientific objectives of the mission will be fulfilled, i.e. the
monitoring of the cometary coma dust environment. The dust flux from
different directions vs. time and the momentum and velocity vs. mass
of particles will be measured, while comet will approach the Sun. The
MAGO (Martian Atmospheric Grain Observer) instrument, under study in
the framework of the next Mars exploration opportunities (e.g.: Mars
Surveyor Program 2003) adopts similar technical solutions and is aimed
at measuring, directly for the first time, the dust mass flux in the
Martian atmosphere and the dynamical properties of airborne particles
vs. time. Finally, similar measurement techniques can be integrated with
other detection/collection systems (e.g. aerogel collectors) to monitor
the dust in the near Earth environment, e.g. from the space station.

---------------------------------------------------------
Title: Preliminary results on the circumstellar envelopes of alpha
ORI and R Leo from CO 4.6 micron line emission
Authors: Ryde, N.; Gustafsson, B.; Hinkle, K. H.; Eriksson, K.;
Lambert, D. L.; Olofsson, H.
1999A&A...347L..35R Altcode:
CO 4.6 mu m vibration-rotational lines are detected in fluorescent
emission from the inner regions of the Betelgeuse (<ASTROBJ>alpha
Orionis</ASTROBJ>) and <ASTROBJ>R Leonis</ASTROBJ> stellar winds. The
spatially and spectrally resolved 1-0 R(1), R(2), and R(3) line profiles
are found to be highly useful probes of circumstellar shells. The
current data sample only a few regions of the circumstellar shells of
the program stars. However, now it should be possible to obtain envelope
maps and absolute flux estimates, allowing new independent estimates
of mass loss rates. This will open up new possibilities in the study
of the structure and dynamics of stellar winds around red giants. The
temperature 4arcsec away from alpha Ori is found to be 38(+6}_{-5} {K)
. For R Leo the temperature 4arcsec North is derived to be 24(+3}_{-2}
{K) and 4arcsec South 35(+7}_{-4} {K) .

---------------------------------------------------------
Title: The Chemical Evolution of Carbon in the Galactic Disk
Authors: Karlsson, T.; Edvardsson, B.; Gustafsson, B.; Olsson, E.;
Ryde, N.
1999Ap&SS.265..261K Altcode:
No abstract at ADS

---------------------------------------------------------
Title: A search for small comets with the Naval Space Command radar
Authors: Knowles, S.; Meier, R. R.; Gustafson, B. Å. S.; Giovane,
F. J.
1999JGR...10412637K Altcode:
We have searched for the hypothetical small comets proposed by Frank
et al. [1986a, b] and Frank and Sigwarth [1993] using the world's
most powerful radar in terms of gain-aperture product. The Naval
Space Surveillance System can detect most space objects in low
Earth orbit with radar cross sections (RCSs) of 0.1 m2
or larger; at higher altitudes of the order of 10,000-20,000 km the
radar can detect objects with RCSs of 1 m2. We carried
out detailed first-principle calculations of the RCS of spherical
comct using the properties proposed by Frank and Sigwarth [1993]. We
find that 8-12 m diameter comets have an average cross section of 0.4
m2 at the radar frequency (217 MHz), with peaks reaching
1 m2. Therefore the Naval radar system has sufficient
sensitivity to detect many small comets, especially as they approach
low Earth orbit. We estimate that at least 800-5000 small comets should
have been detected by the radar during the 37 day search period during
fall 1997. None of the more than 12,000 unidentified detections can be
explained by small comets. The lack of detection of small comets by the
radar can be explained only if small comets have RCSs &lt;0.1% of their
assumed physical size (which is unrealistic, given that human technology
can match this value only by tailoring a design for a specific radar)
or if their impact rate with Earth is some 4 orders of magnitude less
than proposed by Frank et al. [1986a] and Frank and Sigwarth [1993].

---------------------------------------------------------
Title: On the determination of carbon isotopic ratios in cool carbon
stars. II. Accuracy of the iso-intensity method for crowded spectra
Authors: de Laverny, P.; Gustafsson, B.
1999A&A...346..520D Altcode:
de Laverny &amp; Gustafsson (1998, Paper I) questioned the iso-intensity
method used by Ohnaka &amp; Tsuji (1996) to derive carbon isotopic
ratios in cool carbon stars. As a reply, Ohnaka &amp; Tsuji (1998)
pointed out that the method criticized in Paper I differs from the
original one and conclude that our results are unreliable. No comparison
of the two methods was, however, made. The iso-intensity method used in
Paper I and OT96 do slighty differ in their definition. In investigating
the consequences of this difference we have found that they are rather
insignificant. We therefore confirm that the iso-intensity method
is not reliable when applied to crowded spectra of cool stars. That
reinforces the conclusions presented in Paper I.

---------------------------------------------------------
Title: Three years of Ulysses dust data: 1993-1995
Authors: Krüger, H.; Grün, E.; Landgraf, M.; Baguhl, M.; Dermott,
S.; Fechtig, H.; Gustafson, B. A.; Hamilton, D. P.; Hanner, M. S.;
Horányi, M.; Kissel, J.; Lindblad, B. A.; Linkert, D.; Linkert, G.;
Mann, I.; McDonnell, J. A. M.; Morfill, G. E.; Polanskey, C.; Schwehm,
G.; Srama, R.; Zook, H. A.
1999P&SS...47..363K Altcode: 1998astro.ph..9133K
The Ulysses spacecraft is orbiting the Sun on a highly inclined
ellipse (i = 79°). After its Jupiter flyby in 1992 at a heliocentric
distance of 5.4 AU, the spacecraftreapproached the inner solar system,
flew over the Suns south polar region in September 1994,crossed
the ecliptic plane at a distance of 1.3 AU in March 1995, and flew
over the Suns northpolar region in July 1995. We report on dust
impact data obtained with the dust detector onboardUlysses between
January 1993 and December 1995. We publish and analyse the complete
dataset of 509 recorded impacts of dust particles with masses between
10-16 g-10-7 g. Together with 968 dust impacts
from launch until the end of 1992 published earlier ([Gruuml;n et al.,
1995c]), information about 1477 particles detected with theUlysses
sensor between October 1990 and December 1995 is now available. The
impact ratemeasured between 1993 and 1995 stayed relatively constant at
about 0.4 impacts per day andvaried by less than a factor of ten. Most
of the impacts recorded outside about 3.5 AU arecompatible with
particles of interstellar origin. Two populations of interplanetary
particles havebeen recognized: big micrometer-sized particles close
to the ecliptic plane and smallsub-micrometer-sized particles at high
ecliptic latitudes. The observed impact rate is comparedwith a model
for the flux of interstellar dust particles which gives relatively good
agreement withthe observed impact rate. No change in the instruments
noise characteristics or degradation of thechanneltron could be revealed
during the three-year period.

---------------------------------------------------------
Title: Three years of Ulysses dust data: 1993-1995
Authors: rüger, H.; Grün, E.; Landgraf, M.; Baguhl, M.; Dermott,
S.; Fechtig, H.; Gustafson, B. a.; Hamilton, D. P.; Hanner, M. S.;
Horányi, M.; Kissel, J.; Lindblad, B. a.; Linkert, D.; Linkert, G.;
Mann, I.; McDonnell, J. a. m.; Morfill, G. e.; Polanskey, C.; Schwehm,
G.; Srama, R.; Zook, H. a.
1999P&SS...47..363R Altcode:
The Ulysses spacecraft is orbiting the Sun on a highly inclined
ellipse (i = 79°). After its Jupiter flyby in 1992 at a heliocentric
distance of 5.4 AU, the spacecraftreapproached the inner solar system,
flew over the Suns south polar region in September 1994,crossed
the ecliptic plane at a distance of 1.3 AU in March 1995, and flew
over the Suns northpolar region in July 1995. We report on dust
impact data obtained with the dust detector onboardUlysses between
January 1993 and December 1995. We publish and analyse the complete
dataset of 509 recorded impacts of dust particles with masses between
10-16 g-10-7 g. Together with 968 dust impacts
from launch until the end of 1992 published earlier (Grün et al.,
1995c), information about 1477 particles detected with theUlysses
sensor between October 1990 and December 1995 is now available. The
impact ratemeasured between 1993 and 1995 stayed relatively constant at
about 0.4 impacts per day andvaried by less than a factor of ten. Most
of the impacts recorded outside about 3.5 AU arecompatible with
particles of interstellar origin. Two populations of interplanetary
particles havebeen recognized: big micrometer-sized particles close
to the ecliptic plane and smallsub-micrometer-sized particles at high
ecliptic latitudes. The observed impact rate is comparedwith a model
for the flux of interstellar dust particles which gives relatively good
agreement withthe observed impact rate. No change in the instruments
noise characteristics or degradation of thechanneltron could be revealed
during the three-year period.

---------------------------------------------------------
Title: Comparison between Multisphere Light-scattering Calculations:
Rigorous Solution and Discrete-Dipole Approximation
Authors: Xu, Yu-lin; Gustafson, Bo Å. S.
1999ApJ...513..894X Altcode:
We present the comparison of light-scattering calculations between
a rigorous solution and the discrete-dipole approximation (DDA) for
two-sphere aggregates. We also compare theoretical predictions with
laboratory scattering measurements to examine the validity of the
numerical solutions. It is found that there are cases in which the
DDA solution, while satisfying the validity criterion for interdipole
spacing to be small compared with the wavelength of incident radiation,
deviates significantly from the rigorous solution and the experimental
results. We show that the DDA works reasonably well for small-volume
structures and that its validity is challenged, at least as it is
currently implemented, when used on larger structures. We also show
that, besides its advantages in reliability, the rigorous solution
approach is far superior to the approximation method in computing
efficiency as well.

---------------------------------------------------------
Title: The origin of carbon, investigated by spectral analysis of
solar-type stars in the Galactic Disk
Authors: Gustafsson, B.; Karlsson, T.; Olsson, E.; Edvardsson, B.;
Ryde, N.
1999A&A...342..426G Altcode: 1998astro.ph.11303G
Abundance analysis of carbon has been performed in a sample of
80 late F and early G type dwarf stars in the metallicity range
{-1.06&lt;=[Fe/H]&lt;=0.26} using the forbidden [C i] line at 8727
Angstroms. This line is presumably less sensitive to temperature,
atmospheric structure and departures from LTE than alternative carbon
criteria. We find that {[C/Fe]} decreases slowly with increasing
{[Fe/H]} with an overall slope of -0.17+/-0.03. Our results are
consistent with carbon enrichment by superwinds of metal-rich massive
stars but inconsistent with a main origin of carbon in low-mass
stars. This follows in particular from a comparison between the relation
of {[C/O]} with metallicity for the Galactic stars and the corresponding
relation observed for dwarf irregular galaxies. The significance of
intermediate-mass stars for the production of carbon in the Galaxy
is still somewhat unclear. Based on observations carried out at the
European Southern Observatory, La Silla, Chile.

---------------------------------------------------------
Title: The LMC Centre Unfing
Authors: Ardeberg, A.; Linde, P.; Gustafsson, B.
1999IAUS..190..357A Altcode: 1998IAUS..190E.124A
A deep study of individual stars has been made in the dense central
part of the LMC Bar. Stromgren uvby photometry has been used with the
HST PC and WFC and advanced image processing to obtain high spatial
resolution data of high photometric accuracy for a field inaccessible
with conventional tools. We have investigated star formation history
and chemical abundance and evolution. Our study covers a magnitude
interval from V=16 to V=26. Ages of stellar populations and star
formation history are derived from a y versus b-y colour-magnitude
diagram from V=16 to V=24 including approximately 4000 stars. Older
populations range in age from 2 to 9 Gyears. Few if any stars are older
than 10 Gyears or between 300 Myears and 2 Gyears. A striking feature is
a young stellar component with ages below 300 Myears containing around
30% of the total amount of stars in the LMC centre. The abundance of
heavy elements has been determined for a large number of stars close to
the turn off point in the HR diagram. For the great majority of stars,
the metallicity falls close to [Me/H] = -0.6 with a smaller amount of
stars having [Me/H] values well below -1.0. Employing a new method, we
have derived the faint end of the luminosity function down to V=26. The
resulting luminosity function for the LMC Bar centre, from V=16 to V=26,
is similar to that of the solar neighbourhood albeit somewhat steeper.

---------------------------------------------------------
Title: Dating Intermediate-and Low-Mass Stars
Authors: Gustafsson, B.
1999ASPC..192...91G Altcode: 1999sdsg.conf...91G
No abstract at ADS

---------------------------------------------------------
Title: The Centre of the LMC Bar - Analysis of HST Data
Authors: Linde, P.; Ardeberg, A.; Gustafsson, B.
1999IAUS..190..359L Altcode: 1998IAUS..190E.125L
Studies of star formation and stellar populations in the LMC Bar centre
provide important data on galactic evolution. The stellar density and
the distance make photometry the only tool realistic. However, image
crowding implies an absolute need for front line instrumentation and
sophisticated image processing techniques. The high image resolution
of the HST is unique. For studies of a single field in the centre of
the LMC Bar, we have used 14 hours of HST WFPC2 exposures and uvby
photometry. Extraction of precision astrophysical data from raw HST
images requires careful data processing. In the space environment,
interference from cosmic radiation is a severe limiting factor
for longer exposures. To allow a large field, the design of the
WFPC2 notably under-samples the images. This is especially serious
for crowded field photometry requiring high precision. We present
results from some techniques minimising effects of cosmic radiation
interference and image under-sampling. It is demonstrated that efficient
cosmic ray elimination can provide close to intrinsic photometric
accuracy. Further, image dithering and subsequent recombination enhance
the quality of photometric analysis in the LMC core, affected by high
image crowding and under-sampling as in WFPC2 frames.

---------------------------------------------------------
Title: The GIADA Experiment for Rosetta Mission to Comet 46P/Wirtanen:
Design and Performances
Authors: Bussoletti, E.; Colangeli, L.; Lopez Moreno, J. J.; Epifani,
E.; Mennella, V.; Palomba, E.; Palumbo, P.; Rotundi, A.; Vergara, S.;
Girela, F.; Herranz, M.; Jeronimo, J. M.; Lopez-Jimenez, A. C.; Molina,
A.; Moreno, F.; Olivares, I.; Rodrigo, R.; Rodriguez-Gomez, J. F.;
Sanchez, J.; McDonnell, J. A. M.; Leese, M.; Lamy, P.; Perruchot,
S.; Crifo, J. F.; Fulle, M.; Perrin, J. M.; Angrilli, F.; Benini,
E.; Casini, L.; Cherubini, G.; Coradini, A.; Giovane, F.; Grün, E.;
Gustafson, B.; Maag, C.; Weissmann, P. R.
1999AdSpR..24.1149B Altcode:
Rosetta is one of the most ambitious missions planned by ESA for
the beginning of the next millennium. It will explore from very
close a comet nucleus along its trajectory up to perihelion. In the
instrument complex forming the scientific payload, the GIADA (Grain
Impact Analyser and Dust Accumulator) experiment is devoted to study
the cometary dust flux evolution and grain dynamic properties. To
achieve the required performances and the expected scientific return,
GIADA has been designed as a multi-sensor instrument. It is able to
detect grain passage by laser light scattering measurement, particle
momentum through piezoelectric transducers and mass flux by means of
quartz crystal microbalances. In this paper we describe the technical
solutions and performances which have been reached on the development
models of GIADA

---------------------------------------------------------
Title: Old Structure - Young Stars The Stellar Content of the Centre
of the LMC Bar
Authors: Linde, P.; Ardeberg, A.; Gustafsson, B.
1999IAUS..192..108L Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The nature of the circumstellar CO_2 emission from M giants
Authors: Ryde, N.; Eriksson, K.; Gustafsson, B.
1999A&A...341..579R Altcode: 1998astro.ph.11330R
The 13-16mu m region observed by the Infrared Space Observatory (ISO)
of several ABG stars are discussed. We present and analyse spectra
of seven M giants which show carbon dioxide features. To explain the
features of the bands, we suggest they originate from two different
circumstellar layers, one being a warm and high density layer close
to the star, possibly making the 15mbox {\mum} band optically thick,
and the other being a large, cold and optically thin layer extending
far out in the wind. This could explain the difference in temperatures
of the different bands found in the analysis of the spectra and the
number of molecules needed for the emission. It is demonstrated that
in spite of the bands probably not being formed in vibrational LTE,
the temperatures can be estimated from the widths of the bands. Based
on observations with ISO, an ESA project with instruments funded by
ESA Member States (especially the PI countries: France, Germany, the
Netherlands and the United Kingdom) and with the participation of ISAS
and NASA. The SWS is a joint project of SRON and MPE.

---------------------------------------------------------
Title: The GIADA experiment for ROSETTA mission to comet 46P/wirtanen:
Design and performances
Authors: Bussoletti, E.; Colangeli, L.; Lopez Moreno, J. J.; Epifani,
E.; Mennella, V.; Palomba, E.; Palumbo, P.; Rotundi, A.; Vergara, S.;
Girela, F.; Herranz, M.; Jeronimo, J. M.; Lopez-Jimenez, A. C.; Molina,
A.; Moreno, F.; Olivares, I.; Rodrigo, R.; Rodriguez-Gomez, J. F.;
Sanchez, J.; McDonnell, J. A. M.; Leese, M.; Lamy, P.; Perruchot,
S.; Crifo, J. F.; Fulle, M.; Perrin, J. M.; Angrilli, F.; Benini,
E.; Casini, L.; Cherubini, G.; Coradini, A.; Giovane, F.; Grün, E.;
Gustafson, B.; Maag, C.; Weissmann, P. R.
1999AdSpR..24.1139B Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Scattering by complex systems I: Methods
Authors: Gustafson, B. Å. S.
1999ASIC..523..535G Altcode: 1999fess.conf..535G
No abstract at ADS

---------------------------------------------------------
Title: Scattering by complex systems II: Results from microwave
measurements
Authors: Gustafson, B. Å. S.; Kolokolova, L.; Thomas-Osip, J. E.;
Waldemarsson, K. W. T.; Loesel, J.; Xu, Y. -L.
1999ASIC..523..549G Altcode: 1999fess.conf..549G
No abstract at ADS

---------------------------------------------------------
Title: Chemical Abundances of Local “Unevolved” Stars
Authors: Gustafsson, Bengt
1999cezh.conf....1G Altcode:
A number of results from work in recent years on chemical abundances
in main-sequence late-type stars are discussed. This illuminates what
may be discovered when the analyses are carried out with high S/N and
high-resolution spectra, and with accurate and uniform methods for the
analysis and the selection of fundamental stellar parameters. A major
conclusion is that further new important discoveries as regards star
formation, stellar and galactic evolution and nucleosynthesis will
most probably result when the VLT UVES spectrometer, and the next
generation of model atmospheres, are applied in such analyses.

---------------------------------------------------------
Title: Experiments for in-situ monitoring of dust environments in
the Solar System.
Authors: Colangeli, L.; Bussoletti, E.; López-Moreno, J. J.; Epifani,
E.; Esposito, F.; Mennella, V.; Palomba, E.; Palumbo, P.; Rotundi,
A.; Vergara, S.; Jeronimo, J. M.; Lopez-Jimenez, A. C.; Molina, A.;
Morales, R.; Moreno, F.; Olivares, I.; Rodrigo, R.; Rodriguez-Gomez,
J. F.; Ruiz-Falco, A.; Sanchez, J.; McDonnell, J. A. M.; Leese, M.;
Lamy, P.; Perruchot, S.; Crifo, J. F.; Fulle, M.; Perrin, J. M.;
Angrilli, F.; Coradini, A.; Giovane, F.; Gruen, E.; Gustafson, B.;
Maag, C.; Weissman, P. R.
1999BAAS...31R1119C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Late stages of stellar evolution
Authors: Gustafsson, Bengt
1999anot.conf..254G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: A systematic study of light scattering by aggregate particles
using the microwave analog technique: Angular and wavelength
dependence of intensity and polarization
Authors: Gustafson, Bo Å. S.; Kolokolova, Ludmilla
1999JGR...10431711G Altcode:
Microwave analog experiments [e.g., Gustafson, 1996a, 1999]
allow us to simulate light-scattering properties of particles of
almost any combination of composition, size, and shape. We have
taken advantage of this ability and the broadband nature of the
University of Florida microwave facility in a systematic study of
light scattering by aggregates. We present angular dependencies of
intensity and polarization in the scattering angle range 0°-165°,
and in the wavelength interval 2.7-4 mm, which simulates 0.430-0.660
μm in the visual. The data are for a variety of sizes, shapes, and
compositions of the constituent particles, as well as the number of
particles in an aggregate and their packing. Wavelength dependencies
are shown to be powerful diagnostics for the interpretation of comet
dust observations and we urge observers to report color and polarimetric
color. As an example, we estimate the size of constituent particles in
cometary grains (0.1-1μm). We also show that the grains evolve with the
distance from the nucleus and that the reason apparently is the loss
of some dark matter. Techniques and results reported here are general
enough to apply to a broad range of natural and artificial aggregates.

---------------------------------------------------------
Title: Convection in Metal-Poor Stars as Traced from Spectral Line
Asymmetries
Authors: Allende Prieto, C.; Asplund, M.; García López, R. J.;
Gustafsson, B.; Lambert, D. L.
1999ASPC..173..205A Altcode: 1999sstt.conf..205A
No abstract at ADS

---------------------------------------------------------
Title: Another r-Process-Enriched Halo Star: HD 115444
Authors: Westin, J.; Sneden, C.; Gustafsson, B.; Edvardsson, B.;
Cowan, J. J.
1998AAS...193.4501W Altcode: 1998BAAS...30.1317W
A new high resolution very high signal to noise spectrum has been
obtained for the metal-poor giant star HD 115444, first examined in
detail by Griffin et al. (1982, MNRAS, 198, 637). Our new spectrum was
gathered with the High-Resolution Echelle Spectrometer of the McDonald
Observatory 2.7m Telescope. We have performed a model atmosphere
analysis and line identification, emphasizing the neutron-capture
elements; 20 elements with Z&gt;30 have been identified in the HD 115444
spectrum. The overall metallicity was found to be [Fe/H] = --3.0. The
abundances of the light and iron-peak elements show the same pattern
as other very metal-poor stars (e.g. overdeficiencies of Mn and Cr,
overabundances of Co). The initial synthetic spectrum analyses reveal
substantial overabundances of all neutron-capture elements with Z&gt;=56
(Ba and beyond). Moreover, the abundance pattern is clearly consistent
with production dominated by r-process nucleosynthesis (with little
contribution from the s-process), just like that also found in the
metal-poor giant star CS 22892-052 (Sneden et al., 1996, ApJ, 467,
819). To illustrate this, in HD 115444 we find [Ba/Eu] = --0.73, while
in CS 22892-052, this ratio is --0.79. Thus HD 115444 becomes the second
clear example of a very metal-poor yet r-process-rich halo giant. With
(for example) [Eu/Fe] =~ +0.9, HD 115444 is a moderate version of CS
22892-052 (which has [Eu/Fe] =~ +1.7).

---------------------------------------------------------
Title: Three years of Galileo dust data: II. 1993-1995
Authors: Krüger, H.; Grün, E.; Hamilton, D. P.; Baguhl, M.; Dermott,
S.; Fechtig, H.; Gustafson, B. A.; Hanner, M. S.; Horányi, M.; Kissel,
J.; Lindblad, B. A.; Linkert, D.; Linkert, G.; Mann, I.; McDonnell,
J. A. M.; Morfill, G. E.; Polanskey, C.; Riemann, R.; Schwehm, G.;
Srama, R.; Zook, H. A.
1998P&SS...47...85K Altcode: 1999P&SS...47...85K; 1998astro.ph..9318K
Between January 1993-December 1995, the Galileo spacecraft traversed
interplanetaryspace between Earth and Jupiter and arrived at Jupiter
on 7 December 1995. The dust instrumentonboard the spacecraft
was operating during most of the time and data from the instrument
wereobtained via memory readouts which occurred at rates between twice
per day and once per week.All events were classified by an onboard
program into 24 categories. Noise events were usuallyrestricted to the
lowest categories (class 0). During Galileos passage through Jupiters
radiationbelts on 7 December 1995, several of the higher categories
(classes 1 and 2) also show evidencefor contamination by noise. The
highest categories (class 3) were noise-free all the time. Arelatively
constant impact rate of interplanetary and interstellar (big) particles
of 0.4 impacts perday was detected over the whole three-year time
span. In the outer solar system (outside about2.6 AU) they are mostly
of interstellar origin, whereas in the inner solar system they are
mostlyinterplanetary particles. Within about 1.7 AU from Jupiter intense
streams of small dust particleswere detected with impact rates of up
to 20,000 per day whose impact directions are compatiblewith a Jovian
origin. Two different populations of dust particles were detected in
Jovianmagnetosphere: small stream particles during Galileos approach
to the planet and big particlesconcentrated closer to Jupiter between
the Galilean satellites. There is strong evidence that thedust stream
particles are orders of magnitude smaller in mass and faster than
the instrumentscalibration, whereas the calibration is valid for the
big particles. Because the data transmissionrate was very low, the
complete data set for only a small fraction (2525) of all detected
particlescould be transmitted to Earth; the other particles were only
counted. Together with the 358particles published earlier, information
about 2883 particles detected by the dust instrumentduring Galileos
six years journey to Jupiter is now available.

---------------------------------------------------------
Title: A double-arm Møller Polarimeter for Jefferson Lab's Hall B
Authors: Grún, E.; Krúger, H.; Dermott, S.; Fechtig, H.; Graps,
A. L.; Zook, H. A.; Gustafson, B. A.; Hamilton, D. P.; Hanner, M. S.;
Heck, A.; Horányi, M.; Kissel, J.; Lindbad, B. A.; Linkert, D.;
Linkert, G.; Mann, I.; Mcdonnell, J. A. M.; Morfill, G. E.; Polanskey,
C.; Schwehm, G.; Srama, R.
1998APS..DNP..B711G Altcode:
We have constructed and commissioned a double-arm Møller polarimeter
for the Hall B beamline at the Thomas Jefferson National Accelerator
Facility. The polarimeter measures the longitudinal polarization
of the 0.8-4.0 GeV electron beam as it enters the experimental
hall. The primary components of the apparatus are a target chamber,
a pair of quadrupole magnets, and a pair of lead/scintillating-fiber
detectors. The target chamber contains two 20 μm-thick permendur foils
tilted at ± 20^o with respect to the beam axis. A target polarization
of approximately 8% is produced along the beam direction by a 90 G
(nominal) magnetic field generated by a pair of Helmholtz coils. The
scattered Møller-electron pairs are directed toward the detectors by
the quadrupoles. The quadrupoles are are individually tuned--depending
on the beam energy--to center the peak of the Møller asymmetry
(θ_c.m.=90^o) onto the fixed detectors. The real-to-accidental
coincident-detection rate is better than 200:1. The beam polarization
can be measured to a 3% relative statistical precision in less than
30 minutes with a relative systematic uncertainty of less than 5%.

---------------------------------------------------------
Title: Galileo observes electromagnetically coupled dust in the
Jovian magnetosphere
Authors: Grün, E.; Krüger, H.; Graps, A. L.; Hamilton, D. P.; Heck,
A.; Linkert, G.; Zook, H. A.; Dermott, S.; Fechtig, H.; Gustafson,
B. A.; Hanner, M. S.; Horányi, M.; Kissel, J.; Lindblad, B. A.;
Linkert, D.; Mann, I.; McDonnell, J. A. M.; Morfill, G. E.; Polanskey,
C.; Schwehm, G.; Srama, R.
1998JGR...10320011G Altcode:
Measurements of dust coupled to the Jovian magnetosphere have been
obtained with the dust detector on board the Galileo spacecraft. We
report on data obtained during the first four orbits about Jupiter
that had flybys of the Galilean satellites: Ganymede (orbits 1 and 2),
Callisto (orbit 3), and Europa (orbit 4). The most prominent features
observed are highly time variable dust streams recorded throughout the
Jovian system. The impact rate varied by up to 2 orders of magnitude
with a 5 and 10 hour periodicity, which shows a correlation with
Galileo's position relative to the Jovian magnetic field. Around 20
RJ (Jupiter radius, RJ=71, 492 km) in bound a
dip in the impact rate has been found consistently. At the same times,
reversals by 180° in impact direction occurred. This behavior can
be qualitatively explained by strong coupling of nanometer-sized dust
to the Jovian magnetic field. At times of satellite flybys, enhanced
rates of dust impacts have been observed, which suggests that all
Galilean satellites are sources of ejecta particles. Inside about 20
RJ impacts of micrometer-sized particles have been recorded
that could be particles on bound orbits about Jupiter.

---------------------------------------------------------
Title: Microwave analog study of light-scattering properties of
aggregate particles for intepretation of cometary dust observations
Authors: Kolokolova, L.; Gustafson, B. S.; Thomas-Osip, J.; Loesel, J.
1998DPS....30.4007K Altcode: 1998BAAS...30Q1090K
Microwave analog experiments allow us to study particles of almost
any combination of composition, size and shape. We have taken
advantage of this ability and the broadband nature of the University
of Florida microwave facility to obtain the intensity, polarization,
color, and polarimetric color for a range of particle types. Here we
present results for aggregates as the most probable type of cometary
grains. These may be particles of size close to the wavelength of
visible light aggregated to form structures very large compared to
the wavelength. These circumstances make a theoretical study of the
light scattered by cometary dust exceedingly difficult and, at least in
part, beyond the capability of common numerical techniques. We selected
aggregates made of polystyrene, nylon and a mixture of expanded plastic
and iron oxide. These materials are, with their refractive indices
near 1.6-0.03i, 1.74-0.005i, and 1.7 - 0.2i, microwave analogues
to silicates and organic materials expected in cometary dust. The
angular dependencies of intensity and polarization were obtained in the
scattering angle range [0,165(o]) , and in the wavelength intervals
[2.7-3] and [3.5-4] mm, to simulate cometary continuum filters at
0.442 and 0.642 microns . The study of light scattering properties of
a range of aggregate types and the comparison of laboratory data with
data of photometric and polarimetric observations of comets allow us
not only to estimate the size and structure of cometary grains but
also to study their evolution with distance from the nucleus.

---------------------------------------------------------
Title: Boron in Very Metal Poor Stars
Authors: Garcia Lopez, Ramon J.; Lambert, David L.; Edvardsson, Bengt;
Gustafsson, Bengt; Kiselman, Dan; Rebolo, Rafael
1998ApJ...500..241G Altcode: 1998astro.ph..1167G; 1998astro.ph..1167L
We have observed the B I 2497 A line to derive the boron abundances
of two very metal-poor stars selected to help in tracing the origin
and evolution of this element in the early Galaxy: BD +23 3130 and
HD 84937. The observations were conducted using the Goddard High
Resolution Spectrograph on board the Hubble Space Telescope. A
very detailed abundance analysis via spectral synthesis has been
carried out for these two stars, as well as for two other metal-poor
objects with published spectra, using both Kurucz and OSMARCS model
photospheres, and taking into account consistently the NLTE effects
on the line formation. We have also re-assessed all published boron
abundances of old disk and halo unevolved stars. Our analysis shows
that the combination of high effective temperature (Teff &gt; 6000 K,
for which boron is mainly ionized) and low metallicity ([Fe/H]&lt;-1)
makes it difficult to obtain accurate estimates of boron abundances
from the B I 2497 A line. This is the case of HD 84937 and three other
published objects (including two stars with [Fe/H] ~ -3), for which only
upper limits can be established. BD +23 3130, with [Fe/H] ~ -2.9 and
logN(B)_NLTE=0.05+/-0.30, appears then as the most metal-poor star for
which a firm measurement of the boron abundance presently exists. The
evolution of the boron abundance with metallicity that emerges from
the seven remaining stars with Teff &lt; 6000 K and [Fe/H]&lt;-1,
for which beryllium abundances were derived using the same stellar
parameters, shows a linear increase with a slope ~ 1. Furthermore, the
B/Be ratio found is constant at a value ~ 20 for stars in the range
-3&lt;[Fe/H]&lt;-1. These results point to spallation reactions of
ambient protons and alpha particles with energetic particles enriched
in CNO as the origin of boron and beryllium in halo stars.

---------------------------------------------------------
Title: Steps toward interstellar silicate mineralogy. III. The role
of aluminium in circumstellar amorphous silicates
Authors: Mutschke, H.; Begemann, B.; Dorschner, J.; Guertler, J.;
Gustafson, B.; Henning, Th.; Stognienko, R.
1998A&A...333..188M Altcode:
It is a well-known fact that the spectra of oxygen-rich circumstellar
dust envelopes around evolved stars show great diversity, especially
in the 10 mu m silicate band profiles, but also in the longer infrared
wavelength range covered by ISO. This supports earlier conclusions
that the concept of a universal cosmic silicate is inadequate and that
it is reasonable to consider a wider variety of possible silicate
analogues as the basis for an improved modelling of the observed
spectra. In the course of an investigation of the role of aluminium
in cosmic dust, aluminosilicate glasses (ASGs) have been suggested as
interesting laboratory analogues for this purpose. In these glasses,
silicon ions within the SiO_4 tetrahedra are partly substituted by
fourfold coordinated aluminium. In a new laboratory approach to the
silicate dust problem, 13 ASG samples were prepared. Apart from
magnesium and iron, the cosmically most abundant metals, sodium
and calcium, were incorporated as cations. In this paper, these
new silicate dust analogues are analytically and spectroscopically
characterized. The spectroscopic results were obtained in the range
from the UV to the far-infrared, in the millimetre wave range, and
by Raman spectroscopy. Optical constants have been derived for the
wavenumbers 1500-20 cm(-1) (6.7-500 mu m) from infrared reflectance
measurements and for the frequencies 110-75 GHz (2.7-4 mm) from
angle-resolved millimetre-wave scattering at spherical samples from two
of the ASGs. For the electronic and vibrational absorption features,
the dependence on the aluminium/silicon substitution ratio and on the
glass structure is discussed. Relations between the calculated (Rayleigh
case) band positions, widths and strengths of the IR absorption bands
and the chemical compositions are derived. The application of the new
data to the reproduction of observed stardust spectra of the IRAS-LRS
catalogue shows promising results.

---------------------------------------------------------
Title: Is the Sun a Sun-Like Star?
Authors: Gustafsson, B.
1998SSRv...85..419G Altcode:
Various observable properties of the Sun are compared with those
of solar-type stars. It is concluded that the Sun, to a remarkable
degree, is “solar-type”. As regards its particular mass and age,
and probably its non-binarity, “anthropic” explanations may seem
in place. The possible tendency for the Sun, as compared with similar
stars, to be somewhat rich in iron relative to other elements needs
further exploration. This is also true concerning its presently small
micro-variability amplitude.

---------------------------------------------------------
Title: VizieR Online Data Catalog: G and K dwarfs abundances
(Feltzing+ 1998)
Authors: Feltzing, S.; Gustafsson, B.
1998yCat..41290237F Altcode:
The table presents the abundances of all 47 dwarf stars analysed in the
paper. We give abundances relative to the Sun in the standard notation
of [X/H]=log(X/H)star-log(X/H)⊙. The 5 K dwarf
stars and 3 stars in common with Barbuy &amp; Grenon (1990) appear at
the end of the table. The label of each column indicates the ion the
quoted abundances are derived from. For each star we give the abundance,
[X/H], the line-to-line scatter (if more than one line is used) and
the number of lines used. The stars are ordered in the same way as in
Table 1 in the paper, ie. the K dwarf stars and the stars in common
with Barbuy &amp; Grenon (1990) are found at the end. (2 data files).

---------------------------------------------------------
Title: Abundance similarities between the RCrB star V854Cen and the
born-again Sakurai's object
Authors: Asplund, Martin; Gustafsson, Bengt; Kameswara Rao, N.;
Lambert, David L.
1998A&A...332..651A Altcode: 1998astro.ph..1068A
The elemental abundances of the mildly hydrogen-deficient R Coronae
Borealis (RCrB) star V854Cen have been estimated. The RCrB stars
have been divided into majority and minority classes judging by their
abundance patterns. Class assignment has previously been unambiguous
but V854Cen has traits of both the minority and majority class. Neither
V854Cen nor the three obvious minority members show any clear abundance
signatures of having been affected by e.g. dust-gas separation as often
observed in post-AGB stars. By chemical composition, V854Cen closely
resembles Sakurai's object, which has probably recently experienced
a final He-shell flash. Therefore V854Cen and Sakurai's object may
share the same evolutionary background, which would add support for
the final-flash scenario as a viable origin of the RCrB stars. Most
of the few differences in abundance ratios between the stars could if
so be attributed to milder H-ingestion in connection with the final
He-shell flash of V854Cen. The identification of either the majority or
the minority group, if any, as final flash objects, remain uncertain,
however, due to the unclear membership status of V854Cen.

---------------------------------------------------------
Title: South-North and radial traverses through the interplanetary
dust cloud
Authors: Gruen, E.; Staubach, P.; Baguhl, M.; Hamilton, D. P.; Zook,
H. A.; Dermott, S.; Fechtig, H.; Gustafson, B. A.; Hanner, M. S.;
Horanyi, M.; Kissel, J.; Lindblad, B. A.; Linkert, D.; Linkert, G.;
Mann, I.; McDonnell, J. A. M.; Morfill, G. E.; Polanskey, C.; Schwehm,
G.; Srama, R.
1998exdu.work..270G Altcode:
Identical in situ dust detectors are flown on board the Galileo and
Ulysses spacecraft. They record impacts of micrometeoroids in the
ecliptic plane at heliocentric distances from 0.7 to 5.4 AU and in
a plane almost perpendicular to the ecliptic from -79 deg to +79
deg ecliptic latitude. The combination of both Ulysses and Galileo
measurements yield information about the radial and latitudinal
distributions of micron and sub-micron sized dust in the solar
system. Two types of dust particles were found to dominate the dust
flux in interplanetary space: (1) Interplanetary micrometeoroids
covering a wide mass range from 10-16 to 10-6
gr are mostly recorded inside 3 AU, and at latitudes below 30 deg;
and (2) Interstellar grains with masses between 10-14
and 10-12 gr have been positively identified outside 3 AU
near the ecliptic plane and outside 1.8 AU at high ecliptic latitudes
(&gt; 50 deg). Interstellar grains move on hyperbolic trajectories
through the planetary system and constitute the dominant dust flux
(1.5 x 10-4/ sq m sec) in the outer solar system and at high
ecliptic latitudes. In order to compare and analyze the Galileo and
Ulysses data sets, a new model is developed based on Divine's (1993)
"Five populations of interplanetary meteoroids" model. By using this
model, which takes into account the measured velocities and the effect
of radiation pressure on small particles, we define four populations
of meteoroids on elliptical orbits plus one population on hyperbolic
orbits that all can fit the micrometeoroid flux observed by Galileo
and Ulysses.

---------------------------------------------------------
Title: Abundances in metal-rich stars. Detailed abundance analysis
of 47 G and K dwarf stars with [Me/H] &gt; 0.10 dex
Authors: Feltzing, S.; Gustafsson, B.
1998A&AS..129..237F Altcode: 1997astro.ph.10315F
We have derived elemental abundances of O, Na, Mg, Al, Si, Ca, Ti,
Cr, Mn, Fe, Co, Ni as well as for a number of s-elements for 47 G and
K dwarf, with [Me/H]&gt;0.1 dex. The selection of stars was based on
their kinematics as well as on their uvby-beta photometry. One sample
of stars on rather eccentric orbits traces the chemical evolution
interior to the solar orbit and another, on circular orbits, the
evolution around the solar orbit. A few Extreme Population I stars
were included in the latter sample. The stars have -0.1 dex &lt;
[Fe/H] &lt; 0.42 dex. The spectroscopic [Fe/H] correlate well with the
[Me/H] derived from uvby-beta photometry. We find that the elemental
abundances of Mg, Al, Si, Ca, Ti, Cr and Ni all follow [Fe/H]. Our
data put further constraints on models of galactic chemical evolution,
in particular of Cr, Mn and Co which have not previously been studied
for dwarf stars with [Me/H] &gt;0.1 dex. The increase in [Na/Fe] and
[Al/Fe] as a function of [Fe/H] found previously by \cite[Edvardsson
et al. (1993a)]{Edv93} has been confirmed for [Na/Fe]. This upturning
relation, and the scatter around it, are shown not to be due to a
mixture of populations with different mean distances to the galactic
centre. We do not confirm the same trend for aluminium, which is
somewhat surprising since both these elements are thought to be produced
in the same environments in the pre-supernova stars. Nor have we been
able to trace any tendency for relative abundances of O, Si, and Ti
relative to Fe to vary with the stellar velocities, i.e. the stars
present mean distance to the galactic centre. These results imply that
there is no significant difference in the chemical evolution of the
different stellar populations for stars with [Me/H]&gt;0.1 dex. We find
that [O/Fe] continue to decline with increasing [Fe/H] and that oxygen
and europium correlate well. However [Si/Fe] and [Ca/Fe] seem to stay
constant. A real (“cosmic”) scatter in [Ti/Fe] at given [Fe/H] is
suggested as well as a decreasing abundance of the s-elements relative
to iron for the most metal-rich dwarf stars. We discuss our results
in the context of recent models of galactic chemical evolution. In our
sample we have included a few very metal rich stars, sometimes called
SMR (super metal rich) stars. We find these stars to be among the most
iron-rich in our sample but far from as metal-rich as indicated by
their photometric metallicities. SMR stars on highly eccentric orbits,
alleged to trace the evolution of the chemical evolution in the galactic
Bulge, have previously been found overabundant in O, Mg and Si. We
have included three such stars from the study by \cite[Barbuy &amp;
Grenon (1990)]{Bar90}. We find them to be less metal rich and the
other elemental abundances remain puzzling. Detailed spectroscopic
abundance analyses of K dwarf stars are rare. Our study includes 5
K dwarf stars and has revealed what appears to be a striking example
of overionization. The overionization is especially prominent for Ca,
Cr and Fe. The origin of this apparent overionization is not clear and
we discuss different explanations in some detail. Based on observations
at the McDonald Observatory.

---------------------------------------------------------
Title: On the determination of carbon isotopic ratios in cool
carbon stars
Authors: de Laverny, P.; Gustafsson, B.
1998A&A...332..661D Altcode:
We discuss the determination of carbon isotopic ratios (12C) /
(12C) iso in N-type Galactic carbon stars. Ohnaka &amp; Tsuji (1996)
reported (12C) / (12C) iso ratios smaller by a factor 2 or 3 than
the determinations of Lambert et al. (1986). Using synthetic spectra
of carbon stars, we analyse systematic errors in their iso-intensity
method. It is found to be rather sensitive to model parameters and
blends. Furthermore, there are large discrepancies between the effective
temperatures adopted by these two studies (mean discrepancy close to
260 K for the 20 stars in common). That, together with uncertainties
due to model atmospheres, to carbon enrichments and effects of the
blends, could explain most of the discrepancies between these two
studies. The LGEH86 analysis is, on the other hand, rather insensitive
to model parameters. We therefore conclude that large (12C) / (12C)
iso ratios in cool Galactic carbon stars should be favoured.

---------------------------------------------------------
Title: A thin molecular shell around the carbon star TT CYG
Authors: Olofsson, H.; Bergman, P.; Lucas, R.; Eriksson, K.;
Gustafsson, B.; Bieging, J. H.
1998A&A...330L...1O Altcode:
Interferometric CO({\jtra10} and {\tra21}) observations reveal a
remarkably thin shell of molecular gas around the carbon star TT Cyg,
width/radius la 1farcs 3/34arcsec ~ 0.04. It expands at ~13{km s(-1) ,
and contains ~ 0.02M_sun of gas provided the CO abundance with respect
to H_2 is 10(-3) and the distance is 1kpc. Only about a quarter of the
shell has been mapped, but we infer an overall spherical shell with
only small, but clear, deviations at the per cent level. The radial
structure of the shell is barely resolved at the arc second level,
but there exists weak emission extending a few arc seconds inwards
from the peak. A drastic change in mass loss properties, possibly
combined with the effects of interacting winds, provides the most
likely explanation to the origin of the shell. %

---------------------------------------------------------
Title: Tentative Detection of Circumstellar CO2 from the AGB Star
R Crateris
Authors: Ryde, N.; Eriksson, K.; Gustafsson, B.; Lindqvist, M.;
Olofsson, H.
1998Ap&SS.255..301R Altcode: 1997Ap&SS.255..301R
We report on and discuss the detection of an emission feature at 14.98
µm from the oxygen-rich, semi-regularly pulsating Asymptotic Giant
Branch star R Crateris, a feature which we suggest to be due to the
&lt;Stack&gt; 0 1 &lt;/Stack&gt; Q-branch of
circumstellar CO2. We also suggest a reasonable excitation mechanism,
which could explain the height, the width and the asymmetry of the
feature.

---------------------------------------------------------
Title: DFA-the dust flux analyzer for the Rosetta orbiter
Authors: Lamy, P.; Perruchot, S.; Reynaud, J. -L.; Leese, M. R.;
McDonnell, J. A. M.; Green, S. F.; Busoletti, E.; Colangeli, L.;
Fulle, M.; Rotundi, A.; Giovane, F.; Gustafson, B.; Perrin, J. -M.
1998AdSpR..21.1557L Altcode:
We describe the scientific objectives, the design concept and the
implementation of the Dust Flux Analyser (DFA) for the ESA Rosetta
mission. DFA is designed to detect individual dust particles in order
to study their physical and dynamical properties as a function of
time and of orbital position, to monitor the spatial distribution
of the dust production and correlate it with the nucleus emission
sites and to analyse gas-dust interactions and the evolution of the
coma. The instrument is composed of three detectors with a common
electronic box. The Velocity Measurement System (VMS) will measure
the velocity of the incoming dust particles and the dust detector
(MOM), its momentum. A separate deposition system (DEP) composed of
three quartz microbalances will monitor the cometary dust flux in three
directions. DFA will be able to detect dust particles in the size range
5-1000 μm and velocity range 0.1-150 m.s^-1. Required resources are
a mass of 4.9 kg, a power of 3.6 W to 16.7 W and a telemetry of 50 to
512 kBits per hour depending upon the operating modes.

---------------------------------------------------------
Title: Modelling of molecular bands of oxygen-rich AGB stars
Authors: Ryde, N.; Eriksson, K.; Gustafsson, B.; Olofsson, H.; Plez, B.
1998IAUS..191P.118R Altcode:
ISO observations of infrared molecular bands of oxygen-rich AGB stars
are compared with synthetic spectra generated using model atmospheres
from the new large grid of model atmospheres that we are currently
calculating with the newest MARCS code in spherical geometry. Seven
molecular bands of eight M-giants, observed by ISO in medium resolution
mode (SWS06), are analysed in this way.

---------------------------------------------------------
Title: Cosmic Dust Exploration Using Broadband Microwave Analogues
Authors: Gustafson, B. E. S.; Kolokolova, L.; Loesel, J.; Thomas-Osip,
J.; Waldemarsson, T.; Xu, Y. -L.
1998lss..work..143G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Modelling of ISO-SWS spectra of red giants
Authors: Decin, L.; Cohen, M.; Eriksson, K.; Gustafsson, B.; Huygen,
E.; Morris, P.; Plez, B.; Sauval, J.; Vandenbussche, B.; Waelkens, C.
1998IAUS..191P.120D Altcode:
The modelling and interpretation of the ISO-SWS (Infrared Space
Observatory - Short Wavelength Spectrometer) data require accurately
calibrated spectrometers. In the SWS spectral region (2.38-45.2 microns)
the primary standard calibration candles are bright, mostly cool,
stars. The better these calibration sources are known in the infrared,
the more accurate the spectrometers can be calibrated. Since ISO offers
the first opportunity to observe in the infrared with a resolving power
of ~1500, our knowledge on stellar sources -and more specifically on
stellar atmospheres- is not so refined. A full exploitation of the ISO
data will therefore result from an iterative process in which both
accurate observations and new modelling are involved. A comparison
between the observed SWS spectra and the predicted ones based on the
Opacity Sampling spherical models of B. Plez (Plez et al., 1992; 1993)
is performed. This reveals not only calibration problems, but also
shortcomings in generating the synthetic spectra. Our results will not
only contribute to a better calibration of the ISO-SWS data, but also to
a better understanding and modelling of the atmosphere of cool giants.

---------------------------------------------------------
Title: Mid and far-infrared spectra of the third brightest carbon
star IRAS 15194-5115
Authors: Ryde, N.; Eriksson, K.; Gustafsson, B.; Jorgensen, U. G.;
Nyman, L. -Aa.; Olofsson, H.; Plez, B.; Wolstencroft, R.
1998IAUS..191P.312R Altcode:
ISO observations from 2 to 197 microns of the recently discovered,
third brightest (at 12 microns) carbon star IRAS 15194-5115, are
analysed. Eighty spectra, covering the entire range from 2.3 microns
to 45 microns, were observed in the ISO medium-high resolution mode
(SWS06). Also, observations were made with the ISO long wavelength
spectrometer (LWS) from 42 to 197 microns. The evolutionary stage and
chemistry are discussed and a comparison to the similar carbon star
IRC+10216 is made.

---------------------------------------------------------
Title: Experimental Verification of Multisphere Light-Scattering
Calculations: I) Rigorous Solution and II) the DDA
Authors: Xu, Yu-Lin; Gustafson, Bo E. S.
1998lss..work..270X Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Is the Sun a Sun-like Star?
Authors: Gustafsson, B.
1998sce..conf..419G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Episodic mass loss of the carbon star TT CYG
Authors: Olofsson, H.; Bergman, P.; Lucas, R.; Eriksson, K.;
Gustafsson, B.; Bieging, J. H.
1998IAUS..191P.415O Altcode:
There exists now seven carbon stars for which there is good evidence
that the mass loss has been highly episodic. Detached gas shells were
first imaged in circumstellar CO emission, R Scl, U Ant, S Sct, and TT
Cyg (see Olofsson et al. 1996), or in other molecular line emissions,
U Cam. Detached dust shells have been observed towards U Hya, Y CVn, and
U Ant (probably two shells). So far there is only one M-star for which a
similar detached shell has been found, R Hya. It has been suggested that
these shells are due to episodic high mass loss rate events connected
with the thermal pulses of the central star. In this poster we present
high resolution (~2 arcsecond) CO(J = 1-0) observations of the carbon
star TT Cyg performed with the IRAM interferometer on Plateau de Bure,
France (a minor part of the data have been presented in Olofsson et
al. 1998). To cover the entire shell we have observed eight primary
fields. We have used four configurations to be sensitive to extended
as well as sharply peaked emission. The data reveal an overall close
to spherically symmetric, very narrow (width/radius approximately less
than 0.04, except to the north) shell. Yet, there are clear deviations
from perfect spherical symmetry, e.g., the star does not lie exactly
at the centre of the shell, which appears to break up in the north. The
brightness distribution is very patchy. If the shell is due to a phase
of substantially increased mass loss, the time scale for this phase is
at most a few hundred years and the mass loss rate must have approached
10^{-4} Modot yr^{-1} ~5000 years ago (adopting the HIPPARCOS
distance of ~500 pc). The present mass loss of the star is very low.

---------------------------------------------------------
Title: Images in scattered light of detached circumstellar shells
Authors: Delgado, D. G.; Olofsson, H.; Schwarz, H.; Eriksson, K.;
Gustafsson, B.
1998IAUS..191P.404D Altcode:
The temporal variations of the mass loss rate of an AGB-star as it
evolves is to a large extent unknown. This applies to all time scales
from the pulsation period to the full time scale for the AGB-phase. For
the shortest time scales we are limited by the spatial resolution of
the observations, while for the longest time scales we lack suitable
observational probes. On the intermediate time scales (10^2-10^4
yr) there is now growing evidence for substantial variations in the
mass loss rate, perhaps due to the effects of thermal pulses. Some
of the best examples are provided by CO radio line observations of
detached gas shells, and at least in one case the shell is extremely
narrow compared to its radius (width/radius approximately less than
0.04, see P4-15). The interpretation of the CO data are hampered by
the fact that the emission depends on the excitation as well as the
photodissociation of the CO-molecules, and hence the relation between
the density distribution (and consequently the mass loss history)
and the brightness distribution is uncertain. Here we present images
obtained in 50 AA narrow filters (centered on the KI and Na D lines)
with the ESO 3.6m telescope of three carbon stars with detached CO
shells: R Scl, U Ant, and S Sct. In the two former we detect light
scattered in extended envelopes. The brightness is relatively constant
out to a relatively sharp outer radius, R Scl (~19 arcsecond) and U
Ant (~41 arcsecond). For U Ant this radius coincides exactly with the
observed peak radius of the CO shell. For R Scl this radius coincides
with the outer radius of the CO distribution (as estimated from a
model fit to the CO data; the CO shell is only marginally resolved
and hence its radius is not well determined). [In the case of S Sct,
with the largest CO shell radius (~70 arcsecond), no scattered light
is detected.] This strongly supports the conclusion that the density
distribution has a sharp outer edge. The shell distribution of the CO
emission can only be reasonably explained by a sharp inner edge of the
density distribution. Hence, these stars have gone through a period of
significant change in the mass loss rate. Whether the shells are formed
by a brief period of very enhanced mass loss, or are due to a faster
wind sweeping up material from a slower wind remains to be determined.

---------------------------------------------------------
Title: Evidence for Comet Dust Evolution based on Microwave Analogue
Experiments and Polarimetric Observations
Authors: Kolokolova, L.; Gustafson, B. E. S.; Loesel, J.; Thomas-Osip,
J.
1998lss..work..170K Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The centre of the LMC bar
Authors: Ardeberg, A.; Linde, P.; Snel, R.; Gustafsson, B.; Nissen,
P. E.
1998IAUS..184..135A Altcode:
With the HST PC and uvby photometry, we investigate evolutionary
signatures in a field in the centre of the LMC Bar. Field stars close
to the turn off point in the HR diagram are used for a study of ages
and evolution of the stellar populations dominating the Bar as well
as for determination of the abundance of heavy elements. Including
fainter stars, we derive the corresponding luminosity function. Here,
we discuss some results obtained from a preliminary version of our
data. The quality of our data is high. Two strong stellar populations
are obvious. A young component contains approximately 30% of the total
number of stars. At least a considerable fraction of this component
originated less than 500 Myears ago. The older population ranges in
age between around 2 and 9 G years. The abundance of heavy elements is
around [Me/H] = -0.6. The tentative luminosity function, down to y =
24, resembles in shape that predicted from earlier galactic and LMC
data. Parallel to arrival of further HST data, our analysis continues.

---------------------------------------------------------
Title: Molecules in Stellar Atmospheres
Authors: Gustafsson, B.
1998Ap&SS.255..241G Altcode: 1997Ap&SS.255..241G
The effects of molecules on model stellar atmospheres are briefly
reviewed. Molecular diagnostics of stellar fundamental parameters and
of atmospheric structure are discussed, and the presently emerging
"ISO picture" of the outer regions of stars is commented upon.

---------------------------------------------------------
Title: The rise and fall of the NaMgAl stars.
Authors: Tomkin, J.; Edvardsson, B.; Lambert, D. L.; Gustafsson, B.
1997A&A...327..587T Altcode: 1997astro.ph..7208T
We have made new abundance determinations for a sample of NaMgAl
stars. These stars, which are a subgroup of the nearby metal-rich
field F and G disk dwarfs, were first identified by Edvardsson
et al. (1993A&amp;A...275..101E) on the basis of their apparent
enrichment in Na, Mg and Al relative to other elements. The discovery
of a planetary companion to the nearby solar type star 51 Peg (Mayor
&amp; Queloz, 1995Natur.378..355M) combined with Edvardsson et al.'s
earlier identification of 51 Peg as a NaMgAl star highlighted the
group's potential importance. Our new analysis, which uses new spectra
of higher resolution and better wavelength coverage than the analysis
of Edvardsson et al., shows that the Na, Mg and Al abundances of the
NaMgAl stars are indistinguishable from those of non-NaMgAl stars with
otherwise similar properties. The group thus appears to be spurious. Our
study, which includes 51 Peg, also provides the most complete set
of abundances for this star available to date. The new Fe abundance,
[Fe/H]=+0.20+/-0.07, of 51 Peg confirms earlier measurements of its
metal richness. Abundances for 19 other elements, including C, N and O,
reveal a fairly uniform enrichment similar to that of Fe and show no
evidence of abnormality compared to other metal rich stars of similar
spectral type.

---------------------------------------------------------
Title: South-North and Radial Traverses through the Interplanetary
Dust Cloud
Authors: Grün, E.; Staubach, P.; Baguhl, M.; Hamilton, D. P.; Zook,
H. A.; Dermott, S.; Gustafson, B. A.; Fechtig, H.; Kissel, J.; Linkert,
D.; Linkert, G.; Srama, R.; Hanner, M. S.; Polanskey, C.; Horanyi,
M.; Lindblad, B. A.; Mann, I.; McDonnell, J. A. M.; Morfill, G. E.;
Schwehm, G.
1997Icar..129..270G Altcode:
Identicalin situdust detectors are flown on board the Galileo and
Ulysses spacecraft. They record impacts of micrometeoroids in the
ecliptic plane at heliocentric distances from 0.7 to 5.4 AU and in a
plane almost perpendicular to the ecliptic from -79° to +79° ecliptic
latitude. The combination of both Ulysses and Galileo measurements
yields information about the radial and latitudinal distributions of
micron- and sub-micron-sized dust in the Solar System. Two types of
dust particles were found to dominate the dust flux in interplanetary
space. Interplanetary micrometeoroids covering a wide mass range from
10-16to 10-6g are recorded mostly inside 3 AU
and at latitudes below 30°. Interstellar grains with masses between
10-14and 10-12g have been positively identified
outside 3 AU near the ecliptic plane and outside 1.8 AU at high
ecliptic latitudes (&gt;50°). Interstellar grains move on hyperbolic
trajectories through the planetary system and constitute the dominant
dust flux (1.5 × 10-4m-2sec-1)
in the outer Solar System and at high ecliptic latitudes. To
compare and analyze the Galileo and Ulysses data sets, a new model
is developed based onJ. Geophys. Res.98,17029-17048, Divine's (1993,
“five populations of interplanetary meteoroids” model. Both models
describe the interplanetary meteoroid environment in terms of dust
populations on distinct orbits. Taking into account the measured
velocities and the effect of radiation pressure on small particles
(described by the ratio of radiation pressure force to gravity, β),
we define four populations of meteoroids on elliptical orbits and
one population on hyperbolic orbit that can fit the micrometeoroid
flux observed by Galileo and Ulysses. Micrometeoroids with masses
greater than 10-10g and negligible radiation pressure
(β = 0) orbit the Sun on low to moderately eccentric orbits and
with low inclinations (≤30°). Populations of smaller particles
with mean masses of 10-11g (β = 0.3), 10-13g
(β = 0.8), and 5 × 10-15g (β = 0.3), respectively,
have components with high eccentricities and have increasingly wider
inclination distributions with decreasing mass. Similarities among the
orbit distributions of the small particle populations on bound orbits
suggest that all are genetically related and are part of an overall
micrometeoroid complex that prevails in the inner Solar System. The
high-eccentricity component of the small particle populations may
actually be β-meteoroids which are not well characterized by our
measurements. Our modeling suggests further that the interstellar
dust flux is not reduced at Ulysses' perihelion distance (1.3 AU)
and that it contributes about 30% of the total dust flux observed there.

---------------------------------------------------------
Title: VizieR Online Data Catalog: Abundances of 9 solar-type stars
(Tomkin+ 1997)
Authors: Tomkin, J.; Edvardsson, B.; Lambert, D. L.; Gustafsson, B.
1997yCat..33270587T Altcode:
Line identifications, measured equivalent widths and derived chemical
abundances in 9 solar-type dwarf stars, which are identified by their
Bright Star (HR, (Cat. &lt;V/50&gt;)) numbers. (1 data file).

---------------------------------------------------------
Title: Hubble Space Telescope Spectroscopy of the Carbon Star
TX Piscium
Authors: Carpenter, Kenneth G.; Robinson, Richard D.; Johnson, Hollis
R.; Eriksson, Kjell; Gustafsson, Bengt; Pijpers, Frank P.; Querci,
Francois; Querci, Monique
1997ApJ...486..457C Altcode:
Ultraviolet spectra obtained with the Hubble Space Telescope of the
carbon star TX Piscium (HR 9004) are presented, along with analysis
providing information on its outer atmosphere, including flow and
turbulent velocities, line formation mechanisms, and variations with
time. Both thermal (collisionally excited) and fluorescent emission
from the chromosphere of the star appear to be formed near the stellar
rest velocity, i.e., in a region below that in which the stellar wind is
accelerated. Absorption self-reversals in the Mg II emission confirm the
presence of an outflowing stellar wind at a mean velocity of about 9-10
km s-1. Circumstellar absorption features (Mn I and Fe I)
overlying the Mg II emission indicate a cool shell expanding at about
5-6 km s-1 relative to the photosphere. The widths (FWHM)
of various emission lines indicate that the chromospheric turbulence is
at least 16 km s-1, but that it may increase with altitude
to as much as 34 km s-1. Three hours of integration on
the C II] lines are examined for any signs of variability that might
indicate the presence of shocks, but no statistically significant
variations are seen. A previous identification (in spectra of UU Aur)
of an emission line at 2807 Å, seen only in spectra of carbon stars,
as belonging to Fe I multiplet UV45 pumped by the C II] line at 2325 Å
is confirmed by the discovery of an absorption feature corresponding
exactly to the wavelength of the pumped transition (Fe I UV13) near
2325 Å. Lines from Fe II UV165, previously seen in solar off-limb
spectra and in Goddard High-Resolution Spectrograph spectra of α Tau,
are clearly present. The normally much stronger Fe II UV32, 62, and
63 multiplets are seen but are weaker relative to both the UV165 lines
and the intercombination lines of C II] and Si II] than in α Tau. The
weakness of these Fe II lines is indicated both by their absolute flux
levels and by their narrow, single-peaked profiles, which are in sharp
contrast to the broad, double-peaked profiles seen in oxygen-rich cool
giant and supergiant stars. The weakness of the Fe II lines and the
presence of the Fe I 2807 Å line suggest that the ionization fraction
of iron (Fe II/Fe I) is significantly lower in the outer atmospheres of
carbon stars. Fluxes in emission lines of Fe II and Mg II are &gt;=2-3
times lower than in a 1984 IUE spectrum of TX Psc, confirming that
the latter was obtained at an epoch of unusual UV brightness for the
star. The Mg II profiles are heavily mutilated by overlying absorption,
even more so than in 1984. The TX Psc profiles are very similar to
those seen in the carbon star TW Hor but are dramatically different
than those in another carbon star, UU Aur, whose lines show violet
wing emission out to much shorter wavelengths than in the other two
stars. Based on observations with the NASA/ESA Hubble Space
Telescope, which is operated by the Association of Universities for
Research in Astronomy, Inc., under NASA contract NAS 5-26555 and on
observations at the Haute-Provence Observatory.

---------------------------------------------------------
Title: Dust measurements in the Jovian magnetosphere
Authors: Grun, E.; Kruger, H.; Dermott, S.; Fechtig, H.; Graps, A. L.;
Zook, H. A.; Gustafson, B. A.; Hamilton, D. P.; Hanner, M. S.; Heck,
A.; Horanyi, M.; Kissel, J.; Lindblad, B. A.; Linkert, D.; Linkert,
G.; Mann, I.; McDonnell, J. A. M.; Morfill, G. E.; Polanskey, C.;
Schwehm, G.; Srama, R.
1997GeoRL..24.2171G Altcode:
Dust measurements have been obtained with the dust detector onboard
the Galileo spacecraft inside a distance of about 60RJ
from Jupiter (Jupiter radius, RJ = 71,492 km) during two
periods of about 8 days around Galileo's closest approaches to Ganymede
on 27 June and on 6 Sept 1996. The impact rate of submicrometer-sized
particles fluctuated by a factor of several hundred with a period of
about 10 hours, implying that their trajectories are strongly affected
by the interaction with the Jovian magnetic field. Concentrations of
small dust impacts were detected at the times of Ganymede closest
approaches that could be secondary ejecta particles generated upon
impact of other particles onto Ganymede's surface. Micrometer-sized
dust particles, which could be on bound orbits about Jupiter, are
concentrated in the inner Jovian system inside about 20RJ
from Jupiter.

---------------------------------------------------------
Title: (Erratum) Line-blanketed model atmospheres for R Coronae
Borealis stars and hydrogen-deficient carbon stars.
Authors: Asplund, M.; Gustafsson, B.; Kiselman, D.; Eriksson, K.
1997A&A...323..286A Altcode:
Erratum to Astron. Astrophys. 318, 521-534 (1997)

---------------------------------------------------------
Title: Light Scattering by Complex Dust Structures
Authors: Gustafson, B. . S.; Thomas-Osip, J. E.; Waldemarsson,
K. W. T.; Xu, Y. -L.
1997DPS....29.2909G Altcode: 1997BAAS...29.1030G
We present both experimental data and theoretical solutions to
evaluate the scattering of light and other electromagnetic radiation
by complex dust morphologies. This includes porous particles made
of spherical subparticles to represent aggregated structures that
may be relevant models of comet dust and dust in the atmospheres of
Titan and Saturn. Solid cubes represent some asteroid dust and dust
in some planetary atmospheres. The experimental data were obtained in
the microwave analogue to light scattering facility at the Laboratory
for Astrophysics, University of Florida.

---------------------------------------------------------
Title: Molecules in Circumstellar Envelopes of Carbon Stars
Authors: Larsen, F.; Olofsson, H.; Eriksson, K.; Gustafsson, B.
1997Ap&SS.251..235L Altcode:
We have searched for line emission from various transitions of
a number of molecules, including CO, HCN, CN, CS and SiO, as
well as some of their isotopic variants, towards a sample of 68
bright carbon stars. Part of the data has already been published
in Olofsson et al. (1993a,b). The aim of the project is to obtain a
better understanding of the carbon star phenomenon and the processes
involved. In particular, we would like to obtain reliable mass loss
rates and molecular abundances for these objects. This requires careful
and detailed modelling, which is currently underway. Our hope is that
the study of these bright carbon stars will serve as a guide to the
study of higher mass loss rate objects. Some preliminary observational
results are presented here.

---------------------------------------------------------
Title: On the history of star formation in the bar of the Large
Magellanic Cloud.
Authors: Ardeberg, A.; Gustafsson, B.; Linde, P.; Nissen, P. -E.
1997A&A...322L..13A Altcode:
With the HST PC and uvby photometry, we investigate evolutionary
signatures in a field in the centre of the LMC Bar. Field stars close
to the turn off point in the HR diagram are used for a study of ages
and evolution of the stellar populations dominating the Bar as well
as for determination of the abundance of heavy elements. Including
fainter stars, we derive the corresponding luminosity function. Here,
we discuss some results obtained from a preliminary version of our
data. The quality of our data is high. Two strong stellar populations
are obvious. A young component contains approximately 30% of the total
number of stars. At least a considerable fraction of this component
originated less than 500Myears ago. The older population ranges in age
between around 2 and 9Gyears. The abundance of heavy elements is around
[Me/H]=-0.6. The tentative luminosity function, down to y=24, resembles
in shape that predicted from earlier galactic and LMC data. Parallel
to arrival of further HST data, our analysis continues.

---------------------------------------------------------
Title: A stellar endgame - the born-again Sakurai's object.
Authors: Asplund, M.; Gustafsson, B.; Lambert, D. L.; Kameswara Rao, N.
1997A&A...321L..17A Altcode: 1997astro.ph..4005A
The surface chemical composition of this remarkable star shows that it
is hydrogen-deficient, carbon-rich and enriched in the light s-process
elements. Spectra taken in May and October 1996 indicate a decrease in
the surface hydrogen abundance by 0.7dex in five months along with an
increase in the abundances of Li, Sr, Y and Zr. The abundance changes
are in agreement with the hypothesis of the star being a rapidly
evolving "born-again" AGB star experiencing a final He-shell flash,
similar to FGSge. The ^12^C/^13^C ratio in October is very low, also
suggesting hydrogen ingestion. By chemical composition, Sakurai's
object resembles the R Coronae Borealis (RCrB) stars.

---------------------------------------------------------
Title: KI emission from envelopes around N-type stars. Spectroscopic
observations and interpretations.
Authors: Gustafsson, B.; Eriksson, K.; Kiselman, D.; Olander, N.;
Olofsson, H.
1997A&A...318..535G Altcode:
Circumstellar envelopes around three bright N-type stars, R Scl,
X TrA, and V Aql have been detected in emission in resonance lines
from KI. This radiation, which is most probably scattered photospheric
radiation, was first found spectroscopically, but has later been imaged
with coronographic and polarimetric techniques. In the present paper,
which is the first in a series, the spectroscopic KI observations are
discussed. From the observations of the KI 769.9nm emission we find
systemic and expansion velocities in fair agreement with those obtained
from the CO millimetre lines. We find a decline of the emission with
distance from the star, in rough agreement with the assumption of a
constant expansion velocity, mass-loss rate and KI abundance. Our mass
loss rate estimates from the KI line observations agree rather well with
those obtained from CO (ranging from 1/4 to 1/1 of the CO mass loss),
which suggests that a considerable fraction of the potassium stays
neutral through the envelope. This puts strong upper limits on the
photoionizing chromospheric UV emission from the stars. Some indirect
indications that the envelopes have inhomogeneous structures, clumps,
are discussed.

---------------------------------------------------------
Title: Line-blanketed model atmospheres for R Coronae Borealis stars
and hydrogen-deficient carbon stars.
Authors: Asplund, M.; Gustafsson, B.; Kiselman, D.; Eriksson, K.
1997A&A...318..521A Altcode:
We have constructed line-blanketed model atmospheres for the
hydrogen-deficient and carbon-rich R Coronae Borealis (RCrB) stars,
as well as for the similar hydrogen-deficient carbon (HdC) stars and
the cool extreme helium (EHe) stars. Improved continuum opacities have
been used together with realistic line absorption data for atomic
and molecular transitions. The observed dereddened fluxes of R CrB
are compared with the calculated model fluxes and found to agree best
with a model effective temperature of 6900K, while the infrared flux
method gives between 6600 and 6900K, depending on the nature of the
flux excess in the J and H bands compared to the model fluxes. The
excess may correspond to a recently formed dust cloud close to the
star, with a typical temperature around 2000K and a dust mass of
~10^-11^Msun_. The agreement for the ultraviolet flux
distribution is also very satisfactory as seen from IUE spectra of
RCrB. Theoretical broad band photometry is presented and effective
temperatures of RCrB and HdC stars estimated. The constructed
models show a significantly steeper temperature gradient compared
to previously existing models as a result of the line opacity. Due
to the cool surface and high abundance of carbon, molecular bands of
e.g. C_2_ and CO are visible in the spectra even at as high effective
temperatures as 7000K. Furthermore, the high temperatures encountered
at depth explain the observed Hei and CII lines for T_eff_ down to
~7000K. In the inner layers (τ_Ross_ &gt; 3) the models show density
inversions related to the ionization zone of helium. For certain low
gravity models the luminosity exceeds the local Eddington limit and
hence gas pressure inversions occur as well, which could be related
to the decline events of RCrB stars.

---------------------------------------------------------
Title: The ISO-SWS flux standard stars: synthetic spectra and
observations.
Authors: der Bliek, N. S.; Morris, P. W.; Vandenbussche, B.; Waters,
L. B. F. M.; Zaal, P.; Bell, R. A.; Gustafsson, B.; Eriksson, K.;
de Graauw, T.
1997IAUS..189...89D Altcode: 1998IAUS..189...89D
The authors present flux-calibrated, synthetic spectra for the
calibration stars of the Short Wavelength Spectrometer of the Infrared
Space Observatory ISO-SWS.

---------------------------------------------------------
Title: H band spectra of cool dwarfs and giants
Authors: van der Bliek, N. S.; Gustafsson, B.; Eriksson, K.
1997IAUS..189P..32V Altcode: 1998IAUS..189P..32V
No abstract at ADS

---------------------------------------------------------
Title: Accuracy of synthetic far IR fluxes of stars
Authors: van der Bliek, N. S.; Gustafsson, B.; Eriksson, K.
1997IAUS..189P..28V Altcode: 1998IAUS..189P..28V
No abstract at ADS

---------------------------------------------------------
Title: South-north and radial traverses through the zodiacal cloud.
Authors: Baghul, M.; Grün, E.; Staubach, P.; Dermott, S.; Fechtig,
H.; Gustafson, B. A.; Hamilton, D.; Hanner, M. S.; Horany, M.; Kissel,
J.; Lindblad, B. A.; Linkert, D.; Linkert, G.; Mann, I.; McDonnell,
J. A. M.; Morfill, G. E.; Polanskey, C.; Schwehm, G.; Srama, R.;
Zook, H. A.
1997AdSpR..20.1546B Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Comparison Bertween ISO-SWS Observations and Synthetic Spectra
of K Giants and M Giants α Boo and β Peg (Invited Paper)
Authors: Decin, L.; Cohen, M.; Eriksson, K.; Gustafsson, B.; Huygen,
E.; Morris, P.; Plez, B.; Sauval, J.; Vandenbussche, B.; Waelkens, C.
1997ESASP.419..185D Altcode: 1997fiso.work..185D
The accurate flux calibration of SWS requires the observation of spectra
of stellar templates (Schaeidt et al., 1996). On the other hand, our
knowledge of stellar spectra in the broad spectral domain that ISO has
opened for the first time is still incomplete, and must be improved
with these same ISO data. Clearly, the final flux calibration of SWS
data will result from an iterative process, that should benefit to
both our understanding of the instrument and of the atmo- spheres of
cool stars. We report on the progress of a project which confronts SWS
observations of cool stars with state-of-the-art synthetic spectra. The
ISO observations enable us to discriminate between various sources of
molecular data and put tight constraints on the atmospheric parameters
of the stellar templates. Preliminary results suggest that a 2% relative
flux accuracy may be attainable in bands 1 and 2 of the SWS range.

---------------------------------------------------------
Title: Large-scale Star Formation in the Centre of the LMC Bar
Authors: Ardeberg, A.; Gustafsson, B.; Linde, P.; Nissen, P. -E.;
Snel, R.
1997IAUJD...2E..49A Altcode:
With the HST PC and uvby photometry, we investigate evolutionary
signatures in a field in the centre of the LMC Bar. Field stars close
to the turn off point in the HR diagram are used for a study of ages
and evolution of the stellar populations dominating the Bar as well
as for determination of the abundance of heavy elements. Including
fainter stars, we derive the corresponding luminosity function. Here,
we discuss some results obtained from a preliminary version of our
data. The quality of our data is high. Two strong stellar populations
are obvious. A young component contains approximately 30 % of the total
number of stars. At least a considerable fraction of this component
originated less than 500 Myears ago. The older population ranges in
age between around 2 and 9 Gyears. The abundance of heavy elements is
around [Me/H] = -0.6. The tentative luminosity function, down to y =
24, resembles in shape that predicted from earlier galactic and LMC
data. Parallel to arrival of further HST data, our analysis continues.

---------------------------------------------------------
Title: What do we do when models don't fit? On model atmospheres
and real stellar spectra.
Authors: Gustafsson, B.
1997IAUS..189..261G Altcode: 1998IAUS..189..261G
Developments in the modelling of stellar atmospheres and results from
the confrontation between calculated and observed fluxes and spectra
are discussed. It is argued that, although impressive advances in the
study of O-type, WR and cool star spectra have recently occurred,
significant improvements should be possible with already existing
methods in the analysis of, e.g., solar-type stars.

---------------------------------------------------------
Title: Area to mass ratio and packing factor from meteor data
Authors: Gustafson, B. Å. S.; Adolfsson, L. G.
1997ASIC..487..349G Altcode: 1997cduc.conf..349G
No abstract at ADS

---------------------------------------------------------
Title: The Concept of a Facility for Cosmic Dust Research on the Iss
Authors: Blum, J.; Henning, Thomas; Cabane, Michel; Fonda, Mark;
Giovane, Frank; Gustafson, Bo A. S.; Keller, Horst U.; Markiewicz,
Wojciech J.; Nuth, Joseph A.; Rogers, Fred
1996ESASP.385..303B Altcode: 1996ssu..conf..303B
No abstract at ADS

---------------------------------------------------------
Title: An Estimation of the Interstellar Contribution to the Zodiacal
Thermal Emission
Authors: Grogan, K.; Dermott, S. F.; Gustafson, B. A. S.
1996ApJ...472..812G Altcode:
Impact data from the Ulysses dust detector at 5 AU from the Sun have
been interpreted as a flux of submicron interstellar dust particles
arriving from ecliptic longitude 252 deg and ecliptic latitude
2.dg5. By following the motions of these particles under the influence
of solar gravity, radiation pressure, and electromagnetic forces, we
derive a model of the thermal emission from the resultant particle
cloud. Since the distributions of the particles are time variable
depending on the solar cycle, calculations are performed for the years
1984 and 1990, corresponding, respectively, to the times of the IRAS
and COBE observations. We also illustrate how the distributions vary
with particle size (or, at a more basic level beta , the ratio of
the radiation pressure to gravitational force) by presenting results
for three different particle sizes. Patches of emission from our test
cloud reach peak levels of 0.1 MJy sr-1 in the 12 mu m wave band. This
represents 10% of the average brightness asymmetry around the sky
between the trailing/leading telescope pointing directions seen in the
IRAS and COBE data sets. Some of these patches occur at high ecliptic
latitudes where the contribution from the Galaxy is negligible and
emission from the smooth zodiacal background is low compared to that at
low ecliptic latitudes. A strong seasonal variation in the predicted
interstellar emission trailing/leading asymmetry is the most obvious
signature of the interstellar source, and, in addition, the time
variability of the emission will produce different features in the
IRAS and COBE data sets and in any subsequent infrared mission. For
these reasons, a search of the data for the predicted signatures is
certainly justifiable.

---------------------------------------------------------
Title: Dust Measurements During Galileo's Approach to Jupiter and
lo Encounter
Authors: Grun, E.; Hamilton, D. P.; Riemann, R.; Dermott, S.; Fechtig,
H.; Gustafson, B. A.; Hanner, M. S.; Heck, A.; Horanyi, M.; Kissel,
J.; Kruger, H.; Lindblad, B. A.; Linkert, D.; Linkert, G.; Mann,
I.; McDonnell, J. A. M.; Morfill, G. E.; Polanskey, C.; Schwehm, G.;
Srama, R.; Zook, H. A.
1996Sci...274..399G Altcode:
About a hundred dust impacts per day were detected during the first
week in December 1995 by Galileo during its approach to Jupiter. These
impacts were caused by submicrometer-sized particles that were just
above the detection limit. After the closest approach to Io on 7
December, impacts of these small particles ceased. This effect is
expected for dust grains emitted from Io that exit the field of
view of the instrument after the flyby. The impact rate of bigger
micrometer-sized dust grains continued to increase toward Jupiter. These
dust particles are in orbit about Jupiter or are interplanetary grains
that are gravitationally concentrated near Jupiter.

---------------------------------------------------------
Title: Carbon Stars and Nucleosynthesis in Galaxies
Authors: Gustafsson, Bengt; Ryde, Nils
1996astro.ph.10261G Altcode:
The role of carbon stars in the build-up of chemical elements in
galaxies is discussed on the basis of stellar evolution calculations
and estimated stellar yields, abundance analyses of AGB stars,
galactic-evolution models and abundance trends among solar-type disk
stars. We conclude that the AGB stars in general, and carbon stars in
particular, probably are main contributors of $s$-elements, that their
contributions of flourine and carbon are quite significant, and that
possibly their contributions of lithium, $^{13}$C and $^{22}$Ne are of
some importance. Also contributions of N, Na and Al are discussed. The
major uncertainties that characterize almost any statement concerning
these issues are underlined.

---------------------------------------------------------
Title: Investigation of Aggregates as a Model for Titan's Aerosols
Using Microwave Analog Experiments and Radiative Transfer Theory
Authors: Thomas-Osip, J. E.; Gustafson, B. Å. S.
1996DPS....28.2010T Altcode: 1996BAAS...28.1131T
It has been suggested that the aerosols in the atmosphere of Titan
have an aggregate morphology (Bar-Nun et al., 1988: West and Smith,
1991). Previous studies were based on formulations of the Discrete
Dipole Approximation to calculate the single scattering properties
of such aggregates. These studies were limited in the size of
the individual spheres and total size of the aggregate. We present
microwave to light analog scattering measurements and radiative transfer
calculations for aggregates of 250-500 individual spheres near the
Raleigh size limit in a plane parallel atmosphere. The advantages
of using microwave analog experiments include the possibility of
investigating a broad range of particle sizes and morphologies.

---------------------------------------------------------
Title: Polarization of Light by Cometary and Asteroid Dust Models
Authors: Gustafson, B. Å S.; Thomas-Osip, J. E.; Waldemarsson, T. K.;
Xu, Y. -L.
1996DPS....28.1601G Altcode: 1996BAAS...28Q1120G
We have investigated the angular distribution of scattered light by
asteroid dust models using the microwave analog to light scattering
facility at the Laboratory for Astrophysics at the University of
Florida. The main features in the (linear degree of) polarization
in the zodiacal light can be reproduced using comet dust models of
the "Bird's-Nest" type. We show that the polarization also can be
reasonably well reproduced using two asteroid dust models. One model is
a compact aggregate of silicate and refractory materials representing
interstellar grain material. This model is similar to the "Bird's-Nest"
model in composition but the morphology is compacted as opposed to 90%
void. A second model represents sharp corners of asteroid fragments
and breccia using cubes of refractive index near 1.603 -0.003i. This
work is supported by NASA through the Planetary Atmospheres Program

---------------------------------------------------------
Title: Carbon stars with episodic mass loss: observations and models
of molecular emission from detached circumstellar shells.
Authors: Olofsson, H.; Bergman, P.; Eriksson, K.; Gustafsson, B.
1996A&A...311..587O Altcode:
We have obtained detailed CO radio line maps of the circumstellar
medium around the bright carbon stars R Scl, U Ant, S Sct, and TT
Cyg. They provide direct evidence for the existence of large [radii
between 10-70", or (1-5)x10^17^cm], geometrically thin (we estimate
that the shell widths are &lt;~10"), over-all spherically symmetric
shells of CO line-emitting gas around these stars. The shells expand
with velocities in the range 13-20km/s, i.e., their ages lie in
the range (1-10)x10^3^years. Less extensive CO observations of
the carbon star V644 Sco suggest that also it is surrounded by a
detached shell. The expansion velocities of the present mass loss
winds, as evidenced by weak CO emission from regions close to the
stars, are considerably lower, of the order 5km/s. We conclude that
the mass loss characteristics of these, otherwise apparently normal,
carbon stars have changed significantly over the last 10^4^years. For
such a shell structure, the most reasonable cause is a short period
of very intense mass loss (i.e., a mass loss eruption), although
an interacting-wind scenario cannot be excluded. The CO brightness
distributions are very patchy, suggesting an inhomogeneous circumstellar
medium. Using a model where the shell consists of a large number of
small, homogeneous clumps, we estimate that the H_2_-masses of the
four, spatially resolved shells are all around 0.01Msun_
(for an adopted CO abundance with respect to H_2_ of =~10^-3^), and
that in the mass loss eruption -scenario the H_2_-mass loss rates
of the stars were =~10^-5^x(10"/{DELTA}R)Msun_/yr during
the formation of the shells ({DELTA}R being the unresolved shell
width in arc seconds). The present mass loss rates are very low,
&lt;~10^-7^Msun_/yr. These results suggest that the four
stars have all gone through a type of event that led to a dramatic
change in the mass loss characteristics. The adopted model is an
initial, relatively crude, attempt to provide a more realistic base
for the interpretation of line emission from a circumstellar medium
in which, in general, the physical conditions are very likely quite
inhomogeneous. It is the accidental overlap along the line-of-sight
and in velocity space of the many small clumps that in the model
produces a clumpy appearance of the brightness distribution, at the
larger scale set by the observational resolution, that resembles the
observed ones. In the mass loss eruption -scenario the estimated life
time of a CO line-emitting shell of the type discussed in this paper
is =~10^4^years, and it is determined by the photodissociation of the
CO molecules. Only shells younger than =~10^3^years are expected to
be observable in molecular radio lines other than those of CO. There
is a period after formation when such shells should be characterized
by very anomalous line intensity ratios. For instance, in our model
the line intensity ratio between the photodissociation product CN
and the parent molecule HCN increases drastically on a time scale of
hundreds of years as the shell recedes from the star. We suggest that
the shell around R Scl is in this phase, since this is the only object,
among the five observed, in which we have clearly detected also lines
of HCN and CN, albeit with anomalous line intensity ratios.

---------------------------------------------------------
Title: Constraints from Galileo observations on the origin of jovian
dust streams
Authors: Grün, E.; Baguhl, M.; Hamilton, D. P.; Riemann, R.; Zook,
H. A.; Dermott, S.; Fechtig, H.; Gustafson, B. A.; Hanner, M. S.;
Horányi, M.; Khurana, K. K.; Kissel, J.; Kivelson, M.; Lindblad,
B. A.; Linkert, D.; Linkert, G.; Mann, I.; McDonnell, J. A. M.;
Morfill, G. E.; Polanskey, C.; Schwehm, G.; Srama, R.
1996Natur.381..395G Altcode:
THE Ulysses spacecraft detected streams of sub-micrometre-sized dust
particles as it approached Jupiter in 19921,2. Although
interplanetary space was known to contain dust, the presence of discrete
streams was completely unexpected. The directions from which the dust
grains struck the spacecraft strongly suggested that the source lay
somewhere within the Jupiter system. Three origins were proposed, the
comet Shoemaker-Levy 9 (ref. 3), Jupiter's gossamer ring4,
and the volcanoes on Io5, but there was no definitive
evidence for or against any of the options. Here we report the detection
by the Galileo spacecraft of even more intense dust streams-including
three intense dust storms of month-long duration, with impact rates
up to 10 times higher than those observed by Ulysses. Our analysis
of the data confirms that the dust streams originate near Jupiter;
we are able to rule out a cometary origin, but cannot yet determine
conclusively whether the dust comes from Io or the ring.

---------------------------------------------------------
Title: Stellar far-IR fluxes: how accurate are model predictions?
Authors: van der Bliek, N. S.; Gustafsson, B.; Eriksson, K.
1996A&A...309..849V Altcode:
We present the results of an analysis of the accuracy of predicted
far infrared (FIR) fluxes of stars. Sources of errors are a) the input
parameters for the model atmospheres; b) assumptions in the modelling,
resulting in errors in the structure of the model atmospheres; c) the
adopted IR continuous opacity, dominated by the H^-^_ff_ opacity; d)
the possible presence of circumstellar (CS) dust. Stellar effective
temperatures are typically determined with an accuracy of about
100K. This leads to an uncertainty in the predicted far infrared
(FIR) flux of 1 to 4%, depending on the spectral type. Errors in the
other two fundamental parameters of a star, the surface gravity and
the metallicity, have a minor effect on the prediction of stellar FIR
fluxes, less than 1%. The various assumptions made in the modelling
result in errors in the temperature structure T(τ) of model
atmospheres. By using the depth and shape of spectral lines, T(τ)
in the outer layers of the atmosphere, where the lines are formed,
can be pinned down to about 100K, resulting in uncertainties of about
1 to 2% in the FIR. Errors in the H^-^_ff_ opacity are small and as a
result uncertainties in the FIR fluxes due to the continuous opacity are
less than 0.1%. CS dust can have a large impact on the IR fluxes. We
find that the uncertainties due to the possible presence of CS dust
can be more than an order of magnitude larger than the uncertainties
resulting from modelling the stellar atmosphere. Unfortunately with
the present day accuracies of IR data no further constraints can be
set to limit these uncertainties.

---------------------------------------------------------
Title: Microwave analog to light scattering measurements: a modern
implementation of a proven method to achieve precise control.
Authors: Gustafson, B. Å. S.
1996JQSRT..55..663G Altcode:
The experimental determination of scattered electromagnetic radiation
from a known target illuminated by a known source remains an essential
tool to test new scattering theories and to investigate the scattering
by particles for which a theory has not yet been devised. This article
describes a modern broad-band microwave scattering facility capable
of determining the elements of the scattering matrix from 0 to 168°
scattering angle under automated control. The laboratory measurements
can cover the size range from near the Rayleigh limit to geometric
optics. Both phase and intensity are routinely measured at 85-501
discrete wavelengths from 2.7 to 4 mm, which allows the derivation
of all elements in the scattering matrix. The unwanted background
radiation can be removed through vector subtraction and the result
verified using the technique of "time-gating" based on inverse Fourier
transformation and time domain analysis. Measurements are shown to be
repeatable and accurate. This is primarily due to the use of a "clean"
mechanical and electronic design in combination with high mechanical
and thermal stability.

---------------------------------------------------------
Title: Radiation Pressure Correction to Meteor Orbits
Authors: Gustafson, Bo ». S.; Adolfsson, Lars G.
1996EM&P...72..327G Altcode:
We present a method to calculate the radiation pressure force to
gravity ratio on meteoroids from their atmospheric flight. Radiation
pressure corrections to meteor orbits are negligible for fireballs;
of the order of or less than the measurement errors (≈ 1%) for
photographic meteors; of the order of and in some cases substantially
larger than the measurement errors (≈ 10%) for radar meteors.

---------------------------------------------------------
Title: Are the declines of R Coronae Borealis stars caused by super-
Eddington luminosities?
Authors: Asplund, M.; Gustafsson, B.
1996ASPC...96...39A Altcode: 1996hds..conf...39A
No abstract at ADS

---------------------------------------------------------
Title: The Martian Atmosphere as a Meteoroid Detector
Authors: Adolfsson, Lars G.; Gustafson, Bo Å. S.; Murray, Carl D.
1996Icar..119..144A Altcode:
We investigate the plausibility of detecting meteors from the surface
of Mars. We estimate the flux of high-speed photographic meteoroids at
the orbit of Mars to be ∼50% that at Earth. Because the atmospheric
densities of the Earth and Mars are comparable at a height of 120 km,
close to where meteor ablation occurs on Earth, we also expect martian
meteors to ablate at heights similar to those on Earth. By numerical
integration we have modeled the intensity of an “asteroidal”
particle and a “cometary” particle as they enter the atmosphere,
using particle masses in the range 10-8to 102g. We
conclude that high-speed (≳30 km sec-1) meteoroids will
have the same magnitude in both atmospheres; lower speed meteoroids
will be dimmer in Mars' atmosphere. We suggest that future missions
to Mars should include meteor observation programs which would permit
direct measurements of the meteoroid complex in another region of
the solar system as well as providing important information on the
structure and time variability of the martian atmosphere.

---------------------------------------------------------
Title: A Complete and Efficient Multisphere Scattering Theory for
Modeling the Optical Properties of Interplanetary Dust
Authors: Xu, Y. -L.; Gustafson, B. A. S.
1996ASPC..104..419X Altcode: 1996IAUCo.150..419X; 1996pcdi.conf..419X
No abstract at ADS

---------------------------------------------------------
Title: Physics, chemistry, and dynamics of interplanetary dust
Authors: Gustafson, Bo A. S.; Hanner, Martha S.
1996ASPC..104.....G Altcode: 1996pcdi.conf.....G; 1996IAUCo.150.....G
No abstract at ADS

---------------------------------------------------------
Title: Search for the Signature of Interstellar Dust in the COBE Data
Authors: Grogan, K.; Dermott, S. F.; Gustafson, B. A. S.; Jayaraman,
S.; Xu, Y. L.; Hamilton, D.
1996ASPC..104..325G Altcode: 1996pcdi.conf..325G; 1996IAUCo.150..325G
No abstract at ADS

---------------------------------------------------------
Title: An Optical Instrument to Characterize Individual Dust Particles
Authors: Giovane, F.; Gustafson, B. A. S.; Lamy, Ph. L.
1996ASPC..104..247G Altcode: 1996pcdi.conf..247G; 1996IAUCo.150..247G
No abstract at ADS

---------------------------------------------------------
Title: The Metal-Rich Disk Population
Authors: Feltzing, S.; Gustafsson, B.
1996IAUS..171..372F Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Sources of Interplanetary Dust
Authors: Dermott, S. F.; Grogan, K.; Gustafson, B. A. S.; Jayaraman,
S.; Kortenkamp, S. J.; Xu, Y. L.
1996ASPC..104..143D Altcode: 1996IAUCo.150..143D; 1996pcdi.conf..143D
No abstract at ADS

---------------------------------------------------------
Title: Interferometric molecular line observations of the
circumstellar envelope(s) around U Camelopardalis.
Authors: Lindqvist, M.; Lucas, R.; Olofsson, H.; Omont, A.; Eriksson,
K.; Gustafsson, B.
1996A&A...305L..57L Altcode:
We have observed the circumstellar envelope of the carbon star U
Cam in the HCN(J=1-&gt;0) and CN(N=1-&gt;0) lines using the IRAM
Plateau de Bure interferometer. There is evidence of a two-envelope
structure: an outer extended envelope, possibly a shell, with a radius
of ~7x10^16^cm, that expands with a velocity of ~25km/s, surrounding an
inner envelope with a radius of ~6x10^15^cm and an expansion velocity
of only ~13km/s. Mass loss rate estimates based on these data alone
are uncertain, but they suggest that the mass loss rate during the
formation of the outer envelope was higher than during the present
mass loss epoch. Thus, we have evidence for a significant variation
in the mass loss characteristics of U Cam within the last 10^3^years.

---------------------------------------------------------
Title: Model atmospheres of cool hydrogen-deficient carbon stars
Authors: Gustafsson, B.; Asplund, M.
1996ASPC...96...27G Altcode: 1996hds..conf...27G
No abstract at ADS

---------------------------------------------------------
Title: Dust Flux Analyser experiment for the Rosetta mission
Authors: Leese, M. R.; McDonnell, J. A. M.; Green, S. F.; Busoletti,
E.; Clark, B. C.; Colangeli, L.; Crifo, J. F.; Eberhardt, P.; Giovane,
F.; Grün, E.; Gustafson, B.; Hughes, D. W.; Jackson, D.; Lamy, P.;
Langevin, Y.; Mann, I.; McKenna-Lawlor, S.; Tanner, W. G.; Weissman,
P. R.; Zarnecki, J. C.
1996AdSpR..17l.137L Altcode: 1996AdSpR..17..137L
We present the description of a design for a proposed Dust Flux Analyser
for the Rosetta cometary mission. A concept first developed for the
NASA/ESA Tempel II Rendezvous and Halley Intercept Mission /1/, the
instrument is able to measure dust particle parameters and fluxes over
a velocity range typical of emission from cometary surfaces. It would
be mounted on the Rosetta Orbiter and would measure the variation in
flux rate throughout all mission phases at the comet. The instrument
would measure particle flux, velocity, momentum and density, shape
and scattering properties.

---------------------------------------------------------
Title: Interstellar Grain Flow Through the Solar Wind Cavity
around 1992
Authors: Gustafson, B. A. S.; Lederer, S. M.
1996ASPC..104...35G Altcode: 1996IAUCo.150...35G; 1996pcdi.conf...35G
No abstract at ADS

---------------------------------------------------------
Title: Optical Properties of Dust from Laboratory Scattering
Measurements
Authors: Gustafson, B. A. S.
1996ASPC..104..401G Altcode: 1996pcdi.conf..401G; 1996IAUCo.150..401G
No abstract at ADS

---------------------------------------------------------
Title: Dynamic and Probabilistic Relation Between Meteoroids and
Their Parent Bodies
Authors: Adolfsson, L. G.; Gustafson, B. A. S.
1996ASPC..104..133A Altcode: 1996pcdi.conf..133A; 1996IAUCo.150..133A
No abstract at ADS

---------------------------------------------------------
Title: Concepts for Dust Velocity Measurements on a Cometary Orbiter
Authors: Perruchot, S.; Lamy, Ph. L.; Giovane, F.; Gustafson, B. A. S.
1996ASPC..104..255P Altcode: 1996IAUCo.150..255P; 1996pcdi.conf..255P
No abstract at ADS

---------------------------------------------------------
Title: Area to mass ratio and packing factor from meteor data.
Authors: Gustafson, B. Å. S.; Adolfsson, L. G.
1996cduc.conf..349G Altcode:
The authors show that the bulk density of meteoroids during
atmospheric flight can be accurately estimated with the uncertainty
in the deceleration of the meteoroid and the efficiency factor for
drag as the major sources of error. They reinterpret the difference
in photometric mass, which they believe is close to the true mass,
and the dynamical mass in terms of porous meteoroid material. The bulk
density of 0.26 g cm-3 prior to atmospheric entry could be
reliably estimated for one meteoroid. The corresponding packing factor
is 0.12, i.e., 88% of the meteoroid's volume is likely to be cavities.

---------------------------------------------------------
Title: Atmospheres from Within
Authors: Morgan, Thomas; Abshire, James; Clancy, Todd; Fry, Ghee;
Gustafson, Bo; Hecht, Michael; Kostiuk, Theodor; Rall, Jonathan;
Reuter, Dennis; Sheldon, Robert
1996psi..work...51M Altcode:
In this review of atmospheric investigations from planetary surfaces,
a wide variety of measurement and instrument techniques relevant
to atmospheric studies from future planetary lander missions are
discussed. The diversity of planetary surface environments within
the solar system precludes complete or highly specific coverage, but
lander investigations for Mars and cometary missions are presented as
specific cases that represent the broad range of atmospheric-surface
boundaries and that also correspond to high priority goals for future
national and international lander missions.

---------------------------------------------------------
Title: The origin and dynamics of the interplanetary dust cloud.
Authors: Dermott, S. F.; Jayaraman, S.; Xu, Y. L.; Grogan, K.;
Gustafson, B. A. S.
1996AIPC..348...25D Altcode:
Obtaining a model of the zodiacal cloud to predict the flux in a given
waveband, in a given direction, at a given time of the year, to one
per cent of the peak brightness, or better, will require a detailed
understanding of the dynamics of the particles that originate from
each of the various sources. Each component of the cloud (asteroidal,
cometary and interstellar) gives rise to characteristic features and
by resolving the cloud into its various components and determining
the amplitudes of the signals associated with each, one is able to
determine the fractional composition of the cloud. One can expect to
have a good understanding of the dynamics of the asteroidal particles
that give rise to the solar system dust bands and get trapped in the
Earth's circumsolar resonant ring. Interpretations of the dust band
observations and of the cloud's trailing/leading asymmetry indicate that
about one third of the particles in the cloud are asteroidal, implying
that about two thirds of the particles originate from comets. Some
progress has been made with understanding the dynamics of cometary
particles, but this remains a challenging problem. In this paper, to
illustrate the quality of the DIRBE data and to show how the observed
structure of the cloud is amenable to a dynamical interpretation,
the authors analyse the asymmetry of the cloud observed in the DIRBE
12 μm waveband.

---------------------------------------------------------
Title: Chemical Evolution and History of Star Formation in the Large
Magellanic Cloud
Authors: Gustafsson, Bengt
1995hst..prop.6102G Altcode:
Large scale processes controlling star formation and nucleosynthesis are
fundamental but poorly understood. This is especially true for external
galaxies. A detailed study of individual main sequence stars in the LMC
Bar is proposed. The LMC is close enough to allow this, has considerable
spread in stellar ages and a structure permitting identification of
stellar populations and their structural features. The Bar presumably
plays a dominant role in the chemical and dynamical evolution of the
galaxy. Our knowledge is, at best, based on educated guesses. Still,
the major population of the Bar is quite old, and many member stars are
relatively evolved. The Bar seems to contain stars similar to those
of Intermediate to Extreme Pop II in the Galaxy. We want to study
the history of star formation, chemical evolution and initial mass
function of the population dominating the Bar. We will use field stars
close to the turn off point in the HR diagram. From earlier studies,
we know that 250-500 such stars are available for uvby photometry in
the PC field. We aim at an accuracy of 0.1 -0.2 dex in Me/H and 25% or
better in relative ages. This requires an accuracy of about 0.02 mag in
the uvby indices, which can be reached, taking into account errors in
calibration, flat fielding, guiding and problems due to crowding. For
a study of the luminosity function fainter stars will be included as
well. Calibration fields are available in Omega Cen and M 67.

---------------------------------------------------------
Title: Search for the Signature of Interstellar Dust in the COBE Data
Authors: Grogan, K.; Dermott, S. F.; Gustafson, B. A. S.; Jayaraman,
S.; Hamilton, D.
1995DPS....27.4006G Altcode: 1995BAAS...27.1164G
No abstract at ADS

---------------------------------------------------------
Title: Recent Advances on Light Scattering Models of Interplanetary
Dust
Authors: Xu, Y. -L.; Dermott, S. F.; Gustafson, B. Å. S.
1995DPS....27.4007X Altcode: 1995BAAS...27.1164X
No abstract at ADS

---------------------------------------------------------
Title: Outer Layers of a Carbon Star: The View from the Hubble
Space Telescope
Authors: Johnson, Hollis R.; Ensman, Lisa M.; Alexander, David R.;
Avrett, Eugene H.; Brown, Alexander; Carpenter, Kenneth G.; Eriksson,
Kjell; Gustafsson, Bengt; Jorgensen, Uffe G.; Judge, Philip D.; Linsky,
Jeffrey L.; Luttermoser, Donald G.; Querci, Francois; Querci, Monique;
Robinson, Richard D.; Wing, Robert F.
1995ApJ...443..281J Altcode:
To advance our understanding of the relationship between stellar
chromospheres and mass loss, which is a common property of carbon stars
and other asymptotic giant branch stars, we have obtained ultraviolet
spectra of the nearby N-type carbon star UU Aur using the Hubble
Space Telescope (HST). In this paper we describe the HST observations,
identify spectral features in both absorption and emission, and attempt
to infer the velocity field in the chromosphere, upper troposphere,
and circumstellar envelope from spectral line shifts. A mechanism
for producing fluoresced emission to explain a previously unobserved
emission line is proposed. Some related ground-based observations are
also described.

---------------------------------------------------------
Title: Interferometric Observations of HCN and CN towards Carbon Stars
Authors: Lindqvist, M.; Lucas, R.; Olofsson, H.; Omont, A.; Eriksson,
K.; Gustafsson, B.
1995Ap&SS.224..501L Altcode:
Using the IRAM interferometer we have observed four carbon stars (U
Cam, CIT6, Y CVn, IRC+40540) in the HCN(J=1 → 0) and CN(N=1 → 0)
lines. Here we present some results for CIT6 and U Cam.

---------------------------------------------------------
Title: High-Precision Astrometry and the Modelling of Stellar Spectra
Authors: Gustafsson, B.
1995IAUS..166..143G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Opacity incompleteness and atmospheres of cool stars
Authors: Gustafsson, B.
1995HiA....10..579G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Opacity Incompleteness and Atmospheres of Cool Stars
Authors: Gustafsson, B.
1995ASPC...78..347G Altcode: 1995aapn.conf..347G
No abstract at ADS

---------------------------------------------------------
Title: Do We Need the VLT to Study Nearby Stellar Populations?
Authors: Gustafsson, B.
1995svlt.conf...65G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Line asymmetries in the metal-poor star HD 140283
Authors: Allende Prieto, C.; García López, R. J.; Lambert, D. L.;
Gustafsson, B.
1995IAUS..176P.107A Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Star Formation and System Calibration
Authors: Linde, P.; Ardeberg, A.; Gustafsson, B.; Nissen, P. E.
1995chst.conf..334L Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Models of late-type stellar photospheres
Authors: Gustafsson, Bengt; Jorgensen, Uffe Grae
1994A&ARv...6...19G Altcode:
In this review we discuss recent work and progress in the modelling of
photospheres of stars of spectral types F and later. Special emphasis is
laid on advances as regards the consideration of atomic and molecular
blanketing, non-LTE and convection and other dynamic processes. In
a special chapter we discuss the possibilities of semi-empirical
modelling of late-type photospheres. In the conclusions we find that
much important work remains in this field, but that a considerable
part of this work may in fact be carried out in a near future.

---------------------------------------------------------
Title: Boron in the extreme Population II star HD 140283 and the
production of light elements in the Early Galaxy
Authors: Edvardsson, B.; Gustafsson, B.; Johansson, S. G.; Kiselman,
D.; Lambert, D. L.; Nissen, P. E.; Gilmore, G.
1994A&A...290..176E Altcode: 1994astro.ph..3002E
Using observations of the 2496.7A Bi line with the HST GHRS at a
nominal resolving power of 90,000, we have found the abundance of
boron of HD140283 to be logɛ_B_(=12+log(N_B_/N_H_))=0.34+/-0.20. This
result is found when a significant non-LTE effect in the formation of
the Bi line is taken into account. The resulting N_B_/N_Be_ ratio is
about 17 (in the range 9-34), which is in very good agreement with
what is expected from spallation by cosmic rays. We conclude that
this origin of Be and B in the Early Galaxy is the most probable of
recently suggested formation mechanisms.

---------------------------------------------------------
Title: Effect of meteoroid rotation on atmospheric entry heating
and meteor beginning height
Authors: Adolfsson, L. G.; Gustafson, B. A. S.
1994P&SS...42..593A Altcode:
The begining of height of a meteor yaries by ∼ 10 km depending
on the rotation state of a spherical meteoroid as long as the body
sustains a temperature gradient. Such gradients build up in friable
stony metoroids larger than ∼ 0.1 cm and in iron meteoroids that are
∼ 1 cm or larger. The height where 100 μm or smaller zodiacal dust
particles ablate is nearly independent of rotation. Stony particles
in the 100 μm size range ablate near 120 km while both larger and
smaller interoids penetrate deeper. All calculations were made with a
nominal speed of 30 km s -1 and a zenithal distance equal to
zr = 0°. Larger meteoroids cool their surface by conduction
to the interior while smaller meteoroids decelerate significantly
due to their large surface area to mass ratio so that the surface
recieves a lower energy flux. Some micro-meteoroids smaller than ∼
10 μm may escape ablation altogether at the nominal velocity. The
effect of rotation on particle temperature during atmospheric flight
is significant on meteoroids larger than 0.1 cm but may be negligible
on micro-meteorites that are typically 10-50 μm in diameter.

---------------------------------------------------------
Title: A circumsolar ring of asteroidal dust in resonant lock with
the Earth
Authors: Dermott, Stanley F.; Jayaraman, Sumita; Xu, Y. L.; Gustafson,
B. Å. S.; Liou, J. C.
1994Natur.369..719D Altcode:
Numerical simulations of the orbital evolution of asteroidal dust
particles show that the Earth is embedded in a circumsolar ring of
asteroidal dust, and has a cloud of dust permanently in its wake. This
could account for the asymmetry of the zodiacal cloud observed by
the Infrared Astronomical Satellite (IRAS). The resonant trapping and
subsequent release of dust particles by the ring may provide a mechanism
by which carbonaceous material is transported from the asteroid belt
to the Earth.

---------------------------------------------------------
Title: Interstellar dust in the heliosphere
Authors: Gruen, E.; Gustafson, B.; Mann, I.; Baguhl, M.; Morfill,
G. E.; Staubach, P.; Taylor, A.; Zook, H. A.
1994A&A...286..915G Altcode:
A flow of μm-sized interstellar grains has been identified with
the Ulysses dust detector in the outer solar system at about 5 AU
from the Sun. The observed flux is 1.5x10^-4^m^-2^/s of particles
of mean mass 3x10^-13^g, which corresponds to a mass flux of
5x10^-17^g/m^2^/s. The particles on hyperbolic trajectories have
radiants which are compatible with the flow of interstellar gas,
although some velocity dispersion occurs. The grains are on average
a factor 30 more massive than the classical interstellar grains which
cause stellar extinction. However, these smaller grains have not been
detected by Ulysses. It is demonstrated that radiation pressure and
interaction of the charged grains with the interplanetary magnetic
field prevent these small grains from penetrating down to the distance
of Ulysses. The spatial density of interstellar grains is compatible
with zodiacal light observations. Some consequences arising from the
existence of big grains in the interstellar medium are discussed.

---------------------------------------------------------
Title: A New Analog to Light Scattering Laboratory at the University
of Florida
Authors: Gustafson, B. Å. S.
1994DPS....26.0609G Altcode: 1994BAAS...26R1089G
No abstract at ADS

---------------------------------------------------------
Title: Chemical composition and atmospheric parameters of metal-poor
halo stars
Authors: Nissen, P. E.; Gustafsson, B.; Edvardsson, B.; Gilmore, G.
1994A&A...285..440N Altcode:
The abundance of oxygen in 9 metal-poor stars is derived from high
resolution observations of OH lines in the spectral region 3138-3155
A. The same spectra were previously used to determine the beryllium
abundance (Gilmore et al. 1992). In addition, Mg, Ca, Ti, Cr, and
Fe abundances are derived from accurate equivalent widths of weak
atomic absorption lines in the 5100-6100 A spectral region. Atmospheric
parameters, T_eff_ and g, are determined from the Stroemgren photometric
indices b-y and c_1_. New accurate oscillator strengths for the FeI
and FeII lines allow an important check of these parameters as well
as the assumption of LTE; the FeI excitation balance is consistent
with the photometric temperatures, whereas the FeII/FeI ionization
balance suggests an over-ionization of iron amounting to about 0.15
dex with respect to LTE. The derived abundance ratios between the
α-elements and Fe are nearly constant in the metallicity range
-3.2 &lt;~[Fe/H]&lt;~-1.8. Any possible scatter of Mg/Fe, Ca/Fe and
Ti/Fe in the galactic halo is less than 0.06 dex and an upper limit
for the scatter of O/Fe is 0.15 dex. This suggests that the IMF was
similar in different regions of the inner halo and that the mixing
of nucleosynthesis products was very efficient in galactic regions of
typically globular cluster masses.

---------------------------------------------------------
Title: The Production of Beryllium in the Early Galaxy
Authors: Feltzing, Sofia; Gustafsson, Bengt
1994ApJ...423...68F Altcode:
The formation of beryllium in the early Galaxy is discussed. It is
shown that if spallation occurs predominantly in regions rich in heavy
elements, i.e., close to supernovae, the linear relation recently
obtained by Gilmore et al. (1992) between beryllium and oxygen
abundances for Population II stars may be reproduced. Estimates of
relevant timescales for mixing show that the decisive factor, the ratio
of the timescale of cosmic-ray diffusion out of the locally enriched
regions to the decay time of cosmic rays in the Galaxy as a whole,
admits this scenario. Although energetically possible, it requires,
however, very high local cosmic-ray fluxes (greater than or equal to
105/sq cm/s), which predicts gamma-ray fluxes above those
observed from supernova remnants and the Galaxy. We therefore consider
other models, such as those given by Duncan et al. (1992) or Prantzos
et al. (1993), more probable.

---------------------------------------------------------
Title: Modern Sources of Dust in the Solar System
Authors: Dermott, Stanley F.; Durda, D. D.; Gustafson, B. A. S.;
Jayaraman, S.; Liou, J. -C.; Xu, Y. -L.
1994aidp.work...17D Altcode: 1994LPITR9402...17D
The observed size-frequency distributions of the main-belt and family
asteroids and the results of an analysis of the IRAS data on the
zodiacal background and the solar system dustbands were used to estimate
the extent of the contribution of asteroidal dust to the zodiacal
cloud. It is concluded that the total asteroidal contribution to the
zodiacal signal is probably 40% of the total flux. Thus, some 60% of
the flux probably derives from a source other than main-belt asteroids.

---------------------------------------------------------
Title: Zodiacal Dust Bands
Authors: Dermoti, S. F.; Durda, D. D.; Gustafson, B. A. S.; Jayaraman,
S.; Liou, J. C.; Xu, Y. L.
1994IAUS..160..127D Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Physics of Zodiacal Dust
Authors: Gustafson, B. A. S.
1994AREPS..22..553G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The processes of nucleosynthesis and chemical evolution as
observed in stars: three examples
Authors: Gustafsson, B.
1993JPhGS..19....1G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The chemical evolution of the galactic disk II. Observational
data.
Authors: Edvardsson, B.; Andersen, J.; Gustafsson, B.; Lambert, D. L.;
Nissen, P. E.; Tomkin, J.
1993A&AS..102..603E Altcode:
We recently discussed the chemical evolution of the galactic disk based
on the detailed analysis of 189 F and early G disk dwarfs (Edvardsson
et al. 1993). Here we describe the related solar observations, compare
equivalent widths of programme stars observed both from ESO and McDonald
observatories and tabulate equivalent widths.

---------------------------------------------------------
Title: The Chemical Evolution of the Galactic Disk - Part One -
Analysis and Results
Authors: Edvardsson, B.; Andersen, J.; Gustafsson, B.; Lambert, D. L.;
Nissen, P. E.; Tomkin, J.
1993A&A...275..101E Altcode: 2009A&A...500..391E
No abstract at ADS

---------------------------------------------------------
Title: Scattering by aggregates with and without an absorbing mantle:
microwave analog experiments
Authors: Zerull, R. H.; Gustafson, B. A. S.; Schulz, K.;
Thiele-Corbach, E.
1993ApOpt..32.4088Z Altcode:
We present angular scattering functions for loosely packed aggregates
of 250 and 500 identical spheres near the Rayleigh size limit before
and after the application of successive layers of an absorbing
mantle. All measurements were obtained by using the microwave analog
technique. Gross features of the scattering by aggregates without a
mantle can be interpreted in terms of coherent scattering from the unit
spheres acting independently of each other. The largest deviations from
this approximation occur after the first minimum in forward scattering
and extend to a scattering angle of 60 or 80 deg for our models. This
intermediate range is also where the largest differences occur in
the scattering from one aggregate to another. The angular extent of
the range is largest for aggregates with the smallest dimensions. The
scattering function is usually flat in the backscattering hemisphere
and has little or no backscattering increase. The coherent scattering
approximation breaks down when the aggregates are coated, and an
equivalent spheres approximation becomes a better representation. The
maximum degree of polarization near a scattering angle of 90 deg first
decreases and then increases again as the mantle grows thicker.

---------------------------------------------------------
Title: A Study of Circumstellar Envelopes around Bright Carbon
Stars. I. Structure, Kinematics, and Mass-Loss Rate
Authors: Olofsson, H.; Eriksson, K.; Gustafsson, B.; Carlstrom, U.
1993ApJS...87..267O Altcode:
Results are presented of a survey of circumstellar CO emission on a
sample of bright carbon stars, which is relatively complete out to
about 900 pc from the sun. A total of 68 detections were made. All
objects within 600 pc of the sun were detected. It is suggested that the
large majority of all carbon stars have circumstellar envelopes. The
CO-emitting parts of these envelopes have angular sizes less than
about 15 arcsec. The median gas expansion velocity is 12.5 km/s, and
the expansion velocities for the majority of the objects fall in the
range 9-15 km/s. The median mass-loss rate is 1.5 x 10 exp -7 solar
mass/yr, and the mass loss rate for the majority of stars lies within
the narrow range (0.8-2.5) x 10 exp -7 solar mass/yr. Circumstellar
and photospheric HCN, CN, and CS abundances are estimated and compared
for a sample for bright carbon stars. The chemistry in the envelope
around R Scl is determined.

---------------------------------------------------------
Title: A Study of Circumstellar Envelopes around Bright Carbon
Stars. II. Molecular Abundances
Authors: Olofsson, H.; Eriksson, K.; Gustafsson, B.; Carlstroem, U.
1993ApJS...87..305O Altcode:
We have estimated and compared circumstellar and photospheric HCN, CN,
and CS abundances for a sample of bright carbon stars. The circumstellar
HCN and CS abundances roughly correlate with the photospheric ones,
but the former appear to be systematically overestimated by a factor
of 5-10. Although we cannot exclude the presence of a circumstellar
chemistry that efficiently produces HCN and CS in the inner parts
of these relatively hot circumstellar envelopes, we attribute this
difference between photospheric and circumstellar abundances to
errors in the circumstellar envelope model used. In particular,
for the low mass-loss rate objects a systematic underestimate of
the mass-loss rate may be suspected. In addition to this general
trend, stars that are in some sense peculiar also show circumstellar
abundances that deviate significantly from the expected. There is
evidence for the presence of maser features in the HCN (J = 1-0)
emission toward some of the stars. The estimated circumstellar CN
abundances suggest that this species is a photodissociation product of
HCN. A search for circumstellar HNC, SiS, and HC3N shows
that molecular emission from species other than CO, HCN, CN, and CS
is very weak in these low mass-loss rate objects. An attempt has been
made to determine the chemistry in the (probably detached) envelope
around R Scl. The data suggest a carbon-rich chemistry. Finally, it
is shown that the circumstellar 12CO/13CO and
H12CN/H13CN intensity ratios roughly correlate
with the photospheric 12C/13C isotope ratios
for a small number of low mass-loss rate objects, although the former
ratios are systematically lower than the latter by a factor of about 2.

---------------------------------------------------------
Title: A Multi-Wavelength Study of the Potentially Meteorite-producing
Comet P/Wilson-Harrington (4015 1979VA)
Authors: Campins, H.; Osip, D.; Gustafson, B. S. Å.; Rieke, G.;
Rieke, M.; Larson, S.; Schleicher, D.
1993DPS....25.1007C Altcode: 1993BAAS...25R1057C
No abstract at ADS

---------------------------------------------------------
Title: VizieR Online Data Catalog: Chemical evolution of the galactic
disk II. (Edvardsson+ 1993)
Authors: Edvardsson, B.; Andersen, J.; Gustafsson, B.; Lambert, D. L.;
Nissen, P. E.; Tomkin, J.
1993yCat..41020603E Altcode:
(1993A&amp;A...275..101E, see catalog &lt;J/A+A/275/101&gt;) from
observations at ESO and McDonald observatories are compared. (4
data files).

---------------------------------------------------------
Title: VizieR Online Data Catalog: Chemical evolution of the galactic
disk I. (Edvardsson+ 1993)
Authors: Edvardsson, B.; Andersen, J.; Gustafsson, B.; Lambert, D. L.;
Nissen, P. E.; Tomkin, J.
1993yCat..32750101E Altcode:
From high resolution, high S/N spectroscopic observations of carefully
selected northern and southern stars, abundances of O, Na, Mg, Al,
Si, Ca, Ti, Fe, Ni, Y, Zr, Ba and Nd, as well as photometric ages,
are derived for 189 nearby field F and G stars. (2 data files).

---------------------------------------------------------
Title: The observed chemical evolution of the Galactic disk.
Authors: Edvardsson, B.; Gustafsson, B.; Andersen, J.; Nissen, P. E.;
Lambert, D. L.; Tomkin, J.
1993AGAb....8..105E Altcode: 1993AGAb....8..105.
No abstract at ADS

---------------------------------------------------------
Title: A Multi-Wavelength Study of the Potentially Meteorite-producing
Comet P/Wilson-Harrington (4015 1979VA)
Authors: Campins, H.; Osip, D.; Gustafson, B. Å. S.; Rieke, G.;
Rieke, M.; Larson, S.; Schleicher, D.
1993LPICo.810...54C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Is superficial knowledge about stellar surfaces sufficient?
Authors: Gustafsson, Bengt
1993ASPC...40..122G Altcode: 1993IAUCo.137..122G; 1993ist..proc..122G
The significance of a detailed knowledge of the atmosphere of a star for
a proper understanding of its interior is illustrated and discussed. It
is concluded that significant progress in the understanding of stellar
atmospheres is needed in order to match methods, discoveries and needs
in the study of stellar internal structure and evolution. (orig.)

---------------------------------------------------------
Title: Models of the Zodiacal Cloud and the Solar System Dust Bands
for a Spectrum of Wavebands
Authors: Xu, Y. -L.; Dermott, S. F.; Gustafson, B. Å. S.; Liou, J. C.
1993LPICo.810..317X Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Origin of the IRAS dustbands (Invited)
Authors: Dermott, S. F.; Durda, D. D.; Gomes, R. S.; Gustafson,
B. A. S.; Jayaraman, S.; Liou, J. C.; Nicholson, P. D.; Xu, Y. L.
1993mtpb.conf..357D Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Dependence of Meteor Beginning Heights on Meteoroid Rotation
Authors: Adolfsson, L. G.; Gustafson, B. Å. S.
1993LPICo.810....1A Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Optical and Physical Properties of Comet Dust Models; Numerical
and Laboratory Results
Authors: Gustafson, B. Å. S.; Palm, T.; Andersson, M. W.; Adolfsson,
L. G.; Xu, Y. L.; Zerull, R. H.
1993LPICo.810..125G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Meteoroid Material and Beginning Heights Within Meteor Streams
Authors: Adolfsson, L. G.; Gustafson, B. Å. S.
1993LPICo.810....2A Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Tools for the interpretation of stellar data Chemical
composition as a parameter in individual stars
Authors: Gustafsson, B.
1993fces.conf....3G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The production of light elements in the early galaxy
Authors: Feltzing, S.; Gustafsson, B.
1993paas.conf..550F Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Standard stars for the Infrared Space Observatory, ISO.
Authors: van der Bliek, N. S.; Bouchet, P.; Habing, H. J.; Jourdain
de Muizon, M.; Blackwell, D. E.; Gustafsson, B.; Hammersley, P. L.;
Kessler, M. F.; Lim, T. L.; Manfroid, J.; Metcalfe, L.; Salama, A.
1992Msngr..70...28V Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Modeling of Asteroidal Dust Production Rates
Authors: Durda, Daniel D.; Dermott, Stanley F.; Gustafson, Bo A. S.
1992acm..proc..161D Altcode:
The production rate of dust associated with the prominent Hirayama
asteroid families and the background asteroidal population are modeled
with the intent of using the families as a calibrator of mainbelt dust
production. However, the dust production rates of asteroid families may
be highly stochastic; there is probably more than an order of magnitude
variation in the total area of dust associated with a family. Over 4.5
x 109 years of collisional evolution, the volume (mass)
of a family is ground down by an order of magnitude, suggesting a
similar loss from the entire mainbelt population. Our collisional
models show that the number of meteoroids deliverable to Earth also
varies stochastically, but only by a factor of 2 to 3.

---------------------------------------------------------
Title: The Origin and Evolution of the Zodiacal Dust Cloud
Authors: Dermott, Stanley F.; Durda, Daniel D.; Gustafson, Bo A. S.;
Jayaraman, S.; Xu, Y. L.; Gomes, R. S.; Nicholson, P. D.
1992acm..proc..153D Altcode:
We have now analyzed a substantial fraction of the IRAS observations
of the zodiacal cloud, particularly in the 25 micron waveband. We
have developed a gravitational perturbation theory that incorporates
the effects of Poynting-Robertson light drag (Gomes and Dermott,
1992). We have also developed a numerical model, the SIMUL mode,
that reproduces the exact viewing geometry of the IRAS telescope and
calculates the distribution of thermal flux produced by any particular
distribution of dust particle orbits (Dermott and Nicholson, 1989). With
these tools, and using a distribution of orbits based on those of
asteroidal particles with 3.4 micron radii whose orbits decay due
to Poynting-Robertson light drag and are perturbed by the planets,
we have been able to: (1) account for the inclination and node of the
background zodiacal cloud observed by IRAS in the 25 micron waveband;
(2) relate the distribution of orbits in the Hirayama asteroid families
to the observed shapes of the IRAS solar system dustbands; and (3)
show that there is observational evidence in the IRAS data for the
transport of asteroidal particles from the main belt to the Earth by
Poynting-Robertson light drag.

---------------------------------------------------------
Title: Did Earth-Approaching Asteroids 3551, 3908, or 4055 Produce
Meteorites?
Authors: Gustafson, Bo A. S.; Williams, I. P.
1992acm..proc..219G Altcode:
Orbital integrations show that Amor asteroid 3908 could have ejected one
out of four plausible groups of meteorite producing fireballs during a
collision in the asteroid belt. It was suggested by others that such
a collision may also have split asteroids 3551 and 3908. A member of
this group of fireballs is listed as one of the better possibilities
for recovery.

---------------------------------------------------------
Title: Collisional and Dynamic Evolution of Dust from the Asteroid
Belt
Authors: Gustafson, Bo A. S.; Gruen, Eberhard; Dermott, Stanley F.;
Durda, Daniel D.
1992acm..proc..223G Altcode:
The size and spatial distribution of collisional debris from main
belt asteroids is modeled over a 10 million year period. The model
dust and meteoroid particles spiral toward the Sun under the action of
Poynting-Robertson drag and grind down as they collide with a static
background of field particles.

---------------------------------------------------------
Title: Why High Spectral Resolution - Even at Low Signal-To Ratio
Authors: Gustafsson, B.
1992ESOC...40...17G Altcode: 1992hrsw.conf...17G
No abstract at ADS

---------------------------------------------------------
Title: A Rugged Method to Determine the Solar Radiation Pressure
Force to Gravitation Ratio (β) from Meteor Data
Authors: Adolfsson, L. G.; Gustafson, B. S. Å.
1992DPS....24.1108A Altcode: 1992BAAS...24..952A
No abstract at ADS

---------------------------------------------------------
Title: Optical and Physical Properties of Comet Dust Aggregates of
the Vold-Sutherland and Related Types
Authors: Gustafson, B. S. Å.; Palm, T.; Andersson, M.; Shu, Y. -L.;
Zerull, R. H.
1992DPS....24.3802G Altcode: 1992BAAS...24.1017G
No abstract at ADS

---------------------------------------------------------
Title: Is beryllium in metal-poor stars of galactic or cosmological
origin?
Authors: Gilmore, Gerard; Gustafsson, Bengt; Edvardsson, Bengt;
Nissen, Poul E.
1992Natur.357..379G Altcode:
Standard Big Bang nucleosynthesis predicts a very small primordial
abundance of beryllium. Observations of nine very metal-poor stars
indicate a beryllium abundance roughly proportional to the oxygen
abundance, a trend that can be explained in terms of galactic chemical
evolution. Combining this rate of beryllium production with recent
observations of boron and lithium in similar stars yields an upper
limit to the primordial beryllium abundance several orders of magnitude
greater than the cosmological prediction, a result that can be explained
by cosmicray activity in the early Galaxy.

---------------------------------------------------------
Title: Book-Review - the Birth and Early Evolution of Our Universe -
Proceedings of Nobel SYMPOSIUM:79 - Graftavallen - Sweden - 1990
Authors: Nilsson, J. S.; Gustafsson, B.; Skagerstam, B. S.
1992Sci...255.1451N Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Chemical and Dynamical Evolution of the Galactic Disk
Authors: Gustafsson, B.; Edvardsson, B.; Nissen, P.; Lambert, D. L.;
Tomkin, J.; Andersen, J.
1992IAUS..149...75G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Can classical model atmospheres be of any use for the study
of hypergiants
Authors: Gustafsson, B.; Plez, B.
1992iesh.conf...86G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Stellar Abundances - Recent Progress and Expectations
Authors: Gustafsson, B.
1992eatc.conf...78G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The circumstellar envelope of the carbon star S Scuti.
Authors: Olofsson, H.; Carlstrom, U.; Eriksson, K.; Gustafsson, B.
1992A&A...253L..17O Altcode:
CO(J = 1-0) observations of the bright carbon star S Sct show that
the star is surrounded by a large (about 5.3 x 10 exp 17 cm) shell
of gas expanding at a velocity of 16.5 km/s. It was produced during a
brief period (about 1200 years) of high mass loss (about 4 x 10 exp-5
solar mass/yr) about 10 exp 4 years ago. The current mass losss rate
and gas expansion velocity are only about 3 x 10 exp -8 solar mass/yr
and about 5 km/s, respectively. This indicates that the star has gone
through a very eruptive phase, possibly induced by a thermal pulse. The
simple kinematics of the shell makes it possible to infer an overall
spherical symmetry of the otherwise definitely clumpy CO brightness
distribution. Thus, the mass loss must have been globally spherically
symmetric, and the material was probably ejected in the form of lumps.

---------------------------------------------------------
Title: Dynamics of the Zodiacal Cloud (lecture)
Authors: Dermott, S. F.; Gomes, R. S.; Durda, D. D.; Gustafson,
B. Å. S.; Jayaraman, S.; Xu, Y. L.; Nicholson, P. D.
1992IAUS..152..333D Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Laboratory reflectance measurements of analogues to “dirty”
ice surfaces on atmosphereless solar system bodies
Authors: Stephens, John R.; Gustafson, Bo A. S.
1991Icar...94..209S Altcode:
This article presents laboratory measurements of bidirectional
reflectances from particle/ice mixtures representing "dirty" ice
surfaces on atmosphereless Solar System bodies. The reflectance was
monitored as ice sublimed under vacuum from the mixtures leaving behind
porous refractory particle layers up to a millimeter thick. Similar
layers or "dust-mantles" may evolve on cometary surfaces and on icy
asteroids. The measurements cover a 40° to 90° phase angle at a
fixed incidence angle of 20° from the surface normal. The spectral
coverage is from the U band (350 nm) in the ultraviolet to the R band
(720 nm) in the near infrared. Before significant ice sublimation, a 10%
(by mass) colloidal silica in water ice sample was the brightest with
reflectances in the 0.20-0.30 range. A similar mixture with the addition
of 1% carbon had only 0.03 to 0.06 reflectance. A mixture of 1% carbon
in water ice (without silica) had an intermediate reflectance of 0.05 to
0.20. Only carbon in ice showed marked angular dependence with a broad
increase toward the specular angle. The initial reflectance spectra
were slightly blue with reflectivity gradients (RG) &lt; -1.4%/100 nm
except for one carbon/silica/ice sample that was red in color with RG
= 2.2%/100 nm. The formation of porous refractory layers or mantles
through sublimation is coupled with significant changes in reflectance
and color. The silica/ice sample more than doubled in reflectance
to 0.53-0.78 and became bluer with RG &gt; - 5%/100 nm. Reflectance
from the carbon/ice changed to 0.05 with no phase angle dependence and
became slightly red (RG &lt; 1%/100 nm). The optical properties of the
carbon/silica/ice samples are more complex and depend on the thermal
history of the sample. These samples became more blue (RG &lt; -0.67)
as a mantle formed with increased reflectivities in the range of 0.07
to 0.18. The processed carbon/ice sample is optically most similar
to dark icy Solar System bodies including C type asteroids (RG &lt;
3%/100 nm, albedo ( Pv) &lt; 0.05) and the asteroid Chiron
(RG &lt; 1%/100 nm, Pv ≈ 0.1). The sample is more neutral
in color than D type asteroids (RG &gt; 6%/100 nm, Pv &lt;
0.05) and Comet Halley (RG = 6%/100 nm, Pv = 0.06). The
carbon/silica/ices samples, with comparatively high reflectance
and blue reflectivity gradients, are unlike asteroids or comets
despite containing a mixture of silicate and carbonaceous material,
a composition expected of these bodies. Differences in reflectance and
reflectivity gradient between our samples and solar system bodies may
reflect differing physical processes during mantle formation as well as
differences in chemistry of silicate and carbonaceous materials. Further
laboratory and theoretical work are needed to fully understand the
optical consequences of mantle formation on atmosphereless icy Solar
System bodies.

---------------------------------------------------------
Title: Light Scattering by Comet Dust Models
Authors: Gustafson, B. S. Å.; Zerull, R. H.; Schulz, K.; Corbach, E.
1991BAAS...23.1160G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Modelling the Zodiacal Dust Cloud
Authors: Xu, -L. Y.; Dermott, S. F.; Gustafson, B. S. Å.; Jayaraman,
S.; Durda, D. D.
1991BAAS...23.1149X Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Geminid Meteoroids and the Probability for Cometary Activity
on Phaethon
Authors: Adolfsson, L.; Gustafson, B. S. Å.
1991BAAS...23.1141A Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Origin and evolution of the zodiacal dust cloud
Authors: Dermott, S. F.; Durda, D.; Gustafson, B.; Jayaraman, S.;
Xu, Y. -L.; Nicholson, P. D.; Gomes, R. S.
1991pggp.rept..405D Altcode:
The astrophysical importance of the zodiacal cloud became more
apparent. The most useful source of information on the structure
of the zodiacal cloud is the Infrared Astronomical Satellite (IRAS)
observations. A substantial fraction of the extensive IRAS data set
was analyzed. Also, a numerical model was developed (SIMUL) that
allows to calculate the distribution of night-sky brightness that
would be produced by any particular distribution of dust particle
orbits. This model includes the effects of orbital perturbations by
both the planets and solar radiation, it reproduces the exact viewing
geometry of the IRAS telescope, and allows for the eccentricity of the
Earth's orbit. SIMUL now is used to model not just the solar system
dust bands discovered by IRAS but the whole zodiacal cloud.

---------------------------------------------------------
Title: The Origin and Evolution of the Zodiacal Dust Cloud
Authors: Dermott, S. F.; Durda, D.; Gomes, R. S.; Gustafson, B.;
Jayaraman, S.; Xu, Y. -L.; Nicholson, P. D.
1991LPICo.765...49D Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Modelling of Long Term Evolution and Equilibrium State of a
Dust Component from the Asteroid Belt
Authors: Gustafson, B. Å. S.; Grün, E.
1991LPICo.765Q..82G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Spectroscopy of southern active stars. II. HD 32918, HD 82558,
BD -22 3467, AB Doradus (HD 36705) and RST 137B.
Authors: Vilhu, O.; Gustafsson, B.; Walter, F. M.
1991A&A...241..167V Altcode:
We have observed the southern active cool stars HD 32918 (K1
IIIp), HD 82558 (K2 V), BD-22°3467 (G8 III), AB Doradus (HD
36705, K1 IV) and Rst 137 B (M 3-5), each of which lies close
to the chromospheric- coronal saturation limit. The fractional
Hα-luminosities LHα/Lbol of the stars were
close to 10-4. No significant radial velocity variations
were detected in any of the stars. With the variations of the Fe
I 6546-line profiles, as a function of the 9.55 d rotation period, the
existence of a cool spot-region of HD 32918 was traced. The spectra were
analysed by a surface imaging technique by Piskunov et al. (1990). The
resulting image showed a large group of cool spots at the equatorial
belt at one side of the star, and a smaller and less cool one extending
to higher latitudes at the opposite longitude. Old photometry suggests
that the equatorial spots might have been permanent during 7 yr at the
same (active) longitude. The Hα-emission of HD 32918 was variable
and asymmetric, comprising possibly of chromospheric and wind (or
expanding chromosphere) components. The He I 5876 (D 3) absorption
was remarkably strong in HD 32918, pointing to the existence of an
extended and low density chromosphere. BD-22°3467, the cool
companion to the hot central star of the planetary nebula Abell 35,
experiences a photometric wave with a 0.77 d period (Jasniewicz &amp;
Acker, 1988). Our observations, performed around the same time with
this photometry, resolved a blue-shifted Hα-emission at the minimum
light. This behaviour was opposite to that found in HD 32918. The υ
sin i value (90 km s-1) of BD-22°3467 is compatible with
the interpretation that the 0.77 d photometric cycle is the star's
rotation period. The Hα-emission of HD 82558 was stronger than
in the previous observations by Fekel et al. (1986) and variable,
but with no obvious rotational modulation. The Hα-emission strengths
of the young pre-main-sequence pair AB Dor - Rst 137 B are compatible
with those of the Pleiades stars (WHα vs. R - I, Stauffer
&amp; Hartmann 1986), giving additional support to the small age of
the system. Rst 137 B has the He I 5876 triplet in strong emission
(EW = 750±80 mA), and its photospheric lines are broad (υ sin i
around 50 km s-1). These facts suggest that Rst 137 B is
an extremely active M star. In AB Dor we detected two Hα-transients
(the first in emission and the second one in absorption). In the
fastest rotators of our sample, AB Dor (0.51 d) and HD 82558 (1.66 d),
we detected no He I D3 absorption nor emission. The physics of the Hα
and He D3 transitions seem to be related. In low density and active
chromospheres (with large optical thickness and filling factor) the
lines appear in absorption (photo-ionization dominated plasma), while
in very high density chromospheres (Rst 137 B) they are in emission
(collisionally dominated plasma). Intermediate cases show no absorption
nor emission (filled-in level, AB Dor as a typical example). The
lithium-abundances, as determined by us, suggest that AB Dor (logɛ(Li)
= 3.1) and HD82558 (logɛ(Li) = 2.6) are premain-sequence stars,
while HD 32918 (logɛ(Li) = 1.6-2.0) is most probably an evolved object.

---------------------------------------------------------
Title: The birth and early evolution of our
universe. Proceedings. Nobel Symposium 79, Gräftåvallen (Sweden),
11 - 16 Jun 1990.
Authors: Nilsson, J. S.; Gustafsson, B.; Skagerstam, B. -S.
1991PhST...36.....N Altcode:
Contents: 1. Cosmic background radiation - primordial nucleosynthesis -
inflation. 2. Large scale structure. 3. Cosmic strings and textures -
dark matter - standard model physics. 4. Dark matter - standard model
physics. 5. Quantum cosmology.

---------------------------------------------------------
Title: Size Distribution Dependance of Infrared Emission from Models
of Asteroidal and Cometary Dust
Authors: Gustafson, B. Å. S.
1991LPICo.765...81G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Light Scattering by Open-Structured, Filamentary, Comet
Dust Models
Authors: Gustafson, B. Å. S.; Zerull, R. H.; Schulz, K.; Corbach, E.
1991LPICo.765...83G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The future of stellar spectroscopy and its dependence on YOU.
Authors: Gustafsson, B.
1991PhST...34...14G Altcode:
The use of atomic data in contemporary stellar spectroscopy is
illustrated by a number of examples of recent applications. The needs
for extended and improved data are stressed.

---------------------------------------------------------
Title: The Shape of Meteor Streams in Orbital Parameter Space from
Independent Meteor Surveys
Authors: Gustafson, B. Å. S.
1991LPICo.765...80G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Spectroscopy of Southern Active Stars
Authors: Vilhu, O.; Gustafsson, B.; Walter, F. M.
1991LNP...380..492V Altcode: 1991IAUCo.130..492V; 1991sacs.coll..492V
H and HeI D3 lines were observed in five active cool stars over their
relatively short rotation periods. Three of the stars (AB Dor, Rst137B,
HD82558) are in the pre main sequence phase (as deduced from their
lithium abundances), while two are post main sequence FK Comae type
stars (HD32918 and BD-223467) (Vilhu et al., 1991). We present the
results of these observations and point out the physical similarity
of the Ha and He D3 transitions (Fig.1).

---------------------------------------------------------
Title: A Search for Streams Associated with Earth-Approaching
Asteroids 3551, 3908, and 4055
Authors: Gustafson, B. Å. S.; Williams, I. P.
1991LPICo.765R..82G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The birth and early evolution of our universe
Authors: Nillson, J. S.; Gustafsson, B.; Skagerstam, B. -S.
1991beeo.conf.....N Altcode:
No abstract at ADS

---------------------------------------------------------
Title: A uvby-like photometric system for the WF/PC of the HST.
Authors: Kiselman, D.; Oja, T.; Gustafsson, B.
1990A&A...238..265K Altcode:
The possibility of combining four filters of the Hubble Space Telescope
Wide Field/Planetary Camera into a uvby-like photometric system is
discussed. On the basis of earth-based observations with appropriate
filters, such a system consisting of WF/PC filters F 368M, F 413M, F
492M, and F 547M was calibrated for the determination of fundamental
parameters of F dwarf stars. A good agreement was found between this
empirical calibration and a theoretical one by Bell (1988). Good
estimates of effective temperatures and metallicities can be obtained
with this system, while gravity determinations require a UV filter at
shorter wavelengths.

---------------------------------------------------------
Title: Book-Review - Astrophysics
Authors: Gustafsson, B.; Nissen, P. E.
1990Sci...250..702G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Formation of stable dust mantles on short-period comet nuclei
Authors: Rickman, H.; Fernandez, J. A.; Gustafson, B. A. S.
1990A&A...237..524R Altcode:
The study addresses a numerical analysis of the formation and evolution
of dust mantles on the surfaces of cometary nuclei in order to determine
the dependency on the perihelion distance, spin, and size of the
nucleus. Two different regimes - free sublimation and gas diffusion,
are considered. The nucleus is divided into latitude strips evolving
independently of each other, and the computation starts with the whole
nucleus in the free-sublimation regime. With the formation of a mantle,
the code switches to the gas-diffusion regime. The formation of stable
mantles is found to be frequent, most often when the spin axis is
in the orbital plane and the perihelion distance is greater than 2
AU. It is noted that an implication of the presented results is that
the nuclei of short-period comets may become completely mantled during
their dynamical evolution into earth-approaching orbits.

---------------------------------------------------------
Title: Distribution and Thermal Properties of Dust Particles in the
Zodiacal Cloud
Authors: Gustafson, B.; Dermott, S. F.; Gomes, R. S.
1990BAAS...22Q1123G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: IRAS Observations of Cool Dust-Is There Dust in the Outer
Solar System Beyond the Orbit of Pluto?
Authors: Simpson, C.; Dermott, S. F.; Gomes, R. S.; Gottesman, S. T.;
Gustafson, B.; Jayaraman, S.
1990BAAS...22.1118S Altcode:
No abstract at ADS

---------------------------------------------------------
Title: IRAS Observations of the "Ten-Degree" Solar System Dust Bands
Authors: Jayaraman, S.; Dermott, S. F.; Gomes, R. S.; Gustafson, B.;
Simpson, C.; Xu, -L. Y.; Nicholson, P. D.
1990BAAS...22.1123J Altcode:
No abstract at ADS

---------------------------------------------------------
Title: IRAS Observations of the Large-Scale Background Zodiacal Cloud
Authors: Xu, -L. Y.; Dermott, S. F.; Gomes, R. S.; Gustafson, B.;
Jayaraman, S.; Simpson, C.; Nicholson, P. D.
1990BAAS...22.1118X Altcode:
No abstract at ADS

---------------------------------------------------------
Title: IRAS Observations of the "Near-Ecliptic" Solar System Dust
Bands
Authors: Dermott, S. F.; Gomes, R. S.; Gustafson, B.; Jayaraman, S.;
Simpson, C.; Xu, -L. Y.; Nicholson, P. D.
1990BAAS...22.1124D Altcode:
No abstract at ADS

---------------------------------------------------------
Title: A comparison of photospheric and circumstellar HCN / CO
-ratios for bright carbon stars.
Authors: Olofsson, H.; Eriksson, K.; Gustafsson, B.
1990A&A...230..405O Altcode:
Measures of circumstellar HCN/CO abundance ratios for carbon stars are
compared with corresponding ratios estimated from photospheric abundance
analysis. A satisfactory agreement is found for most stars. However, V
Hya and two 60 μm-excess sources have significantly lower circumstellar
ratios than expected, and for the 13C-rich stars the ratios
are somewhat higher.

---------------------------------------------------------
Title: Bright carbon stars with detached circumstellar envelopes -
A naturalconsequence of helium shell flashes ?
Authors: Olofsson, H.; Carlstrom, U.; Eriksson, K.; Gustafsson, B.;
Willson, L. A.
1990A&A...230L..13O Altcode:
CO radio map data are presented for the bright carbon stars R Scl, U
Ant, S Sct, and TT Cyg. The stars are found to have large circumstellar
envelopes which, at least in the last three cases, are geometrically
thin and clearly detached from the stars, indicating that the mass
loss has occurred episodically. The possibility that these episodes
are triggered by helium shell flashes is discussed and found consistent
with existing data.

---------------------------------------------------------
Title: Are the Geminids High Density Porous Flakes from a Surface
Crust on Phaethon?
Authors: Gustafson, B. Å. S.
1990acm..proc..523G Altcode: 1989acm..proc...54G
No abstract at ADS

---------------------------------------------------------
Title: Model Calculations of Mantle Formation on Comet Nuclei
Authors: Rickman, H.; Gustafson, B. Å. S.; Fernández, J. A.
1990acm..proc..423R Altcode: 1989acm..proc..106R
No abstract at ADS

---------------------------------------------------------
Title: Modeling of shells around carbon stars.
Authors: Carlström, U.; Eriksson, K.; Gustafsson, B.; Olofsson, H.;
Stenholm, L.; Willson, L. A.
1990apsu.conf...13C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The chemical evolution of the galactic disk.
Authors: Edvardsson, B.; Gustafsson, B.; Andersen, J.; Nissen, P. E.;
Lambert, D. L.; Tomkin, J.
1990apsu.conf...21E Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Abundances in solar type disk stars.
Authors: Edvardsson, B.; Gustafsson, B.; Andersen, J.; Nissen, P. E.;
Lambert, D. L.; Tomkin, J.
1990nba..meet...93E Altcode: 1990taco.conf...93E
Abundances of O, Na, Mg, Al, Si, Ca, Ti, Fe, Ni, Y, Zr, Ba and Nd
have been derived for up to 189 solar type stars with known ages and
space velocities.

---------------------------------------------------------
Title: A Study of Bright Carbon Stars
Authors: Olofsson, H.; Carlstrom, U.; Eriksson, K.; Gustafsson, B.;
Willson, L. A.
1990fmpn.coll..341O Altcode:
No abstract at ADS