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Author name code: rutten-rob
ADS astronomy entries on 2022-09-14
author:("Rutten, Robert J." OR ="Rutten, Rob" OR ="Rutten, Robert" OR ="Rutten, R.J.") NOT =author:"Rutten, R."
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Title: Cornelis de Jager: In Memoriam
Authors: Rutten, Robert J.; Engvold, Oddbjørn; Nieuwenhuizen,
Adrianus C. T.
2022SoPh..297...15R Altcode: 2022arXiv220111496R
Cornelis ("Kees") de Jager, the co-founder of the journal Solar Physics,
passed away on 27 May 2021. He was an exemplary human being, a great
scientist, and he had a large impact on our field. In this tribute,
we first briefly summarize his life and career and then describe some
of his solar activities, from his Ph.D. thesis on the hydrogen lines in
1952 to the book on cycle-climate relations that he completed last year.
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Title: Compendium solar spectrum formation
Authors: Rutten, Robert J.
2021arXiv210302369R Altcode:
The solar spectrum conveys most of our diagnostics to find out how
our star works. They must be understood for utilization, but solar
spectrum formation is complex because the interaction of matter and
radiation within the solar atmosphere suffers non-local control in
space, wavelength, and time. These complexities are summarized and
illustrated with classic literature. They combine in chromospheric
spectrum formation.
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Title: Small-scale solar surface magnetism
Authors: Rutten, Robert
2020smvc.book...29R Altcode: 2021arXiv210514533R
This contribution to "Solar Magnetic Variability and Climate" reviews
small-scale magnetic features on the solar surface, in particular,
the strong-field but tiny magnetic concentrations that constitute
network and plage and represent most magnetism outside sunspots and
filaments. Where these are mostly of the same polarity, as in active
region plage, their occurrence varies with the activity variations
measured by the sunspot number, but when they appear bipolar-mixed on
small scales they can also result from granular-scale dynamo action
that does not vary with the cycle.
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Title: SolO campfires in SDO images
Authors: Rutten, Robert J.
2020arXiv200900376R Altcode:
I present the appearance of "Solar Orbiter campfires" in simultaneous
images from the Solar Dynamics Observatory where most are visible
although less sharp. I also show such features elsewhere in the SDO
database. I show some in detail and discuss their nature.
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Title: Solar Hα features with hot onsets. IV. Network fibrils
Authors: Rutten, Robert J.; Rouppe van der Voort, Luc H. M.; De
Pontieu, Bart
2019A&A...632A..96R Altcode: 2019arXiv190809315R
Even in quiet areas underneath coronal holes the solar chromosphere
contains ubiquitous heating events. They tend to be small scale and
short lived, hence difficult to identify. Here we do not address
their much-debated contribution to outer-atmosphere heating,
but their aftermaths. We performed a statistical analysis of
high-resolution observations in the Balmer Hα line to suggest
that many slender dark Hα fibrils spreading out from network
represent cooling gas that outlines tracks of preceding rapid
type II spicule events or smaller similar but as yet unresolved
heating agents in which the main gas constituent, hydrogen, ionizes
at least partially. Subsequent recombination then causes dark Hα
fibrils enhanced by nonequilibrium overopacity. We suggest that the
extraordinary fibrilar appearance of the Hα chromosphere around network
results from intermittent, frequent small-scale prior heating. <P
/>Movies associated to Fig. 3 and blinkers are available at <A
href="https://www.aanda.org/10.1051/0004-6361/201936113/olm">https://www.aanda.org</A>
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Title: Non-Equilibrium Spectrum Formation Affecting Solar Irradiance
Authors: Rutten, Robert J.
2019SoPh..294..165R Altcode: 2019arXiv190804624R
This is an overview of non-equilibrium aspects of the formation of
solar continua and lines affecting the contributions by magnetic
network and plage to spectrally resolved solar irradiance. After a
brief summary of these contributions and a compact refresher of solar
spectrum formation, the emphasis is on graphical exposition. Major
obstacles for simulation-based irradiance studies are how to cope
with NLTE scattering in the violet and ultraviolet line haze and how
to cope with retarded hydrogen opacities in infrared and mm radiation.
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Title: Automating Ellerman bomb detection in ultraviolet continua
Authors: Vissers, Gregal J. M.; Rouppe van der Voort, Luc H. M.;
Rutten, Robert J.
2019A&A...626A...4V Altcode: 2019arXiv190107975V
Ellerman bombs are transient brightenings in the wings of Hα 6563 Å
that pinpoint photospheric sites of magnetic reconnection in solar
active regions. Their partial visibility in the 1600 Å and 1700 Å
continua registered routinely by the Atmospheric Imaging Assembly (AIA)
onboard the Solar Dynamics Observatory (SDO) offers a unique opportunity
to inventory such magnetic-field disruptions throughout the AIA database
if a reliable recipe for their detection can be formulated. This is
done here. We have improved and applied an Hα Ellerman bomb detection
code to ten data sets spanning viewing angles from solar disc centre
to the limb. They combine high-quality Hα imaging spectroscopy from
the Swedish 1 m Solar Telescope with simultaneous AIA imaging around
1600 Å and 1700 Å. A trial grid of brightness, lifetime and area
constraints is imposed on the AIA images to define optimal recovery
of the 1735 Ellerman bombs detected in Hα. The best results when
optimising simultaneously for recovery fraction and reliability are
obtained from 1700 Å images by requiring 5σ brightening above the
average 1700 Å nearby quiet-Sun intensity, lifetime above one minute,
area of 1-18 AIA pixels. With this recipe 27% of the AIA detections are
Hα-detected Ellerman bombs while it recovers 19% of these (of which
many are smaller than the AIA resolution). Better yet, among the top
10% AIA 1700 Å detections selected with combined brightness, lifetime
and area thresholds as many as 80% are Hα Ellerman bombs. Automated
selection of the best 1700 Å candidates therefore opens the entire
AIA database for detecting most of the more significant photospheric
reconnection events. This proxy is applicable as a flux-dynamics
tell-tale in studying any Earth-side solar active region since early
2010 up to the present.
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Title: Solar Ultraviolet Bursts
Authors: Young, Peter R.; Tian, Hui; Peter, Hardi; Rutten, Robert J.;
Nelson, Chris J.; Huang, Zhenghua; Schmieder, Brigitte; Vissers, Gregal
J. M.; Toriumi, Shin; Rouppe van der Voort, Luc H. M.; Madjarska, Maria
S.; Danilovic, Sanja; Berlicki, Arkadiusz; Chitta, L. P.; Cheung, Mark
C. M.; Madsen, Chad; Reardon, Kevin P.; Katsukawa, Yukio; Heinzel, Petr
2018SSRv..214..120Y Altcode: 2018arXiv180505850Y
The term "ultraviolet (UV) burst" is introduced to describe small,
intense, transient brightenings in ultraviolet images of solar active
regions. We inventorize their properties and provide a definition
based on image sequences in transition-region lines. Coronal signatures
are rare, and most bursts are associated with small-scale, canceling
opposite-polarity fields in the photosphere that occur in emerging flux
regions, moving magnetic features in sunspot moats, and sunspot light
bridges. We also compare UV bursts with similar transition-region
phenomena found previously in solar ultraviolet spectrometry and
with similar phenomena at optical wavelengths, in particular Ellerman
bombs. Akin to the latter, UV bursts are probably small-scale magnetic
reconnection events occurring in the low atmosphere, at photospheric
and/or chromospheric heights. Their intense emission in lines with
optically thin formation gives unique diagnostic opportunities
for studying the physics of magnetic reconnection in the low solar
atmosphere. This paper is a review report from an International Space
Science Institute team that met in 2016-2017.
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Title: Solar ALMA predictions: tutorial
Authors: Rutten, R. J.
2017IAUS..327....1R Altcode: 2016arXiv161105308R
I have proposed that long Hα fibrils are caused by heating events
of which the tracks are afterwards outlined by contrails of cooling
gas with extraordinary Hα opacity and yet larger opacity at the ALMA
wavelengths. Here I detail the radiative transfer background.
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Title: Slender Ca II H Fibrils Mapping Magnetic Fields in the Low
Solar Chromosphere
Authors: Jafarzadeh, S.; Rutten, R. J.; Solanki, S. K.; Wiegelmann, T.;
Riethmüller, T. L.; van Noort, M.; Szydlarski, M.; Blanco Rodríguez,
J.; Barthol, P.; del Toro Iniesta, J. C.; Gandorfer, A.; Gizon, L.;
Hirzberger, J.; Knölker, M.; Martínez Pillet, V.; Orozco Suárez,
D.; Schmidt, W.
2017ApJS..229...11J Altcode: 2016arXiv161003104J
A dense forest of slender bright fibrils near a small solar active
region is seen in high-quality narrowband Ca II H images from the SuFI
instrument onboard the Sunrise balloon-borne solar observatory. The
orientation of these slender Ca II H fibrils (SCF) overlaps with the
magnetic field configuration in the low solar chromosphere derived
by magnetostatic extrapolation of the photospheric field observed
with Sunrise/IMaX and SDO/HMI. In addition, many observed SCFs are
qualitatively aligned with small-scale loops computed from a novel
inversion approach based on best-fit numerical MHD simulation. Such
loops are organized in canopy-like arches over quiet areas that differ
in height depending on the field strength near their roots.
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Title: Solar H-alpha features with hot onsets. III. Long fibrils in
Lyman-alpha and with ALMA
Authors: Rutten, R. J.
2017A&A...598A..89R Altcode: 2016arXiv160901122R
In H-alpha most of the solar surface is covered by dense canopies of
long opaque fibrils, but predictions for quiet-Sun observations with
ALMA have ignored this fact. Comparison with Ly-alpha suggests that
the extraordinary opacity of H-alpha fibrils is caused by hot precursor
events. Application of a recipe that assumes momentary Saha-Boltzmann
extinction during their hot onset to millimeter wavelengths suggests
that ALMA will observe H-alpha-like fibril canopies, not acoustic shocks
underneath, and will yield data more interesting than if these canopies
were transparent. <P />An additional file is available at the end of
the PDF file of this article.This study is offered as compliment to
M.W.M. de Graauw. Our ways, objects, instruments and spectral domains
parted after the 1970 eclipse but converge here.
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Title: Observations and diagnostics of the solar chromosphere
Authors: Rutten, Rob
2017psio.confE..42R Altcode:
No abstract at ADS
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Title: Solar Hα features with hot onsets. II. A contrail fibril
Authors: Rutten, R. J.; Rouppe van der Voort, L. H. M.
2017A&A...597A.138R Altcode: 2016arXiv160907616R
The solar chromosphere observed in Hα consists mostly of narrow
fibrils. The longest typically originate in network or plage and arch
far over adjacent internetwork. We use data from multiple telescopes
to analyze one well-observed example in a quiet area. It resulted from
the earlier passage of an accelerating disturbance in which the gas was
heated to high temperature as in the spicule-II phenomenon. After this
passage a dark Hα fibril appeared as a contrail. We use Saha-Boltzmann
extinction estimation to gauge the onset and subsequent visibilities in
various diagnostics and conclude that such Hα fibrils can indeed be
contrail phenomena, not indicative of the thermodynamic and magnetic
environment when they are observed but of more dynamic happenings
before. They do not connect across internetwork cells but represent
launch tracks of heating events and chart magnetic field during launch,
not at present.
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Title: Reconnection brightenings in the quiet solar photosphere
Authors: Rouppe van der Voort, Luc H. M.; Rutten, Robert J.; Vissers,
Gregal J. M.
2016A&A...592A.100R Altcode: 2016arXiv160603675R
We describe a new quiet-Sun phenomenon which we call quiet-Sun
Ellerman-like brightenings (QSEB). QSEBs are similar to Ellerman bombs
(EB) in some respects but differ significantly in others. EBs are
transient brightenings of the wings of the Balmer Hα line that mark
strong-field photospheric reconnection in complex active regions. QSEBs
are similar but smaller and less intense Balmer-wing brightenings
that occur in quiet areas away from active regions. In the Hα wing,
we measure typical lengths of less than 0.5 arcsec, widths of 0.23
arcsec, and lifetimes of less than a minute. We discovered them
using high-quality Hα imaging spectrometry from the Swedish 1-m
Solar Telescope (SST) and show that, in lesser-quality data, they
cannot be distinguished from more ubiquitous facular brightenings,
nor in the UV diagnostics currently available from space platforms. We
add evidence from concurrent SST spectropolarimetry that QSEBs also
mark photospheric reconnection events, but in quiet regions on the
solar surface. <P />The movies are available in electronic form at <A
href="http://www.aanda.org/10.1051/0004-6361/201628889/olm">http://www.aanda.org</A>
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Title: Hα features with hot onsets. I. Ellerman bombs
Authors: Rutten, R. J.
2016A&A...590A.124R Altcode: 2016arXiv160103280R
Ellerman bombs are transient brightenings of the wings of the Balmer
lines that uniquely mark reconnection in the solar photosphere. They are
also bright in strong Ca II and ultraviolet lines and in ultraviolet
continua, but they are not visible in the optical continuum and the
Na I D and Mg I b lines. These discordant visibilities invalidate
all published Ellerman bomb modeling. I argue that the assumption
of Saha-Boltzmann lower-level populations is informative to estimate
bomb-onset opacities for these diverse diagnostics, even and especially
for Hα, and employ such estimates to gauge the visibilities of
Ellerman bomb onsets in all of them. They constrain Ellerman bomb
formation to temperatures 10 000-20 000 K and hydrogen densities around
10<SUP>15</SUP> cm<SUP>-3</SUP>. Similar arguments likely hold for
Hα visibility in other transient phenomena with hot and dense onsets.
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Title: Ellerman Bombs at High Resolution. III. Simultaneous
Observations with IRIS and SST
Authors: Vissers, G. J. M.; Rouppe van der Voort, L. H. M.; Rutten,
R. J.; Carlsson, M.; De Pontieu, B.
2015ApJ...812...11V Altcode: 2015arXiv150700435V
Ellerman bombs (EBs) are transient brightenings of the extended wings
of the solar Balmer lines in emerging active regions. We describe
their properties in the ultraviolet lines sampled by the Interface
Region Imaging Spectrograph (IRIS), using simultaneous imaging
spectroscopy in Hα with the Swedish 1-m Solar Telescope (SST) and
ultraviolet images from the Solar Dynamics Observatory for Ellerman
bomb detection and identification. We select multiple co-observed
EBs for detailed analysis. The IRIS spectra strengthen the view that
EBs mark reconnection between bipolar kilogauss fluxtubes with the
reconnection and the resulting bi-directional jet located within the
solar photosphere and shielded by overlying chromospheric fibrils in
the cores of strong lines. The spectra suggest that the reconnecting
photospheric gas underneath is heated sufficiently to momentarily reach
stages of ionization normally assigned to the transition region and the
corona. We also analyze similar outburst phenomena that we classify as
small flaring arch filaments and ascribe to reconnection at a higher
location. They have different morphologies and produce hot arches in
million-Kelvin diagnostics.
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Title: Ellerman Bombs at High Resolution. IV. Visibility in Na I
and Mg I
Authors: Rutten, R. J.; Rouppe van der Voort, L. H. M.; Vissers,
G. J. M.
2015ApJ...808..133R Altcode: 2015arXiv150604426R
Ellerman bombs are transient brightenings of the wings of the solar
Balmer lines that mark reconnection in the photosphere. Ellerman noted
in 1917 that he did not observe such brightenings in the Na i D and
Mg i b lines. This non-visibility should constrain EB interpretation,
but has not been addressed in published bomb modeling. We therefore
test Ellerman’s observation and confirm it using high-quality imaging
spectrometry with the Swedish 1-m Solar Telescope. However, we find
a diffuse brightness in these lines that seems to result from prior
EBs. We tentatively suggest this is a post-bomb hot-cloud phenomenon
also found in recent EB spectroscopy in the ultraviolet.
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Title: Ellerman Bombs at High Resolution. II. Triggering, Visibility,
and Effect on Upper Atmosphere
Authors: Vissers, Gregal J. M.; Rouppe van der Voort, Luc H. M.;
Rutten, Robert J.
2013ApJ...774...32V Altcode: 2013arXiv1307.1547V
We use high-resolution imaging spectroscopy with the Swedish 1-m Solar
Telescope (SST) to study the transient brightenings of the wings
of the Balmer Hα line in emerging active regions that are called
Ellerman bombs. Simultaneous sampling of Ca II 8542 Å with the SST
confirms that most Ellerman bombs also occur in the wings of this
line, but with markedly different morphology. Simultaneous images
from the Solar Dynamics Observatory (SDO) show that Ellerman bombs
are also detectable in the photospheric 1700 Å continuum, again with
differing morphology. They are also observable in 1600 Å SDO images,
but with much contamination from C IV emission in transition-region
features. Simultaneous SST spectropolarimetry in Fe I 6301 Å shows that
Ellerman bombs occur at sites of strong-field magnetic flux cancellation
between small bipolar strong-field patches that rapidly move together
over the solar surface. Simultaneous SDO images in He II 304 Å, Fe IX
171 Å, and Fe XIV 211 Å show no clear effect of the Ellerman bombs
on the overlying transition region and corona. These results strengthen
our earlier suggestion, based on Hα morphology alone, that the Ellerman
bomb phenomenon is a purely photospheric reconnection phenomenon.
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Title: Ellerman bombs: fallacies, fads, usage
Authors: Rutten, Robert J.; Vissers, Gregal J. M.; Rouppe van der
Voort, Luc H. M.; Sütterlin, Peter; Vitas, Nikola
2013JPhCS.440a2007R Altcode: 2013arXiv1304.1364R
Ellerman bombs are short-lived brightenings of the outer wings of Hα
that occur in active regions with much flux emergence. We point out
fads and fallacies in the extensive Ellerman bomb literature, discuss
their appearance in various spectral diagnostics, and advocate their
use as indicators of field reconfiguration in active-region topography
using AIA 1700 Å images.
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Title: Twists to Solar Spicules
Authors: Rutten, R. J.
2013ASPC..470...49R Altcode: 2012arXiv1205.5114R
Type-II solar spicules appear as long, thin, highly dynamic strands
of field-tied matter that feed significant mass and energy to the
corona and solar wind. A recent result is that they exhibit torsional
Alfvén waves in addition to accelerating outflows and swaying motions
due to transverse Alfvénic waves. I summarize this finding and then
re-interpret older observations in its light: the striking similarity
of near-limb scenes in the outer blue and red wings of H α, and the
tilts of absorption lines with respect to emission lines in eclipse
spectra taken in 1973.
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Title: LEMUR: Large European module for solar Ultraviolet
Research. European contribution to JAXA's Solar-C mission
Authors: Teriaca, Luca; Andretta, Vincenzo; Auchère, Frédéric;
Brown, Charles M.; Buchlin, Eric; Cauzzi, Gianna; Culhane, J. Len;
Curdt, Werner; Davila, Joseph M.; Del Zanna, Giulio; Doschek, George
A.; Fineschi, Silvano; Fludra, Andrzej; Gallagher, Peter T.; Green,
Lucie; Harra, Louise K.; Imada, Shinsuke; Innes, Davina; Kliem,
Bernhard; Korendyke, Clarence; Mariska, John T.; Martínez-Pillet,
Valentin; Parenti, Susanna; Patsourakos, Spiros; Peter, Hardi; Poletto,
Luca; Rutten, Robert J.; Schühle, Udo; Siemer, Martin; Shimizu,
Toshifumi; Socas-Navarro, Hector; Solanki, Sami K.; Spadaro, Daniele;
Trujillo-Bueno, Javier; Tsuneta, Saku; Dominguez, Santiago Vargas;
Vial, Jean-Claude; Walsh, Robert; Warren, Harry P.; Wiegelmann,
Thomas; Winter, Berend; Young, Peter
2012ExA....34..273T Altcode: 2011ExA...tmp..135T; 2011arXiv1109.4301T
The solar outer atmosphere is an extremely dynamic environment
characterized by the continuous interplay between the plasma and the
magnetic field that generates and permeates it. Such interactions play a
fundamental role in hugely diverse astrophysical systems, but occur at
scales that cannot be studied outside the solar system. Understanding
this complex system requires concerted, simultaneous solar observations
from the visible to the vacuum ultraviolet (VUV) and soft X-rays, at
high spatial resolution (between 0.1” and 0.3”), at high temporal
resolution (on the order of 10 s, i.e., the time scale of chromospheric
dynamics), with a wide temperature coverage (0.01 MK to 20 MK,
from the chromosphere to the flaring corona), and the capability of
measuring magnetic fields through spectropolarimetry at visible and
near-infrared wavelengths. Simultaneous spectroscopic measurements
sampling the entire temperature range are particularly important. These
requirements are fulfilled by the Japanese Solar-C mission (Plan B),
composed of a spacecraft in a geosynchronous orbit with a payload
providing a significant improvement of imaging and spectropolarimetric
capabilities in the UV, visible, and near-infrared with respect to
what is available today and foreseen in the near future. The Large
European Module for solar Ultraviolet Research (LEMUR), described
in this paper, is a large VUV telescope feeding a scientific payload
of high-resolution imaging spectrographs and cameras. LEMUR consists
of two major components: a VUV solar telescope with a 30 cm diameter
mirror and a focal length of 3.6 m, and a focal-plane package composed
of VUV spectrometers covering six carefully chosen wavelength ranges
between 170 Å and 1270 Å. The LEMUR slit covers 280” on the Sun with
0.14” per pixel sampling. In addition, LEMUR is capable of measuring
mass flows velocities (line shifts) down to 2 km s<SUP> - 1</SUP> or
better. LEMUR has been proposed to ESA as the European contribution
to the Solar C mission.
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Title: The quiet-Sun photosphere and chromosphere
Authors: Rutten, R. J.
2012RSPTA.370.3129R Altcode: 2011arXiv1110.6606R
The overall structure and the fine structure of the solar photosphere
outside active regions are largely understood, except possibly important
roles of a turbulent near-surface dynamo at its bottom, internal
gravity waves at its top, and small-scale vorticity. Classical 1D static
radiation-escape modelling has been replaced by 3D time-dependent MHD
simulations that come closer to reality. The solar chromosphere, in
contrast, remains ill-understood although its pivotal role in coronal
mass and energy loading makes it a principal research area. Its fine
structure defines its overall structure, so that hard-to-observe
and hard-to-model small-scale dynamical processes are the key to
understanding. However, both chromospheric observation and chromospheric
simulation presently mature towards the required sophistication. The
open-field features seem of greater interest than the easier-to-see
closed-field features.
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Title: Ubiquitous Torsional Motions in Type II Spicules
Authors: De Pontieu, B.; Carlsson, M.; Rouppe van der Voort, L. H. M.;
Rutten, R. J.; Hansteen, V. H.; Watanabe, H.
2012ApJ...752L..12D Altcode: 2012arXiv1205.5006D
Spicules are long, thin, highly dynamic features that jut out
ubiquitously from the solar limb. They dominate the interface between
the chromosphere and corona and may provide significant mass and energy
to the corona. We use high-quality observations with the Swedish 1
m Solar Telescope to establish that so-called type II spicules are
characterized by the simultaneous action of three different types of
motion: (1) field-aligned flows of order 50-100 km s<SUP>-1</SUP>,
(2) swaying motions of order 15-20 km s<SUP>-1</SUP>, and (3) torsional
motions of order 25-30 km s<SUP>-1</SUP>. The first two modes have been
studied in detail before, but not the torsional motions. Our analysis
of many near-limb and off-limb spectra and narrowband images using
multiple spectral lines yields strong evidence that most, if not all,
type II spicules undergo large torsional modulation and that these
motions, like spicule swaying, represent Alfvénic waves propagating
outward at several hundred km s<SUP>-1</SUP>. The combined action
of the different motions explains the similar morphology of spicule
bushes in the outer red and blue wings of chromospheric lines, and
needs to be taken into account when interpreting Doppler motions to
derive estimates for field-aligned flows in spicules and determining
the Alfvénic wave energy in the solar atmosphere. Our results also
suggest that large torsional motion is an ingredient in the production
of type II spicules and that spicules play an important role in the
transport of helicity through the solar atmosphere.
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Title: Chromospheric backradiation in ultraviolet continua and Hα
Authors: Rutten, R. J.; Uitenbroek, H.
2012A&A...540A..86R Altcode: 2012arXiv1203.0396R
A recent paper states that ultraviolet backradiation from the solar
transition region and upper chromosphere strongly affects the degree of
ionization of minority stages at the top of the photosphere, i.e., in
the temperature minimum of the one-dimensional static model atmospheres
presented in that paper. We show that this claim is incompatible with
observations and we demonstrate that the pertinent ionization balances
are instead dominated by outward photospheric radiation, as in older
static models. We then analyze the formation of Hα in the above model
and show that it has significant backradiation across the opacity gap
by which Hα differs from other strong scatttering lines.
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Title: Graphical introduction to chromospheric line formation
Authors: Rutten, Rob
2012decs.confE.110R Altcode:
The basics of chromospheric line formation theory were laid out
in the 1960s and 1970s by e.g., Thomas, Avrett, Hummer, Jefferies,
Mihalas, Shine, Milkey. Since then there has been a long silence,
without much progress in understanding the chromosphere or its
diagnostics. At present, the situation changes thanks to better
ground-based observing, space-based monitoring, and increasingly
realistic numerical simulations. There is a now a strong need to revamp
classical one-dimensional static modeling as basis for chromospheric
line interpretation into 3D dynamic understanding of the major
diagnostics, including IRIS's Mg II h&k. In this introduction I
aim to explain the old wisdom in tutorial fashion, using cartoons and
graphs as means towards an intuitive grasp of fads and fallacies of
chromospheric line formation.
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Title: Ellerman Bombs at High Resolution. I. Morphological Evidence
for Photospheric Reconnection
Authors: Watanabe, Hiroko; Vissers, Gregal; Kitai, Reizaburo; Rouppe
van der Voort, Luc; Rutten, Robert J.
2011ApJ...736...71W Altcode: 2011arXiv1105.4008W
High-resolution imaging-spectroscopy movies of solar active region NOAA
10998 obtained with the Crisp Imaging Spectropolarimeter at the Swedish
1-m Solar Telescope show very bright, rapidly flickering, flame-like
features that appear intermittently in the wings of the Balmer Hα line
in a region with moat flows and likely some flux emergence. They show
up at regular Hα blue-wing bright points that outline the magnetic
network, but flare upward with much larger brightness and distinct "jet"
morphology seen from aside in the limbward view of these movies. We
classify these features as Ellerman bombs and present a morphological
study of their appearance at the unprecedented spatial, temporal, and
spectral resolution of these observations. The bombs appear along the
magnetic network with footpoint extents up to 900 km. They show apparent
travel away from the spot along the pre-existing network at speeds
of about 1 km s<SUP>-1</SUP>. The bombs flare repetitively with much
rapid variation at timescales of seconds only, in the form of upward
jet-shaped brightness features. These reach heights of 600-1200 km and
tend to show blueshifts; some show bi-directional Doppler signature
and some seem accompanied with an Hα surge. They are not seen in the
core of Hα due to shielding by overlying chromospheric fibrils. The
network where they originate has normal properties. The morphology of
these jets strongly supports deep-seated photospheric reconnection of
emergent or moat-driven magnetic flux with pre-existing strong vertical
network fields as the mechanism underlying the Ellerman bomb phenomenon.
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Title: Quiet-Sun imaging asymmetries in Na I D<SUB>1</SUB> compared
with other strong Fraunhofer lines
Authors: Rutten, R. J.; Leenaarts, J.; Rouppe van der Voort, L. H. M.;
de Wijn, A. G.; Carlsson, M.; Hansteen, V.
2011A&A...531A..17R Altcode: 2011arXiv1104.4307R
Imaging spectroscopy of the solar atmosphere using the Na I
D<SUB>1</SUB> line yields marked asymmetry between the blue and
red line wings: sampling a quiet-Sun area in the blue wing displays
reversed granulation, whereas sampling in the red wing displays normal
granulation. The Mg I b<SUB>2</SUB> line of comparable strength does
not show this asymmetry, nor does the stronger Ca II 8542 Å line. We
demonstrate the phenomenon with near-simultaneous spectral images in
Na I D<SUB>1</SUB>, Mg I b<SUB>2</SUB>, and Ca II 8542 Å from the
Swedish 1-m Solar Telescope. We then explain it with line-formation
insights from classical 1D modeling and with a 3D magnetohydrodynamical
simulation combined with NLTE spectral line synthesis that permits
detailed comparison with the observations in a common format. The
cause of the imaging asymmetry is the combination of correlations
between intensity and Dopplershift modulation in granular overshoot
and the sensitivity to these of the steep profile flanks of the Na
I D<SUB>1</SUB> line. The Mg I b<SUB>2</SUB> line has similar core
formation but much wider wings due to larger opacity buildup and
damping in the photosphere. Both lines obtain marked core asymmetry
from photospheric shocks in or near strong magnetic concentrations,
less from higher-up internetwork shocks that produce similar asymmetry
in the spatially averaged Ca II 8542 Å profile.
---------------------------------------------------------
Title: The quiet chromosphere. Old wisdom, new insights, future needs
Authors: Rutten, Robert J.
2010MmSAI..81..565R Altcode: 2010arXiv1002.1482R; 2010MmSAI..81....1R
The introduction to this review summarizes chromosphere observation
with two figures. The first part showcases the historical emphasis
on the eclipse chromosphere in the development of NLTE line formation
theory and criticizes 1D modeling. The second part advertises recent
breakthroughs after many decades of standstill. The third part discusses
what may or should come next.
---------------------------------------------------------
Title: Waves in the chromosphere: observations
Authors: Rutten, R. J.
2010arXiv1012.1196R Altcode:
I review the literature on observational aspects of waves in the solar
chromosphere in the first part of this contribution. High-frequency
waves are invoked to build elaborate cool-star chromosphere heating
theories but have not been detected decisively so far, neither
as magnetic modes in network elements nor as acoustic modes in
below-the-canopy internetwork regions. Three-minute upward-propagating
acoustic shocks are thoroughly established through numerical
simulation as the cause of intermittent bright internetwork grains,
but their pistoning and their role in the low-chromosphere energy
budget remain in debate. Three-minute wave interaction with magnetic
canopies is a newer interest, presently progressing through numerical
simulation. Three-minute umbral flashes and running penumbral waves seem
a similar acoustic-shock phenomenon awaiting numerical simulation. The
low-frequency network Doppler modulation remains enigmatic. In
the second part, I address low-frequency ultraviolet brightness
variations of the internetwork chromosphere in more detail. They
contribute about half of the internetwork brightness modulation and
presumably figure in cool-star basal flux. They appear to be a mixture
of inverse-contrast granular overshoot at small scales and gravity-wave
interference at mesogranular scales. I present TRACE evidence for the
latter interpretation, and speculate that the low-frequency brightness
minima map canopy heights.
---------------------------------------------------------
Title: The Irkutsk Barium filter for narrow-band wide-field
high-resolution solar images at the Dutch Open Telescope
Authors: Hammerschlag, Robert H.; Skomorovsky, Valery I.; Bettonvil,
Felix C. M.; Kushtal, Galina I.; Olshevsky, Vyacheslav L.; Rutten,
Robert J.; Jägers, Aswin P. L.; Sliepen, Guus; Snik, Frans
2010SPIE.7735E..85H Altcode: 2010SPIE.7735E.265H
A wide-field birefringent filter for the barium II line at 455.4nm is
developed in Irkutsk. The Barium line is excellent for Doppler-shift
measurements because of low thermal line-broadening and steep
flanks of the line profile. The filter width is 0.008nm and the
filter is tunable over 0.4nm through the whole line and far enough
in the neighboring regions. A fast tuning system with servomotor is
developed at the Dutch Open Telescope (DOT). Observations are done
in speckle mode with 10 images per second and Keller-VonDerLühe
reconstruction using synchronous images of a nearby bluecontinuum
channel at 450.5nm. Simultaneous observation of several line positions,
typically 3 or 5, are made with this combination of fast tuning and
speckle. All polarizers are birefringent prisms which largely reduced
the light loss compared to polarizing sheets. The advantage of this
filter over Fabry-Perot filters is its wide field due to a large
permitted entrance angle and no need of polishing extremely precise
surfaces. The BaII observations at the DOT occur simultaneously with
those of a fast-tunable birefringent H-alpha filter. This gives the
unique possibility of simultaneous speckle-reconstructed observations
of velocities in photosphere (BaII) and chromosphere (H-alpha).
---------------------------------------------------------
Title: Solar Spectroscopy and (Pseudo-)Diagnostics of the Solar
Chromosphere
Authors: Rutten, Robert J.
2010ASSP...17..163R Altcode: 2009arXiv0905.2623R; 2010rast.conf..163R; 2010rasp.book..163R
I first review trends in current solar spectrometry and then
concentrate on comparing various spectroscopic diagnostics of the
solar chromosphere. Some are actually not at all chromospheric but
just photospheric or clapotispheric and do not convey information on
chromospheric heating, even though this is often assumed. Balmer Hα
is the principal displayer of the closed-field chromosphere, but it
is unclear how chromospheric fibrils gain their large Hα opacity. The
open-field chromosphere seems to harbor most if not all coronal heating
and solar wind driving, but is hardly seen in optical diagnostics.
---------------------------------------------------------
Title: The Quiet Solar Atmosphere Observed and Simulated in Na
I D<SUB>1</SUB>
Authors: Leenaarts, J.; Rutten, R. J.; Reardon, K.; Carlsson, M.;
Hansteen, V.
2010ApJ...709.1362L Altcode: 2009arXiv0912.2206L
The Na I D<SUB>1</SUB> line in the solar spectrum is sometimes
attributed to the solar chromosphere. We study its formation in
quiet-Sun network and internetwork. We first present high-resolution
profile-resolved images taken in this line with the imaging
spectrometer Interferometric Bidimensional Spectrometer at the Dunn
Solar Telescope and compare these to simultaneous chromospheric images
taken in Ca II 8542 Å and Hα. We then model Na I D<SUB>1</SUB>
formation by performing three-dimensional (3D) non-local
thermodynamic equilibrium profile synthesis for a snapshot from a
3D radiation-magnetohydrodynamics simulation. We find that most Na I
D<SUB>1</SUB> brightness is not chromospheric but samples the magnetic
concentrations that make up the quiet-Sun network in the photosphere,
well below the height where they merge into chromospheric canopies,
with aureoles from 3D resonance scattering. The line core is sensitive
to magneto-acoustic shocks in and near magnetic concentrations, where
shocks occur deeper than elsewhere, and may provide evidence of heating
deep within magnetic concentrations.
---------------------------------------------------------
Title: Magnetic Coupling between the Interior and Atmosphere of
the Sun
Authors: Hasan, S. S.; Rutten, R. J.
2010ASSP...19.....H Altcode: 2010mcia.conf.....H
No abstract at ADS
---------------------------------------------------------
Title: Dual-Line Spectral Imaging of the Chromosphere
Authors: Cauzzi, G.; Reardon, K.; Rutten, R. J.; Tritschler, A.;
Uitenbroek, H.
2010ASSP...19..513C Altcode: 2010mcia.conf..513C
Hα filtergrams are notoriously difficult to interpret, "beautiful
to view but not fit for analysis." We try to remedy this by using
the IBIS bi-dimensional spectrometer at the Dunn Solar Telescope at
NSO/Sacramento Peak to compare the quiet-sun chromosphere observed in
Hα to what is observed simultaneously in Ca II 854.2 nm, sampling both
lines with high angular and spectral resolution and extended coverage
of space, time, and wavelength. Per (x, y, t) pixel we measured the
intensity and Dopplershift of the minimum of each line's profile at
that pixel, as well as the width of their inner chromospheric cores. A
paper submitted to A&A (December 2008) compares these measurements
in detail.
---------------------------------------------------------
Title: The solar chromosphere at high resolution with
IBIS. IV. Dual-line evidence of heating in chromospheric network
Authors: Cauzzi, G.; Reardon, K.; Rutten, R. J.; Tritschler, A.;
Uitenbroek, H.
2009A&A...503..577C Altcode: 2009arXiv0906.2083C
The structure and energy balance of the solar chromosphere remain
poorly known. We used the imaging spectrometer IBIS at the Dunn Solar
Telescope to obtain fast-cadence, multi-wavelength profile sampling
of Hα and Ca ii 854.2 nm over a sizable two-dimensional field of view
encompassing quiet-Sun network. We provide a first inventory of how the
quiet chromosphere appears in these two lines by comparing basic profile
measurements in the form of image displays, temporal-average displays,
time slices, and pixel-by-pixel correlations. We find that the two lines
can be markedly dissimilar in their rendering of the chromosphere,
but that, nevertheless, both show evidence of chromospheric heating,
particularly in and around network: Hα in its core width and Ca ii
854.2 nm in its brightness. We discuss venues for improved modeling.
---------------------------------------------------------
Title: Dynamic Lyα jets
Authors: Koza, J.; Rutten, R. J.; Vourlidas, A.
2009A&A...499..917K Altcode: 2008arXiv0807.4889K
Context: The solar chromosphere and transition region are highly
structured and complex regimes. A recent breakthrough has been
the identification of dynamic fibrils observed in Hα as caused
by field-aligned magnetoacoustic shocks. <BR />Aims: We seek to
find whether such dynamic fibrils are also observed in Lyα. <BR
/>Methods: We used a brief sequence of four high-resolution Lyα
images of the solar limb taken by the Very high Angular resolution
ULtraviolet Telescope (VAULT), which displays many extending and
retracting Lyα jets. We measured their top trajectories and fitted
parabolas to the 30 best-defined ones. <BR />Results: Most jet tops move
supersonically. Half of them decelerate, sometimes superballistically,
the others accelerate. This bifurcation may arise from incomplete
sampling of recurrent jets. <BR />Conclusions: The similarities between
dynamic Lyα jets and Hα fibrils suggest that the magnetoacoustic
shocks causing dynamic Hα fibrils also affect dynamic Lyα jets.
---------------------------------------------------------
Title: Explanation of the activity sensitivity of Mn I 5394.7 Å
Authors: Vitas, N.; Viticchiè, B.; Rutten, R. J.; Vögler, A.
2009A&A...499..301V Altcode: 2008arXiv0811.3555V
There is a long-standing debate why the Mn i 5394.7 Å line in the
solar irradiance spectrum brightens more at higher activity than
other photospheric lines. The claim that this is caused by spectral
interlocking to chromospheric emission in the Mg ii h & k lines
is disputed. In this paper we settle this issue, using classical
one-dimensional modeling for demonstration and modern three-dimensional
MHD simulation for verification and analysis. The unusual sensitivity
of the Mn i 5394.7 Å line to solar activity is due to its excessive
hyperfine structure. This overrides the thermal and granular Doppler
smearing through which the other, narrower, photospheric lines lose
such sensitivity. We take the nearby Fe i 5395.2 Å line as example
of the latter, and analyze the formation of both lines in detail to
demonstrate and explain the granular Doppler brightening which affects
all narrow photospheric lines. Neither the chromosphere nor Mg ii h
& k emission play a role, nor is it correct to describe the activity
sensitivity of Mn i 5394.7 Å in terms of plage models with outward
increasing temperature contrast. The Mn i 5394.7 Å line represents a
proxy diagnostic of strong-field magnetic concentrations in the deep
solar photosphere comparable to the G band and the blue wing of Hα,
but not a better one than these. The Mn i lines are more promising as
diagnostics of weak fields in high-resolution Stokes polarimetry.
---------------------------------------------------------
Title: Hα as a Chromospheric Diagnostic
Authors: Rutten, R. J.
2008ASPC..397...54R Altcode:
I first illustrate with images from the Dutch Open Telescope (DOT)
that Hα is the principal diagnostic of the solar chromosphere. The
DOT movies at http://dot.astro.uu.nl demonstrate this fact even more
vividly. <P />I then summarize, on the basis of the recent numerical
simulations by <P />Leenaarts et al. (2007), <P />why Halpha; is
such an omnipresent diagnostic of the chromosphere. The ubiquity of
Hα fibrils in both hot and cool gas is due to (i)- the presence of
shocks everywhere, guided by the magnetic field into dynamic fibrils
near the network and pushing the canopy and transition region upward
in weaker-field internetwork regions, (ii)- the large rate difference
between the fast hydrogen ionization/recombination balancing in hot
shocks and the slow balancing in cool post-shock gas, and (iii)- the
large excitation energy of Hα's nis2 lower level, causing strong
coupling to the ion population. These three facts combine to cause
appreciable Hα opacity throughout the chromosphere, enormously in
excess of instantaneous Saha-Boltzmann partitioning in cool post-shock
gas. Thus, sluggish post-shock recombination causes Hα to be visible
everywhere. <P />Finally, I address Hα observing. Since Hinode's
Hα imaging is affected by bubbles and limited in cadence, the DOT
may serve as a complementary facility furnishing profile-sampling Hα
image sequences at the same 0.3 arcsec angular resolution as Hinode
whenever the La Palma seeing is good. However, imminent loss of DOT
funding requires outside financing of an on-site observer for DOT
utilization in co-pointed joint observing.
---------------------------------------------------------
Title: DOT Tomography of the Solar Atmosphere VII. Chromospheric
Response to Acoustic Events
Authors: Rutten, R. J.; van Veelen, B.; Sütterlin, P.
2008SoPh..251..533R Altcode: 2008arXiv0801.0374R; 2008SoPh..tmp...28R
We use synchronous movies from the Dutch Open Telescope sampling the G
band, Ca II H, and Hα with five-wavelength profile sampling to study
the response of the chromosphere to acoustic events in the underlying
photosphere. We first compare the visibility of the chromosphere in
Ca II H and Hα, demonstrate that studying the chromosphere requires
Hα data, and summarize recent developments in understanding why this
is so. We construct divergence and vorticity maps of the photospheric
flow field from the G-band images and locate specific events through
the appearance of bright Ca II H grains. The reaction of the Hα
chromosphere is diagnosed in terms of brightness and Doppler shift. We
show and discuss three particular cases in detail: a regular acoustic
grain marking shock excitation by granular dynamics, a persistent
flasher, which probably marks magnetic-field concentration, and an
exploding granule. All three appear to buffet overlying fibrils, most
clearly in Dopplergrams. Although our diagnostic displays to dissect
these phenomena are unprecedentedly comprehensive, adding even more
information (photospheric Doppler tomography and magnetograms along
with chromospheric imaging and Doppler mapping in the ultraviolet)
is warranted.
---------------------------------------------------------
Title: Dynamic Fibrils in Ly-alpha
Authors: Koza, J.; Rutten, R. J.; Vourlidas, A.; Suetterlin, P.
2008ESPM...12.2.16K Altcode:
We have detected dynamic fibrils (DFs) in Ly-alpha filtergrams taken
with the rocket-borne Very high Angular resolution ULtraviolet Telescope
(VAULT). Although the data consist of only a 1-min sequence of 4
images taken near the solar limb during the second VAULT flight, they
enable us to identify and study the time evolution of over 50 DFs. Most
show parabolic trajectories in their angular extent, with supersonic
maximum velocities. The measured decelerations vary from sub-ballistic
to super-ballistic. The similarities with DFs seen in Halpha suggest a
common cause, possibly the presence of hot transition-region interfaces
around cool oscillation-fed jets.
---------------------------------------------------------
Title: Concluding remarks
Authors: Rutten, R. J.
2008ESPM...12..7.1R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On the solar abundance of indium
Authors: Vitas, N.; Vince, I.; Lugaro, M.; Andriyenko, O.; Gošić,
M.; Rutten, R. J.
2008MNRAS.384..370V Altcode: 2008MNRAS.tmp...25V; 2007arXiv0711.2166V
The generally adopted value for the solar abundance of indium is over
six times higher than the meteoritic value. We address this discrepancy
through numerical synthesis of the 451.13-nm line on which all indium
abundance studies are based, both for the quiet Sun and the sunspot
umbra spectrum, employing standard atmosphere models and accounting
for hyperfine structure and Zeeman splitting in detail. The results,
as well as a re-appraisal of indium nucleosynthesis, suggest that
the solar indium abundance is close to the meteoritic value, and
that some unidentified ion line causes the 451.13-nm feature in the
quiet-Sun spectrum.
---------------------------------------------------------
Title: Search for photospheric footpoints of quiet Sun transition
region loops
Authors: Sánchez Almeida, J.; Teriaca, L.; Sütterlin, P.; Spadaro,
D.; Schühle, U.; Rutten, R. J.
2007A&A...475.1101S Altcode: 2007arXiv0709.3451S
Context: The footpoints of quiet Sun Transition Region (TR) loops
do not seem to coincide with the photospheric magnetic structures
appearing in traditional low-sensitivity magnetograms. <BR />Aims: We
look for the so-far unidentified photospheric footpoints of TR loops
using G-band bright points (BPs) as proxies for photospheric magnetic
field concentrations. <BR />Methods: We compare TR measurements with
SoHO/SUMER and photospheric magnetic field observations obtained with
the Dutch Open Telescope. <BR />Results: Photospheric BPs are associated
with bright TR structures, but they seem to avoid the brightest parts
of the structure. BPs appear in regions that are globally redshifted,
but they avoid extreme velocities. TR explosive events are not clearly
associated with BPs. <BR />Conclusions: The observations are not
inconsistent with the BPs being footpoints of TR loops, although we
have not succeeded to uniquely identify particular BPs with specific
TR loops.
---------------------------------------------------------
Title: Non-equilibrium hydrogen ionization in 2D simulations of the
solar atmosphere
Authors: Leenaarts, J.; Carlsson, M.; Hansteen, V.; Rutten, R. J.
2007A&A...473..625L Altcode: 2007arXiv0709.3751L
Context: The ionization of hydrogen in the solar chromosphere and
transition region does not obey LTE or instantaneous statistical
equilibrium because the timescale is long compared with important
hydrodynamical timescales, especially of magneto-acoustic shocks. Since
the pressure, temperature, and electron density depend sensitively on
hydrogen ionization, numerical simulation of the solar atmosphere
requires non-equilibrium treatment of all pertinent hydrogen
transitions. The same holds for any diagnostic application employing
hydrogen lines. <BR />Aims: To demonstrate the importance and to
quantify the effects of non-equilibrium hydrogen ionization, both
on the dynamical structure of the solar atmosphere and on hydrogen
line formation, in particular Hα. <BR />Methods: We implement an
algorithm to compute non-equilibrium hydrogen ionization and its
coupling into the MHD equations within an existing radiation MHD code,
and perform a two-dimensional simulation of the solar atmosphere from
the convection zone to the corona. <BR />Results: Analysis of the
simulation results and comparison to a companion simulation assuming
LTE shows that: a) non-equilibrium computation delivers much smaller
variations of the chromospheric hydrogen ionization than for LTE. The
ionization is smaller within shocks but subsequently remains high in
the cool intershock phases. As a result, the chromospheric temperature
variations are much larger than for LTE because in non-equilibrium,
hydrogen ionization is a less effective internal energy buffer. The
actual shock temperatures are therefore higher and the intershock
temperatures lower. b) The chromospheric populations of the hydrogen
n = 2 level, which governs the opacity of Hα, are coupled to the
ion populations. They are set by the high temperature in shocks
and subsequently remain high in the cool intershock phases. c)
The temperature structure and the hydrogen level populations differ
much between the chromosphere above photospheric magnetic elements
and above quiet internetwork. d) The hydrogen n = 2 population and
column density are persistently high in dynamic fibrils, suggesting
that these obtain their visibility from being optically thick in Hα
also at low temperature. <P />Movie and Appendix A are only available
in electronic form at http://www.aanda.org
---------------------------------------------------------
Title: Chromospheric and Transition-Region Dynamics in Plage
Authors: de Wijn, A. G.; de Pontieu, B.; Rutten, R. J.
2007ASPC..368..137D Altcode:
We study the dynamical interaction of the solar chromosphere with
the transition region in mossy and non-mossy active-region plage. We
carefully align image sequences taken with the Transition Region And
Coronal Explorer (TRACE) in the ultraviolet passbands around 1550, 1600,
and 1700 Å and the extreme ultraviolet passbands at 171 and 195 Å. We
compute Fourier phase-difference spectra that are spatially averaged
separately over mossy and non-mossy plage to study temporal modulations
as a function of temporal frequency. The 1550 versus 171 Å comparison
shows zero phase difference in non-mossy plage. In mossy plage, the
phase differences between all UV and EUV passbands show pronounced
upward trends with increasing frequency, which abruptly changes
into zero phase difference beyond 4 -- 6 mHz. The phase difference
between the 171 and 195 Å sequences exhibits a shallow dip below 3
mHz and then also turns to zero phase difference beyond this value. We
attribute the various similarities between the UV and EUV diagnostics
that are evident in the phase-difference diagrams to the contribution
of the C IV resonance lines in the 1550 and 1600 Å passbands. The
strong upward trend at the lower frequencies indicates the presence of
upward-traveling disturbances. It points to correspondence between the
lower chromosphere and the upper transition region, perhaps by slow-mode
magnetosonic disturbances, or by a connection between chromospheric and
coronal heating mechanisms. The transition from this upward trend to
zero phase difference at higher frequencies is due to the intermittent
obscuration by fibrils that occult the foot points of hot loops,
which are bright in the EUV and C IV lines, in oscillatory manner.
---------------------------------------------------------
Title: ESMN in Memoriam (1998 -- 2006)
Authors: Rutten, R. J.
2007ASPC..368...21R Altcode:
The EC-FP5 European Solar Magnetism Network (ESMN) was terminated during
this conference. Together with its FP4 predecessor, the European Solar
Magnetometry Network (ESMN), it funded 22 postdoc and 9 graduate-student
appointments at nine solar physics groups in Western Europe, it enhanced
Europe-wide collaboration in solar physics, and it contributed to the
integration of East-European groups in West-European enterprises. Its
unfortunate demise results from lack of further fortune in the FP6
lottery. The FP6-funded Utrecht-Stockholm-Oslo graduate school in
solar physics represents offspring, the FP6 Solaire network is a
partial replacement, and the EAST undertaking and pledge to build an
EST is a most worthy FP7 stake. The EC's policy shifts from postdoc
to predoc funding and from requiring (too) small to requiring (too)
large consortia are criticized.
---------------------------------------------------------
Title: Aperture Increase Options for the Dutch Open Telescope
Authors: Hammerschlag, R. H.; Bettonvil, F. C. M.; Jägers, A. P. L.;
Rutten, R. J.
2007ASPC..368..573H Altcode: 2007astro.ph..3638H
This paper is an invitation to the international community to
participate in the usage and a substantial upgrade of the Dutch Open
Telescope on La Palma (DOT, http://dot.astro.uu.nl). <P />We first
give a brief overview of the approach, design, and current science
capabilities of the DOT. It became a successful 0.2-arcsec-resolution
solar movie producer through its combination of (i) an excellent
site, (ii) effective wind flushing through the fully open design and
construction of both the 45-cm telescope and the 15-m support tower,
(iii) special designs which produce extraordinary pointing stability of
the tower, equatorial mount, and telescope, (iv) simple and excellent
optics with minimum wavefront distortion, and (v) large-volume
speckle reconstruction including narrow-band processing. The DOT's
multi-camera multi-wavelength speckle imaging system samples the
solar photosphere and chromosphere simultaneously in various optical
continua, the G band, Ca II H (tunable throughout the blue wing),
and Hα (tunable throughout the line). The resulting DOT data sets
are all public. The DOT database (http://dotdb.phys.uu.nl/DOT)
now contains many tomographic image sequences with 0.2-0.3 arcsec
resolution and up to multi-hour duration. You are welcome to pull them
over for analysis. <P />The main part of this contribution outlines
DOT upgrade designs implementing larger aperture. The motivation
for aperture increase is the recognition that optical solar physics
needs the substantially larger telescope apertures that became useful
with the advent of adaptive optics and viable through the DOT's open
principle, both for photospheric polarimetry at high resolution and
high sensitivity and for chromospheric fine-structure diagnosis at
high cadence and full spectral sampling. <P />Our upgrade designs for
the DOT are presented in an incremental sequence of five options of
which the simplest (Option I) achieves 1.4 m aperture using the present
tower, mount, fold-away canopy, and multi-wavelength speckle imaging
and processing systems. The most advanced (Option V) offers unblocked
2.5 m aperture in an off-axis design with a large canopy, a wide 30-m
high support tower, and image transfer to a groundbased optics lab for
advanced instrumentation. All five designs employ adaptive optics. The
important advantages of fully open, wind-transparent and wind-flushed
structure, polarimetric constancy, and absence of primary-image rotation
remain. All designs are relatively cheap through re-using as much of
the existing DOT hardware as possible. <P />Realization of an upgrade
requires external partnership(s). This report about DOT upgrade options
therefore serves also as initial documentation for potential partners.
---------------------------------------------------------
Title: Observing the Solar Chromosphere
Authors: Rutten, R. J.
2007ASPC..368...27R Altcode: 2007astro.ph..3637R
This review is split into two parts: one on chromospheric line formation
in answer to the frequent question “where is my line formed”,
and one presenting state-of-the-art imagery of the chromosphere. In
the first part I specifically treat the formation of the Na D lines,
Ca II H&K, and Hα. In the second I show DOT, IBIS, VAULT, and
TRACE images as evidence that the chromosphere consists of fibrils of
intrinsically different types. The straight-up ones are hottest. The
slanted ones are filled by shocks and likely possess thin transition
sheaths to coronal plasma. The ones hovering horizontally over
“clapotispheric” cell interiors outline magnetic canopies and are
buffeted by shocks, most violently in the quietest regions. <P />In
the absence of integral-field ultraviolet spectrometry, Hα remains
the principal chromosphere diagnostic. The required fast-cadence
profile-sampling imaging is an important quest for new telescope
technology.
---------------------------------------------------------
Title: The Physics of Chromospheric Plasmas
Authors: Heinzel, P.; Dorotovič, I.; Rutten, R. J.
2007ASPC..368.....H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Fourier Analysis of Active-Region Plage
Authors: de Wijn, A. G.; De Pontieu, B.; Rutten, R. J.
2007ApJ...654.1128D Altcode: 2007arXiv0706.2014D
We study the dynamical interaction of the solar chromosphere with
the transition region in mossy and nonmossy active-region plage. We
carefully align image sequences taken with the Transition Region And
Coronal Explorer (TRACE) in the ultraviolet passbands around 1550,
1600, and 1700 Å and the extreme ultraviolet passbands at 171 and 195
Å. We compute Fourier phase-difference spectra that are spatially
averaged separately over mossy and nonmossy plage to study temporal
modulations as a function of temporal frequency. The 1550 versus 171
Å comparison shows zero phase difference in nonmossy plage. In mossy
plage, the phase differences between all UV and EUV passbands show
pronounced upward trends with increasing frequency, which abruptly
changes into zero phase difference beyond 4-6 mHz. The phase difference
between the 171 and 195 Å sequences exhibits a shallow dip below 3
mHz and then also turns to zero phase difference beyond this value. We
attribute the various similarities between the UV and EUV diagnostics
that are evident in the phase-difference diagrams to the contribution
of the C IV resonance lines in the 1550 and 1600 Å passbands. The
strong upward trend at the lower frequencies indicates the presence of
upward-traveling disturbances. It points to correspondence between the
lower chromosphere and the upper transition region, perhaps by slow-mode
magnetosonic disturbances, or by a connection between chromospheric and
coronal heating mechanisms. The transition from this upward trend to
zero phase difference at higher frequencies is due to the intermittent
obscuration by fibrils that occult the footpoints of hot loops, which
are bright in the EUV and C IV lines, in an oscillatory manner.
---------------------------------------------------------
Title: The Ba II 4554 / Hβ Imaging Polarimeter for the Dutch Open
Telescope
Authors: Snik, F.; Bettonvil, F. C. M.; Jägers, A. P. L.;
Hammerschlag, R. H.; Rutten, R. J.; Keller, C. U.
2006ASPC..358..205S Altcode:
In order to expand the high-resolution, multi-wavelength imaging
capabilities of the Dutch Open Telescope (DOT), an additional
polarimetric channel based on a 80 mÅ tunable Lyot filter for Ba
II 4554 and Hβ has been designed and constructed. The large atomic
mass and the resulting steep line wings, make Ba II 4554 particularly
suitable for the creation of photospheric Dopplergrams and Stokes-V
magnetograms. The line also yields a significant degree of linear
(scattering) polarization for observations near the limb of the Sun,
which is modified by both horizontal and vertical weak-field topologies
through the Hanle effect and hyperfine-structure level crossing. The
polarimeter is based on liquid crystal variable retarders (LCVRs)
as polarization modulators in combination with the Lyot filter's
entrance polarizer. The tunability of the LCVRs is exploited to enable
specific wavelength calibration, selection of the reference frame of
linear polarization, and optimization of instrumental polarization
cross-talk, which for the DOT is constant in time. With the future
Ba II 4554 photospheric magnetograms, we expect to be able to discern
magnetic structures of about 150 km with field strengths down to 100 G,
and that Hanle-type observations can be performed at a resolution of
about 1 arcsec. The range of applicability of Hβ imaging polarimetry
has to be explored after installation.
---------------------------------------------------------
Title: Magnetic Patches in Internetwork Areas
Authors: de Wijn, A. G.; Rutten, R. J.; Haverkamp, E. M. W. P.;
Sütterlin, P.
2006ASPC..354...20D Altcode:
We present a study of internetwork magnetic elements that appear as
bright points in G-band (photosphere) and Ca II H (low chromosphere)
image sequences from the Dutch Open Telescope. Many bright points
appear intermittently in groups of long-lived structures that we call
“magnetic patches”. We develop an algorithm for the identification
of bright points and magnetic patches. The average internetwork bright
point lifetimes is measured to be 3.5 minutes in the G band, and 4.3
minutes in the Ca II H. We find an internetwork bright point number
density of 0.02 Mm^{-2} in the G-band sequence and 0.05 Mm^{-2} in
the Ca II H sequence. The bright points show a bimodal distribution
of the frame-to-frame horizontal velocities, with a peak at 0 km
s^{-1} and a wide hump centered around 1.2 km s^{-1}. The patches
last much longer than granular time scales (about nine hours) and
outline cell-like structures on mesogranular scale. We conclude that
transient internetwork bright points trace the locations of strong
magnetic fields that exist before the bright point appears and remain
after it disappears.
---------------------------------------------------------
Title: Fourier analysis of chromospheric and transition region
emission above active region plage
Authors: de Wijn, A. G.; de Pontieu, B.; Rutten, R. J.
2006AGUFMSH23B0364D Altcode:
We study the dynamical interaction of the solar chromosphere with the
transition region (TR) in mossy and non-mossy active region plage, and
find evidence for correlated brightness changes or upward travelling
disturbances between the low chromosphere and the upper transition
region. We carefully align image sequences taken with the Transition
Region and Coronal Explorer (TRACE) in the ultraviolet passbands around
1550, 1600 and 1700 Å\ (indicative of low chromosphere and low TR)
and the extreme ultraviolet passbands at 171 and 195 Å\ (indicative of
upper transition region). We compute Fourier phase-difference spectra
that are spatially averaged separately over mossy and non-mossy plage to
study temporal modulations as a function of temporal frequency. We find
that in non-mossy plage there is zero phase difference between 1550 Å\
and 171 Å. In mossy plage, the phase differences between all UV and EUV
passbands show pronounced upward trends with increasing frequency, which
abruptly changes into zero phase differences for frequencies beyond 4-6
mHz. The phase difference between the 171 and 195 Å\ sequences exhibits
a shallow dip below 3 mHz and then also turns to zero phase difference
beyond this value. We attribute some of the various similarities between
the UV and EUV diagnostics that are evident in the phase-difference
diagrams to the contribution of the C IV resonance lines in the 1550 and
1600 Å\ passbands. The strong upward trend at lower frequencies in the
phase difference between all UV passbands (including 1700 Å) and 171
Å\ indicates the presence of upward travelling disturbances. Since
1700 Å\ does not contain C IV emission (low TR), this points to a
correlation between brightness changes in the lower chromosphere and
the upper TR, perhaps by slow-mode disturbances, or by a connection
between chromospheric and coronal heating mechanisms. We find that
such correlated brightness changes first occur in the low chromosphere,
and are followed about 400 s later in the upper TR. The transition from
the upward trend in phase difference at low frequencies to zero phase
difference at higher frequencies is due to the intermittent obscuration
by fibrils. These chromospheric jets occult the footpoints of hot loops,
which are bright in the EUV and C IV lines, in oscillatory manner.
---------------------------------------------------------
Title: On the Nature of the Solar Chromosphere
Authors: Rutten, R. J.
2006ASPC..354..276R Altcode: 2007astro.ph..1379R
DOT high-resolution imagery suggests that only internetwork-spanning
Hα “mottles” constitute the quiet-Sun chromosphere, whereas more
upright network “straws” in “hedge rows” reflect transition-region
conditions.
---------------------------------------------------------
Title: Tunable H-alpha Lyot filter with advanced servo system and
image processing: instrument design and new scientific results with
the Dutch Open Telescope
Authors: Bettonvil, Felix C. M.; Hammerschlag, Robert H.; Sütterlin,
Peter; Rutten, Robert J.; Jägers, Aswin P. L.; Sliepen, Guus
2006SPIE.6269E..0EB Altcode: 2006SPIE.6269E..12B
The Dutch Open Telescope (DOT; http://dot.astro.uu.nl) on La Palma
is a revolutionary open solar telescope, on an excellent site, on
top of a transparent tower of steel framework, and uses natural
air flow to minimize local seeing. The DOT is a high-resolution
multi-wavelength imager capable of long-duration time series aiming
at magnetic fine structure, topology and dynamics in the photosphere
and low- and high chromosphere. In this paper we describe the latest
addition to the multi-wavelength imaging system: a Lyot H-alpha
camera channel operating at a wavelength of 656.3 nm, being of major
interest for high-chromospheric phenomena. The channel is operated
strictly synchronous with the other channels and all data are speckle
reconstructed. The channel permits profile sampling and delivers
Dopplergrams in a 15 second time cadence, up to several hours long
and adding up to a total data amount of 1.6 Terabyte/day. A dedicated
computer (DSP, DOT Speckle Processor) has been built for processing
the data overnight.
---------------------------------------------------------
Title: A comparison of solar proxy-magnetometry diagnostics
Authors: Leenaarts, J.; Rutten, R. J.; Carlsson, M.; Uitenbroek, H.
2006A&A...452L..15L Altcode:
Aims.We test various proxy-magnetometry diagnostics, i.e., brightness
signatures of small-scale magnetic elements, for studying magnetic
field structures in the solar photosphere.<BR /> Methods: .Images are
numerically synthesized from a 3D solar magneto-convection simulation
for, respectively, the G band at 430.5 nm, the CN band at 388.3 nm,
and the blue wings of the H α, H β, Ca ii H, and Ca ii 854.2 nm
lines.<BR /> Results: .Both visual comparison and scatter diagrams of
the computed intensity versus the magnetic field strength show that,
in particular for somewhat spatially extended magnetic elements, the
blue H α wing presents the best proxy-magnetometry diagnostic, followed
by the blue wing of H β. The latter yields higher diffraction-limit
resolution.<BR /> Conclusions: .We recommend using the blue H α wing
to locate and track small-scale photospheric magnetic elements through
their brightness appearance.
---------------------------------------------------------
Title: DOT tomography of the solar atmosphere. VI. Magnetic elements
as bright points in the blue wing of Hα
Authors: Leenaarts, J.; Rutten, R. J.; Sütterlin, P.; Carlsson, M.;
Uitenbroek, H.
2006A&A...449.1209L Altcode:
High-resolution solar images taken in the blue wing of the Balmer H
α line with the Dutch Open Telescope show intergranular magnetic
elements as strikingly bright features, similar to, but with
appreciably larger contrast over the surrounding granulation than
their more familiar manifestation as G-band bright points. Part of
this prominent appearance is due to low granular contrast, without
granule/lane brightness reversal as, e.g., in the wings of Ca II H
& K. We use 1D and 2D radiative transfer modeling and 3D solar
convection and magnetoconvection simulations to reproduce and explain
the H α wing images. We find that the blue H α wing obeys near-LTE
line formation. It appears particularly bright in magnetic elements
through low temperature gradients. The granulation observed in the blue
wing of H α has low contrast because of the lack of H α opacity in the
upper photosphere, Doppler cancellation, and large opacity sensitivity
to temperature working against source function sensitivity. We conclude
that the blue H α wing represents a promising proxy magnetometer to
locate and track isolated intermittent magnetic elements, a better one
than the G band and the wings of Ca II H & K although less sharp
at given aperture.
---------------------------------------------------------
Title: Small Scale Magnetic Elements as Bright Points in the Blue
Hα Wing
Authors: Leenaarts, J.; Sütterlin, P.; Rutten, R. J.; Carlsson, M.;
Uitenbroek, H.
2005ESASP.596E..15L Altcode: 2005ccmf.confE..15L
No abstract at ADS
---------------------------------------------------------
Title: DOT tomography of the solar atmosphere. IV. Magnetic patches
in internetwork areas
Authors: de Wijn, A. G.; Rutten, R. J.; Haverkamp, E. M. W. P.;
Sütterlin, P.
2005A&A...441.1183D Altcode: 2007arXiv0706.2008D
We use G-band and Ca ii H image sequences from the Dutch Open
Telescope (DOT) to study magnetic elements that appear as bright
points in internetwork parts of the quiet solar photosphere and
chromosphere. We find that many of these bright points appear
recurrently with varying intensity and horizontal motion within
longer-lived magnetic patches. We develop an algorithm for detection
of the patches and find that all patches identified last much longer
than the granulation. The patches outline cell patterns on mesogranular
scales, indicating that magnetic flux tubes are advected by granular
flows to mesogranular boundaries. Statistical analysis of the emergence
and disappearance of the patches points to an average patch lifetime
as long as 530±50~min (about nine hours), which suggests that the
magnetic elements constituting strong internetwork fields are not
generated by a local turbulent dynamo.
---------------------------------------------------------
Title: The wings of Ca II H and K as solar fluxtube diagnostics
Authors: Sheminova, V. A.; Rutten, R. J.; Rouppe van der Voort,
L. H. M.
2005A&A...437.1069S Altcode:
We combine high-resolution Ca II H and K spectrograms from the
Swedish Vacuum Solar Telescope with standard fluxtube modeling to
derive photospheric temperature and velocity stratifications within
individual magnetic elements in plage near a sunspot. We find that 1D
on-axis modeling gives better consistency than spatial averaging over
flaring-fluxtube geometry. Our best-fit temperature stratifications
suggest that magnetic elements are close to radiative equilibrium
throughout their photospheres. Their brightness excess throughout the
H and K wings compared with the quiet photosphere is primarily due to
low density, not to mechanical heating. We conclude that the extended
H and K wings provide excellent fine-structure diagnostics for both
high-resolution observations and simulations of the solar photosphere.
---------------------------------------------------------
Title: The temperature gradient in and around solar magnetic fluxtubes
Authors: Sheminova, V. A.; Rutten, R. J.; Rouppe van der Voort,
L. H. M.
2005KFNTS...5..110S Altcode:
We use spectra covering the outer part of the extended wing of the solar
Ca II K line observed at high angular resolution with the Swedish Vacuum
Solar Telescope to test standard solar fluxtube models. The wings of the
Ca II resonance lines are formed in LTE both with regard to excitation
(source function) and to ionization (opacity) and, therefore, sample
temperature stratifications in relatively straightforward fashion. We
obtain best fits by combining steeper temperature gradients than
those in the standard models for both the tube inside and the tube
environment. Similarly steep gradients are also determined from a
numerical magnetoconvection simulation by the late A. S. Gadun. It
is found that the energy balance in the individual magnetic elements
appears to be close to radiative equilibrium throughout the photosphere.
---------------------------------------------------------
Title: MAO-SIU solar physics collaborations
Authors: Rutten, R. J.
2005KFNTS...5...11R Altcode:
The Kyiv-Utrecht collaboration in solar physics has a long history
and a bright future. In this report I highlight some of our joint
analyses in the past, discuss the general solar physics context as
I see it at present, and describe exciting research challenges which
fit the Kyiv-Utrecht expertise and interests.
---------------------------------------------------------
Title: Dynamics of the solar chromosphere. V. High-frequency
modulation in ultraviolet image sequences from TRACE
Authors: de Wijn, A. G.; Rutten, R. J.; Tarbell, T. D.
2005A&A...430.1119D Altcode: 2007arXiv0706.1987D
We search for signatures of high-frequency oscillations in the upper
solar photosphere and low chromosphere in the context of acoustic
heating of outer stellar atmospheres. We use ultraviolet image
sequences of a quiet center-disk area from the Transition Region
and Coronal Explorer (TRACE) mission which were taken with strict
cadence regularity. The latter permits more reliable high-frequency
diagnosis than in earlier work. Spatial Fourier power maps, spatially
averaged coherence and phase-difference spectra, and spatio-temporal
(k<SUB>h</SUB>,f) decompositions all contain high-frequency features
that at first sight seem of considerable intrinsic interest but actually
are more likely to represent artifacts of different nature. Spatially
averaged phase difference measurement provides the most sensitive
diagnostic and indicates the presence of acoustic modulation up to
f≈20 mHz (periods down to 50 s) in internetwork areas.
---------------------------------------------------------
Title: DOT++: the Dutch Open Telescope with 1.4-m aperture
Authors: Bettonvil, Felix C.; Hammerschlag, Robert H.; Sütterlin,
Peter; Rutten, Robert J.; Jägers, Aswin P.; Snik, Frans
2004SPIE.5489..362B Altcode:
The Dutch Open Telescope (DOT; http://dot.astro.uu.nl) on La Palma is
a revolutionary open solar telescope, on an excellent site, on top
of a transparent steel tower, and uses natural air flow to minimize
local seeing. The aim is long-duration high-resolution imaging with
a multi-wavelength camera system. In order to achieve this, the DOT
is equipped with a diffraction limited imaging system and uses the
speckle reconstruction technique for removing the remaining atmospheric
turbulence. The DOT optical system is simple and consists currently of
a 0.45m/F4.44 parabolic mirror and a 10x enlargement lens system. We
present our plans to increase the aperture of the DOT from 0.45m to
1.4m. The mirror support and telescope top shall be redesigned, but
telescope, tower, multi-wavelength camera system and speckle system
remain intact. The new optical design permits user selectable choice
between angular resolution and field size, as well as transversal pupil
shift introducing the possibility to use obstruction free apertures up
to 65cm. The design will include a low order AO system, which improves
the speckle S/N substantially during moderate seeing conditions.
---------------------------------------------------------
Title: DOT tomography of the solar atmosphere. II. Reversed
granulation in Ca II H
Authors: Rutten, R. J.; de Wijn, A. G.; Sütterlin, P.
2004A&A...416..333R Altcode:
High-quality simultaneous image sequences from the Dutch Open Telescope
(DOT) in the G band and the Ca II H line are used to quantify the
occurrence of reversed granulation as a constituent of the subsonic
brightness pattern observed as a background to acoustic oscillations
in the quiet-Sun internetwork atmosphere. In the middle photosphere
reversed granulation constitutes a much larger part of this background
than at the larger heights sampled by ultraviolet radiation. The
anticorrelation with the underlying granulation reaches about 50% at a
temporal delay of 2-3 min, and increases with spatial image smoothing to
mesogranular resolution. We discuss the nature of reversed granulation
in terms of convection reversal, gravity waves, acoustic waves, and
intergranular magnetism, suggest that the internetwork background
pattern is primarily a mixture of the first two ingredients, and
speculate that it is also an inverse canopy mapper.
---------------------------------------------------------
Title: The Dutch Open Telescope on La Palma
Authors: Rutten, R. J.; Bettonvil, F. C. M.; Hammerschlag, R. H.;
Jägers, A. P. L.; Leenaarts, J.; Snik, F.; Sütterlin, P.; Tziotziou,
K.; de Wijn, A. G.
2004IAUS..223..597R Altcode: 2005IAUS..223..597R
The Dutch Open Telescope (DOT) on La Palma is an innovative solar
telescope combining open telescope structure and an open support tower
with a multi-wavelength imaging assembly and with synchronous speckle
cameras to generate high-resolution movies which sample different
layers of the solar atmosphere simultaneously and co-spatially at high
resolution over long durations. The DOT test and development phase is
nearly concluded. The installation of an advanced speckle processor
enables full science utilization including "Open-DOT" time allocation
to the international community. Co-pointing with spectropolarimeters
at other Canary Island telescopes and with TRACE furnishes valuable
Solar-B precursor capabilities.
---------------------------------------------------------
Title: DOT tomography of the solar atmosphere. I. Telescope summary
and program definition
Authors: Rutten, R. J.; Hammerschlag, R. H.; Bettonvil, F. C. M.;
Sütterlin, P.; de Wijn, A. G.
2004A&A...413.1183R Altcode:
The Dutch Open Telescope (DOT) on La Palma is an innovative optical
solar telescope capable of reaching 0.2 arcsec angular resolution
over extended durations. The DOT presently progresses from technology
testbed to a stable science configuration providing multi-wavelength
imaging and multi-camera speckle data acquisition for tomographic
mapping of the solar atmosphere. Large-volume speckle processing will
soon enable frequent usage and community-wide time allocation, in
particular for tandem operation with other solar telescopes pursuing
spectropolarimetry and EUV imaging. We summarize the DOT hardware and
software in the context of this increasing availability and outline
the corresponding “open-DOT” program.
---------------------------------------------------------
Title: Dynamics of the solar chromosphere IV. Evidence for atmospheric
gravity waves from TRACE
Authors: Rutten, R. J.; Krijger, J. M.
2003A&A...407..735R Altcode:
We study the low-frequency brightness modulation of internetwork
regions in the low solar chromosphere using simultaneous ultraviolet
and white-light image sequences from the Transition Region and Coronal
Explorer (TRACE). The ultraviolet sequences exhibit a slowly varying
brightness pattern in internetwork regions on which the more familiar
acoustic three-minute oscillation is superimposed, with about half of
the peak brightness reached in internetwork grains contributed by the
low-frequency background. We address the nature of the latter, applying
two-dimensional Fourier filtering to isolate it from the acoustic
modulation. Spatio-temporal comparisons and selective time-delay scatter
correlations between the ultraviolet and white-light low-frequency
sequences establish that reversed granulation constitutes at most a
minor part of the ultraviolet background. Fourier analysis shows that
the meso-scale contribution dominates and consists of atmospheric
gravity waves.
---------------------------------------------------------
Title: The Dutch Open Telescope
Authors: Rutten, Robert J.
2003ASSL..288..111R Altcode: 2003ASSL..287..411R
No abstract at ADS
---------------------------------------------------------
Title: La Palma observations of umbral flashes
Authors: Rouppe van der Voort, L. H. M.; Rutten, R. J.; Sütterlin,
P.; Sloover, P. J.; Krijger, J. M.
2003A&A...403..277R Altcode:
We present high-quality Ca II H & K data showing chromospheric
flashes in sunspot umbrae collected with the Swedish Vacuum Solar
Telescope, the Dutch Open Telescope, and the Swedish 1-m Solar Telescope
at the Roque de los Muchachos Observatory on La Palma. Differential
movies, time slices, spectrograms, and Fourier power maps demonstrate
that umbral flashes and running penumbral waves are closely related
oscillatory phenomena, combining upward shock propagation with coherent
wave spreading over the entire spot. We attribute the flash brightening
to large redshift by post-shock material higher up. We find no obvious
relation between umbral dots and umbral flashes.
---------------------------------------------------------
Title: Radiative Transfer in Stellar Atmospheres
Authors: Rutten, Robert J.
2003rtsa.book.....R Altcode:
The main topic treated in these graduate course notes is the classical
theory of radiative transfer for explaining stellar spectra. It
needs relatively much attention to be mastered. Radiative transfer in
gaseous media that are neither optically thin nor fully opaque and
scatter to boot is a key part of astrophysics but not a transparent
subject. These course notes represent a middle road between Mihalas'
"Stellar Atmospheres" (graduate level and up) and the books by Novotny
and Boehm-Vitense (undergraduate level). They are at about the level
of Gray's "The observation and analysis of stellar photospheres" but
emphasize NLTE radiative transfer rather than observational techniques
and data interpretation.
---------------------------------------------------------
Title: Multi-wavelength imaging system for the Dutch Open Telescope
Authors: Bettonvil, Felix C.; Suetterlin, Peter; Hammerschlag, Robert
H.; Jagers, Aswin P.; Rutten, Robert J.
2003SPIE.4853..306B Altcode:
The Dutch Open Telescope (DOT) is an innovative solar telescope,
completely open, on an open steel tower, without a vacuum system. The
aim is long-duration high resolution imaging and in order to achieve
this the DOT is equipped with a diffraction limited imaging system
in combination with a data acquisition system designed for use with
the speckle masking reconstruction technique for removing atmospheric
aberrations. Currently the DOT is being equipped with a multi-wavelength
system forming a high-resolution tomographic imager of magnetic
fine structure, topology and dynamics in the photosphere and low-
and high chromosphere. Finally the system will contain 6 channels:
G-band (430.5 nm), Ca II H (K) (396.8 nm), H-α (656.3 nm), Ba II
(455.4 nm), and two continuum channels (432 and 651 nm). Two channels
are in full operation now and observations show that the DOT produces
real diffraction limited movies (with 0.2" resolution) over hours in
G-band (430.5 nm) and continuum (432 nm).
---------------------------------------------------------
Title: Utrecht Radiative Transfer Courses
Authors: Rutten, R. J.
2003ASPC..288...99R Altcode: 2003sam..conf...99R
The Utrecht course “The Generation and Transport of Radiation” teaches
basic radiative transfer to second-year students. It is a much-expanded
version of the first chapter of Rybicki & Lightman's “Radiative
Processes in Astrophysics”. After this course, students understand why
intensity is measured per steradian, have an Eddington-Barbier feel for
optically thick line formation, and know that scattering upsets LTE. The
text is a computer-aided translation by Ruth Peterson of my 1992
Dutch-language course. My aim is to rewrite this course in non-computer
English and make it web-available at some time. In the meantime, copies
of the Peterson translation are made yearly at Uppsala -- ask them,
not me. Eventually it should become a textbook. <P />The Utrecht course
“Radiative Transfer in Stellar Atmospheres” is a 30-hour course for
third-year students. It treats NLTE line formation in plane-parallel
stellar atmospheres at a level intermediate between the books by Novotny
and Boehm-Vitense, and Mihalas' “Stellar Atmospheres”. After this
course, students appreciate that epsilon is small, that radiation
can heat or cool, and that computers have changed the field. This
course is web-available since 1995 and is regularly improved --
but remains incomplete. Eventually it should become a textbook. <P
/>The three Utrecht exercise sets “Stellar Spectra A: Basic Line
Formation”, “Stellar Spectra B: LTE Line Formation”, and “Stellar
Spectra C: NLTE Line Formation” are IDL-based computer exercises for
first-year, second-year, and third-year students, respectively. They
treat spectral classification, Saha-Boltzmann population statistics,
the curve of growth, the FAL-C solar atmosphere model, the role of
H-minus in the solar continuum, LTE formation of Fraunhofer lines,
inversion tactics, the Feautrier method, classical lambda iteration,
and ALI computation. The first two sets are web-available since 1998;
the third will follow. <P />Acknowledgement. Both courses owe much
to previous Utrecht courses taught by the late Kees Zwaan. The third
exercise set was developed by Phil Judge, Mandy Hagenaar, and Thijs
Krijger. <P />Reverse acknowledgement. If you are a user of this free
material you might refer to this summary and so boost my citation
standing. Corrections are also welcome.
---------------------------------------------------------
Title: NLTE in a Hot Hydrogen Star: Auer & Mihalas Revisited
Authors: Wiersma, J.; Rutten, R. J.; Lanz, T.
2003ASPC..288..130W Altcode: 2003sam..conf..130W
We pay tribute to two landmark papers published by Auer & Mihalas
in 1969. They modeled hot-star NLTE-RE hydrogen-only atmospheres,
using two simplified hydrogen atoms: ApJ 156, 157: H I levels 1,
2 and c, Lyman α the only line ApJ 156, 681: H I levels 1, 2, 3 and
c, Balmer α the only line and computed LTE and NLTE models with the
single line turned on and off. The results were extensively analyzed
in the two papers. <P />Any student of stellar line formation should
take these beautiful papers to heart. The final exercise in Rutten's
lecture notes “Radiative Transfer in Stellar Atmospheres” asks the
student to work through five pages of questions concerning diagrams from
the first paper alone! That exercise led to the present work in which
we recompute the Auer-Mihalas hot-hydrogen-star models with TLUSTY,
adding results from a complete hydrogen atom for comparison. <P />Our
motivation for this Auer-Mihalas re-visitation is twofold: <P />1. to
add diagnostic diagrams to the ones published by Auer & Mihalas,
in particular B<SUB>ν</SUB>, J<SUB>ν</SUB>, S<SUB>ν</SUB> graphs to
illustrate the role of the radiation field, and radiative heating &
cooling graphs to illustrate the radiative energy budget, <P />2. to
see the effect of adding the rest of the hydrogen atom.
---------------------------------------------------------
Title: Dynamical Behavior of the Upper Solar Photosphere
Authors: Rutten, R. J.
2003IAUS..210..221R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solar Atmosphere Models
Authors: Rutten, R. J.
2002JAD.....8....8R Altcode:
This contribution honoring Kees de Jager's 80th birthday is a review of
"one-dimensional" solar atmosphere modeling that followed on the initial
"Utrecht Reference Photosphere" of Heintze, Hubenet & de Jager
(1964). My starting point is the Bilderberg conference, convened by de
Jager in 1967 at the time when NLTE radiative transfer theory became
mature. The resulting Bilderberg model was quickly superseded by the
HSRA and later by the VAL-FAL sequence of increasingly sophisticated
NLTE continuum-fitting models from Harvard. They became the "standard
models" of solar atmosphere physics, but Holweger's relatively simple
LTE line-fitting model still persists as a favorite of solar abundance
determiners. After a brief model inventory I discuss subsequent
work on the major modeling issues (coherency, NLTE, dynamics)
listed as to-do items by de Jager in 1968. The present conclusion
is that one-dimensional modeling recovers Schwarzschild's (1906)
finding that the lower solar atmosphere is grosso modo in radiative
equilibrium. This is a boon for applications regarding the solar
atmosphere as one-dimensional stellar example - but the real sun,
including all the intricate phenomena that now constitute the mainstay
of solar physics, is vastly more interesting.
---------------------------------------------------------
Title: Dutch Open Telescope: status, results, prospects
Authors: Rutten, Robert J.; Sütterlin, Peter; de Wijn, Alfred G.;
Hammerschlag, Robert H.; Bettonvil, Felix C. M.; Hoogendoorn, Piet W.;
Jägers, Aswin P. L.
2002ESASP.506..903R Altcode: 2002svco.conf..903R; 2002ESPM...10..903R
The Dutch Open Telescope (DOT) on La Palma is a revolutionary telescope
achieving high-resolution imaging of the solar surface. The DOT combines
a pioneering open design at an excellent wind-swept site with image
restoration through speckle interferometry. Its open principle is now
followed in major solar-telescope projects elsewhere. In the past three
years the DOT became the first solar telescope to regularly obtain 0.2"
resolution in extended image sequences, i.e., reaching the diffraction
limit of its 45-cm primary mirror. Our aim for 2003-2005 is to turn
the DOT into a 0.2" tomographic mapper of the solar atmosphere with
frequent partnership in international multi-telescope campaigns through
student-serviced time allocation. After 2005 we aim to triple the DOT
resolution to 0.07" by increasing the aperture to 140 cm and to renew
the speckle cameras and the speckle pipeline in order to increase
the field size and sequence duration appreciably. These upgrades will
maintain the DOT's niche as a tomographic high-resolution mapper in
the era when GREGOR, Solar-B and SDO set the stage.
---------------------------------------------------------
Title: Opening the Dutch Open Telescope
Authors: Rutten, R. J.; de Wijn, A. G.; Sütterlin, P.; Bettonvil,
F. C. M.; Hammerschlag, R. H.
2002ESASP.505..565R Altcode: 2002IAUCo.188..565R; 2002solm.conf..565R
We hope to "open the DOT" to the international solar physics
community as a facility for high-resolution tomography of the solar
atmosphere. Our aim is to do so combining peer-review time allocation
with service-mode operation in a "hands-on-telescope" education
program bringing students to La Palma to assist in the observing and
processing. The largest step needed is considerable speedup of the
DOT speckle processing.
---------------------------------------------------------
Title: European Solar Magnetism Network
Authors: Rutten, Robert J.
2002ESASP.505..569R Altcode: 2002IAUCo.188..569R; 2002solm.conf..569R
The future European Solar Magnetism Network (ESMN) will continue and
expand collaborations of the past European Solar Magnetometry Network
(ESMN). Both ESMN incarnations are funded by the European Commission,
in the Fourth and Fifth Framework programmes respectively. The major
past and future ESMN activity is the employment/deployment of European
postdocs.
---------------------------------------------------------
Title: Small-scale topology of solar atmospheric dynamics. V. Acoustic
events and internetwork grains
Authors: Hoekzema, N. M.; Rimmele, T. R.; Rutten, R. J.
2002A&A...390..681H Altcode:
We use high-quality observations from the Dunn Solar Telescope
at NSO/Sacramento Peak to study spatio-temporal co-location of
acoustic flux events in the photosphere and internetwork grains
in the chromosphere. The events are diagnosed as sites with excess
upward-propagating five-minute waves measured from Dopplergrams. The
grains are repetitive bright internetwork features in simultaneous
\CaII \KtwoV filtergrams. We find that the largest-flux sites in
the granulation have appreciably larger than random probability to
co-locate with exceptionally bright chromospheric internetwork grains,
at an average delay of about two minutes which is likely to represent
sound travel time to the chromosphere. This finding strengthens the
case for acoustic grain excitation.
---------------------------------------------------------
Title: The European Solar Magnetometry Network in 2000 - 2001
Authors: Rutten, R. J.
2002joso.book....7R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Dynamics of the solar chromosphere. III. Ultraviolet brightness
oscillations from TRACE
Authors: Krijger, J. M.; Rutten, R. J.; Lites, B. W.; Straus, Th.;
Shine, R. A.; Tarbell, T. D.
2001A&A...379.1052K Altcode:
We analyze oscillations in the solar atmosphere using image sequences
from the Transition Region and Coronal Explorer (TRACE) in three
ultraviolet passbands which sample the upper solar photosphere and
low chromosphere. We exploit the absence of atmospheric seeing in
TRACE data to furnish comprehensive Fourier diagnostics (amplitude
maps, phase-difference spectra, spatio-temporal decomposition) for
quiet-Sun network and internetwork areas with excellent sampling
statistics. Comparison displays from the ground-based Ca Ii H
spectrometry that was numerically reproduced by Carlsson &
Stein are added to link our results to the acoustic shock dynamics
in this simulation. The TRACE image sequences confirm the dichotomy
in oscillatory behaviour between network and internetwork and show
upward propagation above the cutoff frequency, the onset of acoustic
shock formation in the upper photosphere, phase-difference contrast
between pseudo-mode ridges and the interridge background, enhanced
three-minute modulation aureoles around network patches, a persistent
low-intensity background pattern largely made up of internal gravity
waves, ubiquitous magnetic flashers, and low-lying magnetic canopies
with much low-frequency modulation. The spatio-temporal occurrence
pattern of internetwork grains is found to be dominated by acoustic
and gravity wave interference. We find no sign of the high-frequency
sound waves that have been proposed to heat the quiet chromosphere, but
such measurement is hampered by non-simultaneous imaging in different
passbands. We also find no signature of particular low-frequency
fluxtube waves that have been proposed to heat the network. However,
internal gravity waves may play a role in their excitation.
---------------------------------------------------------
Title: Ba II 4554 Å speckle imaging as solar Doppler diagnostic
Authors: Sütterlin, P.; Rutten, R. J.; Skomorovsky, V. I.
2001A&A...378..251S Altcode:
We present observations testing the Dopplergram capability of a
narrow-band (80 mÅ) Lyot filter imaging the solar surface in the
wings of the Ba II 4554 Å resonance line in combination with speckle
reconstruction to obtain high angular resolution. The Ba II 4554 Å line
is found to be an excellent tool for high-resolution Doppler mapping
thanks to opacity insensitivity to temperature variations and line-width
insensitivity to thermal broadening. The resulting Dopplergrams show
concentrated downflows of 1.2-2.2 km;s<SUP>-1</SUP> in intergranular
lanes that probably mark magnetic fluxtubes. Two-wavelength
profile sampling is found to suffice for high-resolution Dopplergram
construction. The filter will be installed as part of a multi-wavelength
speckle imaging system on the new Dutch Open Telescope.
---------------------------------------------------------
Title: DOT strategies versus Orbiter strategies
Authors: Rutten, Robert J.
2001ESASP.493..357R Altcode: 2001sefs.work..357R
No abstract at ADS
---------------------------------------------------------
Title: ESMN / European solar physics research area
Authors: Rutten, Robert J.
2001ESASP.493..353R Altcode: 2001sefs.work..353R
No abstract at ADS
---------------------------------------------------------
Title: Proxy Magnetometry with the Dutch Open Telescope
Authors: Rutten, R. J.; Hammerschlag, R. H.; Sütterlin, P.; Bettonvil,
F. C. M.
2001ASPC..236...25R Altcode: 2001aspt.conf...25R
No abstract at ADS
---------------------------------------------------------
Title: A Multi-Channel Speckle Imaging System for the DOT
Authors: Sütterlin, P.; Hammerschlag, R. H.; Bettonvil, F. C. M.;
Rutten, R. J.; Skomorovsky, V. I.; Domyshev, G. N.
2001ASPC..236..431S Altcode: 2001aspt.conf..431S
No abstract at ADS
---------------------------------------------------------
Title: Solar Atmospheric Dynamics (CD-ROM Directory: contribs/rutten)
Authors: Rutten, R. J.
2001ASPC..223..117R Altcode: 2001csss...11..117R
No abstract at ADS
---------------------------------------------------------
Title: The formation of G-band bright points I: Standard LTE modelling
Authors: Kiselman, D.; Rutten, R. J.; Plez, B.
2001IAUS..203..287K Altcode:
Assuming LTE, we investigate the formation of the G band in models of
quiet solar photosphere and a semiempirical flux-tube model (Briand
& Solanki 1995). Preliminary results agree with observations of
of G-band bright-point contrast, though this a sensitive function
of the amount of scattered light in the observations. Thus LTE line
modelling in models constructed under the LTE assumptions seems to fit
observations. This does not, however, necessarily imply that LTE is
valid here. We also present LTE synthetic spectra of the same models
for the full wavelength range from UV to IR. This serves to point out
other promising pass bands for the observations of flux-tube structures.
---------------------------------------------------------
Title: Proxy Magnetometry of the Photosphere: Why are G-Band Bright
Points so Bright?
Authors: Rutten, R. J.; Kiselman, D.; Rouppe van der Voort, L.;
Plez, B.
2001ASPC..236..445R Altcode: 2001aspt.conf..445R
No abstract at ADS
---------------------------------------------------------
Title: The formation of G-band bright points. I: Standard LTE
modelling
Authors: Kiselman, D.; Rutten, R. J.; Plez, B.
2000astro.ph.10390K Altcode:
Assuming LTE, we synthesise solar G band spectra from the semiempirical
flux-tube model of Briand Solanki (1995). The results agree with
observed G-band bright-point contrasts within the uncertainty set by the
amount of scattered light. We find that it is the weakening of spectral
lines within the flux tube that makes the bright-point contrast in the
G band exceed the continuum contrast. We also synthesise flux-tube
spectra assuming LTE for the full wavelength range from UV to IR,
and identify other promising passbands for flux-tube observations.
---------------------------------------------------------
Title: Dutch Open Telescope: Status and Prospects
Authors: Rutten, R. J.; Hammerschlag, R. H.; Bettonvil, F. M.;
Suetterlin, P.
2000SPD....3102107R Altcode: 2000BAAS...32.1290R
The Dutch Open Telescope (DOT) on La Palma in the Canary Islands is
a small but revolutionary solar telescope of which the image quality
matches the superb imaging of the Swedish Vacuum Solar Telescope (from
whose building the DOT is operated). The DOT is an open parabolic 45cm
reflector on an open 15m high tower, relying on mirror flushing by the
trade winds that bring the best seeing at La Palma to avoid internal
turbulence. A water-cooled field stop in the primary image reflects
most sunlight and heat out of the telescope. The first data from the
DOT combined with speckle reconstruction have yielded sunspot movies
of outstanding quality. At present, a multi-channel imaging system is
in construction for simultaneous registration of speckle sequences in
the G band, in Ca II K and in Hα. The data pipeline permits continuous
speckle data acquisition up to 0.5 Tb per day. The advantage of speckle
reconstruction over adaptive optics is the much larger field of the
restored scene, with the DOT camera's 100x130 arcsec at 0.2 arcsec
resolution. The DOT science program is to study magnetic topology and
dynamics throughout the photosphere and chromosphere.
---------------------------------------------------------
Title: C. Fröhlich, M. C. E. Huber, S. K. Solanki and R. von Steiger
(eds.), Solar Composition and its Evolution from Core to Corona
Authors: Rutten, R. J.
1999SSRv...90..526R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: (Inter-),Network Structure and DynamicS
Authors: Rutten, R. J.
1999ASPC..184..181R Altcode:
The dynamical nature of the low solar atmosphere outside active regions
is emphasized by recent observations and simulations alike. La Palma
images, MDI maps, SUMER spectra, TRACE movies, hydrodynamic shock
simulations and magnetohydrodynamic sheet simulations all impart
non-quiet behavior to the "quiet Sun". This review begins with a brief
summary of current insights and then focuses on various quiet-Sun
questions that seem pertinent and solvable.
---------------------------------------------------------
Title: C. Zwaan (1928 - 16 June 1999).
Authors: Rutten, R. J.; Schrijver, C. J.
1999SoPh..188.....R Altcode: 1999SoPh..188....0R
No abstract at ADS
---------------------------------------------------------
Title: Dynamics of the Solar Chromosphere. II. Ca II H<SUB>2V</SUB>
and K<SUB>2V</SUB> Grains versus Internetwork Fields
Authors: Lites, B. W.; Rutten, R. J.; Berger, T. E.
1999ApJ...517.1013L Altcode:
We use the Advanced Stokes Polarimeter at the NSO/Sacramento Peak
Vacuum Tower Telescope to search for spatio-temporal correlations
between enhanced magnetic fields in the quiet solar internetwork
photosphere and the occurrence of Ca II H<SUB>2V</SUB> grains in the
overlying chromosphere. We address the question of whether the shocks
that produce the latter are caused by magnetism-related processes,
or whether they are of purely hydrodynamic nature. The observations
presented here are the first in which sensitive Stokes polarimetry is
combined synchronously with high-resolution Ca II H spectrometry. We pay
particular attention to the nature and significance of weak polarization
signals from the internetwork domain, obtaining a robust estimate of
our magnetographic noise level at an apparent flux density of only
3 Mx cm<SUP>-2</SUP>. For the quiet Sun internetwork area analyzed
here, we find no direct correlation between the presence of magnetic
features with apparent flux density above this limit and the occurrence
of H<SUB>2V</SUB> brightenings. This result contradicts the one-to-one
correspondence claimed by Sivaraman & Livingston. We also find no
correspondence between H<SUB>2V</SUB> grains and the horizontal-field
internetwork features discovered by Lites et al.
---------------------------------------------------------
Title: F.-L. Deubner, J. Christensen-Dalsgaard, and D. Kurtz (eds.),
New Eyes to See Inside the Sun and Stars, Proceedings of the 185th
Symposium of the International Astronomical Union held in Kyoto,
Japan, August 18 22, 1997
Authors: Rutten, R. J.
1999SSRv...88..605R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Magnetic Fields and Oscillations
Authors: Rutten, Robert J.
1999PASP..111..380R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Dutch Open Telescope
Authors: Rutten, R. J.; Hammerschlag, R. H.; Bettonvil, F. C. M.
1999ASPC..158...57R Altcode: 1999ssa..conf...57R
No abstract at ADS
---------------------------------------------------------
Title: Internetwork Grains with TRACE
Authors: Rutten, R. J.; de Pontieu, B.; Lites, B.
1999ASPC..183..383R Altcode: 1999hrsp.conf..383R
No abstract at ADS
---------------------------------------------------------
Title: Dynamics of the Quiet Solar Chromosphere
Authors: Rutten, R. J.; Lites, B. W.; Berger, T. E.; Shine, R. A.
1999ASPC..158..249R Altcode: 1999ssa..conf..249R
No abstract at ADS
---------------------------------------------------------
Title: Obituary: Cornelis Zwaan, 1928-1999
Authors: Rutten, Rob; Schrijver, Karel
1999BAAS...31.1612R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Radiative Transfer for Grabs
Authors: Rutten, R. J.
1999ASPC..158..306R Altcode: 1999ssa..conf..306R
No abstract at ADS
---------------------------------------------------------
Title: Site tests for CLEAR by solar scintillometry
Authors: Beckers, Jacques M.; Rutten, Robert J.
1998NewAR..42..489B Altcode:
We briefly describe the ongoing site survey for the NSO CLEAR project
which aims to put a large-aperture solar telescope at a superior
location. The initial results indicate that lake sites are far better
than mountain sites, at least in the US.
---------------------------------------------------------
Title: The Lower Solar Atmosphere Rapporteur Paper II
Authors: Rutten, Robert J.
1998SSRv...85..269R Altcode:
This “rapporteur” report discusses the solar photosphere and low
chromosphere in the context of chemical composition studies. The highly
dynamical nature of the photosphere does not seem to jeopardize precise
determination of solar abundances in classical fashion. It is still an
open question how the highly dynamical nature of the low chromosphere
contributes to first ionization potential (FIP) fractionation.
---------------------------------------------------------
Title: Small-scale topology of solar atmosphere
dynamics. III. Granular persistence and photospheric wave amplitudes
Authors: Hoekzema, N. M.; Brandt, P. N.; Rutten, R. J.
1998A&A...333..322H Altcode:
We use a superb five-hour sequence of 900 solar images taken at La
Palma to study long-duration persistence in the solar granulation,
in the context of the long-lived “intergranular holes” discovered by
\cite*{Roudier+others1997} %T AA: intergranular plumes + BP formation
and the contention that these mark sites of convective downflow
plumes. We develop a procedure to locate “persistency regions” that
contain granular brightness maxima or minima over extended periods
(up to 45 min), while allowing for lateral drifts due to horizontal
flows. Statistical evaluation of the co-location probability for
different pixel classes is first used to quantify the likelihood of
long-term stationarity for different granular brightness classes and for
the persistency regions, and then to evaluate the amount of preferential
alignment, at different frequencies and time delays, between excessive
Fourier modulation and granular brightness and persistence. The results
support the existence of long-lived intergranular holes. There is large
persistency difference between the brightest and the darkest features;
some of the latter have location memories as long as two hours. In
addition, the darkest intergranular features are found to be sites of
enhanced Fourier modulation in the 3-min acoustic regime, improving
earlier results through much higher statistical significance. However,
the persistency regions containing intergranular holes do not seem
to produce the excess acoustic emission that would be expected above
downflow plumes.
---------------------------------------------------------
Title: Small-scale topology of solar atmosphere dynamics. I. Wave
sources and wave diffraction
Authors: Hoekzema, N. M.; Rutten, R. J.; Brandt, P. N.; Shine, R. A.
1998A&A...329..276H Altcode:
We study the small-scale topology of dynamical phenomena in the
quiet-sun internetwork atmosphere, using short-duration Fourier analysis
of high-resolution filtergram sequences to obtain statistical estimates
for the co-location probability of different fine-structure elements
and wave modes. In this initial paper we concentrate on the topology
of short-duration Fourier amplitude maps for the photosphere and the
simultaneously observed overlying chromosphere. We find that these
maps portray a complex mix of global modes and locally excited waves
which necessitates a statistical approach. Various aspects including
mesoscale patterning indicate the presence of subsurface wave sources
and of subsurface wave diffraction by convective inhomogeneities.
---------------------------------------------------------
Title: The Lower Solar Atmosphere
Authors: Rutten, R. J.
1998sce..conf..269R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Problem of iron abundance in the solar photosphere.
Authors: Kostyk, R. I.; Shchukina, N. G.; Rutten, R. J.
1998BCrAO..94..118K Altcode:
The authors analyze the causes of the discrepancies.
---------------------------------------------------------
Title: Small-scale topology of solar atmosphere
dynamics. II. Granulation, K2v grains and waves
Authors: Hoekzema, N. M.; Rutten, R. J.
1998A&A...329..725H Altcode:
We continue studying the small-scale topology of dynamical phenomena in
the quiet-sun internetwork atmosphere through statistical estimation
of the co-location probability of different fine-structure elements
and wave modes. In this paper we chart spatial alignments between the
granular brightness structuring of the photosphere, Ca ii K<SUB>2V</SUB>
brightness patterns in the chromosphere, and wave amplitude patterns
in both regimes as a function of time delay between the occurrences of
the various features. These charts confirm the presence of excess 2--4
min waves above dark intergranular lanes, the absence of excess 5 min
waves above bright granules, the absence of expected alignments between
photospheric and chromospheric wave patterning, and the broad-band
nature of Ca ii K<SUB>2V</SUB> grain formation. In addition, they show
significant alignments at large time delays that seem to be regulated
by mesoscale patterning and pattern = migration.
---------------------------------------------------------
Title: The Dutch Open Telescope
Authors: Rutten, R. J.; Hammerschlag, R. H.; Bettonvil, F. M.
1997ASSL..225..289R Altcode: 1997scor.proc..289R
The Dutch Open Telescope is now being installed at La Palma. It
is intended for optical solar observations with high spatial
resolution. Its open design aims to minimize disturbances of the
local air flow and so reduce the locally-generated component of
the atmospheric seeing. This paper briefly describes the design,
construction, short-term plans, and longer-term prospects.
---------------------------------------------------------
Title: E. Kontizas, M. Kontizas, D.H. Morgan, and G.P. Vettolani
(eds.). Wide-Faceted Field Spectroscopy, Proceedings of the 2nd
Conference of the Working Group of IAU Commission 9 on "Wide-Field
Imaging".
Authors: Rutten, R. J.
1997SSRv...82..467R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Modeling LiI and KI sensitivity to Pleiades activity.
Authors: Stuik, R.; Bruls, J. H. M. J.; Rutten, R. J.
1997A&A...322..911S Altcode:
We compare schematic modeling of spots and plage on the surface of
cool dwarfs with Pleiades data to assess effects of magnetic activity
on the strengths of the LiI and KI resonance lines in Pleiades
spectra. Comprehensive LiI and KI NLTE line formation computation is
combined with comparatively well-established empirical solar spot and
plage stratifications for solar-like stars. For other stars, we use
theoretical constructs to model spots and plage that portray recipes
commonly applied in stellar activity analyses. We find that - up to
B-V=~1.1 - neither the LiI 670.8nm nor the KI 769.9nm line is sensitive
to the presence of a chromosphere, in contrast to what is often
supposed. Instead, both lines respond to the effects of activity on the
stratification in the deep photosphere. They do so in similar fashion,
making the KI line a valid proxy to study LiI line formation without
spread from abundance variations. The computed effects of activity on
line strength are opposite between plage and spots, differ noticeably
between the empirical and theoretical solar-like stratifications, and
considerably affect stellar broad-band colors. Our results indicate that
one can neither easily establish, nor easily exclude, magnetic activity
as major provider of KI line strength variation in the Pleiades. Since
LiI line formation follows KI line formation closely, the same holds
for LiI and the apparent lithium abundance.
---------------------------------------------------------
Title: Ultraviolet Jets and Bright Points in the Solar
Chromosphere. II. Statistical Correlations
Authors: Hoekzema, N. M.; Rutten, R. J.; Cook, J. W.
1997ApJ...474..518H Altcode:
We use HRTS-VI rocket observations of the solar chromosphere to search
for relationships between high-Dopplershift “jets” observed in the C
I lines near λ = 156 nm and internetwork “bright points” observed
in the λ = 160 nm continuum, in sequel to the analysis by Cook et
al. which failed to find a direct connection between these phenomena. We
now use the same data to establish statistical correlations between
C I Dopplershift and 160 nm brightness modulation in internetwork
areas. These mean relations emerge only after extensive spatial
averaging and have small amplitude, but are definitely significant. They
show that both C I Dopplershift and 160 nm brightness participate
in oscillatory behavior with 3 minute periodicity and mesoscale (8
Mm wavelength) as well as small-scale (1.4 Mm wavelength) spatial
patterning. We find spatial and temporal phase relations between
Dopplershift and brightness that confirm that jets and bright points
should not be interpreted as isolated entities. Rather, they are
chromospheric manifestations, with much pattern interference, of the
oscillatory acoustic shock dynamics in the internetwork which also
cause Ca II K<SUB>2V</SUB> grains. Additional small-scale modulation
is present which we attribute to waves with f-mode character.
---------------------------------------------------------
Title: First Results from SOHO on Waves Near the Solar Transition
Region
Authors: Steffens, S.; Deubner, F. -L.; Fleck, B.; Wilhelm, K.;
Schuhle, U.; Curdt, W.; Harrison, R.; Gurman, J.; Thompson, B. J.;
Brekke, P.; Delaboudiniere, J. -P.; Lemaire, P.; Hessel, B.; Rutten,
R. J.
1997ASPC..118..284S Altcode: 1997fasp.conf..284S
We present first results from simultaneous observations with the
CDS, EIT and SUMER instruments {please see Solar Physics 162 (1995)
for a description of the instruments} onboard SOHO and the VTT at
Tenerife. Our aim is to study the wave propagation, shock formation,
and transmission properties of the upper chromosphere and transition
region. The preliminary results presented here include the variation
of velocity power spectra with height, difference in power between
internetwork and network regions, and variations in mean flows displayed
by different spectral lines.
---------------------------------------------------------
Title: Chromospheric Dynamics and the FIP Flip
Authors: Rutten, R. J.
1997ASPC..118..298R Altcode: 1997fasp.conf..298R
This paper consists of two parts. The first, resembling many other SOHO
contributions in this volume, reports on a recent campaign in which
SUMER was employed simultaneously with groundbased telescopes. The
campaign is described but results are not yet in hand. The second
part differs by proposing SUMER measurements and analysis to be
contributed by you. It calls attention to the FIP effect, a puzzling
outer-atmosphere element segregation that may have to do with quiet-sun
chromospheric dynamics. SUMER data, including yours, may provide
pertinent diagnostics.
---------------------------------------------------------
Title: Dutch Open Telescope: Status and Prospects
Authors: Rutten, R. J.; Hammerschlag, R. H.; Bettonvil, F. C. M.
1997ASPC..118..335R Altcode: 1997fasp.conf..335R
The Dutch Open Telescope represents a new solar telescope concept. Being
open rather than evacuated, it leads the way to large-aperture high
resolution telescopes. It is now being installed on La Palma.
---------------------------------------------------------
Title: Ultraviolet Jets and Bright Points in the Solar
Chromosphere. I. Search for One-to-One Relationships
Authors: Cook, J. W.; Rutten, R. J.; Hoekzema, N. M.
1996ApJ...470..647C Altcode:
Ultraviolet spectrograms and spectroheliograms of the solar chromosphere
are used to test the suggestion of Dere, Bartoe, & Brueckner
and Rutten & Uitenbroek that bright points in quiet Sun cell
interiors observed at = 1600 A, chromospheric jets observed in C I
lines near λ = 1560 Å, and Ca II K<SUB>2v</SUB> bright points are
associated with each other and that they are all manifestations of the
same wave interaction in the nonmagnetic chromosphere. We search for
spatio-temporal connections between 1600 Å bright points and C I blue
jets using data from the High Resolution Telescope and Spectrograph
VI rocket flight, comparing 1600 A spectrohellograms and a cospatial
C I Doppler shift map on a pixel-by-pixel basis. We find no direct
evidence for spatial colocation of bright points and jets, not for
instantaneous correspondence and also not when allowing for phase
delays as long as 3 minutes. Also, the average brightness evolution
and its rms fluctuation are not obviously different between sites of
large C I blueshift and the remaining surface.
---------------------------------------------------------
Title: Book reviews
Authors: Humphreys, R. M.; Kemp, S.; Savonije, G.; van der Hucht,
K. A.; van der Kruit, P. C.; Miley, G.; Bumba, V.; van Nieuwkoop,
J.; van Hoolst, T.; Cox, A.; Rutten, R. J.; Kleczek, J.; de Jager,
Cornelis; Jerzykiewicz, M.; Zwaan, C.; Poedts, S.; Sakai, Jun-Ichi;
Pecker, J. -C.; Heikkila, W.; de Jong, T.; Wilson, P. R.; Müller,
E. A.; Hoyng, P.; Icke, V.; Shore, S. N.; Achterberg, A.; Lucchin, F.;
Butcher, H.; Ne'Eman, Y.; Heidmann, J.; Belton, M. J. S.; de Graauw,
Th.; Waters, L. B. F. M.; Pacini, F.; Hultqvist, B.; Akasofu, S. -I.;
Vial, J. -C.; Schatzman, E.; van der Laan, H.; Cole, K. D.; Vanbeveren,
D.; Southwood, D.; van der Klis, M.; Katgert, Peter
1996SSRv...76..339H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The solar iron abundance: not the last word.
Authors: Kostik, R. I.; Shchukina, N. G.; Rutten, R. J.
1996A&A...305..325K Altcode:
Determinations of the solar iron abundance have converged to the
meteoritic value with the FeII studies of Holweger et al. (1990),
Biemont et al. (1991) and Hannaford et al. (1992) and the FeI results
of Holweger et al. (1991). However, the latter authors pointed out
that Blackwell et al. (1984) obtained a discordant result from similar
oscillator strengths. A recent debate on this lingering discrepancy
by the Oxford and Kiel contenders themselves has not clarified
the issue. We do so here by showing that it stems from systematic
differences between equivalent widths and oscillator strengths which
masquerade as difference in fitted damping enhancement factors. We first
discuss the various error sources in classical abundance determination
and then emulate both sides of the debate with abundance fits of our
own. Our emulation of the Oxford side shows that the abundance anomaly
claimed by Blackwell et al. (1984) for solar FeI 2.2eV lines vanishes
when equivalent width measurements from other authors are combined
with better evaluation of the collisional damping parameter. On the
Kiel side, we find that the oscillator strengths of Bard et al. (1991)
used by Holweger et al. (1991) produce a suspicious trend when used
to fit solar FeI lines, whereas comparable application of oscillator
strengths from Oxford does not. The trend is mainly set by categories
of FeI lines not measured at Oxford; for lines of overlap the two sets
agree and deliver the iron abundance value A_Fe_=7.62+/-0.04 which
exceeds the meteorite value. The dissimilar lines may suffer from
solar line-formation effects. We conclude that the issue of the solar
iron abundance remains open. Definitive oscillator strengths are still
needed, as well as verification of classical abundance determination
by more realistic representations of the solar photosphere and of
photospheric line formation.
---------------------------------------------------------
Title: Chromospheric Oscillations
Authors: Rutten, R. J.
1995ESASP.376a.151R Altcode: 1995heli.conf..151R; 1995soho....1..151R
Concentrates on the quiet-Sun chromosphere. Its internetwork areas
are dynamically dominated by the so-called chromospheric three-minute
oscillation. They are interpretationally dominated by the so-called Ca
II K<SUB>2v</SUB> and H<SUB>2v</SUB> grains. The main points of this
review are that the one phenomenon explains the other (both ways),
that the quiet-Sun chromosphere is a clapotisphere pervaded by shocks
above h ≍ 1 Mm, and that the existence of the classical temperature
minimum is in doubt.
---------------------------------------------------------
Title: The Determination of the Solar Iron Abundance from Fe I Lines
Authors: Kostik, R. I.; Shchukina, N. G.; Rutten, R. J.
1995ASPC...78..399K Altcode: 1995aapn.conf..399K
No abstract at ADS
---------------------------------------------------------
Title: Infrared lines as probes of solar magnetic features. VIII. MgI
12μm diagnostics of sunspots.
Authors: Bruls, J. H. M. J.; Solanki, S. K.; Rutten, R. J.; Carlsson,
M.
1995A&A...293..225B Altcode:
Due to their large Zeeman sensitivity, the MgI lines at 12μm are
important diagnostics of solar magnetism. The formation of their
central emission features is now understood, enabling quantitative
modeling and diagnostic application of these lines. We supply the
first systematic analysis of solar MgI 12μm Stokes profiles employing
detailed line-profile synthesis. We compute Stokes profiles of MgI
12.32μm for the quiet Sun, for sunspot penumbrae and for the extended
("superpenumbral") magnetic canopies surrounding sunspots. We use these
computations to analyze recent MgI 12μm observations by Hewagama
et al. (1993). Our results are the following: (1) -Saha-Boltzmann
temperature sensitivity explains that the emission peaks are stronger in
penumbrae than in the quiet Sun, and that they disappear in umbrae. (2)
-The formation heights of the emission features are approximately the
same in penumbrae and in the quiet Sun, namely τ_500_=~10^-3^. (3)
-The simple Seares formula allows relatively accurate determinations
of field strength and magnetic inclination. (4) -The observed excess
broadening of the σ-component peaks compared with the π component
in penumbrae is well explained by primarily horizontal, smooth radial
variation of the magnetic field strength. Additional small-scale
variations are less than {DELTA}B =~200G. (5) -The vertical field
gradients dB/dz in penumbrae range from 0.7G/km to 3G/km; the larger
gradients occur near the umbra, the smaller ones near the outer edge of
the penumbra. (6) -The MgI 12μm lines are well-suited to measure the
base heights of superpenumbral magnetic canopies. These heights range
between 300km and 500km above τ_500_=1 out to twice the sunspot radius,
in excellent agreement with determinations from other infrared lines.
---------------------------------------------------------
Title: Books-Received - Solar Surface Magnetism
Authors: Rutten, R. J.; Schrijver, C. J.
1994Sci...265.1902R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The non-LTE formation of Li I lines in cool stars
Authors: Carlsson, M.; Rutten, R. J.; Bruls, J. H. M. J.; Shchukina,
N. G.
1994A&A...288..860C Altcode:
We study the non-LTE (non local thermodynamic equilibrium)
formation of Li I lines in the spectra of cool stars for a grid of
radiative-equilibrium model atmospheres with variation in effective
temperature, gravity, metallicity and lithium abundance. We analyze
the mechanisms by which departures from LTE (local thermodynamic
equilibrium) arise for Li I lines, first for the young sun (prior to
its lithium depletion) and then across the cool-star grid. There are
various mechanisms which compete in their effects on emergent Li I
line strengths. Their neglect produces errors in lithium abundance
determinations that vary in sign as well as size, both across the
stellar grid and between different Li I lines (Figs). The errors are
appreciable for all cooler stars and largest for cool lithium-rich
metal-poor giants. They reverse sign between lithium-rich stars and
lithium-poor stars for the λ=670.8nm resonance line, but not for the
λ=610.4nm subordinate line. The non-LTE corrections are large enough
that they should be taken into account in ongoing debates on lithium
synthesis and depletion. We provide convenient numerical approximations
of our results (Table 1) to this purpose. We end the paper with some
examples in which non-LTE corrections change the slope of published
relationships.
---------------------------------------------------------
Title: The SIMURIS interferometric mission: Solar physics objectives
and model payload
Authors: Dame, L.; Rutten, R. J.; Thorne, A. P.; Vial, J. C.
1994AdSpR..14d.167D Altcode: 1994AdSpR..14..167D
We describe the SIMURIS Mission with emphasis on the scientific goals
and related capabilities of the major instruments of the model payload.
---------------------------------------------------------
Title: Book reviews
Authors: Burlaga, L. F.; Kleczek, J.; Schatzman, E.; Adams, D. J.;
Rutten, R. J.; van der Kruit, P. C.; de Jager, Cornelis; Trams, N. R.;
Righini, Alberto; Ergma, E.; Grün, Eberhard; Icke, Vincent
1994SSRv...67..223B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Formation of Infrared Rydberg Lines
Authors: Rutten, R. J.; Carlsson, M.
1994IAUS..154..309R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Computation of Infrared Hydrogen Lines
Authors: Carlsson, M.; Rutten, R. J.
1994IAUS..154..341C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Non-LTE Formation of Li I Lines from Cool Stars
Authors: Carlsson, M.; Rutten, R. J.; Bruls, J. H. M. J.; Shchukina,
N. G.
1994ASPC...64..270C Altcode: 1994csss....8..270C
No abstract at ADS
---------------------------------------------------------
Title: Chromospheric oscillations
Authors: Lites, B. W.; Rutten, R. J.; Thomas, J. H.
1994ASIC..433..159L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On photospheric flows and chromospheric corks
Authors: Brandt, P. N.; Rutten, R. J.; Shine, R. A.; Trujillo Bueno, J.
1994ASIC..433..251B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Book Review: Sunspots: theory and observations / Kluwer, 1992
Authors: Rutten, R. J.
1994SSRv...67..227R Altcode: 1994SSRv...67..227T
No abstract at ADS
---------------------------------------------------------
Title: Solar Surface Magnetism
Authors: Rutten, Robert J.; Schrijver, Carolus J.
1994ASIC..433.....R Altcode: 1994ssm..work.....R
No abstract at ADS
---------------------------------------------------------
Title: MgI 12 μm diagnostics of sunspot penumbrae
Authors: Bruls, J. H. M. J.; Solanki, S. K.; Rutten, R. J.; Carlsson,
M.
1994smf..conf..191B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Dynamics of the Solar Chromosphere. I. Long-Period Network
Oscillations
Authors: Lites, B. W.; Rutten, R. J.; Kalkofen, W.
1993ApJ...414..345L Altcode:
We analyze differences in solar oscillations between the chromospheric
network and internetwork regions from a 1 hr sequence of spectrograms
of a quiet region near disk center. The spectrograms contain Ca II
H, Ca I 422.7 nm, and various Fe I blends in the Ca II H wing. They
permit vertical tracing of oscillations throughout the photosphere
and into the low chromosphere. We find that the rms amplitude of
Ca II H line center Doppler fluctuations is about 1.5 km/s for both
network and internetwork, but that the character of the oscillations
differs markedly in these two regions. Within internetwork areas the
chromospheric velocity power spectrum is dominated by oscillations
with frequencies at and above the acoustic cutoff frequency. They are
well correlated with the oscillations in the underlying photosphere,
but they are much reduced in the network. In contrast, the network Ca
II H line center velocity and intensity power spectra are dominated by
low-frequency oscillations with periods of 5-20 min. Their signature
is much clearer in our Ca II H line center measurements than in
previously used diagnostics which are contaminated by signals from
deeper layers. We find that these long-period oscillations are not
correlated with underlying photospheric disturbances, and we discuss
their nature.
---------------------------------------------------------
Title: Book reviews
Authors: Murawski, K.; Grevesse, N.; Piteri, S.; Nieuwenhuyzen, H.;
van der Hage, J. C. H.; Icke, Vincent; Hovenier, J. W.; Rutten, R. J.;
De Greve, J. P.; Kaufmann, P.; Burki, G.; de Jager, Cornelis
1993SSRv...65..365M Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Prospects for very-high-resolution solar physics with the
Simuris interferometric mission.
Authors: Dame, L.; Martic, M.; Rutten, R. J.
1993ESASP1157..119D Altcode: 1993srfs.book..119D
Simuris - the Solar, Solar System, and Stellar Interferometric Mission
for Ultra-high Resolution Imaging and Spectroscopy - employs advanced
interferometric techniques. Its payload includes two major instruments,
which are the Solar Ultraviolet Network (SUN), an interferometric
array of four 20 cm telescopes on a 2 m baseline, and the Imaging
Fourier-Transform Spectrometer (IFTS), which uses light from a 40 cm
Gregory telescope. Both instruments have active pointing capabilities of
3 mas stability, and in addition SUN has an active co-phasing control
to 1/50th of a wavelength. EUV multi-layer telescopes complete the
payload for diagnostics of the very-high-temperature plasma.
---------------------------------------------------------
Title: Book reviews
Authors: Rutten, R. J.; Mewe, R.; Houziaux, L.; Cheng, Chung-Chieh;
van der Klis, M.; Sylwester, Janusz; Tajima, T.; Kresák, Ľ.; Minarik,
S.; de Jager, Cornelis; van der Kruit, P. C.
1993SSRv...65..181R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Oscillations of the Magnetic Network
Authors: Lites, B. W.; Rutten, R. J.; Kalkofen, W.
1993ASPC...46..530L Altcode: 1993mvfs.conf..530L; 1993IAUCo.141..530L
No abstract at ADS
---------------------------------------------------------
Title: Stellar objectives of SIMURIS
Authors: Damé, L.; Coradini, M.; Foing, B.; Rutten, R. J.; Thorne,
A.; Vial, J. C.
1993MmSAI..64..345D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Book Review: The observation and analysis of stellar
photospheres / Cambridge U Press, 1992
Authors: Rutten, R. J.
1993SSRv...65..183R Altcode: 1993SSRv...65..183G
No abstract at ADS
---------------------------------------------------------
Title: SIMURIS: High-Resolution Solar Physics
Authors: Rutten, R. J.; Dame, L.
1993ASPC...46..184R Altcode: 1993mvfs.conf..184R; 1993IAUCo.141..184R
No abstract at ADS
---------------------------------------------------------
Title: Book-Review - the Sun - a Laboratory for Astrophysics
Authors: Schmelz, J. T.; Brown, J. C.; Rutten, R. J.
1993SSRv...65..370S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The SIMURIS interferometric mission: solar physics objectives
and model payload (invited paper)
Authors: Damé, L.; Coradini, M.; Foing, B.; Rutten, R. J.; Thorne,
A.; Vial, J. C.
1993MmSAI..64..333D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: High resolution solar physics.
Authors: Rutten, Robert J.
1992ESASP.354..163R Altcode: 1992tsbi.rept..163R
Solar physics is a prime example of the quest for high spatial
resolution as the coming space frontier of astrophysics. The proximity
of the Sun brings the enormous advantage that modest baselines suffice
to fulfill an important goal: to resolve basic plasma processes at
their characteristic scales. At such resolution, the solar atmosphere
represents a plasma physics laboratory of broad interest. Concerted
observations combining high spatial and temporal resolution with
narrow-band diagnostics in the ultraviolet and the visible will deliver
detailed insights is plasma processes that are ubiquitous in the cosmos,
but resolvable only for the Sun. Space interferometry is the obvious
way to fulfill this promise.
---------------------------------------------------------
Title: The formation of helioseismology lines. I. NLTE effects in
alkali spectra.
Authors: Bruls, J. H. M. J.; Rutten, R. J.; Shchukina, N. G.
1992A&A...265..237B Altcode:
The authors study the NLTE formation of the solar K I and Na I resonance
lines employed in helioseismology. They combine standard modeling of
the solar atmosphere with comprehensive alkali model atoms, complete
up to the Rydberg regime near the continuum, to study various NLTE
mechanisms which interact to make the alkali population balances more
complex than is the case for other minority species. In particular,
they discuss a "photon suction" process which produces overpopulation
of the neutral stage by driving a population flow from the reservoir in
the singly ionized stage. They isolate this and other mechanisms with
specifically tailored model atoms and provide a choice of simplified
model atoms, trading precision against size, which are appropriate
for future use in numerical simulations of the solar atmosphere.
---------------------------------------------------------
Title: The formation of helioseismology lines. II. Modeling of alkali
resonance lines with granulation.
Authors: Bruls, J. H. M. J.; Rutten, R. J.
1992A&A...265..257B Altcode:
The authors model the NLTE formation of the solar Na I and
K I resonance lines for an array of one-dimensional atmospheric
models taken from a numerical simulation of the solar granulation by
Nordlund and Stein. They discuss the nature of alkali-line sensitivity
to granulation using hot and cool extremes from the simulation and
study the granular modulation of diagnostics such as line bisectors and
helioseismological resonance-cell response. They also show that granular
structuring produces apparent spatially-averaged line broadening of
similar magnitude as the ad hoc microturbulent and damping broadening
invoked in traditional plane-parallel modeling.
---------------------------------------------------------
Title: Model payload and system design of the SIMURIS interferometric
mission
Authors: Dame, L.; Rutten, R. J.; Thorne, A. P.; Vial, J. C.
1992wadc.iafcZ....D Altcode:
SIMURIS (Solar, Solar System, and Stellar Interferometric Mission
for Ultrahigh Resolution Imaging and Spectroscopy) has been proposed
to ESA as a Mission in the context of the Space Station in November
1989 in answer to the Call for the Next Medium Size Mission (M2). It
has completed, since, an Assessment Study, and is now proceeding for
a Phase A. SIMURIS employs advanced interferometric techniques. The
payload includes two major instruments which are the Solar Ultraviolet
Network (SUN), an interferometric array of four 20-cm telescopes on
a 2-m baseline, and the Imaging Fourier Transform Spectrometer (IFTS)
which uses light from a 40-cm Gregory telescope. Both instruments have
active pointing capabilities of 3 milliarcsec stability, and SUN has,
in addition, an active cophasing control to 1/50th of a wavelength. EUV
multilayer telescopes complete the payload for diagnostics of the very
high temperature plasma. The SIMURIS model payload will be described
with emphasis on the system design of the interferometric aspects of
the instruments.
---------------------------------------------------------
Title: Solar hydrogen lines in the infrared
Authors: Carlsson, M.; Rutten, R. J.
1992A&A...259L..53C Altcode:
We study recently observed H I lines in the infrared solar spectrum,
employing detailed NLTE modeling to explain their formation and to
evaluate their diagnostic merits. The solar infrared H I lines vary much
in character, depending on opacity and wavelength; our computations
reproduce the observations closely. The line wings are primarily set
by Stark broadening due to metal ions and protons; the line cores are
sensitive to NLTE population departure divergence which is driven by
Balmer-continuum photoionization. The formation heights of the H I
lines range from the deep photosphere for near-infrared line wings
to the chromosphere for line cores with wavelengths greater than 10
microns; these features provide valuable diagnostics of the thermal
structure of the solar atmosphere.
---------------------------------------------------------
Title: Prospects with SIMURIS.
Authors: Dame, L.; Rutten, R. J.
1992ESASP.344...21D Altcode: 1992spai.rept...21D
The authors give an introductory overview of the SIMURIS payload by
briefly presenting its goals and concepts.
---------------------------------------------------------
Title: Design Rationale of the Solar Ultraviolet Network / Sun
Authors: Dame, L.; Acton, L.; Bruner, M. E.; Connes, P.; Cornwell,
T. J.; Curdt, W.; Foing, B. H.; Hammer, R.; Harrison, R.; Heyvaerts,
J.; Karabin, M.; Marsch, E.; Martic, M.; Mattic, W.; Muller, R.;
Patchett, B.; Roca-Cortes, T.; Rutten, R. J.; Schmidt, W.; Title,
A. M.; Tondello, G.; Vial, J. C.; Visser, H.
1992ESOC...39..995D Altcode: 1992hrii.conf..995D
No abstract at ADS
---------------------------------------------------------
Title: The formation of the MG I emission features near 12 microns
Authors: Carlsson, M.; Rutten, R. J.; Shchukina, N. G.
1992A&A...253..567C Altcode:
The formation of two Mg I 12-micron emission features in the
solar spectrum, the existence of which was reported by Murcray et
al. (1981), is explained using plane-parallel nonlocal thermodynamic
equilibrium modeling with a radiative-equilibrium model atmosphere
without chromosphere. It is shown that these emissions are a natural
consequence of population depletion by line photon losses followed by
population replenishment from the ionic reservoir in the highly excited
levels. The results confirm the suggestion by Lemke and Holweger (1987)
that the 12-micron lines are formed in the photosphere and disprove
the claim by Zirin and Popp (1989) that the temperature minimum occurs
much deeper than in standard models of the solar atmosphere.
---------------------------------------------------------
Title: Formation of the MG 112 TTM Lines
Authors: Carlsson, M.; Rutten, R. J.; Shchukina, N. G.
1992ASPC...26..518C Altcode: 1992csss....7..518C
No abstract at ADS
---------------------------------------------------------
Title: Dynamics of the Quiet Solar Atmosphere: K2v Cell Grains Versus
Magnetic Elements
Authors: Brandt, P. N.; Rutten, R. J.; Shine, R. A.; Trujillo Bueno, J.
1992ASPC...26..161B Altcode: 1992csss....7..161B
No abstract at ADS
---------------------------------------------------------
Title: Ca uc(ii) H<SUB>2v</SUB> and K<SUB>2v</SUB> cell grains
Authors: Rutten, Robert J.; Uitenbroek, Han
1991SoPh..134...15R Altcode:
The bright Ca II H<SUB>2v</SUB> and K<SUB>2v</SUB> grains, which
are intermittently present in the interiors of network cells in
quiet-Sun areas, should provide important diagnostics of the dynamical
interaction between the quiet photosphere and the chromosphere
above it, but their nature has so far eluded identification. We
review the extensive observational literature on these grains and on
related phenomena. We resolve various contradictions, connect hitherto
unconnected observations, distill new constraints and relate signatures
in the measurement domain to signatures in the Fourier domain. We then
review interpretations and simulation efforts, adding computations of
our own to illustrate modeling options. We conclude that the grains are
a hydrodynamical phenomenon in which magnetic fields do not play a major
role. The grains are due to interference between a pervasive standing
oscillation with about a 180 s periodicity and an 8 Mm horizontal
wavelength in the chromosphere and the wave trains of the evanescent
p-mode interference pattern in the upper photosphere. The roles of
short-period waves, shock formation and granular piston excitation
and the issue of long-lived patterning remain open; we suggest avenues
for further research.
---------------------------------------------------------
Title: Photospheric dynamics and the NLTE formation of the solar K
I 769.9 NM line
Authors: Gomez, M. T.; Severino, G.; Rutten, R. J.
1991A&A...244..501G Altcode:
Earlier analyses of the K I 769.9 nm resonance line are extended
as a diagnostic of dynamical phenomena in the solar photosphere by
evaluating the effects of dynamical variations on departures from LTE
in the K I spectrum. Representative models for the solar granulation
and the solar five-minute oscillation are used to estimate dynamical
NLTE departures in the K I populations and to compare these to standarad
plane-parallel NLTE modeling. Various NLTE mechanisms operate together
in K I simultaneously with fortuitous cancellations; the resulting
population departures vary less than 30 percent between dynamical
perturbations. These results validate the assumption of departure
invariance, i.e., adopting NLTE population departure coefficients from
a standard static model for use in dynamical perturbations, as a good
first-order approximation in K I 769.9 nm formation studies.
---------------------------------------------------------
Title: Long-Period Oscillations of the Chromospheric Network
Authors: Lites, B. W.; Kalkofen, W.; Rutten, R. J.
1991BAAS...23.1050L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Book-Review - Solar and Stellar Granulation
Authors: Rutten, R. J.; Severino, G.; Rudiger, G.
1991AN....312..147R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: K<SUB>2V</SUB> Cell Grains and Chromospheric Heating (With
1 Figure)
Authors: Rutten, R. J.; Uitenbroek, H.
1991mcch.conf...48R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The solar photosphere: video movies and computer simulations.
Authors: Rutten, R. J.
1990ComAp..14..297R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Temperature Diagnostics of the Upper Photosphere
Authors: Shchukina, N. G.; Shcherbina, T. G.; Rutten, R. J.
1990IAUS..138...29S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Sun-As Line Formation
Authors: Rutten, Robert J.
1990ASPC....9...91R Altcode: 1990csss....6...91R
Spectral line formation in the upper solar photosphere
and temperature-minimum region is discussed to examine the
effectiveness of spatially averaged '1D' modeling in solar and stellar
applications. Problems associated with NLTE radiative transfer are
described for the two-level atom, one bound level with a continuum,
three bound levels, and for multiple levels. Successful applications
of 1D modeling are reviewed where solar photospheric optical lines are
used to calibrate stellar abundance determinations. The homogeneity
or 1D LTE-RE formation of the sun is doubted, and the atmosphere
is described as being highly dynamic. The LTE-RE assumption can be
applied to the spatially averaged upper photosphere, but the problems
associated with the NLTE effects must be considered to investigate
the fine elements of solar structure.
---------------------------------------------------------
Title: The Formation of the Mg I 12-Micron Emission Lines
Authors: Carlsson, M.; Rutten, R. J.; Shchukina, N. G.
1990PDHO....7..260C Altcode: 1990dysu.conf..260C; 1990ESPM....6..260C
Contents: The Mg I 12 μm line, LTE or NLTE, chromospheric formation,
photospheric formation, collisional NLTE; departure diffusion.
---------------------------------------------------------
Title: Solar Oscillator Strengths as a Diagnostic Tool
Authors: Gurtovenko, E. A.; Kostik, R. I.; Rutten, R. J.
1990IAUS..138...35G Altcode:
No abstract at ADS
---------------------------------------------------------
Title: New solar oscillator strengths from Kiev
Authors: Gurtovenko, E. A.; Kostik, R. I.; Rutten, R. J.
1990asos.conf...92G Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Summary Lecture
Authors: Rutten, R. J.
1990IAUS..138..501R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Book-Review - Solar and Stallar Granulation
Authors: Rutten, R. J.; Severino, G.
1989Sci...246..137R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Book-Review - Physics of Formation of Feii Lines Outside LTE
Authors: Viotti, R.; Vittone, A.; Friedjung, M.; Rutten, R. J.
1989SSRv...50..617V Altcode: 1989IAUCo.107..617V
No abstract at ADS
---------------------------------------------------------
Title: Book Review: Physics of formation of Fe II lines outside LTE
(IAU Coll. 94) / Reidel, 1988
Authors: Viotti, R.; Vittone, A.; Friedjung, M.; Rutten, R. J.
1989SSRv...50..618V Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Book-Review - Space - the Next Twenty-Five Years
Authors: Manno, V.; Kresák, Ľ.; de Jong, T.; Trimble, Virginia;
Marov, Mikhail Ya.; Rutten, Robert J.; Vreeburg, J. P. B.; Kaufmann, P.
1989SSRv...50..615M Altcode: 1989IAUCo.107..615M
No abstract at ADS
---------------------------------------------------------
Title: Workshop Introduction
Authors: Rutten, R. J.
1989ASIC..263....1R Altcode: 1989ssg..conf....1R
No abstract at ADS
---------------------------------------------------------
Title: The Granulation Sensitivity of Neutral Metal Lines
Authors: Bruls, J. H. M. J.; Uitenbroek, H.; Rutten, R. J.
1989ASIC..263..311B Altcode: 1989ssg..conf..311B
No abstract at ADS
---------------------------------------------------------
Title: Solar and stellar granulation
Authors: Rutten, Robert J.; Severino, Giuseppe
1989ASIC..263.....R Altcode: 1989ssg..conf.....R
No abstract at ADS
---------------------------------------------------------
Title: Granulation and the NLTE Formation of K I 769. 9
Authors: Gomez, M. T.; Severino, G.; Rutten, R. J.
1989ASIC..263..565G Altcode: 1989ssg..conf..565G
No abstract at ADS
---------------------------------------------------------
Title: The Solar Photosphere: Video Movies and Computer Simulations
Authors: Rutten, Robert J.
1989ComAp..14..297R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The granulation sensitivity of helioseismology lines.
Authors: Rutten, R. J.; Bruls, J. H. M. J.; Gomez, M. T.; Severino, G.
1988ESASP.286..251R Altcode: 1988ssls.rept..251R
The authors address the sensitivity of the Ni I 676.78 nm GONG line and
the K I 769.9 nm resonance line to the temperature fluctuations present
in the solar granulation. The temperature contrasts due to granulation
are probably small in the upper photosphere where the cores of these
two helioseismology lines are formed. However, the cores are sensitive
also to the granulation temperature contrasts in the deep photosphere,
through non-local NLTE effects in their formation. The largest effects
are due to the ultraviolet radiation field, which is strongly modulated
by the granulation in the deep layers where it escapes and carries these
contrasts upwards to the line formation height. The authors discuss
the resulting NLTE mechanisms and their influence on the two lines.
---------------------------------------------------------
Title: The NLTE formation of iron lines in the solar photosphere
Authors: Rutten, Robert J.
1988ASSL..138..185R Altcode: 1988IAUCo..94..185R; 1988pffl.proc..185R
The use of solar iron lines as diagnostics of the solar photosphere is
discussed. NLTE in photospheric iron lines is discussed, including NLTE
mechanisms, the description of NLTE, and published NLTE modeling of Fe
I and Fe II. Iron NLTE and the mean atmosphere is addressed, including
empirical plane-parallel modeling from lines and from continua and
radiative-equilibrium modeling. The use of NLTE to study granulation,
flux tubes, and flux bifurcations in the sun is considered.
---------------------------------------------------------
Title: Oscillator Strengths from the High S/n Solar Spectrum
Authors: Rutten, R. J.
1988IAUS..132..367R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Feii Prospects in Solar Physics
Authors: Rutten, R. J.
1988ASSL..138..317R Altcode: 1988IAUCo..94..317R; 1988pffl.proc..317R
No abstract at ADS
---------------------------------------------------------
Title: Empirical gf-determination from the solar spectrum
Authors: Rutten, Robert J.; Kostik, Roman I.
1988ASSL..138...83R Altcode: 1988IAUCo..94...83R; 1988pffl.proc...83R
The reliability of Fe I and Fe II oscillator strengths determined
empirically from optical solar lines is tested. A comparison is made
between gfW fits to the equivalent widths and gfD fits to the depths
of 354 Fe I lines and 22 Fe II lines for various combinations of input
parameters. The resulting scatter diagrams provide a measure of the
attainable precision.
---------------------------------------------------------
Title: Book reviews
Authors: Kleczek, J.; van Gent, R. H.; Rutten, Robert J.; de Munck,
J. C.; Slottje, C.; Severne, G.; Pecker, Jean-Claude; Postma, H.;
Grishchuk, L. P.; Niewenhuijzen, H.; Schuiling, R. D.; van Beek, H. F.;
Reijnen, G. C. M.; Heidmann, Jean; Lemaire, J.; Bleeker, Johan; Icke,
V.; Neéman, Y.; Feast, M. W.; de Graaff, W.
1986SSRv...43..383K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Book-Review - Progress in Stellar Spectral Line Formation
Theory
Authors: Beckman, J. E.; Crivellari, L.; Rutten, R. J.
1986SSRv...43Q.384B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Book-Review - the A-Stars - Problems and Perspectives
Authors: Wolff, S. C.; Rutten, R. J.
1985SSRv...41..396W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Book-Review - Stellar Atmospheric Structural Patterns
Authors: Thoma, R. N.; Rutten, R. J.
1985SSRv...41..394T Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Velocity Field in the Region of the Temperature Minimum of
the Solar Atmosphere - Preliminary Results of a Determination of
the Amplitude of the General Velocity Field
Authors: Gurtovenko, E. A.; Sheminova, V. A.; Rutten, R. J.
1985SvA....29...72G Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Velocity field in the region of the temperature minimum of
the solar atmosphere - Preliminary results of a determination of
the amplitude of the general velocity field
Authors: Gurtovenko, E. A.; Sheminova, V. A.; Rutten, R. J.
1985AZh....62..124G Altcode:
The weak Fraunhofer lines in the near wings of H, K Ca II lines have
been analysed to study the velocity amplitude of the general velocity
field in the middle and outer photospheric layers. The results
confirm the basic well-known data on the velocity amplitude in the
middle photospheric layers. Besides, it is shown that the radial and
tangential components of the velocity amplitude continue to decrease
with height also in the outer photosphere.
---------------------------------------------------------
Title: Clean lines in the solar flux spectrum
Authors: Rutten, R. J.; van der Zalm, E. B. J.
1984A&AS...55..171R Altcode:
Profile parameters of 602 unblended lines in the Sacramento Peak Atlas
of the visual solar irradiance spectrum are profiled and compared
to earlier measurements of the same lines in the Jungfraujoch Atlas
of the solar disk-center intensity spectrum. The expected effects
of solar rotation and of center-to-limb variations in the intensity
profiles are discussed and compared to the actual trends. Finally,
the spread is discussed.
---------------------------------------------------------
Title: Revision of solar equivalent widths, Fe I oscillator strengths
and the solar iron abundance.
Authors: Rutten, R. J.; van der Zalm, E. B. J.
1984A&AS...55..143R Altcode:
The authors employ detailed modelling of solar Fe I and Fe II lines
to calibrate the correction of equivalent widths for contamination
by unresolved blends. They then determine the equivalent widths
of 750 clean lines in the Jungfraujoch Atlas of the optical solar
spectrum, and they compare these to the values given for the Utrecht
Atlas by Moore et al. (1966). The authors also select clean Fe I
lines, discuss their NLTE formation, construct a NLTE Fe I curve of
growth, provide new oscillator strengths for weak Fe I lines, and
revise the solar iron abundance to N<SUB>Fe</SUB>/N<SUB>H</SUB> =
(4.3±0.5)10<SUP>-5</SUP>. The authors use the results to appraise
the basis and methods of classical stellar abundance determination.
---------------------------------------------------------
Title: Spectral Lines: Diagnostics
Authors: Rutten, R. J.
1984ssdp.conf..379R Altcode:
The author discusses three aspects of employing spatially-averaged
solar lines as diagnostics of small-scale photospheric structure: (1)
partial redistribution vs. turbulence, (2) advertising the extreme limb,
(3) quality of mean models.
---------------------------------------------------------
Title: One Eye Closed - Two Eyes Closed
Authors: Rutten, R. J.
1984ssdp.conf..446R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Book-Review - Automated Data Retrieval in Astronomy
Authors: Jaschek, G.; Heintz, W.; Rutten, R. J.
1983SSRv...36..417J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Book reviews
Authors: Kleczek, J.; Nussbaumer, H.; van der Hucht, K. A.; De Greve,
J. P.; Ooms, G.; Rutten, R. J.; van der Laan, H.; Jäger, F. W.;
Reijnen, G. C. M.; Bijleveld, W.; Kistemaker, J.; de Jager, C.;
Mustel, E. R.; Ne'Eman, Y.; Priest, E. R.; Stiller, H.; Seifert, W.;
Namba, O.; Kuperus, M.; Hoekstra, Roel; Stumpers, F. L. H. M.; Frank,
S.; Zimmerman, J. T. F.; De Loore, C.; Gendrin, R.; Schrijver, J.;
Mulder, P. S.; Pounds, K. A.; Young, R. S.; Houziaux, L.; Engvold,
O.; Bok, B. J.; de Graaff, W.
1983SSRv...36..415K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Empirical NLTE analyses of solar spectral lines. IV - The Fe
I curve of growth
Authors: Rutten, R. J.; Zwaan, C.
1983A&A...117...21R Altcode:
The effects of departures from local thermodynamic equilibrium on
the equivalent widths of solar Fe I lines are studied as an example
for the analysis of the stellar curve of growth. The solar curve of
growth obtained is based on the nonlocal thermodynamic equilibrium
(NLTE) modeling of the solar spectrum of Lites (1972, 1973) and the
best available oscillator strengths for 991 Fe I lines. The empirical
curve obtained relating the equivalent width-wavelength ratio to the
oscillator strength under NLTE is shown to differ appreciably from
curves neglecting the NLTE ionization departures, although these effects
may be corrected by assuming a NLTE-masking model. Theoretical NLTE
curves of growth are also presented, and splittings due to wavelength
dependency, differences in NLTE excitation, and variation in collisional
damping, which are largely hidden by noise in observed values, are
discussed. A new value for the solar iron abundance of 0.000047 times
the hydrogen abundance is also derived.
---------------------------------------------------------
Title: NLTE masking and the Kiev Fe I oscillator strengths.
Authors: Rutten, R. J.
1983HiA.....6..801R Altcode:
This paper describes the empirical solar-spectrum determinations of
the oscillator strengths of 860 Fe I lines by Gurtovenko and Kostik
(1981), and attempts to show their particular value for abundance
analyses of cool stars.
---------------------------------------------------------
Title: Empirical NLTE analyses of solar spectral lines. III - Iron
lines versus LTE models of the photosphere
Authors: Rutten, R. J.; Kostik, R. I.
1982A&A...115..104R Altcode:
We compare observational indications of departures from LTE in
solar Fe I lines with published NLTE computations in the context of
discrepancies between empirical LTE and NLTE models of the solar
atmosphere. We find that the importance of departures from LTE in
Fe I and similar spectra is often underestimated through neglect of
opacity departures. We demonstrate with numerical experiments that the
peculiarities of the LTE models are artifacts due to the neglect of NLTE
departures; in particular, we so explain the Holweger-Müller LTE model
quantitatively. However, we show also that the NLTE formation of most
optical metal lines is fortuitously well-mimicked by LTE computation
when using LTE models. Thus, LTE-derived metal abundances and empirical
oscillator strengths happen to be fairly precise. The same may hold
for the use of theoretical radiative- equilibrium models in stellar
abundance determinations.
---------------------------------------------------------
Title: Rhe sun as a star.
Authors: Rutten, R. J.; Cram, L. E.
1981NASSP.450..473R Altcode: 1981suas.nasa..473R
The ways in which solar astrophysics serves to improve the methodology
for the interpretation of stellar observations and the construction of
stellar atmospheric models are summarized. The astrophysical processes
highlighted are: stellar mass; stellar rotation; stellar magnetism;
stellar composition; stellar companions; and evolutionary history.
---------------------------------------------------------
Title: On the formation of Fe II lines in stellar spectra. I. Solar
spatial intensity variation of lambda 3969.4.
Authors: Cram, L. E.; Rutten, R. J.; Lites, B. W.
1980ApJ...241..374C Altcode:
High-spatial-resolution solar observations of the weak Fe II lambda
3969.4 line are employed to study non-local thermodynamic equilibrium
effects in Fe II line formation. This line is superposed on the wing
of the Ca II H line, which raises its height of formation. The line
shows extraordinary spatial intensity variations, including emission
features whose contrast increases toward the limb. Observed profiles
of the Fe II resonance lines in the UV are used to define formation
parameters in a 15-level atomic model computation, which shows that Fe
II subordinate lines are generally formed out of local thermodynamic
equilibrium as a result of pumping by UV line-wing photons from the
deep photosphere. For the lambda 3969.4 line, this pumping results in
large sensitivity to the atmospheric structure in layers deeper than
the layer of formation of the H-wing background intensity. The absence
of intense emission cores in the Fe II resonance lines, the effects
of partially coherent scattering, and the effects of chromospheric and
photospheric inhomogeneities are discussed. It is found that emission
of lambda 3969.4 provides a diagnostic of the inhomogeneous structure
of the deep photosphere, for the sun and for late-type stars.
---------------------------------------------------------
Title: Solar limb emission lines near CA II H & K and their
spatial intensity variations
Authors: Rutten, R. J.; Stencel, R. E.
1980A&AS...39..415R Altcode:
The paper employs solar observations of high spatial and spectral
resolution to identify emission lines seen in the extended wings of Ca
II H & K near the solar limb. Emission lines in the wings of H &
K represent valuable diagnostics of the atmospheres of cool stars,
with a varying information content which depends on their particular
formation mechanism. In solar spectrograms different emission line
formation mechanisms can be distinguished by the character of the
spatial intensity variation (SIV) apparent in the lines. Various classes
of H & K emission features, their spatial intensity variations and
their formation mechanisms (of which some pose further problems) are
discussed. A new extended list of line identifications is compiled based
on their formation class and compared with other line lists. Evidence
is found that stellar luminosity-sensitive lines tend to show large
spatial intensity variation on the sun.
---------------------------------------------------------
Title: Report from the discussion group on two dimensional
spectroscopy
Authors: Righini, A.; Rutten, R. J.
1980fsoo.conf..308R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Afbuiging van straling door de zon. 1. De zonsverduistering
van 1919.
Authors: Rutten, R. J.
1980Zenit...7..276R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Afbuiging van straling door de zon. 2. Nieuwe metingen.
Authors: Rutten, R. J.
1980Zenit...7..372R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: An open LEST?
Authors: Hammerschlag, R. H.; Rutten, R. J.
1980fsoo.conf..115H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solar observations with high spectral purity: needs and
constraints (This paper was actually presented at the end of
session 4.)
Authors: Rutten, R. J.
1980fsoo.conf..221R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Diagnostic Use of Feii H and K Wing Emission Lines
Authors: Cram, L. E.; Rutten, R. J.; Lites, B. W.
1980LNP...114..102C Altcode: 1980IAUCo..51..102C; 1980sttu.coll..102C
No abstract at ADS
---------------------------------------------------------
Title: Partial redistribution in the solar photospheric Ba II
spectrum.
Authors: Rutten, R. J.; Milkey, R. W.
1979ApJ...231..277R Altcode:
Recent studies of the effects of partial frequency redistribution
(PRD) on the formation of strong chromospheric resonance lines are
extended to weaker lines formed in the photosphere. Methods that have
been derived to compute the PRD formation of the Ca II spectrum are
applied to the solar Ba II spectrum. It is found that PRD is important
in the formation of the 4554-A resonance line, and the results confirm
that its effects on the line source function explain the emission
wings of this line observed near the limb. Source function structure
and line profiles for Ba II 4554 A and Ba II 5854 A are discussed;
they may serve as an example for estimating effects of PRD in other
photospheric lines in stellar atmospheres.
---------------------------------------------------------
Title: An open LEST (Large European Solar Telescope)?
Authors: Hammerschlag, R. H.; Rutten, R. J.
1979MmArc.106..115H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solar observations with high spectral purity: needs and
constraints.
Authors: Rutten, R. J.
1979MmArc.106..221R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Report from the discussion on two-dimensional spectroscopy
requirements for Lest (Large European Solar Telescope).
Authors: Righini, A.; Rutten, R. J.
1979MmArc.106..308R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Empirical NLTE analyses of solar spectral lines. II: The
formation of the Ba II lambda 4554 resonance line.
Authors: Rutten, R. J.
1978SoPh...56..237R Altcode:
The center-to-limb behaviour of the Ba II λ4554 resonance line is
analyzed together with data from the extreme limb, flash intensities
and profiles of other Ba II lines. An empirical NLTE method is employed
in which the observed profiles are compared with synthesized profiles
based on a standard one-dimensional model atmosphere, with the line
source function, the barium abundance, the collisional damping and
the atmospheric turbulence as free parameters.
---------------------------------------------------------
Title: Report from the discussion group on two dimensional
spectroscopy
Authors: Righini, A.; Rutten, R. J.
1978fsoo.conf..308R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solar observations with high spectral purity: needs and
constraints
Authors: Rutten, R. J.
1978fsoo.conf..221R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: An open LEST?
Authors: Hammerschlag, R. H.; Rutten, R. J.
1978fsoo.conf..115H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Extreme limb observations of Ba II λ 4554 and Mg i λ 4571
Authors: Rutten, R. J.
1977SoPh...51....3R Altcode:
Profiles of the Ba II λ 4554 resonance line and the Mg I λ 4571
intercombination line are presented, observed near the limb of the
Sun. They are obtained from eclipse spectrograms with good spectroscopic
resolution and an accurate height calibration. The reduction of the
observations is described and detailed profiles are given for a range
of viewing angles (1/cos θ = 4 - 22).
---------------------------------------------------------
Title: Report of the Dutch expedition to the 1970 March 7 solar
eclipse.
Authors: Houtgast, J.; Namba, C.; Rutten, R. J.
1976PKNAW..79..221H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Report of the Dutch expedition to the 1970 March 7 solar
eclipse. Ch. 1.
Authors: Houtgast, J.; Namba, O.; Rutten, R. J.
1976seob.conf....3H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solar Eclipse Observations and Ba II line formation
Authors: Rutten, Robert Jelle Rob
1976PhDT.......177R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Report of the Dutch expedition to the 1970 March 7 solar
eclipse.
Authors: Houtgast, J.; Namba, O.; Rutten, R. J.
1976PRNAA..79..221H Altcode: 1976RNAAS..79..221H
No abstract at ADS