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Author name code: neckel
ADS astronomy entries on 2022-09-14
author:"Neckel, Heinz"
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Title: Analytical Reference Functions F(λ) for the Sun's Limb
Darkening and Its Absolute Continuum Intensities (λλ 300 to 1100 m)
Authors: Neckel, Heinz
2005SoPh..229...13N Altcode:
It is shown (1) that the coefficients A<SUB>i</SUB> of the limb
darkening functions I(μ)/I<SUB>center</SUB> = P<SUB>5</SUB> (μ) =
∑A<SUB>i</SUB> μ<SUP>i</SUP> (i = 0... 5; μ = cos ϑ), which had
been published by Neckel and Labs (Solar Phys.153, 91, 1994), can
well be approximated by analytical functions of wavelength λ, and
(2) that at first sight purely formal extrapolation of the functions
P<SUB>5</SUB>(μ) to the very limb (μ = 0.0) is not meaningless:
in combination with absolute intensities for the disk center these
functions yield `limb intensities' which all correspond to almost the
same `limb temperature', T<SUB>limb</SUB>≈4746 K. Together these
results lead to `reference functions' which can quickly yield rather
reliable values of the Sun's continuum intensities, for any values of
μ and λ.
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Title: On the sun's absolute disk-center and mean disk intensities,
its limb darkening, and its `limb temperature' (λλ330 to 1099 nm)
Authors: Neckel, Heinz
2003SoPh..212..239N Altcode:
The coefficients A<SUB>0</SUB> of the limb-darkening functions
I(μ)/I<SUB>center</SUB>=P<SUB>5</SUB>(μ)=ΣA<SUB>i</SUB>μ<SUP>i</SUP>
(i=0,...5, μ=cos θ), published by Neckel and Labs (1994), and the
corresponding disk-center intensities I<SUB>center</SUB>=I(μ=1),
which were taken from the absolutely calibrated Kitt Peak FTS
Atlas of the disk center (Brault et al., see Neckel and Labs,
1984, and Neckel 1999), are used to derive `limb intensities'
I<SUB>limb</SUB>=I(μ=0)=A<SUB>0</SUB>I<SUB>center</SUB>. The
corresponding `limb temperatures' T<SUB>limb</SUB> vary only
slightly with wavelength; the mean value (≃4750 K) and the
wavelength of maximum intensity (≃605 nm) conform to Wien's law
(λ<SUB>max</SUB>T=0.288 cm K). Further, T<SUB>limb</SUB> agrees closely
with that temperature, which follows from Avrett's (2000) model of the
photosphere for τ<SUB>500</SUB>≃0.006; for this layer the optical
thickness along the line of sight is close to 1 (`the limb'; compare
Unsöld, 1968). The slight variation of T<SUB>limb</SUB> with wavelength
is presumably due to systematic errors in the Neckel and Labs intensity
data: it corresponds almost precisely to the differences between their
data and the more recent ones provided by, e.g., Burlov-Vasiljev,
Gurtovenko, and Matvejev (1995), and Burlov-Vasiljev, Matvejev, and
Vasiljeva (1998). Two simple correction functions (for λ≦550 nm and
λ≧550 nm) are proposed, which apply to all Neckel and Labs intensity
data (disk center and full disk, line spectrum and (quasi) continuum),
and to the absolutely calibrated Kitt-Peak FTS Atlas (spectra of disk
center and full disk) as well.
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Title: Solar Photosphere: Center-to-limb Variation
Authors: Neckel, H.
2001eaa..bookE2012N Altcode:
Many phenomena which are observable on the Sun's `surface' change
in characteristic ways between the center and LIMB of the apparent
disk (e.g. the shapes of sunspots, the profiles of Fraunhofer lines,
etc). The most obvious and easily noticeable (e.g. at sunrise or sunset,
or on a good photograph) center-to-limb variation is the decrease of
brightness from the disk center ...
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Title: Alfred Bohrmann (28. Februar 1904 - 4. Januar 2000).
Authors: Neckel, H.
2000MitAG..83....5N Altcode:
No abstract at ADS
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Title: Announcement
Authors: Neckel, H.
1999SoPh..184..421N Altcode:
Announcement of the on-line availability of a digital atlas of the solar
disk-center intensity spectrum and the disk-averaged flux spectrum,
both based on observations with the Fourier Transform Spectrometer at
the McMath-Pierce telescope at Kitt Peak by Brault and Testerman and
calibrated to absolute intensity units following the analyses of Labs
and Neckel.
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Title: On the Wavelength Dependency (and its Variations) of the
Ratio Disk-Averaged to Disk-Center Intensity, F/I<SUB>0</SUB>
(λλ0.385 to 10 µm)
Authors: Neckel, Heinz
1997SoPh..171..257N Altcode:
In the whole wavelength range, 0.385 to 10.0 µm, the ratios
F/I<SUB>0</SUB> of disk-averaged intensity F to disk-center intensity
I<SUB>0</SUB> follow very closely the simple relation F/I<SUB>0</SUB>
= 0.975 - 0.091λ<SUP>-1</SUP> - 0.00024λ<SUP>-5</SUP>. The residuals
exhibit a well-defined structure with minima and maxima in the order
of± 5 × 10<SUP>-3</SUP> , which reflect the wavelength-dependency
of the source function B(λ,τ) and the continuous absorption
coefficient . The fact that the scatter of the coefficients of
the relevant limb-darkening functions is usually much larger
than the scatter of the F/I<SUB>0</SUB> ratios seems to confirm
the occurrence of limb-darkening variations, which however leave
the F/I<SUB>0</SUB> ratios almost unchanged. Nevertheless, minor
differences between different observations, which concern the details
in the wavelength-dependency of the F/I<SUB>0</SUB> residuals, seem to
indicate that even the F/I<SUB>0</SUB> ratios undergo minor variations.
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Title: On the consistency of solar limb darkening observations at
UV wavelengths (2000-3300A).
Authors: Greve, A.; Neckel, H.
1996A&AS..120...35G Altcode:
Limb darkening observations are important for the construction and
verification of solar model atmospheres. We investigate the consistency
of solar limb darkening data, published for the UV wavelength region
between 2000 and 3300A, from the comparison of F/I_0_ ratios based
either on direct limb darkening observations or on absolute irradiance
(F) and disk-center intensity (I_0_) measurements. There exists
a discrepancy between the limb darkening data of Moe & Milone
(1978ApJ...226..301M) and other, direct or indirect, limb darkening
observations.
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Title: On the wavelength dependency of solar limb darkening (λλ303
to 1099 nm)
Authors: Neckel, Heinz
1996SoPh..167....9N Altcode:
The limb-darkening data published by Neckel and Labs (1994) (5th-order
polynomials P<SUB>5</SUB>(μ), μ = cos θ) are used to represent the
limb darkening by the functions L<SUB>n</SUB>(μ), proposed first by
Kourganoff (1949a). When plotted against wavelength, the coefficients
of these functions show a rather low scatter and appear to be linear
functions of either λ<SUP>−1</SUP> or λ<SUP>#x2212;5</SUP>.
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Title: A study of solar analogues in the ultraviolet.
Authors: Fernley, J.; Neckel, H.; Solano, E.; Wamsteker, W.
1996A&A...311..245F Altcode:
We have made a comparative study of the Sun and solar analogue stars
using the published solar ultraviolet fluxes and IUE low dispersion
spectra of the solar analogues. The Hyades dwarf HD 28099 (vB64)
shows a flux excess below 2500A which is probably due to chromospheric
activity since it is a relatively young star. HD 44594, 186408 (16CygA)
and 186427 (16CygB) all show very similar ultraviolet spectra to the
Sun. From a comparison with Kurucz ATLAS9 models we find 16CygA and B
to be metal-rich by 0.02+/-0.03dex with temperatures of 5790+/-20K and
5750+/-20K respectively, assuming a solar temperature of 5770K. These
results are consistent with other recent work. For HD 44594 we find
T_e_=5760+/-20K and [M/H]=0.01+/-0.03 which is significantly less
metal-rich than found in the recent work of Cayrel de Strobel &
Bentolila (1989). We have also checked the ultraviolet absolute flux
scale by comparing the ratio of the solar analogue fluxes to the solar
flux at both optical and ultraviolet wavelengths. For 16CygA and B
we find that, after normalising in the optical and using the ATLAS9
models to correct the ultraviolet fluxes of the solar analogues for
their small metallicity excess, there is a discrepancy of 16(+/-4)%
in the sense that the IUE absolute calibration gives fluxes that are
too low or the absolute scale of the solar uv flux measurements is
too high. This can be reduced to 6(+/-4)% if we firstly accept a 7%
higher IUE absolute scale as suggested by independent evidence, and
secondly use only the older solar ultraviolet flux measurements of
Heath (1980) & Mentall et al. (1981) and ignore the more recent
work of Labs et al. (1987). Finally we have inverted the problem and
asked which of the three solar flux measurements (Heath, Mentall et
al. or Labs et al.) fit better the slope of the ultraviolet continuum
of the solar analogue IUE data. As with the absolute scale we find
better agreement with the older measurements of Heath and Mentall et
al. than with the more recent work of Labs et al.
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Title: On the Relation between the Sun's (Geocentric) Angular Diameter
and the Observed (Topocentric) `Drift Time'
Authors: Wittmann, Axel D.; Neckel, Heinz
1996SoPh..163....1W Altcode:
It is pointed out that the relation between the Sun's geocentric
diameter and the so-called drift time observed on the Earth's surface
does not depend on topocentric data (distance, declination, parallax,
refraction), but only on the geocentric values of distance, declination,
and variation of right ascension.
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Title: The Solar Radius Derived from Limb-Darkening Scans Obtained
in 1981 and from 1986 to 1990
Authors: Neckel, Heinz
1995SoPh..156....7N Altcode:
Solar-radius data are presented which result from observations made
in 1981 and from 1986 to 1990. These data, which are a by-product of
the limb-darkening observations made by Neckel and Labs (1984, 1994),
do not show significant deviations from the value which is adopted
from Auwers (1891) for computations of solar eclipses and of the Sun's
ephemeris in theAstronomical Almanac.
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Title: Solar Limb Darkening 1986-1990 Lambda 303-NANOMETERS to
1099-NANOMETERS
Authors: Neckel, Heinz; Labs, Dietrich
1994SoPh..153...91N Altcode:
The Sun's limb darkening was observed repeatedly between the 1986
minimum and the 1990 maximum of solar activity.Systematic variations,
which could depend either on the momentary activity and/or the phase in
the solar cycle, werenot detectable, either at continuum wavelengths or
in two broad-band spectral intervals. Completelyirregular variations,
which concern not only individual, successive scans (due to granulation,
etc.), but also thedaily andseasonal averages, are usually less
than 1%, but can reach occasionally 2% or even more. Minoreast-west
asymmetries even in the seasonal means seem to be well established,
mainly for λ < 400 nm. Thefinal, mean limb-darkening coefficients
agree basically with those published by Pierce and Slaughter (1977)
and Pierce, Slaughter, and Weinberger (1977), but show a much lower
scatter when plotted against wavelength.
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Title: Solar Absolute Reference Spectrum
Authors: Neckel, H.
1994svsp.coll...37N Altcode: 1994IAUCo.143P..37N
No abstract at ADS
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Title: Variations of `wavelengths' and `bisector indices' of 70
solar spectral lines between 3300 and 3960 Å in Kitt Peak FTS spectra
Authors: Neckel, Heinz; Labs, Dietrich
1990SoPh..126..207N Altcode:
Wavelengths and bisector indices (a special measure for the asymmetry
of a line near its bottom) are determined for 70 lines in each of 47
high-dispersion spectra. The spectra were obtained with the Fourier
Transform Spectrograph connected to the McMath Telescope at Kitt Peak
National Observatory; they all cover the same spectral range from
3200 to 4000 Å and concern either the full disk (19 `disk' spectra),
or the disk center (9 `center' spectra), or two areas at sin ϑ =
0.85 on the west- and east-side of the disk (19 `limb' spectra). The
main observing seasons were June 1986, June 1987, April and June/July
1988. The - relative - position of an individual line in one spectrum
can be established with a precision of about 4 m s<SUP>-1</SUP>,
the precision of one bisector index is 1-2 m s<SUP>-1</SUP>.
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Title: The role of telescopic stray light in limb-darkening scans
obtained in April 1981 (and later)
Authors: Neckel, Heinz; Labs, Dietrich
1990SoPh..126...47N Altcode:
The suspicion of Elste (1990), that telescopic stray light together
with imperfect collimation of telescope and spectrograph could be a
possible explanation for the systematic differences and variations found
by Neckel and Labs (1987) in many limb-darkening scans, proves to be
unfounded for the following reasons: (1)The collimation was performed
very precisely; (2) the telescope mirrors remained fixed in position
and direction during most of the observing period; (3) stray light
effects depending on hour angle were not detectable; (4) in the same
collimation status, also many almost symmetric scans had been recorded;
(5) the observed east-west differences in the solar intensities are
partly even larger than the total amount of stray light (from telescope
and sky!) observed as `sky'-background just outside the limb; (6)
any east-west differences in the `sky'-background near the limb are
just a few 0.01% of the disk center intensity; (7) the differences of
the average intensities along eastern and western radius appear to be
correlated with the east-west differences of the intensity's R.M.S.
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Title: Pennäler-Astronomie in verrückter Zeit.
Authors: Neckel, H.
1989S&W....28..296N Altcode:
No abstract at ADS
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Title: Multiplier hysteresis and image motion errors in limb darkening
scans obtained in April 1981 (and later)
Authors: Neckel, Heinz; Labs, Dietrich
1989SoPh..120..205N Altcode:
In response to the comment of P. Foukal (1989) we show that in our
limb darkening observations multiplier hysteresis and image motion
(seeing) can be ruled out as major sources of error.
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Title: SYSTEMATIC OBSERVATIONS OF THE SUN (In honour of Helen Dodson
Prince): Observations
Authors: McIntosh, P.; Snodgrass, H.; Mouradian, Z.; Harvey, K.;
Altrock, R.; Simon, P.; Legrand, J. -P.; Alissandrakis, G.; Neckel,
H.; Petropoulos, P.; Poulakis, X.; Gokhale, M. H.; Sivaraman, K. R.;
Pap, J.
1989HiA.....8..672M Altcode:
No abstract at ADS
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Title: Asymmetry and Variations of Solar Limb Darkening
Authors: Neckel, H.; Labs, D.
1988srov.proc..201N Altcode:
No abstract at ADS
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Title: Ultraviolet Solar Irradiance Measurement from 200-NM to 358-NM
during SPACELAB-1 Mission
Authors: Labs, D.; Neckel, H.; Simon, P. C.; Thuillier, G.
1987SoPh..107..203L Altcode:
The paper presents the results obtained from the UV-spectrometer of the
`Solar Spectrum Experiment' during the Spacelab 1 mission in December
1983. The irradiance data concern 492 passbands, which are located
between 200 and 358 nm at almost equidistant wavelengths separated by
about 0.3 nm. The passbands have a well-defined, bell-shaped profile
with a full width at half maximum of about 1.3 nm. The data, which
have an error budget between 4 and 5%, agree closely with the spectral
distributions observed by Heath (1980) and Mentall et al. (1981) and
confirm that the solar irradiance and the fluxes of Sun-like stars
show about the same spectral distribution down to at least 240 nm.
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Title: Erratum - the Bright Stars with Ubv-Colors Close to those of
the Sun
Authors: Neckel, H.
1987A&A...176..372N Altcode:
No abstract at ADS
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Title: Asymmetry and variations of solar limb darkening along the
diameter defined by diurnal motion in April 1981
Authors: Neckel, Heinz; Labs, Dietrich
1987SoPh..110..139N Altcode:
Unexpected asymmetries and variations, which showed up in the first,
preliminary reductions of new limb-darkening observations made in
June 1986, near the present minimum of solar activity, stimulated a
re-analysis of our limb-darkening observations made in April 1981 at
Kitt Peak (Neckel and Labs, 1984). The results seem to indicate rather
definitely that the intensity distribution across the disk varies at
all observed wavelengths between 3300 and 6600 Å with amplitudes in
the order of 1-2 % and time-scales from minutes to hours. Asymmetries
in the intensity distribution with respect to the disk center are a
frequent phenomenon. There can be no doubt, that also the absolute
disk center intensity undergoes variations with comparable size
and modulation, as they were in fact recently observed by Koutchmy
and Lebecq (1986). Presumably, the solar oscillations contribute a
significant part to the observed effects. However, due to the 5-7 min
periodicity of our observations no definite conclusions can be drawn.
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Title: Ultraviolet solar irradiance measurement from 200 to 358 NM
during Spacelab 1 mission
Authors: Labs, D.; Neckel, H.; Simon, P. C.; Thuillier, G.
1987STIN...8725262L Altcode:
Results obtained from the UV-spectrometer of the Solar Spectrum
Experiment during the Spacelab 1 mission are presented. The irradiance
data concern 492 passbands, which are located between 200 and 358 nm
at almost equidistant wavelengths separated by 0.3 nm. The passbands
have a well defined, bell-shaped profile with a full width at half
maximum of 1.3 nm. The data, which have an error budget between 4%
and 5%, agree closely with the spectral distributions observed by Heath
(1980) and Mentall et al (1981) and confirm that the solar irradiance
and the fluxes of Sun-like stars show the same spectral distribution
down to at least 240 nm.
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Title: The "bright stars" with UBV-colors close to those of the Sun.
Authors: Neckel, H.
1986A&A...169..194N Altcode:
The paper provides a compilation of the main physical characteristics of
all stars included in the "Bright Star Catalogue" (and of four fainter
stars), which are quoted to be of luminosity class IVa to Vb and which
fulfil one of the following conditions: (1) B-V and U-B are close to the
solar values; (2) B-V and spectral type are close to the solar values,
while U-B is unknown; (3) the BSC-spectral type is G2 V, but B-V and/or
U-B differ appreciably from the solar values. The compilation is given
to facilitate the selection of stars which are most suited to serve
as a Sun's proxy in the night-sky or which even can be considered as a
"solar analog" in as many desired aspects as possible.
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Title: Absolute magnitudes and luminosity-related physical parameters
of the'solar analog' - candidates 16 CYG A and B.
Authors: Neckel, H.
1986A&A...167...97N Altcode:
Supposing that 16 Cyg A and B are the components of a binary system
and therefore have the same age, upper limits of the luminosity can be
derived from the conditions that (1) in a luminosity-T<SUB>eff</SUB>
diagram both stars should lie on or near the same isochrone and (2)
the variations of position angle and apparent distance with time and the
difference in radial velocity are the result of the orbital motion. Both
methods yield maximum distances to 16 Cyg significantly smaller than
the distance following from the trigonometric parallax. A differential
treatment of the evolutionary tracks of stars with masses around
one solar mass yields for the two stars: age between 7 and 9 billion
years, absolute visual magnitudes M<SUB>A</SUB> ≈ 4<SUP>m</SUP>.26,
M<SUB>B</SUB> ≈ 4<SUP>m</SUP>.50 (M_sun; = 4<SUP>m</SUP>.82), masses
M<SUB>A</SUB> ≈ 0.99 M_sun;, M<SUB>B</SUB> ≈ 0.96 M_sun;, radii
R<SUB>A</SUB> ≈ 1.25 R_sun;, R<SUB>B</SUB> ≈ 1.15 R_sun;. As a
by-product one obtains also the corresponding data for another 'solar
analog'-candidate, namely van Bueren 64: age about 0.8 billion years,
M<SUB>64</SUB> = 4<SUP>m</SUP>.91, M<SUB>64</SUB> ≈ 1.03 M_sun;,
R<SUB>64</SUB> ≈ 0.95 R_sun;.
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Title: The absolute energy distributions of the sun, of the 'solar
analogs' 16 CYG B, Hyades VB 64, 16 CYG A and of the standard stars
alpha LYR and 29 Psc.
Authors: Neckel, H.
1986A&A...159..175N Altcode:
The absolute energy distributions of the solar analog 16 Cyg B,
which have been published by Hardorp (1980b) and Taylor (1984a),
are compared with the Sun's absolute energy distribution by Neckel
and Labs (1984). To avoid any passband mismatches, the absolutely
calibrated (Neckel and Labs, 1984) version of the high resolution
solar flux atlas of Kurucz et al. (1984) was used to derive solar
magnitudes for exactly the same passbands that were used for the
stellar measurements. The magnitude differences star minus Sun reveal
an overall, λ/1-proportional gradient corresponding to Δ(Θ)
= Δ(5040/T) ≍ 0.009 ± 0.002, on which is superimposed a wavy
pattern with amplitudes being generally near 0.<SUP>m</SUP>02. At a
few wavelengths one or the other stellar data set - but never both -
yields residuals up to 0.<SUP>m</SUP>04. Regarding also the differences
(a) between observed and model-predicted energy distributions,
(b) between 'old' and 'new' energy distribution of α Lyr, and (c)
between the energy distributions of different solar analogs, it seems
that most if not all of the wavy pattern is caused by systematic,
wavelength-dependent errors originating somewhere in the long sequence
of observations rather than by genuine characteristics of the stellar
or solar radiation. Supposing then that the 'true' 16 Cyg B minus Sun
differences run as smoothly as the observed differences between 16
Cyg B and other solar-type stars (e.g. 16 Cyg A), and allowing for
remaining errors in the absolute energy distributions involved, the
solar UBV-colors should lie within the following limits (see Table
4): (B - V)<SUB>sun</SUB> = 0.<SUP>m</SUP>650 ± O.<SUP>m</SUP>005,
(U - B)<SUB>sun</SUB> = O.<SUP>m</SUP>195 ± O.<SUP>m</SUP>005. With
V<SUB>αLyr</SUB> = 0.<SUP>m</SUP>03 and V<SUB>16CygB</SUB> =
6.<SUP>m</SUP>20 we get V<SUB>sun</SUB> = - 26.<SUP>m</SUP>75; its
error is presumably less than ± 0.<SUP>m</SUP>025.
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Title: On the absolute energy distributions of the sun, of the
"solar analogs" 16 Cyg B, 16 Cyg A, VB 64 and of Vega.
Authors: Neckel, H.
1986HiA.....7..863N Altcode:
The internal errors and overall accuracy of the disk-center and
disk-averaged solar spectra of Neckel and Labs (1984) are analyzed;
the absolute solar flux spectrum is compared with the predictions of the
Kurucz (1979) model and with the absolute spectra of four solar analogs;
and the physical parameters of 16 Cyg A and B are discussed. The
results are presented in graphs and tables and characterized. Error
waves of amplitude less than 1 percent are found in the spectra of
the sun and Vega. Assuming an orbital period of less than 200,000 yr
and a radial velocity of about 1 km/s for 16 Cyg A/B, the upper limit
of its distance is estimated as 23 pc, corresponding to an absolute
magnitude of 4.4 or fainter for 16 Cyg B.
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Title: Solar line blocking for disk-center and disk-averaged radiation
from 3300 to 6860 Å
Authors: Neckel, H.; Labs, D.
1985SoPh...95..229N Altcode:
The line blocking is tabulated for 10 Å (λ < 6300 Å) or 20 Å
(λ > 6300 Å) wide intervals. It follows from the spectral averages
and the local continuum derived by Neckel and Labs from high-resolution
Fourier transform spectra, which had been obtained by J. Brault at
Kitt Peak. The internal accuracy (the scatter) is in the order of
0.1%. Significant systematic errors arising from local distortions
of the adopted continuum level can be excluded. Larger errors are to
be expected only near the Balmer limit, where the localization of the
`continuum' is very ambiguous.
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Title: On the absolute energy distributions of the Sun, of the "solar
analogs" 16 Cyg B, Hyades VB 64, 16 Cyg A, and of the standard stars
α Lyr and 29 Psc.
Authors: Neckel, H.
1985SSNew...7....4N Altcode:
No abstract at ADS
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Title: High-precision solar radiation data for λλ3300 - 12500 Å.
Authors: Neckel, H.; Labs, D.
1985IAUS..111..473N Altcode:
No abstract at ADS
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Title: Recent improvements of the basic solar radiation data for
λλ 3300-12500 å
Authors: Neckel, H.
1984SSRv...38..187N Altcode:
This paper reviews shortly the most reliable observations, which are
available at present to describe the basic characteristics of the
solar radiation: absolute measurements of the disk-center intensity,
high resolution spectra of disk-center intensity and irradiance, and
scans of the center to limb variation at continuum wavelengths and
for the line-averaged radiation. Further it reports recent results
obtained by the merging of these observations, namely high precision
data for disk-center intensity and irradiance, which concern not only
the line-averaged radiation, but also the position of the continuum.
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Title: Measurement of the Solar Spectral Irradiance from 200 to
3000 Nanometers
Authors: Thuillier, G.; Goutail, J. P.; Simon, P. C.; Pastiels, R.;
Labs, D.; Neckel, H.
1984Sci...225..182T Altcode:
The solar spectrum experiment on Spacelab 1 measured 98 percent of
the sun's total energy output. It improved the absolute accuracy of
solar irradiance data, especially in the ultraviolet and infrared
regions. In order to detect any variation in the spectrum on future
shuttle flights, the data were obtained in a radiation scale that
can be preserved with high precision over many years. The instrument
performance and preliminary data reduction are described.
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Title: The solar radiation between 3300 and 12500 Å
Authors: Neckel, H.; Labs, D.
1984SoPh...90..205N Altcode:
Results are presented, which follow from the merging of: (a) our
previously published absolute integrals of the disk-center intensity
for 20 Å wide spectral bands; (b) the ratios of mean to central
intensity derived from recent observations of the center-to-limb
variation of those bands (λ <6600 Å); (c) the ratios of mean to
central intensity derived from the observations of the center-to-limb
variation at continuum-wavelengths according to Pierce and Slaughter (λ
>6600 Å); (d) the high resolution Fourier transform spectra obtained
by J. Brault at Kitt Peak for the disk-center and the irradiance;
(e) some further auxiliary data, which served mainly to eliminate the
local perturbations caused by lines of telluric molecular bands.
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Title: Erratum - the Solar Radiation Between 3300 and 12500A
Authors: Neckel, H.; Labs, D.
1984SoPh...92..391N Altcode:
No abstract at ADS
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Title: Sonnenbeobachtungen vom Raumlabor "Spacelab" aus.
Authors: Neckel, H.
1983wuh..conf...27N Altcode:
No abstract at ADS
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Title: An instrument to measure the solar spectrum from 170 to 3200
nm on board Spacelab.
Authors: Thuillier, G.; Simon, P. C.; Labs, D.; Pastiels, R.;
Neckel, H.
1981SoPh...74..531T Altcode:
This instrument, at the present time in development, will fly on board
Spacelab I in May 1983. Other flights are foreseen during the following
missions. This instrument is composed by three double monochromators
covering the range 170 to 3200 nm. The spectrometers have band-passes
of 1 nm up to 900 nm and 20 nm from 850 to 3200 nm with an accuracy
10<SUP>−2</SUP> nm. Calibration lamps are included in the instrument
to monitor any change of its sensitivity and wavelength scale.
---------------------------------------------------------
Title: An instrument to measure the solar spectrum from 170 to 3200
NM on board Spacelab
Authors: Thuillier, G.; Simon, P. C.; Pastiels, R.; Labs, D.;
Neckel, H.
1981NASCP2191..165T Altcode: 1981vsc..conf..165T
This instrument, at the present time in development, will fly on board
Spacelab I in May 1983. Other flights are foreseen during the following
missions. The instrument is composed of three double monochromators
covering the range 170 to 3200 nm. The spectrometers have bandpasses
of 1 nm up to 900 nm and 20 nm from 850 to 3200 nm with an accuracy
1/100 nm. Calibration lamps are included in the instrument to monitor
any change of its sensitivity and wavelength scale.
---------------------------------------------------------
Title: Improved Data of Solar Spectral Irradiance from 0.33-MICRONS
to 1.25-MICRONS
Authors: Neckel, H.; Labs, D.
1981SoPh...74..231N Altcode:
The conversion of our centre of disk intensities published in 1968/70
into mean disk intensities has been repeated, using more accurate
data for the centre-to-limb variation of both continuous radiation
and strong absorption lines.
---------------------------------------------------------
Title: An Instrument to Measure the Solar Spectrum from 170 TO 3200
NM on Board Spacelab
Authors: Thuillier, G.; Simon, P. C.; Labs, D.; Pastiels, R.;
Neckel, H.
1981sucl.conf..421T Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The distribution of masses, ages and luminosities of population
I field giants.
Authors: Neckel, H.
1975A&A....42..379N Altcode:
An attempt is made to obtain an independent semitheoretical estimate
of the actual mass, age, and luminosity distributions of stars in
the giant region of the HR diagram. An analytical approximation for
the mass spectrum of the field giants is derived using the initial
luminosity function, the time dependence of the stellar birth rate, and
the lifetimes of stars on the main sequence and in the giant region. The
predicted mass spectrum is found to exhibit a very pronounced maximum
for stars with masses slightly exceeding one solar mass and which were
born on the main sequence in the first stages of star formation. The
resulting space density is shown to be in close agreement with values
deduced from star counts. The predicted magnitude distribution and
the predicted position of the field giant branch in the HR diagram
are found to agree well with results obtained by recalibrating the
Mt. Wilson absolute magnitudes for giants and supergiants using the
Wilson-Bappu effect.
---------------------------------------------------------
Title: Helligkeiten und Farben von 1030 frühen M-Sternen in der
nördlichen Milchstraße
Authors: Neckel, H.
1975MitAG..36..160N Altcode:
During the time period from 1967 to 1971 measurements were conducted
in Greece and Chile of the brightness and the color of 1030 M2 and
M3 stars which are located in a zone along the galactic equator. The
zone is 12 deg wide and an area from 6 to 235 deg longitude has
been considered. Aspects of interstellar absorption are discussed
and attention is given to questions concerning the variability of
giant stars.
---------------------------------------------------------
Title: Absolute Helligkeiten und Massen der Sterne des Feldriesenastes
Authors: Neckel, H.
1975MitAG..36..166N Altcode:
Equations are presented for calculation of the Ca II K emission
linewidth, gravitational acceleration, effective temperature, mass,
and absolute magnitude of stars in the giant sequence. The time
course of these quantities is also evaluated. Results of the present
and previous calculations are graphed and analyzed. The emission
linewidth is influenced by metal frequency; giants low in metal
content are developed stars of relatively small mass which because of
their development occur to the right in the main sequence. Low metal
frequency thus causes a decrease in linewidth, i.e., leads the star
back into the neighborhood of the main sequence.
---------------------------------------------------------
Title: Precision and Consistency of Current Solar Radiation Data
Authors: Neckel, H.
1975scea.conf..317N Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On a possible generalization of the Wilson-Bappu effect.
Authors: Neckel, H.
1974A&A....35...99N Altcode:
Summary. A dependence of the Ca ii K line emission width W0 on gravity
g and effective temperature Te as suggested by Reimers (1973) for
late type stars would imply the following facts: 1. Main sequence
stars and stars with horizontal evolutionary tracks in the Mbol -
log Te diagram obey strictly a linear relation between log W0 and
visual absolute magnitude M ("main sequence relation"). 2. Stars
with an upward component (A MboI) of the evolutionary track fall
below the main sequence relation by an amount which is 0.33 A Mbol
and which corresponds to the systematic deviations to be found in
any two-dimensional spectral classification. 3. In the Mv - log W0
diagram the evolutionary tracks of stars, which deviate from the
mass-luminosity re lation, are straight lines which are slightly
tilted against the main sequence relation. Stars with different masses
move along parallel lines. 4. Metal deficiency in old stars with an
essentially upward evolution could tend to preserve the main sequence
relation. 5 Mv and log W0 fix essentially mass and evolutionary status
(namely A Mbot) of single stars, if their metal content is normal or
metal deficiency can be accounted for. Key words: Wilson-Bappu effect
absolute magnitudes - masses of late type stars
---------------------------------------------------------
Title: Photoelectric catalogue of 1030 BD M-type stars located along
the galactic equator.
Authors: Neckel, H.
1974A&AS...18..169N Altcode:
The majority of the catalogued stars, all of which are of spectral
type M2 or M3, have been observed two or more times. Because all
stars are potential candidates for being variable, the magnitudes (V)
and colours (BV) are given for each individual observation. The mean
errors are estimated to be about + 0W()20 in V and + 0T01 5 in B-V 63
stars are known or suspected variables. 128 stars are new variables
according to these observations. A crude estimate indicates that about
20 per cent of the M2 stars, and 35 per cent of the M3 stars will show
noticeable variations. Some stars with a relatively low colour index
may be nearby dwarfs; two stars are suspected to be flare stars. Key
words: photoelectric magnitudes - M-type stars
---------------------------------------------------------
Title: Absolute Solar Intensities and the Solar Constant
Authors: Neckel, H.; Labs, D.
1973IAUS...54..149N Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Intensity of the center of the solar disk in the spectral
region 0.33 to 1.25 micron measured from high mountain station
Authors: Labs, D.; Neckel, H.
1973srmi.symp..269L Altcode:
The method and techniques of absolute radiation measurements are
examined. Topics discussed include: calibration procedures; measurement
of the intensity of the center of the solar disk vs the mean intensity
of the whole disk; high spectral resolution vs a larger bandwidth;
and ground-based measurements vs airborne measurements. Measurements
of the intensity of the center of the solar disk from a high mountain
station are described.
---------------------------------------------------------
Title: Absolute Magnitudes and Colours of Field Giant Branch Stars
Authors: Neckel, H.; Klawitter, P.
1973IAUS...54...57N Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Proposal for a consistent system of the basic solar radiation
data
Authors: Neckel, H.; Labs, D.
1973srmi.symp..326N Altcode:
The interrelationships between solar radiation data are
considered. Consistent solar radiation tables are constructed. The
tables are easily compared and checked with both observations and
computations of the central disk continuum as well as with observations
of the solar irradiance or its integral value, the solar constant.
---------------------------------------------------------
Title: Remarks on the Convergency of Photospheric Model Conceptions
and the Solar Quasi Continuum
Authors: Labs, Dietrich; Neckel, Heinz
1972SoPh...22...64L Altcode:
A comparison is made of the observed intensity in the solar continuous
spectrum with those predicted by some models. Arguments are given
that the bend-off observed for λ< 0.6 μ is a real phenomenon,
and due to a veiled line haze.
---------------------------------------------------------
Title: The Solar Constant (A Compilation of Recent Measurements)
Authors: Labs, Dietrich; Neckel, Heinz
1971SoPh...19....3L Altcode:
A detailed compilation of the most recent values of the solar constant
is given (13 values published from 1967 to 1970). The most probable
value seems to be 1.95 cal cm<SUP>−2</SUP> min<SUP>−1</SUP>
or 1.36 kW m<SUP>−2</SUP> with a formal rms error of ± 0.3%. The
corresponding effective temperature is 5770K.
---------------------------------------------------------
Title: Transformation of the absolute solar radiation data into the
`International Practical Temperature Scale of 1968'
Authors: Labs, Dietrich; Neckel, Heinz
1970SoPh...15...79L Altcode:
Corrections are given which transform the Tables of the solar
radiation data (Labs and Neckel, 1968) into the `International Practical
Temperature Scale of 1968'. Additionally, for the adjustment of the data
of the `true continuum' and the corresponding line blanketing as well,
the veiled line effect mentioned first by Carbon et al. (1968), but
studied in more detail by Holweger (1970a), has been considered also.
---------------------------------------------------------
Title: The Radiation of the Solar Photosphere from 2000 Å to 100 μm
Authors: Labs, D.; Neckel, H.
1968ZA.....69....1L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Die absolute Strahlungsintensität der Mitte der Sonnenscheibe
im Spektralbereich 3288 <= λ <= 12480 Å
Authors: Labs, D.; Neckel, H.
1967ZA.....65..133L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The use of early M-type stars for determining interstellar
absorption
Authors: Neckel, H.
1967lts..conf..447N Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Die optische Dicke der galaktischen Absorptionsschicht bei
Berücksichtigung der Helligkeitsverteilung in den Galaxien. Mit
1 Textabbildung
Authors: Neckel, H.
1965ZA.....62..180N Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Absolute Intensities of the Center of the Solar Disk in the
Spectral Range from 6389 TO 12480.
Authors: Labs, A. D.; Neckel, H.
1963ApJ...138..296L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Die absolute Strahlungsintensität der Mitte der Sonnenscheibe
im Spektralbereich 6389 >= λ >= 12480 Å. Mit 3 Textabbildungen
Authors: Labs, D.; Neckel, H.
1963ZA.....57..283L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Absolute Intensities in the Visible Part of the Solar Spectrum.
Authors: Labs, D.; Neckel, H.
1962ApJ...135..969L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Lichtelektrische Infrarot-Farbenindizes Roter Sterne. Mit
4 Textabbildungen
Authors: Neckel, H.
1962ZA.....55..166N Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Die absolute Strahlungsintensität der Sonnenmitte im
Spektralbereich 4010 <= λ <= 6569 Å. Mit 11 Textabbildungen
Authors: Labs, D.; Neckel, H.
1962ZA.....55..269L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Approximate Positions of Minor Planets Observed at Heidelberg
Authors: Konig, A.; Richter, G.; Neckel, H.; Wenzel, W.
1958MPC...1825...1K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Distribution of the BD M-Type Stars Along the Galactic
Equator.
Authors: Neckel, Heinz
1958ApJ...128..510N Altcode:
A catalogue is presented containing all BD stars with spectral type M2
or later in a zone 12' wide along the galactic equator While the stars
of type MS or later show a rather uniform distribution with galactic
longitude, a maximum at t 30' and a minimum at 1 120' is present in the
distribution of the stars of type M2-M4, this distribution being similar
to that of the Mira-type variables This indicates a concentration of
these stars within the local spiral arm. The space density within 430
pc is found to be about 6 X 10-6 pc-3 for the group M2-M4 and about
0 5 X pc-3 for the group MS or later. The average ratio of early to
late M's within 1000 pc is 7.
---------------------------------------------------------
Title: A Photographic Observation of the Satellite 1957 Beta leaving
the Earth's Shadow
Authors: Neckel, Heinz
1958Natur.181..257N Altcode:
ON December 15 a photograph of the satellite 1957 Beta was taken at
the Warner and Swasey Observatory of the Case Institute of Technology,
Cleveland, Ohio, which shows the satellite coming out of the Earth's
shadow (Fig. 1). This observation can be used for deriving the
distance of the satellite from the Earth's surface. It was concluded
from visual observations made the previous morning that the satellite
should leave the Earth's shadow in the constellation Ursa Major. An
exposure, therefore, was started at 5h. 10m. OOs. E.S.T. with Ursa
Major in the centre of the field, although the satellite was not
yet visible. The satellite was first observed visually between
5h. 10m. 20s. and 5h. 10m. 30s. It is estimated that it came out
of the shadow not earlier than 5h. 10m. 10s. The position where the
track is first recorded on the photograph is α = 11h. 53m., δ = +
54.8°. It is possible that the satellite at this position had already
left the shadow, but was not recorded earlier because it was at minimum
brightness. Nevertheless, since the period of light variation was about
40 sec., the real position should be between the value already given and
α = 11h. 37m., δ = + 61°. From these two positions, heights above
the surface of 770 and 800 km. respectively were derived, assuming a
spherical Earth and a cylindrical shadow with a radius equal to that
of the Earth. If refraction isrtaken into account, smaller values of
the height result. Assuming a deflexion of the light rays from the Sun
of 1°, the corresponding heights are 713 and 739 km. It would appear
then that the derived value of 785 +/- 15 km. is a maximum one. From
predictions of the Smithsonian Institution a height of about 1,000
km. was expected. According to our observations this is too large by
at least 200 km.
---------------------------------------------------------
Title: Die Temperaturverteilung der Sonnenphotosphäre aus
Restintensitäten von Fraunhoferlinien. Mit 2 Textabbildungen
Authors: Neckel, H.
1958ZA.....44..100N Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Die Randverdunklung der Sonne bei 4674 Å und die
Temperatureverteilung in den äuβersten Photosphärenschichten. Mit
4 Textabbildungen.
Authors: Neckel, H.
1958ZA.....44..153N Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Die vertikale Temperaturverteilung in den äußeren
Photosphärenschichten der Sonne
---------------------------------------------------------
Title: Die vertikale
Temperaturverteilung in den äußeren Photosphärenschichten der
Sonne
---------------------------------------------------------
Title: The vertical temperature distribution in the outer
photosphere layers of the sun;
Authors: Neckel, Heinz
1956PhDT........15N Altcode:
No abstract at ADS
