J/A+A/615/A115 HST Hot Star Library (Khan+, 2018)
Hot Star Extension to the Hubble Space Telescope Stellar Spectral Library.
Khan I., Worthey G.
<Astron. Astrophys. 615, A115 (2018)>
=2018A&A...615A.115K 2018A&A...615A.115K (SIMBAD/NED BibCode)
ADC_Keywords: Stars, O ; Stars, horizontal branch ; Stars, giant ; Spectroscopy
Keywords: atlases - stars: horizontal branch - stars: AGB and post-AGB -
stars: early type - ISM: dust, extinction -
Hertzsprung-Russell and C-M diagrams
Abstract:
Libraries of stellar spectra find many uses in astrophysics, from
photometric calibration to stellar population synthesis. We present
low resolution spectra of 40 stars from 0.2 micrometers (ultraviolet)
to 1.0 micrometers (near infrared) with excellent fluxing. The stars
include normal O-type stars, helium-burning stars, and post-asymptotic
giant branch (PAGB) stars. Spectra were obtained with the Space
Telescope Imaging Spectrograph (STIS) installed in the Hubble Space
Telescope (HST) using three low resolution gratings, G230LB, G430L,
and G750L. Cosmic ray hits and fringing in the red were corrected. A
correction for scattered light was applied, significant only for our
coolest stars. Cross-correlation was used to bring the spectra to a
common, final, zero velocity wavelength scale. Finally, synthetic
stellar spectra were used to estimate line of sight dust extinction to
each star, and a five-parameter dust extinction model was fit, or a
one-parameter fit in the case of low extinction. These spectra
dovetail with the similar Next Generation Stellar Library (NGSL)
spectra, extending the NGSL's coverage of stellar parameters, and
extending to helium burning stars and stars that do not fuse. The
fitted dust extinction model showed considerable variation from star
to star, indicating variations in dust properties for different lines
of sight. Interstellar absorption lines are present in most stars,
notably MgII.
Description:
Fully reduced spectra (41 observations of 40 stars) of the hot star
library are presented, averaged over all three HST/STIS settings to
contiguously span the entire wavelength coverage. They are presented
in a rebinned, logarithmic wavelength scale [log lambda(Angstroms)]
for pixel number one is 3.215 and the logarithmic delta is 0.0002) and
also in a ragged list of wavelengths corresponding to the native
instrumental pixels. Units for spectra and errors:
milliWatt/s/m2/Angstroem, or, equivalently, erg/s/cm2/Angstroem.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tableb1.dat 149 41 List of the 40 newly observed stars
fits/* . 41 Individual fits spectra
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Description of file: fits/*
Byte-by-byte description of primary data (extension 0):
-------------------------------------------------------------------------------
Col units label Explanation
-------------------------------------------------------------------------------
1 mW/s/m+2/Angstroem F_lambda dust corrected flux
2 mW/s/m+2/Angstroem err_Flam dust corrected flux uncertainty
3 mW/s/m+2/Angstroem F_lambda raw flux (before correction)
4 mW/s/m+2/Angstroem err_Flam raw flux uncertainty
5 unitless ratio extinction model extinction curve
-------------------------------------------------------------------------------
Byte by byte description of extension 1:
-------------------------------------------------------------------------------
Col Units Label Explanation
-------------------------------------------------------------------------------
1 Angstroem wavelength wavelength
2 mW/s/m+2/Angstroem F_lambda dust corrected flux
3 mW/s/m+2/Angstroem err_Flam dust corrected flux uncertainty
4 mW/s/m+2/Angstroem F_lambda raw flux (before correction)
5 mW/s/m+2/Angstroem err_Flam raw flux uncertainty
6 unitless ratio extinction model extinction curve
-------------------------------------------------------------------------------
Byte by byte description of extension 2:
-------------------------------------------------------------------------------
Col Units Label Explanation
-------------------------------------------------------------------------------
1 --- obs_set HST observation label
-------------------------------------------------------------------------------
Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Type Type
19- 20 I2 --- N Internal catalog number based on the
70 SNAP-mode candidate stars (1)
22- 36 A15 --- Name Name of the star
38- 43 F6.3 mag Vmag apparent magnitude through the V filter
45- 50 F6.3 mag B-V B-V colour index
51 A1 --- n_B-V [*] * when 2MASS J-K colour index instead
of B-V in B-V column
53- 58 I6 K Teff Effective temperature
60- 63 F4.2 [cm/s2] logg Surface gravity
65- 68 F4.2 mag AV Extinction in V
70- 73 F4.2 --- R ? Ratio of total to selective extinction at V
75- 78 F4.2 um-1 x0 ? Bump position
80- 83 F4.2 um-1 gamma ? Bump width
85- 89 F5.2 --- cs ? Bump strength
91-129 A39 --- Ref Reference
131-149 A19 --- FileName Name of the file with spectra in
subdirectory fits
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Note (1): The internal catalog number becomes the HST dataset number if you
prepend the characters ocy5, so that, for example,
star 33 is HST dataset ocy533.
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Acknowledgements:
Guy Worthey, gworthey(at)wsu.edu
(End) Patricia Vannier [CDS] 09-Apr-2018