Issue |
A&A
Volume 662, June 2022
|
|
---|---|---|
Article Number | A66 | |
Number of page(s) | 30 | |
Section | Catalogs and data | |
DOI | https://doi.org/10.1051/0004-6361/202141570 | |
Published online | 17 June 2022 |
Stellar labels for hot stars from low-resolution spectra
I. The HotPayne method and results for 330 000 stars from LAMOST DR6★
1
Max-Planck-Institut für Astronomy,
Königstuhl 17,
69117
Heidelberg,
Germany
e-mail: mxiang@mpia.de
2
Institute for Advanced Study,
Princeton,
NJ
08540,
USA
3
Department of Astrophysical Sciences, Princeton University,
Princeton,
NJ
08544,
USA
4
Observatories of the Carnegie Institution of Washington,
813 Santa Barbara Street,
Pasadena,
CA
91101,
USA
5
Research School of Astronomy & Astrophysics, Australian National University,
Canberra
ACT 2611,
Australia
6
LMU München, Universitätatssternwarte,
Scheinerstr. 1,
81679
München,
Germany
7
Institute for Astronomy, University of Hawaii at Manoa,
2680 Woodlawn Drive,
Honolulu,
HI
96822,
USA
8
Center for Astrophysics, Harvard & Smithsonian,
Cambridge,
MA
02138,
USA
9
National Astronomical Observatories, Chinese Academy of Sciences,
Beijing
100012,
PR China
10
University of Chinese Academy of Sciences,
Beijing
100049,
PR China
11
Institut für Astro- und Teilchenphysik, Universität Innsbruck,
Technikerstrasse 25,
6020
Innsbruck,
Austria
12
Institute of Astronomy,
KU Leuven, Celestijnenlaan 200D,
3001
Leuven,
Belgium
13
South-Western Institute for Astronomy Research, Yunnan University,
Kunming
650500,
PR China
Received:
16
June
2021
Accepted:
19
February
2022
We set out to determine stellar labels from low-resolution survey spectra of hot stars, specifically OBA stars with Teff ≳ 7500 K. This fills a gap in the scientific analysis of large spectroscopic stellar surveys such as LAMOST, which offers spectra for millions of stars at R ~ 1800 and covers 3800 Å ≤ λ ≤ 9000 Å. We first explore the theoretical information content of such spectra to determine stellar labels via the Cramér-Rao bound. We show that in the limit of perfect model spectra and observed spectra with signal-to-noise ratio ~50–100, precise estimates are possible for a wide range of stellar labels: not only the effective temperature, Teff, surface gravity, log g, and projected rotation velocity, vsin i, but also the micro-turbulence velocity,vmic, helium abundance, NHe/Ntot, and the elemental abundances [C/H], [N/H], [O/H], [Si/H], [S/H], and [Fe/H]. Our analysis illustrates that the temperature regime of Teff ~ 9500 K is challenging as the dominant Balmer and Paschen line strengths vary little with Teff. We implement the simultaneous fitting of these 11 stellar labels to LAMOST hot-star spectra using the Payne approach, drawing on Kurucz’s ATLAS12/SYNTHE local thermodynamic equilibrium spectra as the underlying models. We then obtain stellar parameter estimates for a sample of about 330 000 hot stars with LAMOST spectra, an increase by about two orders of magnitude in sample size. Among them, about 260 000 have good Gaia parallaxes (ω/σω > 5), and their luminosities imply that ≳95% of them are luminous stars, mostly on the main sequence; the rest are evolved lower luminosity stars, such as hot subdwarfs and white dwarfs. We show that the fidelity of the results, particularly for the abundance estimates, is limited by the systematics of the underlying models as they do not account for nonlocal thermodynamic equilibrium effects. Finally, we show the detailed distribution of vsin i of stars with 8000–15 000 K, illustrating that it extends to a sharp cutoff at the critical rotation velocity, vcrit, across a wide range of temperatures.
Key words: techniques: spectroscopic / surveys / catalogs / stars: massive / stars: fundamental parameters / stars: abundances
The catalog is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/662/A66
© M. Xiang et al. 2022
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Open Access funding provided by Max Planck Society.
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