An HST COS ultraviolet spectroscopic survey of 311 DA white dwarfs – I. Fundamental parameters and comparative studies

Author:

Sahu Snehalata1ORCID,Gänsicke Boris T1ORCID,Tremblay Pier-Emmanuel1ORCID,Koester Detlev2ORCID,Hermes J J3ORCID,Wilson David J4ORCID,Toloza Odette5ORCID,Hoskin Matthew J1ORCID,Farihi Jay6ORCID,Manser Christopher J7ORCID,Redfield Seth8ORCID

Affiliation:

1. Department of Physics, University of Warwick , Coventry CV4 7AL , UK

2. Institut für Theoretische Physik und Astrophysik, University of Kiel , D-24098 Kiel , Germany

3. Department of Astronomy & Institute for Astrophysical Research, Boston University , 725 Commonwealth Ave., Boston, MA 02215 , USA

4. Laboratory for Atmospheric and Space Physics, University of Colorado , Boulder, CO 80303 , USA

5. Departamento de Física, Universidad Técnica Federico Santa María , Avenida España 1680, Valparaíso , Chile

6. Department of Physics & Astronomy, University College London , Gower Street, London WC1E 6BT , UK

7. Department of Physics, Astrophysics Group, Imperial College London , Prince Consort Rd, London SW7 2AZ , UK

8. Astronomy Department and Van Vleck Observatory, Wesleyan University , Middletown, CT 06459-0123 , USA

Abstract

ABSTRACT White dwarf studies carry significant implications across multiple fields of astrophysics, including exoplanets, supernova explosions, and cosmological investigations. Thus, accurate determinations of their fundamental parameters (Teff and log g) are of utmost importance. While optical surveys have provided measurements for many white dwarfs, there is a lack of studies utilizing ultraviolet (UV) data, particularly focusing on the warmer ones that predominantly emit in the UV range. Here, we present the medium-resolution far-UV spectroscopic survey of 311 DA white dwarfs obtained with Cosmic Origins Spectrograph (COS) onboard Hubble Space Telescope confirming 49 photometric Gaia candidates. We used 3D extinction maps, parallaxes, and hydrogen atmosphere models to fit the spectra of the stars that lie in the range $12\, 000 \lt \mbox{$T_{\mathrm{eff}}$}\lt 33\, 000$ K, and $7 \le \mbox{$\log g$}\lt 9.2$. To assess the impact of input physics, we employed two mass–radius relations in the fitting and compared the results with previous studies. The comparisons suggest the COS Teff are systematically lower by 3 per cent, on average, than Balmer line fits while they differ by only 1.5 per cent from optical photometric studies. The mass distributions indicate that the COS masses are smaller by ≈0.05  and 0.02 M⊙ than Balmer lines and photometric masses, respectively. Performing several tests, we find that the discrepancies are either arising due to issues with the COS calibration, broadening theories for hydrogen lines, or interstellar reddening which needs further examination. Based on comparative analysis, we identify 30 binary candidates drawing attention for follow-up studies to confirm their nature.

Funder

NASA

ESA

European Research Council

STFC

FONDECYT

Publisher

Oxford University Press (OUP)

Subject

Space and Planetary Science,Astronomy and Astrophysics

Cited by 1 articles. 订阅此论文施引文献 订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献

1. The 40 pc sample of white dwarfs from Gaia;Monthly Notices of the Royal Astronomical Society;2023-11-27

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