Sahu, S;
Gänsicke, BT;
Tremblay, PE;
Koester, D;
Hermes, JJ;
Wilson, DJ;
Toloza, O;
... Redfield, S; + view all
(2023)
An HST COS ultraviolet spectroscopic survey of 311 DA white dwarfs – I. Fundamental parameters and comparative studies.
Monthly Notices of the Royal Astronomical Society
, 526
(4)
pp. 5800-5823.
10.1093/mnras/stad2663.
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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 < Teff < 33 000 K, and 7 ≤ log g < 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.
| Type: | Article |
|---|---|
| Title: | An HST COS ultraviolet spectroscopic survey of 311 DA white dwarfs – I. Fundamental parameters and comparative studies |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1093/mnras/stad2663 |
| Publisher version: | https://doi.org/10.1093/mnras/stad2663 |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher's terms and conditions. |
| Keywords: | techniques: spectroscopic, catalogues, stars: white dwarfs, ultraviolet: stars, stars: fundamental parameters |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10183340 |
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