A Comprehensive Spectroscopic Analysis of DB White Dwarfs

AbstractAs they evolve, white dwarfs undergo major changes in their atmospheric composition, a phenomenon known as spectral evolution. In particular, most hot He-rich (DO) stars transform into H-rich (DA) stars as they cool off, most likely as a result of the float-up of residual H. We investigate this DO-to-DA transition by taking advantage of the extensive spectroscopic dataset provided by the Sloan Digital Sky Survey (SDSS). Using our new state-of-the-art non-LTE model atmospheres, we perform a spectroscopic analysis of 1882 hot (Teff >30,000 K) white dwarfs identified in the SDSS. We find that at least 15% of all white dwarfs are born with a He-dominated atmosphere. Among these, ∼2/3 turn into H-rich stars before they reach Teff ∼40,000 K, while the remaining ∼1/3 maintain their He-rich surface throughout their entire evolution. We speculate on the origin of these two groups of objects.

Download Full-text

SPECTROSCOPIC ANALYSIS OF HOT, HYDROGEN-RICH WHITE DWARFS: THE PRESENCE OF METALS AND THE BALMER-LINE PROBLEM

The Astrophysical Journal ◽

10.1088/0004-637x/720/1/581 ◽

2010 ◽

Vol 720 (1) ◽

pp. 581-602 ◽

Cited By ~ 51

Author(s):

A. Gianninas ◽

P. Bergeron ◽

J. Dupuis ◽

M. T. Ruiz

Keyword(s):

White Dwarfs ◽

Spectroscopic Analysis ◽

Balmer Line

Download Full-text

A spectroscopic analysis of DAO and hot DA white dwarfs: The implications of the prescence of helium and the nature of DAO stars

The Astrophysical Journal ◽

10.1086/174571 ◽

1994 ◽

Vol 432 ◽

pp. 305 ◽

Cited By ~ 87

Author(s):

P. Bergeron ◽

F. Wesemael ◽

A. Beauchamp ◽

M. A. Wood ◽

R. Lamontagne ◽

...

Keyword(s):

White Dwarfs ◽

Spectroscopic Analysis

Download Full-text

Photometric and Spectroscopic Analysis of Cool White Dwarfs with Trigonometric Parallax Measurements

The Astrophysical Journal Supplement Series ◽

10.1086/320356 ◽

2001 ◽

Vol 133 (2) ◽

pp. 413-449 ◽

Cited By ~ 269

Author(s):

P. Bergeron ◽

S. K. Leggett ◽

Maria Teresa Ruiz

Keyword(s):

White Dwarfs ◽

Spectroscopic Analysis ◽

Trigonometric Parallax ◽

Cool White Dwarfs

Download Full-text

Computational tools for the spectroscopic analysis of white dwarfs

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2165 ◽

2020 ◽

Vol 497 (3) ◽

pp. 2688-2698 ◽

Cited By ~ 2

Author(s):

Vedant Chandra ◽

Hsiang-Chih Hwang ◽

Nadia L Zakamska ◽

Tamás Budavári

Keyword(s):

White Dwarf ◽

White Dwarfs ◽

Spectroscopic Analysis ◽

Theoretical Models ◽

Sloan Digital Sky Survey ◽

Random Forest Regression ◽

Computational Tools ◽

Sky Survey ◽

Stellar Photosphere ◽

Temperature Surface

ABSTRACT The spectroscopic features of white dwarfs are formed in the thin upper layer of their stellar photosphere. These features carry information about the white dwarf’s surface temperature, surface gravity, and chemical composition (hereafter ‘labels’). Existing methods to determine these labels rely on complex ab-initio theoretical models, which are not always publicly available. Here, we present two techniques to determine atmospheric labels from white dwarf spectra: a generative fitting pipeline that interpolates theoretical spectra with artificial neural networks and a random forest regression model using parameters derived from absorption line features. We test and compare our methods using a large catalogue of white dwarfs from the Sloan Digital Sky Survey (SDSS), achieving the same accuracy and negligible bias as compared to previous studies. We package our techniques into an open-source python module ‘wdtools’ that provides a computationally inexpensive way to determine stellar labels from white dwarf spectra observed from any facility. We will actively develop and update our tool as more theoretical models become publicly available. We discuss applications of our tool in its present form to identify interesting outlier white dwarf systems including those with magnetic fields, helium-rich atmospheres, and double-degenerate binaries.

Download Full-text