SPECTROSCOPIC ANALYSIS OF DA WHITE DWARFS: STARK BROADENING OF HYDROGEN LINES INCLUDING NONIDEAL EFFECTS

By P.-E. Tremblay, Pierre Bergeron. 2009

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We present improved calculations for the Stark broadening of hydrogen lines in dense plasmas typical of white dwarf atmospheres. Our new model is based on the unified theory of Stark broadening from Vidal, Cooper, and Smith. For the first time, we account for the nonideal effects in a consistent way directly inside the line profile calculations. The Hummer and Mihalas theory is used to describe the nonideal effects due to perturbations on the absorber from protons and electrons. We use a truncation of the electric microfield distribution in the quasi-static proton broadening to take into account the fact that high electric microfields dissociate the upper state of a transition. This approach represents a significant improvement over previous calculations that relied on the use of an ad hoc parameter to mimic these nonideal effects. We obtain the first model spectra with line profiles that are consistent with the equation of state. We revisit the properties of DA stars in the range 40,000 K >Teff> 13,000 K by analyzing the optical spectra with our improved models. The updated atmospheric parameters are shown to differ substantially from those published in previous studies, with a mean mass shifted by +0.034 M☉. We also show that these revised atmospheric parameters yield absolute visual magnitudes that remain in excellent agreement with trigonometric parallax measurements.

Subfields: Astronomy and Astrophysics, Mechanics of Materials

View Paper: https://www.semanticscholar.org/paper/e14c6835e36017af8449127b60af3e7694ee7c56

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Citations in the corpus

On the Spectral Evolution of Hot White Dwarf Stars. I. A Detailed Model Atmosphere Analysis of Hot White Dwarfs from SDSS DR12 (2020, methodology): “Regarding other important ionic species, we used the detailed Stark profiles of Tremblay & Bergeron (2009) for H I lines and of Schöning & Butler (1989) for He II lines; both already included in TLUSTY and SYNSPEC.”
SDSS DR7 WHITE DWARF CATALOG (2012, methodology): “Our sample is ﬁve times larger, however, and we have removed suspected magnetic DAs from our sample, which would otherwise increase our measured mean mass. Limoges & Bergeron (2010), with the same models as Tremblay & Bergeron (2009), obtained a mean mass of 0 .”
KNOW YOUR NEIGHBORHOOD: A DETAILED MODEL ATMOSPHERE ANALYSIS OF NEARBY WHITE DWARFS (2012, methodology): “Our model atmospheres and synthetic spectra are derived from the LTE model at- mosphere code originally described in Bergeron et al. (1995a) and references therein, with recent improvements discussed in Tremblay & Bergeron (2009).”
A COMPREHENSIVE SPECTROSCOPIC ANALYSIS OF DB WHITE DWARFS (2011, methodology): “Our model atmospheres and synthetic spectra are built from the model atmosphere code described in Tremblay & Bergeron (2009) and references therein, in which we have incorporated the improved Stark profiles of neutral helium of Beauchamp et al. (1997).”
Spectroscopic analysis of DA white dwarfs with 3D model atmospheres (2013, methodology): “Their purpose was to update the position of the instability strip given the improved 1D model atmospheres of Tremblay & Bergeron (2009) and the resulting change in the MLT calibration from ML2/α = 0.6 to 0.8.”
SUB-CHANDRASEKHAR WHITE DWARF MERGERS AS THE PROGENITORS OF TYPE Ia SUPERNOVAE (2010, background): “This mass is close to the empirical mean mass of WDs (∼ 0.65M⊙; Tremblay & Bergeron 2009), and thus, in our picture, the merger should lead to a typical SN Ia.”
AN IMPROVED SPECTROSCOPIC ANALYSIS OF DA WHITE DWARFS FROM THE SLOAN DIGITAL SKY SURVEY DATA RELEASE 4 (2011, methodology): “This small difference is entirely consistent with the shift produced by the use of our improved Stark profiles, and it is comparable to the shift observed for the PG sample (Tremblay & Bergeron 2009) where we found a significantly higher mean mass (by ∼5”
The frequency of planetary debris around young white dwarfs (2014, methodology): “The only important change compared to the grid used for the analysis of the SPY survey (Koester et al. 2009) are the inclusion of the non-ideal Balmer line Stark profiles as calculated by Tremblay & Bergeron (2009) and new Lymanα profiles.”
The White Dwarf Initial–Final Mass Relation for Progenitor Stars from 0.85 to 7.5 M⊙ (2018, methodology): “…atmospheric analysis in our paper series has and continues to use the 1D models of Tremblay et al. (2011) with the Stark broadening profiles of 8 Available at http://www.ucolick.org/∼xavier/IDL/ Tremblay & Bergeron (2009) and the automated spectral fitting techniques of Bergeron et al. (1992).”
Techniques and Review of Absolute Flux Calibration from the Ultraviolet to the Mid-Infrared (2014, methodology): “Our Tlusty NLTE models (version 204) include the Tremblay & Bergeron (2009) Stark profiles (see also Tremblay et al. 2011, G11), and incorporate similar physics to the Rauch models.”
Post common envelope binaries from SDSS - XI. The white dwarf mass distributions of CVs and pre-CVs (2011, background): “As discussed in detail in Rebassa-Mansergas et al. (2010), recent work (Falcon et al. 2010; Tremblay & Bergeron 2009) suggests that WD mass determinations from fitting model atmospheres to observed spectra may underestimate the masses of the WDs.”
The chemical diversity of exo-terrestrial planetary debris around white dwarfs (2012, methodology): “All observed HST/COS and optical spectra were analysed with theoretical model atmospheres using input physics as described in Koester (2010), and including the Lyman and Balmer line profiles of Tremblay & Bergeron (2009).”