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We describe the spectral classification of white dwarfs and some of the physical processes important for their understanding. In the major part of this paper we discuss the input physics and computational methods for one of the most widely…

Astrophysics · Physics 2008-12-03 Detlev Koester

From data collection to photometric fitting and analysis of white dwarfs to generating a white dwarf luminosity function requires numerous Astrophysical, Mathematical and Computational domain knowledge. The steep learning curve makes it…

Instrumentation and Methods for Astrophysics · Physics 2022-10-25 M. C. Lam , K. W. Yuen , M. J. Green , W. Li

With the imminent data releases from next-generation spectroscopic surveys, hundreds of thousands of white dwarf spectra are expected to become available within the next few years, increasing the data volume by an order of magnitude. This…

Solar and Stellar Astrophysics · Physics 2025-03-18 Olivier Vincent , Pierre Bergeron , Patrick Dufour

With tens to hundreds of spectra of white dwarfs being taken each night from multi-object spectroscopic surveys, automated spectral classification is essential as part of efficient data processing. In this study, we design a neural network…

It is possible to reliably identify white dwarfs (WDs) without recourse to spectra, instead using photometric and astrometric measurements to distinguish them from Main Sequence stars and quasars. WDs' colours can also be used to infer…

Astrophysics · Physics 2010-02-22 Daniel J. Mortlock , Hiranya V. Peiris , Zeljko Ivezic

White dwarfs carry information on the structure and evolution of the Galaxy, especially through their luminosity function and initial-to-final mass relation. Very cool white dwarfs provide insight into the early ages of each population.…

The next generation of spectroscopic surveys is expected to provide spectra for hundreds of thousands of white dwarf (WD) candidates in the upcoming years. Currently, spectroscopic classification of white dwarfs is mostly done by visual…

Solar and Stellar Astrophysics · Physics 2023-03-01 Olivier Vincent , Pierre Bergeron , Patrick Dufour

The determination of atmospheric parameters of white dwarf stars (WDs) is crucial for researches on them. Traditional methodology is to fit the model spectra to observed absorption lines and report the parameters with the lowest $\chi ^2$…

Instrumentation and Methods for Astrophysics · Physics 2021-11-29 Yong Yang , Jingkun Zhao , Jiajun Zhang , Xianhao Ye , Gang Zhao

So far no diffuse emissions in dwarf spheroidal satellites of the Milky Way have ever been observed. Given that dwarf galaxies are predominantly composed of Dark Matter, the discovery of these signals could offer valuable insights into…

High Energy Astrophysical Phenomena · Physics 2024-01-11 Martin Vollmann , Finn Welzmüller , Lovorka Gajović

We present improved atmospheric parameters of nearby white dwarfs lying within 20 pc of the Sun. The aim of the current study is to obtain the best statistical model of the least-biased sample of the white dwarf population. A homogeneous…

Solar and Stellar Astrophysics · Physics 2015-06-04 Noemi Giammichele , Pierre Bergeron , Patrick Dufour

Aims. The derivation of spectroscopic parameters for M dwarf stars is very important in the fields of stellar and exoplanet characterization. The goal of this work is the creation of an automatic computational tool, able to derive quickly…

Solar and Stellar Astrophysics · Physics 2020-04-08 A. Antoniadis-Karnavas , S. G. Sousa , E. Delgado-Mena , N. C. Santos , G. D. C. Teixeira , V. Neves

Reliable modeling of the atmospheres of cool white dwarfs is crucial for understanding the atmospheric evolution of these stars and for accurate white dwarfs cosmochronology. Over the last decade {\it ab initio} modeling entered many…

Solar and Stellar Astrophysics · Physics 2015-05-20 Piotr M. Kowalski

White dwarfs with metal lines in their spectra act as signposts for post-main sequence planetary systems. Searching the Sloan Digital Sky Survey (SDSS) data release 12, we have identified 231 cool (<9000 K) DZ white dwarfs with strong metal…

Solar and Stellar Astrophysics · Physics 2017-02-08 Mark Hollands , Detlev Koester , Vadim Alekseev , Emma Herbert , Boris T. Gaensicke

An initial assessment is made of white dwarf and hot subdwarf stars observed in the Sloan Digital Sky Survey. In a small area of sky (190 square degrees), observed much like the full survey will be, 269 white dwarfs and 56 hot subdwarfs are…

Planetary systems that orbit white dwarf stars can be studied via spectroscopic observations of the stars themselves. Numerous white dwarfs are seen to have accreted mostly rocky minor planets, the remnants of which are present in the…

Earth and Planetary Astrophysics · Physics 2019-02-06 B. Zuckerman , E. D. Young

We have conducted a spectroscopic survey of over 1300 bright (V < 17.5), hydrogen-rich white dwarfs based largely on the last published version of the McCook & Sion catalog. The complete results from our survey, including the spectroscopic…

Solar and Stellar Astrophysics · Physics 2015-05-30 Alexandros Gianninas , Pierre Bergeron , Maria Teresa Ruiz

Over the last decade {\it ab initio} modeling of material properties has become widespread in diverse fields of research. It has proved to be a powerful tool for predicting various properties of matter under extreme conditions. We apply…

Solar and Stellar Astrophysics · Physics 2015-05-20 Piotr M. Kowalski , Mukremin Kilic

We present an analysis of all single white dwarf stars known to exhibit spectroscopic signatures of neutral helium line splitting due to the presence of a strong magnetic field. Using state-of-the-art models taking into account the effects…

Solar and Stellar Astrophysics · Physics 2023-02-01 François Hardy , Patrick Dufour , Stefan Jordan

The space density of white dwarfs is highly uncertain even nearby. This results from the fact that the known sample of white dwarfs is largely incomplete in part because most white dwarfs have been discovered as by-products in non-dedicated…

Astrophysics · Physics 2007-05-23 L. Morales-Rueda , P. J. Groot , R. Napiwotzki , J. Drew , the EGAPS collaboration

The T\"ubingen NLTE Model-Atmosphere Package (TMAP) calculates fully metal-line blanketed white dwarf model atmospheres and spectral energy distributions (SEDs) at a high level of sophistication. Such SEDs are easily accessible via the…

Solar and Stellar Astrophysics · Physics 2011-09-01 Thomas Rauch
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