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17th European White Dwarf Workshop: Ab initio Stellar Astrophysics - Reliable Modeling of Cool White Dwarf Atmospheres
Kowalski, Piotr (2010)
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mla
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Kowalski P. "17th European White Dwarf Workshop: Ab initio Stellar Astrophysics - Reliable Modeling of Cool White Dwarf Atmospheres.", timms video, Universität Tübingen (2010): https://timms.uni-tuebingen.de:443/tp/UT_20100819_017_eurowd_0001. Accessed 30 Oct 2020.
apa
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Kowalski, P. (2010). 17th European White Dwarf Workshop: Ab initio Stellar Astrophysics - Reliable Modeling of Cool White Dwarf Atmospheres. timms video: Universität Tübingen. Retrieved October 30, 2020 from the World Wide Web https://timms.uni-tuebingen.de:443/tp/UT_20100819_017_eurowd_0001
harvard
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Kowalski, P. (2010). 17th European White Dwarf Workshop: Ab initio Stellar Astrophysics - Reliable Modeling of Cool White Dwarf Atmospheres [Online video]. 19 August. Available at: https://timms.uni-tuebingen.de:443/tp/UT_20100819_017_eurowd_0001 (Accessed: 30 October 2020).
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title: 17th European White Dwarf Workshop: Ab initio Stellar Astrophysics - Reliable Modeling of Cool White Dwarf Atmospheres
alt. title: 17th European White Dwarf Workshop - Physical processes in white dwarfs and magnetic white dwarfs
creator: Kowalski, Piotr (author)
subjects: Astronomie, Physik, Astrophysik, Workshop, White Dwarf, Ab initio Stellar Astrophysics, Reliable Modeling, Cool White Dwarf Atmospheres, Piotr Kowalski
description: 17th European White Dwarf Workshop, 16. bis 20. August 2010
abstract: Ab initio Stellar Astrophysics: Reliable Modeling of Cool White Dwarf Atmospheres (Piotr M. Kowalski1, Mukremin Kilic2, George G. Pavlov3) (1Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany, 2Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138, USA, 3Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Lab., University Park, PA 16802, USA) Over the last decade ab initio modeling entered various research fields and proved to be a good tool for predicting various properties of matter under different, even extreme conditions. In our work we apply modern computational chemistry and materials science methods, including density functional theory (DFT), to solve important problems encountered in the modeling of the dense atmospheres of cool white dwarfs (Teff less than 7000K). Our work on the revision and improvements of the absorption mechanisms in hydrogen and helium dominated atmospheres resulted in a new set of atmosphere models. By inclusion of Ly-alpha red wing opacity we successfully fitted the entire spectral energy distributions of known cool DA stars. In the subsequent work we fitted the majority of the coolest stars with hydrogen-rich models. This finding challenges our understanding of the white dwarfs atmospheric evolution. We will show and discuss examples of such fits, including Halo candidates and the cool white dwarf star belonging to the binary system with pulsar PSR J0437-4715 and discuss the implications. The two problems important for the understanding of cool white dwarfs are the behavior of negative hydrogen ion and molecular carbon in a fluid-like, helium dominated medium. Using ab initio methods we investigate the stability and opacity of these two species in dense helium. We will show that the negative hydrogen ion does not undergo pressure ionization up to a density of 4 g/cm3, but its bound-free absorption edge moves to the shorter wavelengths with increasing helium density. Our investigation of C2 indicates that the absorption features observed in the peculiar, cool DQ white dwarfs resemble the absorption of perturbed C2 in dense helium, however the photospheric densities needed to explain the observed Swan bands shifts are one order of magnitude smaller than the ones predicted by the current atmosphere models.
publisher: ZDV Universität Tübingen
contributor: ZDV Universität Tübingen (producer)
creation date: 2010-08-19
dc type: image
localtype: video
identifier: UT_20100819_017_eurowd_0001
language: eng
rights: Url: https://timmsstatic.uni-tuebingen.de/jtimms/TimmsDisclaimer.html?637396148970719794