| KRTIČKA, Jiří, Adela KAWKA, Zdeněk MIKULÁŠEK, Luca FOSSATI, Iva KRTIČKOVÁ, Milan PRVÁK, Jan JANÍK, Richard LIPTAJ, Miloslav ZEJDA and Ernst PAUNZEN. EPIC 206197016: A very hot white dwarf orbited by a strongly irradiated red dwarf. Astronomy and Astrophysics. EDP Sciences, 2023, vol. 674, A94, p. 1-8. ISSN 0004-6361. Available from: https://dx.doi.org/10.1051/0004-6361/202245551. |
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@article{2324543,
author = {Krtička, Jiří and Kawka, Adela and Mikulášek, Zdeněk and Fossati, Luca and Krtičková, Iva and Prvák, Milan and Janík, Jan and Liptaj, Richard and Zejda, Miloslav and Paunzen, Ernst},
article_number = {A94},
doi = {http://dx.doi.org/10.1051/0004-6361/202245551},
keywords = {white dwarfs; stars: variables: general; binaries: spectroscopic; stars: atmospheres},
language = {eng},
issn = {0004-6361},
journal = {Astronomy and Astrophysics},
title = {EPIC 206197016: A very hot white dwarf orbited by a strongly irradiated red dwarf},
url = {https://www.aanda.org/articles/aa/pdf/2023/06/aa45551-22.pdf},
volume = {674},
year = {2023}
}
TY - JOUR
ID - 2324543
AU - Krtička, Jiří - Kawka, Adela - Mikulášek, Zdeněk - Fossati, Luca - Krtičková, Iva - Prvák, Milan - Janík, Jan - Liptaj, Richard - Zejda, Miloslav - Paunzen, Ernst
PY - 2023
TI - EPIC 206197016: A very hot white dwarf orbited by a strongly irradiated red dwarf
JF - Astronomy and Astrophysics
VL - 674
IS - A94
SP - 1-8
EP - 1-8
PB - EDP Sciences
SN - 00046361
KW - white dwarfs
KW - stars: variables: general
KW - binaries: spectroscopic
KW - stars: atmospheres
UR - https://www.aanda.org/articles/aa/pdf/2023/06/aa45551-22.pdf
N2 - Context. Very precise satellite photometry has revealed a large number of variable stars whose variability is caused either by surface spots or by binarity. Detailed studies of such variables provide insights into the physics of these objects. Aims. We study the nature of the periodic light variability of the white dwarf EPIC 206197016 that was observed by the K2 mission. Methods. We obtain phase-resolved medium-resolution spectroscopy of EPIC 206197016 using X-shooter spectrograph at VLT to understand the nature of the white dwarf variability. We use non-local thermodynamical equilibrium model atmospheres to determine stellar parameters at individual phases. Results. EPIC 206197016 is a hot DA white dwarf with T-eff = 78 kK. The analysis of the spectra reveals periodic radial velocity variations that can result from gravitational interaction with an invisible secondary whose mass corresponds to a red dwarf. The close proximity of the two stars where the semimajor axis is about 3 R-circle dot results in the irradiation of the companion with temperatures more than twice as high on the illuminated side compared to the nonilluminated hemisphere. This effect can explain the observed light variations. The spectra of the white dwarf show a particular feature of the Balmer lines called the Balmer line problem, where the observed cores of the lower Balmer lines are deeper than predicted. This can be attributed to either weak pollution of hydrogen in the white dwarf atmosphere by heavy elements or to the presence of a circumstellar cloud or disk.
ER -
KRTIČKA, Jiří, Adela KAWKA, Zdeněk MIKULÁŠEK, Luca FOSSATI, Iva KRTIČKOVÁ, Milan PRVÁK, Jan JANÍK, Richard LIPTAJ, Miloslav ZEJDA and Ernst PAUNZEN. EPIC 206197016: A very hot white dwarf orbited by a strongly irradiated red dwarf. \textit{Astronomy and Astrophysics}. EDP Sciences, 2023, vol.~674, A94, p.~1-8. ISSN~0004-6361. Available from: https://dx.doi.org/10.1051/0004-6361/202245551.
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