EPIC 206197016: A very hot white dwarf orbited by a strongly irradiated red dwarf

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216224%3A14310%2F23%3A00131883" target="_blank" >RIV/00216224:14310/23:00131883 - isvavai.cz</a>

Výsledek na webu

<a href="https://www.aanda.org/articles/aa/pdf/2023/06/aa45551-22.pdf" target="_blank" >https://www.aanda.org/articles/aa/pdf/2023/06/aa45551-22.pdf</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1051/0004-6361/202245551" target="_blank" >10.1051/0004-6361/202245551</a>

Jazyk výsledku

angličtina

Název v původním jazyce

EPIC 206197016: A very hot white dwarf orbited by a strongly irradiated red dwarf

Popis výsledku v původním jazyce

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.

Název v anglickém jazyce

EPIC 206197016: A very hot white dwarf orbited by a strongly irradiated red dwarf

Popis výsledku anglicky

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.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10308 - Astronomy (including astrophysics,space science)

Projekt

—

Návaznosti

S - Specificky vyzkum na vysokych skolach<br>I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2023

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Astronomy and Astrophysics

ISSN

0004-6361

e-ISSN

1432-0746

Svazek periodika

674

Číslo periodika v rámci svazku

A94

Stát vydavatele periodika

FR - Francouzská republika

Počet stran výsledku

8

Strana od-do

1-8

Kód UT WoS článku

001005140300007

EID výsledku v databázi Scopus

2-s2.0-85162255608