A Roche lobe-filling hot subdwarf and white dwarf binary: possible detection of an ejected common envelope

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F22%3A00560481" target="_blank" >RIV/67985815:_____/22:00560481 - isvavai.cz</a>

Result on the web

<a href="https://doi.org/10.1093/mnras/stac1768" target="_blank" >https://doi.org/10.1093/mnras/stac1768</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1093/mnras/stac1768" target="_blank" >10.1093/mnras/stac1768</a>

Result language

angličtina

Original language name

A Roche lobe-filling hot subdwarf and white dwarf binary: possible detection of an ejected common envelope

Original language description

Binaries consisting of a hot subdwarf star and an accreting white dwarf (WD) are sources of gravitational wave radiation at low frequencies and possible progenitors of Type Ia supernovae if the WD mass is large enough. Here, we report the discovery of the third binary known of this kind: It consists of a hot subdwarf O (sdO) star and a WD with an orbital period of 3.495 h and an orbital shrinkage of 0.1 s in 6 yr. The sdO star overfills its Roche lobe and likely transfers mass to the WD via an accretion disc. From spectroscopy, we obtain an effective temperature of T-eff = 54 240 +/- 1840 K and a surface gravity of log g = 4.841 +/- 0.108 for the sdO star. From the light curve analysis, we obtain an sdO mass of M-sdO = 0.55 M-circle dot and a mass ratio of q = M-WD/M-sdO = 0.738 +/- 0.001. Also, we estimate that the disc has a radius of similar to 0.41 R-circle dot and a thickness of similar to 0.18 R-circle dot. The origin of this binary is probably a common envelope ejection channel, where the progenitor of the sdO star is either a red giant branch star or, more likely, an early asymptotic giant branch star, the sdO star will subsequently evolve into a WD and merge with its WD companion, likely resulting in an R Coronae Borealis (R CrB) star. The outstanding feature in the spectrum of this object is strong Ca H&K lines, which are blue-shifted by similar to 200 km s(-1) and likely originate from the recently ejected common envelope, and we estimated that the remnant common envelope (CE) material in the binary system has a density similar to 6 x 10(-1)0 g cm(-3).

Czech name

—

Czech description

—

Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

10308 - Astronomy (including astrophysics,space science)

Project

<a href="/en/project/GA22-34467S" target="_blank" >GA22-34467S: Binary interaction on the red giant branch: Hot subdwarfs as a test case.</a><br>

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2022

Confidentiality

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

Name of the periodical

Monthly Notices of the Royal Astronomical Society

ISSN

0035-8711

e-ISSN

1365-2966

Volume of the periodical

515

Issue of the periodical within the volume

3

Country of publishing house

GB - UNITED KINGDOM

Number of pages

13

Pages from-to

3370-3382

UT code for WoS article

000836707600002

EID of the result in the Scopus database

2-s2.0-85136265923