A seven-Earth-radius helium-burning star inside a 20.5-min detached binary

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F24%3A00585616" target="_blank" >RIV/67985815:_____/24:00585616 - isvavai.cz</a>

Výsledek na webu

<a href="https://doi.org/10.1038/s41550-023-02188-2" target="_blank" >https://doi.org/10.1038/s41550-023-02188-2</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1038/s41550-023-02188-2" target="_blank" >10.1038/s41550-023-02188-2</a>

Jazyk výsledku

angličtina

Název v původním jazyce

A seven-Earth-radius helium-burning star inside a 20.5-min detached binary

Popis výsledku v původním jazyce

Binary evolution theory predicts that the second common envelope ejection can produce low-mass (0.32-0.36 M⊙) subdwarf B (sdB) stars inside ultrashort-orbital-period binary systems, as their helium cores are ignited under nondegenerate conditions. With the orbital decay driven by gravitational-wave (GW) radiation, the minimum orbital periods of detached sdB binaries could be as short as ∼20 min. However, only four sdB binaries with orbital periods below an hour have been reported so far, and none of them has an orbital period approaching the above theoretical limit. Here we report the discovery of a 20.5-min-orbital-period ellipsoidal binary, TMTS J052610.43+593445.1, in which the visible star is being tidally deformed by an invisible carbon-oxygen white dwarf companion. The visible component is inferred to be an sdB star with a mass ∼0.33 M⊙ approaching the helium-ignition limit, although a He-core white dwarf cannot be completely ruled out. In particular, the radius of this low-mass sdB star is only 0.066 R⊙, about seven Earth radii. Such a system provides a key clue in mapping the binary evolution scheme from the second common envelope ejection to the formation of AM CVn stars having a helium-star donor. It may also serve as a crucial verification binary of space-borne GW observatories such as LISA and TianQin in the future.

Název v anglickém jazyce

A seven-Earth-radius helium-burning star inside a 20.5-min detached binary

Popis výsledku anglicky

Binary evolution theory predicts that the second common envelope ejection can produce low-mass (0.32-0.36 M⊙) subdwarf B (sdB) stars inside ultrashort-orbital-period binary systems, as their helium cores are ignited under nondegenerate conditions. With the orbital decay driven by gravitational-wave (GW) radiation, the minimum orbital periods of detached sdB binaries could be as short as ∼20 min. However, only four sdB binaries with orbital periods below an hour have been reported so far, and none of them has an orbital period approaching the above theoretical limit. Here we report the discovery of a 20.5-min-orbital-period ellipsoidal binary, TMTS J052610.43+593445.1, in which the visible star is being tidally deformed by an invisible carbon-oxygen white dwarf companion. The visible component is inferred to be an sdB star with a mass ∼0.33 M⊙ approaching the helium-ignition limit, although a He-core white dwarf cannot be completely ruled out. In particular, the radius of this low-mass sdB star is only 0.066 R⊙, about seven Earth radii. Such a system provides a key clue in mapping the binary evolution scheme from the second common envelope ejection to the formation of AM CVn stars having a helium-star donor. It may also serve as a crucial verification binary of space-borne GW observatories such as LISA and TianQin in the future.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10308 - Astronomy (including astrophysics,space science)

Projekt

<a href="/cs/project/GA22-34467S" target="_blank" >GA22-34467S: Interakce dvojhvězd na větvi červených obrů: horcí podtrpaslíci jako testovací případ.</a><br>

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2024

Kód důvěrnosti údajů

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

Název periodika

Nature Astronomy

ISSN

2397-3366

e-ISSN

2397-3366

Svazek periodika

8

Číslo periodika v rámci svazku

April

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

13

Strana od-do

491-503

Kód UT WoS článku

001161147700002

EID výsledku v databázi Scopus

2-s2.0-85184514183