A seven-Earth-radius helium-burning star inside a 20.5-min detached binary
The result's identifiers
Result code in 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>
Result on the web
<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>
Alternative languages
Result language
angličtina
Original language name
A seven-Earth-radius helium-burning star inside a 20.5-min detached binary
Original language description
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.
Czech name
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Czech description
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Classification
Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
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OECD FORD branch
10308 - Astronomy (including astrophysics,space science)
Result continuities
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
Others
Publication year
2024
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Nature Astronomy
ISSN
2397-3366
e-ISSN
2397-3366
Volume of the periodical
8
Issue of the periodical within the volume
April
Country of publishing house
US - UNITED STATES
Number of pages
13
Pages from-to
491-503
UT code for WoS article
001161147700002
EID of the result in the Scopus database
2-s2.0-85184514183