Filling the gap between synchronized and non-synchronized sdBs in short-period sdBV plus dM binaries with TESS: TIC 137608661, a new system with a well-defined rotational splitting

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F22%3A00555050" target="_blank" >RIV/67985815:_____/22:00555050 - isvavai.cz</a>

Result on the web

<a href="https://doi.org/10.1093/mnras/stac160" target="_blank" >https://doi.org/10.1093/mnras/stac160</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1093/mnras/stac160" target="_blank" >10.1093/mnras/stac160</a>

Result language

angličtina

Original language name

Filling the gap between synchronized and non-synchronized sdBs in short-period sdBV plus dM binaries with TESS: TIC 137608661, a new system with a well-defined rotational splitting

Original language description

TIC 137608661/TYC 4544-2658-1/FBS 0938+788 is a new sdBV+dM reflection-effect binary discovered by the TESS space mission with an orbital period of 7.21 h. In addition to the orbital frequency and its harmonics, the Fourier transform of TIC 137608661 shows many g-mode pulsation frequencies from the subdwarf B (sdB) star. The amplitude spectrum is particularly simple to interpret as we immediately see several rotational triplets of equally spaced frequencies. The central frequencies of these triplets are equally spaced in period with a mean period spacing of 270.12 s, corresponding to consecutive l = 1 modes. From the mean frequency spacing of 1.25 mu Hz we derive a rotation period of 4.6 d in the deep layers of the sdB star, significantly longer than the orbital period. Among the handful of sdB+dM binaries for which the sdB rotation was measured through asteroseismology, TIC 137608661 is the non-synchronized system with both the shortest orbital period and the shortest core rotation period. Only NY Vir has a shorter orbital period but it is synchronized. From a spectroscopic follow-up of TIC 137608661 we measure the radial velocities of the sdB star, determine its atmospheric parameters, and estimate the rotation rate at the surface of the star. This measurement allows us to exclude synchronized rotation also in the outer layers and suggests a differential rotation, with the surface rotating faster than the core, as found in few other similar systems. Furthermore, an analysis of the spectral energy distribution of TIC 137608661, together with a comparison between sdB pulsation properties and asteroseismic models, gives us further elements to constrain the system.

Czech name

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Czech description

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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/GA18-20083S" target="_blank" >GA18-20083S: Gaia-GALEX survey of hot subdwarf stars</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

511

Issue of the periodical within the volume

2

Country of publishing house

GB - UNITED KINGDOM

Number of pages

17

Pages from-to

2201-2217

UT code for WoS article

000754319100010

EID of the result in the Scopus database

2-s2.0-85125455984