Astronomers inspect a peculiar pulsating variable white dwarf

Astronomers have performed spectroscopic and photometric observations of a peculiar pulsating variable white dwarf often known as TMTS J17184064+2524314. Outcomes of the observational marketing campaign, published January 26 on the preprint server arXiv, present important data concerning the properties and conduct of this object.

White dwarfs (WDs) are stellar cores left behind after a star has exhausted its nuclear fuel. On account of their excessive gravity, they’re recognized to have atmospheres of both pure hydrogen or pure helium. Nonetheless, a small fraction of WDs exhibits traces of heavier parts.

In pulsating white dwarfs, luminosity varies because of non-radial gravity wave pulsations inside these objects. One subtype of pulsating WDs is called DAVs, or ZZ Ceti stars—these are white dwarfs of spectral kind DA, having solely hydrogen absorption traces of their spectra.

At a distance of about 228.5 light years away, TMTS J17184064+2524314 (or J1718 for brief) is a DA white dwarf with a mass of roughly 0.63 solar masses and an efficient temperature of 11,361 Okay. In 2020, J1718 was labeled as considered one of many new ZZ Ceti WDs, with a major pulsation interval of 731 seconds.

Now, a workforce of astronomers led by Jincheng Guo of Beijing Planetarium in China has combed via the info obtained primarily by the Tsinghua College-Ma Huateng Telescope for Survey (TMTS) and NASA’s Transiting Exoplanet Survey Satellite tv for pc (TESS), as a way to study extra concerning the properties of this peculiar variable star.

By performing an intensive asterosesimological evaluation, Guo’s workforce managed to derive correct parameters for J1718. All in all, they recognized 10 pulsating intervals and three mixture intervals of this variable.

The rotation period of J1718 was calculated to be roughly 25.12 hours. The age of the white dwarf was discovered to be about 510 million years, whereas its effective temperature was measured to be somewhat increased than beforehand thought—at a degree of 11,640 Okay.

The mass of J1718 was estimated to be about 0.75 solar plenty, due to this fact the star turned out to be extra huge than beforehand urged. The research additionally discovered that the carbon and oxygen abundances within the core of J1718 turned out to be roughly 0.43 and 0.57, respectively.

In response to the authors of the paper, the obtained outcomes verify that J1718 is a comparatively huge DAV with a barely thick hydrogen environment.

“From the asteroseismological end result, it may be realized that J1718 is a comparatively huge pulsating WD with a barely thick hydrogen environment. The ultimate outcomes are in line with the parameters derived from spectral becoming of our follow-up spectrum,” the researchers concluded.

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