Variable star GD 99 investigated by researchers

Tomasz Nowakowski is a member of the physics.org community.

Hungarian astronomer have observed a variable star with the help of the Konkoly Observatory and the TESS satellite. The results of the study were published on arXiv.

Variable stars could offer clues into aspects of stellar structure. A better understanding of the distance scale of the universe can be achieved by investigating variables.

The variables with modest luminosity variations and periods between 30 and 1200 seconds are called ZZ Ceti stars. The white dwarfs have a pure hydrogen outer layer.

One of the best ZZ Ceti stars isGD 99. Although it was identified as a variable white dwarf almost 50 years ago, its behavior and asteroseismology have not been thoroughly studied. The Konkoly Observatory, led by Zsfia Bognr, has carried out long-term, single-site observations ofGD 99 in order to change this.

"GD 99 was selected for a long-time ground-based follow-up measurement, which resulted in 30 nights of observations, lasting more than 120 hours." The Piszkésteto mountain station of Konkoly Observatory is located in Hungary. The researchers wrote in the paper that TESS observedGD 99 for 27.4 days in sector 21 with the 120-second short-cadence mode.

The team was able to identify eleven eigenmodes for seismology. Given that the astronomer detected seven new periods, it was found that GD 99 is rich in pulsation modes.

The fundamental parameters ofGD 99 were determined by the astronomer based on the results. The star's mass was calculated to be about 0.8 solar mass and its effective temperature was estimated to be around 15000 K.

The results show that GD 99 is more massive and closer to the ground than previously thought. The stars may be at the blue edge of the ZZ Ceti instability strip, which is occupied by several related classes of variables.

There is a group of white dwarf pulsators that are rich in oscillation modes.

There is more information. ArXiv is an old ZZ Ceti companion. There is a book titled "arxiv.2211.11676."

Journal information: arXiv

There is a science network.

Citation: Variable star GD 99 investigated by researchers (2022, November 29) retrieved 29 November 2022 from https://phys.org/news/2022-11-variable-star-gd.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.