Recently, Dr. LIAO Wenping and her co-authors from Yunnan Observatories of the Chinese Academy of Sciences obtained new results in the field of close binaries in multiple star systems. They found a special quintuple stellar system composed of an active and deep contact binary, single-lined spectroscopic binary and a visual companion. The research revealed that companion stars play a very important role in the formation and evolution of close binaries. The results were online published in The Astrophysical Journal recently.

The observation and analysis of close binaries in multiple star system not only provides a good opportunity to study their formations and evolutions, but also provides rich clues for the study of early star formation and dynamic interaction. Researchers used 1-m, 60-cm and 70-cm telescopes at Yunnan Observatories to carry out a long-term multicolor photometric observation, and the 2.16-m telescope in Xinglong station for a spectra observation. Additionally, they collected data and information from worldwide photometric surveys, such as TESS (Transiting Exoplanet Survey Satellite), SWASP (SuperWide Angle Search for Planets), KWS (Kamogata/Kiso/Kyoto Wide-field Survey) and Gaia mission. Based on all the available data, they analyzed and studied the contact binary V410 Aur in detail for the first time.

Although the tertiary component around V410 Aur has been detected in the spectroscopic observations and photometric solutions, it is not clearly seen in the LTTE (Light travel time effect). In order to study the physical and orbital characteristics of the tertiary companion, they gave a detailed analysis of the orbital period changes for the system based on 117 new eclipse times and those collected from the literature. They found a cyclical variation in orbital period study, which was analyzed for the LTTE due to the tertiary companion. Then, they calculated the minimum mass of the third body, which is much larger than the inferred value of spectroscopic investigation.

Their results indicate that the spectroscopic tertiary component is a single-lined spectroscopic binary with an unseen component. By using the well-known Wilson–Devinney (W–D) program, they solved TESS photometric solutions. They found that V410 Aur is an active and deep contact binary with a relatively large additional light contribution.

Finally, they calculated the distance parameter of the system by considering Gaia astrometry parameters. They found that the contact binary, single-lined spectroscopic binary and the visual companion detected by Gaia are at practically the same distance from the Sun, which nicely confirmed the physical bond between them. Thus V410 Aur contains a single-lined spectroscopic binary with a visual companion in a quintuple stellar system.

Their results indicate that the interaction between components in multiple star system can not only drive the formation of close binaries; but also drive the formation of low mass ratio and deep overcontact binaries (such as V410 Aur), finally, they may merger into a rapidly rotating single star and result in bright red nova explosions.

Contact:

LIAO, Wenping, Yunnan Observatories, CAS

liaowp@ynao.ac.cn