Recently, PhD student LI Fuxing, Prof. QIAN Shengbang et al., from Yunnan Observatories of the Chinese Academy of Sciences discovered a newly formed massive contact binary in a hierarchical triple system. Its third body is also a massive star obtained for the first time. The result of this study was online published in The Astrophysical Journal on January 10.

Massive contact binaries contain two early-type stars which have filled their respective critical Roche lobes and share a common radiative envelope. Their formation and evolution are still unknown.

Researchers studied the light curves of V606 Centauri (V606 Cen is an early B-type close binary) with the high-precision continuous data from TESS (Transiting Exoplanet Survey Satellite). They obtained photometric observations of minima from the 0.60-m HSH (Helen Sawyer Hogg) Telescope in Argentina. Additionally, they collected the light curve data from worldwide photometric surveys, such as DASCH (Digital Access to a Sky Century at Harvard), ASAS (All Sky Automated Survey) and GDS (Bochum Survey of the Southern Galactic Disk) and obtained more eclipse times spanning around 120 years. Based on all available data, they constructed the O-C diagram and gave a detailed analysis of the orbital period changes for the first time.

They found that V606 Cen is a marginal contact binary with a very low fill-out factor of about 2%. Their O-C results have been found to show a downward parabolic change together with a cyclic oscillation, and indicate the mass transfer from the more massive component to the less massive one between components with a massive third body. Both the marginal contact configuration and the continuous period decrease suggest that V606 Cen is a newly formed contact binary via Case A mass transfer.

Interestingly, V606 Cen is in a unique stage of evolution different from that of massive binaries which have been reported and it is a newly formed massive contact binary created by mass transfer from the primary to the secondary.

Contact:

LI Fuxing, Yunnan Observatories, Chinese Academy of Sciences

lfx@ynao.ac.cn