Secondary components of W UMa-type contact binaries exhibit an excess in radius and luminosity. Based on these two properties, Ph.D. student ZHANG Xudong, Prof. QIAN Shengbang, and Dr. LIAO Wenping from Yunnan Observatories of the Chinese Academy of Sciences revealed the different evolutionary pathways for A- and W-subtype contact binaries. Overluminosity in the A subtype is because the secondary components evolved from initially more massive stars, while in the W-subtype it is due to energy transfer. The study was published in Monthly Notices of the Royal Astronomical Society.
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Source: Phys.org