A research team led by Prof. Qian Shengbang and Ph.D. Li Fuxing, a student at the Yunnan Observatory of the Chinese Academy of Sciences, found that the formation and evolution of massive binary systems in the Milky Way and the Andromeda Galaxy (M31) may share the same mechanism.
Their findings are published in Monthly notices of the Royal Astronomical Society and The Astrophysical Journal.
Massive binary systems contain at least one early type star whose spectral type is O, B-type. These binary systems have high energy radiation like X-rays and can create neutron stars or black holes. The forerunners of these semi-separate binaries are the individual binaries, where the original, more massive components evolve faster and first fill their critical Roche shares, and then transfer the mass of their satellites with the evolution of Case A.
During this process, the orbital period of the system will be reduced and mass ratio will be increased. When the system evolved to critical condition where the mass ratio is equal to one (double binary), this binary has the shortest orbital period. Then the mass ratio of the binary file will be inverted with mass transfer from the less massive component to the more massive after this special stage.
In the study published in Monthly notices of the Royal Astronomical Societyresearchers have studied the evolutionary stage of V375 Cassiopeia (V375 Cas), a massive binary and containing two B-type components.
They analyzed the light curves of the V375 Cas and found that the V375 Cas had to undergo a late transfer of mass A from the less massive component to the more massive one.
Meanwhile, according to statistics, these massive semi-separate binary systems have a third body with different periods. From the HR chart, the components of the massive binary are almost the stars of the main sequence, and the evolutionary age of the secondary component is greater than that of the primary for the V375 Cas. “V375 Cas is a hierarchical triple system in which a massive main sequence star accompanies a massive semi-separate binary system with mass transfer based on third light estimation,” Lee said.
The researchers also found two massive close binary numbers with double components in M31. M31 is the closest spiral galaxy to the Milky Way and the largest galaxy in the Local Group, and its structure and metallicity are very close to those of the Milky Way.
Photometric solutions were performed by the WD method from 437 dimming binary numbers, with two double binaries detected. One system is a binary contact with a mass ratio of 0.974, and the other system is a semi-separate binary with a mass ratio of 0.924. This result suggests that massive binaries are a rarity in M31.
Based on a study of changes in the orbital period of OC diagrams and binary system configurations, the researchers found that these two massive binary binary systems are at different evolutionary stages with similar mass ratios (close to unity). Binary contact with double contact is about to enter the critical evolutionary stage of the shortest period of rapid mass transfer. The semi-binary system has undergone this stage of evolution and fails to form a contact binary during the orbit reduction phase with case A of mass transfer.
These findings are published in The Astrophysical Journal.
These two works show that the evolution of massive binary systems is possible in the same way in the Milky Way and M31, and these binary files at a special stage create an ideal test for evolutionary models of massive binaries.
FX Li et al, The V375 Cassiopeia massive system is a semi-crazy binary mass transfer system with a massive stellar satellite, Monthly notices of the Royal Astronomical Society (2022). DOI: 10.1093 / mnras / stac1327
F.-X. Li et al, Two massive close binary files with dual components in the nearby Galaxy M31, The Astrophysical Journal (2022). DOI: 10.3847 / 1538-4357 / ac6c81
Chinese Academy of Sciences
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