Most of what we know about the universe comes from studies of stars, and about half of celebrities are in binary systems. Close binary interaction between stellar components can change the fate of stars.
A research team from the Yunnan Observatories of the Chinese Academy of Sciences has developed a new approach to investigate the mass ratio distribution of binary stars identified from the Large Sky Field Multi-Object Fiber Spectroscopy Telescope using Moderate Resolution Survey (LAMOST-MRS). ). Mass ratio distribution and binary fractions are essential for the study of the binary formation and binary evolution.
This work was published July 8 in The Astrophysical Journal.
Binary is common among stars, and the binary fraction goes up to 70% for massive stars, while it drops to 44% for solar-type stars. Such information suggests that the binary fraction plays a non-negligible role in the binary population.
Binary evolution may result in the formation of stellar objects with exotic observational phenomena crucial to the development of astrophysics, such as Type Ia supernovae, binary black holes, binary neutron stars, millisecond pulsars, and X-ray binaries. Compact systems contribute to galaxies’ chemical evolution and provide the early universe’s re-ionizing photons.
The observational characteristics of binary populations are vital to understanding binary evolution. These include binary fraction, binary orbital period distribution, mass ratio distribution, and dependence of the distribution on stellar spectral type and metallicity. The statistical characteristics of the binary population are poorly understood due to the lack of a large and consistent sample available.
However, such a situation has changed drastically thanks to the large sample of spectroscopic observations obtained from LAMOST-MRS, which allowed researchers to probe the mass-ration distribution and binary fraction properties.
The researchers developed a peak amplitude ratio (PAR) approach to obtain the mass ratio of the double-line spectroscopic binaries identified in the LAMOST-MRS study. Based on the different radial velocities measured from the component stars in a binary system, a system was defined as a double-line spectroscopic binary (SB2) system when two peaks appeared in the cross-correlation functions (CCFs). The PAR of the CCF peaks may depend on the mass ratio of the binary.
Using spectral observations from LAMOST-MRS Data Publication 6 and 7, the researchers applied this PAR approach to generate distributions of the derived mass ratio of binary systems by spectral types (including A-, F-, and G-). Medicine). The researchers found that G-type stars are likelier to be seen as twins.