Researchers Discover Algol-type Binary Formed Through Extremely Helium-poor Mass Accretion (Cosmology)

Recently, Dr. CHEN Xinghao from Yunnan Observatories of the Chinese Academy of Sciences and his collaborators performed a comprehensive asteroseismic study for the eclipsing binary OO Dra by reproducing the frequencies of delta Scuti-type oscillations. This study was published in The Astrophysical Journal.  

OO Dra is an Algol-type eclipsing binary with delta Scuti-type pulsations. Its pulsating primary star is formed through accreting mass from its companion star, and the secondary star is still nearly filling its Roche lobe. Pulsational characteristics of delta Scuti stars in eclipsing binary are very similar to those of single pulsators, but their evolutionary tracks are distinctly different due to the influence of mass accretion process.

The researchers obtained seven independent pulsation frequencies based on 2-minutes Transiting Exoplanet Survey Satellite (TESS) data. They reproduced those pulsation frequencies with the method of asteroseismology, and found that the pulsating primary star had nearly unevolved and its surface helium abundance was extremely poor.

Through helium-poor mass accreting modeling, the researchers determined its age to be 0.14-0.67 Myr, confirming that OO Dra just went through a helium-poor mass accreting process.

The mass-transfer process is still the largest uncertainties in the theory of binary, and present theories often use helium-rich mass accreting process. The findings of this study present new constraints on this process, and is of great significance to improve the theory of stellar structure and evolution.

Featured image: Light curve and O-C residuals of OO Dra. The upper panel presents the light curve (black circles), and the lower panel presents the O-C residuals. The red line in the upper panel denotes the synthesis mean curve. Credit: Chen et al., 2021.


Reference

OO Dra: An Algol-type Binary Formed through an Extremely Helium-poor Mass Accretion Revealed by Asteroseismology


Provided by Chinese Academy of Sciences

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