The researchers are detecting a continuous expansion of the ultrafine X-ray source’s orbit

Researchers led by a Ph.D. Candidate Zang Lei and Professor Qian Shengbang of the Yunnan Observatories of the Chinese Academy of Sciences (CAS) discovered that the orbital period of the QR Andromeda ultrasoft X-ray source (QRAnd) is constantly increasing. QRAnd’s orbital evolution is mainly due to a mass transition from its low-mass companion to the white dwarf on the Kelvin-Helmholtz time scale.

This work was published in Monthly Notices of the Royal Astronomical Society.

QR is the brightest optically brightest ultrafine X-ray source in the galaxy, as mass is transferred from a secondary donor to a primary massive white dwarf via accumulator disc.

To further study the mass exchange and orbital evolution, the researchers analyzed QR’s orbital period variation in detail, using continuous light curves from the Exoplanet Survey Satellite (TESS) and photometric observations collected by the American Variable Star Observers Association (AAVSO). ) Database. They found that the orbital period is constantly increasing.

Moreover, based on the results of previous research, the researchers estimated that the mass of the secondary donor is about 0.5 solar masses with a detailed analysis, while the mass of the white dwarf is about 1.2 solar masses.

Therefore, the continuous increase in orbital Mainly because block transfer from a low-mass companion to a white dwarf on its Kelvin-Helmholtz time scale, while the loss of wind mass from the accretion disk may also contribute to the period difference.”

cluster f Angular momentum Brought by winds from the accretion disc delays the orbital expansion of QR and . And so, the Companion star With a low mass the critical Roche lobe can always be filled and material transferred to the white dwarf.

The researchers also estimated the mass transfer rate range for the QR and in this scenario, they roughly estimate that the QRAnd may reach the Chandrasekhar limit in at least 1.5 million years, and then may explode as a type Ia supernova.