Contact binaries are pairs of stars orbiting so close together that their atmospheres touch each other. It is generally thought that their masses should be comparable. However, the new TYC 3801-1529-1 system defies these assumptions.
Contact binary system
Scientists from South Korea and China on November 19 announced the discovery of a contact binary system with a record value. The article about it was published on the arXiv preprint server on November 19.
In general, contact binary systems are quite rare, but far from unique cases when two luminaries are so close to each other that their atmospheres touch each other.
It is now considered proven that the components of such systems should necessarily have the same temperature. As for their masses, this is considered optional. At least contact binaries in which component masses differ by a factor of 1.5-2 are common.
However, most scientists believe that there is still a certain limit to the mass ratio of contact binaries. According to recently published data, it is 0.038-0.041. That is, the difference cannot be more than a few tens of times.
System that challenges the perceptions of scientists
And that’s where the TYC 3801-1529-1 system comes in. The fact that it is a binary contact, scientists found out back in 2020. This pair of stars is 1,260 light-years away and has an orbital period of 0.366 days. However, the masses of the components were still unknown.
They were established in a new study using data from the Weihai and Xinlong observatories and NASA’s Transiting Exoplanet Survey Satellite (TESS). The scientists obtained light curves and radial velocities.
And it happens that these data indicate that the mass ratio of the components in the TYC 3801-1529-1 system is 0.0356. This is lower than the limit set before. And it defies previous theoretical calculations.
One of the stars has a mass of 2.096 solar masses and 1.96 of its radius. The second one has 0.075 solar mass and 0.043 radius of our luminary. At the same time, the contact area is 35.7%. In addition, it turned out that the system was farther away than previously thought. The distance to it is 2035.
Also, studies show that the curves of the closed system are asymmetric. Scientists attribute this to the fact that the larger of the stars has a hot spot on its surface. In general, however, they make the assumption that the two components should soon merge together.
Provided by https://phys.org
