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always. Stars that exist in such pairs transfer their masses to each other due to proximity, which causes the aforementioned decrease or increase in orbital periods.
Studying this variation of orbital periods can also possibly lead to the discovery of a third unseen body in such systems: a mystery body, which could be an exoplanet or a low- mass star. Imagine standing on that exoplanet, and looking up at the sky to see two stars ... much like Luke Skywalker saw in the skies above Tatooine!
Contact binaries are binary stars that are so close to each other that their gaseous envelopes touch each other and mass transfer happens between them. Their orbital periods are quite low, often less than 12 h, as low as their angular momentum.
The existence of such stable, yet short-period, binary systems is a strange phenomenon.
When astronomers
first discovered them, the
assumption was that they were
simply binary stars that had
come close enough to each
other and become contact
systems over a long period of
time through a loss of mass
and angular momentum. But
astronomers had to abandon
this idea when it became
clear that some of the stars in
these contact binaries were
too young to have undergone
such a lengthy process. And
that is what led to the new,
more curious hypothesis that
there might be a third body, yet
unknown to us, which drained
enough angular momentum from a binary system, forcing the two stars to come closer.
The study of these third bodies in contact binaries is crucial to understanding the
Ms. Malu S. || 489
evolution of the systems themselves. And if they are indeed exoplanets, that thriving field of research benefits as well.
Eventually, these contact binary stars come closer and closer to each other till they merge into one single, fast-rotating star. Or so it has been theorized. There has been only one such case of a contact binary merger recorded so far. Thus, it becomes even more vital that potential merger candidates be studied.
My group has been studying contact binary systems that appear to be on the verge of merging. They can be identified based on their low mass ratio (<0.2) between the secondary and primary component stars. We are, in fact, focusing on especially those systems that appear to be eclipsing each other when viewed from the earth. This creates a periodic variation in the light we receive from them, and that is the essential aspect for us. With that variation, we get to understand the changes
in their orbital structure. This helps to decipher the possibility of the existence of a third body and the examples of the mass transfer in these systems.
Using the 1.3-m J.C. Bhattacharya telescope located at Kavalur, Tamil Nadu, operated by the Indian Institute of Astrophysics, Bengaluru, India, and IUCAA Girawali observatory, Pune, operated by the Inter-University Centre for Astronomy and Astrophysics, Pune, India, we collected the light from these systems in image frames in order to obtain the light variations over time. Data from several other sky
survey missions, such as the All-Sky Automated Survey, the Northern Sky Variability Survey, and also the Kepler K2 Space telescope, were utilized in this endeavour. When combined,
In the last decades, much to the fascination of astronomers, it was discovered that a significant fraction of stars existed as part of binary systems, that is, in pairs. Furthermore, around 10%–20% of stars seem to exist in triple systems, whose evolution continues to be heavily debated in the scientific community.