Recurrent outburst of twin star points towards rare future supernovae

Source: The post is based on the article “Recurrent outburst of twin star points towards rare future supernovae” published in PIB on 22nd November 2022.

What is the News?

Astronomers tracking the constellation Ophiuchus have spotted a recurrent nova system approximately 5,000 light-years away.  

Note: Nova is a transient astronomical event that causes the sudden appearance of a bright, apparently “new” star that slowly fades over weeks or months.

What is RS Ophiuchi?

RS Ophiuchi is a recurrent nova system approximately 5,000 light-years away in the constellation Ophiuchus. 

It has shown recurrent eruptions since 1985. The latest was in August 2021, when it reached a peak visual magnitude of 4.6 – bright enough to be seen with the naked eye. 

It is a binary system of a white dwarf star and a red giant in which the latter supplies the white dwarf with fresh, hydrogen-rich fuel for nova eruption. 

With enough fuel, the material on the surface of the white dwarf achieves a critically high temperature and pressure, and a thermonuclear runaway (TNR) ensues, which lasts for about 1000 seconds. This explosion generates huge energy making the system visible from a far distance. 

What has been detected by Astronomers?

Astronomers have been studying the data from the outburst of the star called RS Ophiuchi detected in 2021.

They found that with every eruption, the white dwarf accretes at least 10% of the ejected mass. They believe that eventually, it will explode as a Type 1a supernova. 

This event, if and when it occurs, will be the final proof of the conjecture around Type 1a supernova which states that if a white dwarf crosses the Chandrasekhar Limit of 1.4 Solar Mass, it collapses under its own gravitational pressure and gives birth to a Type 1a supernova.

Note: A Type 1a supernova is a rare type of supernova that occurs in binary systems (two stars orbiting one another) in which one of the stars is a white dwarf.