'Jekyll and Hyde' binary stars discovered by Indian-origin scientist

• Terzan 5 CX1 is a binary star system with an alter ego.
• The star system was able to switch identities in a fraction of the time it takes other star systems to do the same.
• The discovery was led by Indian-origin scientist Arash Bahramian for the International Centre for Radio Astronomy Research (ICRAR) in Australia.
• Bahramian and his team believe Terzan 5 CX1 is exhibiting “Jekyll and Hyde” behaviour.

A binary star system just under 20,000 light-years from Earth is unlike the others. Armed with an alter ego, the two stars called Terzan 5 CX1 managed to switch their identities in 11 years — a process that takes billions of years in other star systems.

One star is like the Sun and the other is a neutron star, the remnant of a supernova explosion.

The discovery was led by a scientist of Indian-origin, Arash Bahramian of the International Center for Radio Astronomy Research (ICRAR). Bahramian and his team used nearly a decade and a half of data from National Aeronautics and Space Administration’s (NASA) Chandra X-ray Observatory to determine that the stars were exhibiting a “Jekyll and Hyde” behaviour.

The Strange Case of Dr Jekyll and Mr Hyde

Terzan 5 CX1 was originally discovered in 2003 when it was acting like a low-mass X-ray binary.

This is when the neutron star is pulling material from its Sun-like companion. The material creates a ring called an accretion disk that can be detected by the bright X-ray light that they give off.

At the time, Terzan 5 CX1 was giving off brighter X-ray than any of the other stars in the cluster around it. However, new data from 2009 to 2014 showed that the star was 10-times fainter — now a millisecond pulsar.

“Researchers noticed that a stellar duo behaved like one type of object before switching its identity, and then returning to its original state after a few years,” said NASA.

According to the study, the material caught in the accretion disk fell onto the surface of the neutron star, making it rotate even faster. Eventually, it was rotating at fast enough for the transfer of matter to slow down. Any left-over material got swept away by the neutron star’s magnetic field.

This implied that just like Robert Louis Stevenson’s classic novel Strange Case of Dr.Jekyll and Mr.Hyde, the new star system has a dual personality.

It’s a rare occurrence
According to NASA, only three such “Jekyll and Hyde” examples of binary star systems have been discovered so far.

The first was in 2013 where the binary stars IGR J18245 was observed by the Chandra X-ray Observatory to find that it went from being a low-mass x-ray binary to a millisecond pulsar within seven years.

So far, Bahramian and his team observed Terzan 5 CX1’s x-rays. Now, they plan on detecting radio pulses as well to confirm their thesis.

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