Astronomers have discovered something quite peculiar in the centre of the Milky Way. They’ve found six objects orbiting Sagittarius A* that are very different from anything else found in the galaxy. These objects have been assigned a class of their own – ‘The G objects’.
Two out of these six objects were discovered a couple of decades ago, and astronomers spent a few years trying to understand their pattern of orbits and nature. They resembled gas clouds, stretching 100 AU across, and showed dust and gas emission spectra. But none of their behavioural patterns resembled those of a gas cloud.
Recently, a team of astronomers led by Anna Cuirlo from UCLA identified the remaining four ‘G objects’. These four objects have very different orbits as compared to those of G1 and G2. Scientists first figured out that these weren’t JUST gas clouds when, in 2014, G2 passed close to an SMBH (Super Massive Black Hole) and wasn’t disrupted by the tidal forces.
They expected G2 to get torn apart and consumed by Sagittarius A*, which would then produce some supermassive black hole accretion fireworks. This is the usual behaviour shown by hydrogen gas clouds and the fact that nothing happened left scientists bewildered.
Since this scenario has the unusual requirement that G2 has been fortuitously observed during the exact decade of its entire existence, many alternative models containing a central stellar source have been proposed. The presence of a central star in the middle of this ‘gas cloud’ would allow G2 to survive its closest approach and would not demand a recent formation event.
The theory is that this is the result of two twin stars colliding into one another, producing vast clouds of gas/dust surrounding one big star. The others could also be binary star mergers, as these tend to happen quite frequently in the centre of the galaxy.
“Black holes may be driving binary stars to merge. It’s possible that many of the stars we’ve been watching and not understanding may be the end product of mergers that are calm now. We are learning how galaxies and black holes evolve. The way binary stars interact with each other and with the black hole is very different from how single stars interact with other single stars and with the black hole.” said physicist and astronomer Andrea Ghez of the University of California, Los Angeles.
All of the G objects have a lot in common and finding more with similar characteristics is the only way to go about figuring out information to solve this enigma. All weird things which might be going on in this far corner of space will only reveal their true intent with the passage of time.