Even though it was heading straight for supermassive black hole Sagittarius A*, instead of being devoured by it, it went through it without causing any significant changes to the surrounding environment.
On January 5, 2012, a paper published in ‘Nature’ verified that G2, a gas cloud detected ten years earlier near the core of our galaxy, was heading directly towards Sagittarius A *, the massive black hole that lies at the heart of the Milky Way.
From that moment on, astronomers all across the world began intently following the cloud’s progress toward its ultimate end. It would also be the first time scientists could see a black hole’s “snack.” But things did not go as planned.
The cloud’s closest approach to Sagittarius A * happened in May 2014, but to everyone’s surprise and disappointment, G2 emerged virtually undamaged from the encounter.
How could that be? Why did G2 survive Sagittarius A *’s voracious gravitational appetite, a 44 million km2 “space monster” with almost four million times the mass of the Sun?
Following this, in March 2015, an ESO research group determined that the object had not only survived, but was remained compact and had not been “stretched” or bent by the immense black hole gravity. Sagittarius A * also showed no signs of increasing activity.
A disappointment as well as a puzzle
Nothing happened, which disappointed scientists and led them to call the occurrence a “cosmic leak.” After passing the black hole, G2 reverted to its previous form. But what exactly happened?
Another thing that’s weird about the G2 is that it’s very hot, which isn’t what a cloud of dust and gas should be. Though initially considered to be heating the object, measurements revealed that it remained constant in temperature as it moved around Sagittarius A * and other neighboring stars. That meant the source of G2’s heat was inside the cloud, not outside.
Doubt gripped the experts. What if G2 wasn’t just a cloud of dust, but had at least one star in it? Another research published last year suggested this possibility. In addition to causing the remarkable warmth, the cloud is the product of two partner stars violently merging. The same investigation found four more G2-like objects surrounding the galactic core, bringing the total to six. Too many merging binary stars.
A possible solution
Astrophysicist Florian Peißker and his team have spent 14 years studying data from the Very Large Telescope’s (VLA) SINFONI instrument. They have now come up with a different explanation, which has just been published in The Astrophysical Journal.
In this new analysis, G2 is expected to be home to not one, but three very young stars, all less than a million years old. They are so young for researchers that they are still surrounded by cloud stuff.
In Peißker’s words, the fact that “G2 actually consists of three evolving young stars is sensational.”
The cluster S is an unusual collection of young stars in the Milky Way’s core. The G2 stars could be part of this population, according to Peißker’s model.
Individual stars in a myriad of orbits around Sagittarius A* could have formed in the same ‘stellar hotspot,’ forming a group that has since disbanded.
Even if they weren’t part of the S cluster, the stars in G2 were undoubtedly formerly part of a larger group. Other dusty objects orbiting the massive black hole could be young member stars of this cluster, destroyed by gravity as they moved closer to Sagittarius A *.
In order to discover the origins of G2 and other G objects, further research will be required because the black hole’s atmosphere is not considered favorable to star formation.
“The new results,” says Peißker, “provide unique insights into how black holes work. We can use the environment of SgrA* as a blueprint to learn more about the evolution and processes of other galaxies in completely different corners of our Universe.”
Source: The Astrophysical Journal
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