Sagittarius A* Dust Cloud: Planets May Be Devoured By Milky Way Black Hole In 2013

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A new study suggests that stars near the Milky Way’s central black hole may well form planets. The researchers based their analysis on a very recent discovery of a gas cloud making its way toward the galactic center.

On December 14 an international team of astronomers led by Stefan Gillessen of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, announced that they had spotted something heading toward a close encounter with the central black hole, known as Sagittarius A* (Sgr A*), which has as much mass as four million suns. Gillessen and his colleagues interpreted the object to be a dusty gas cloud about three times as massive as Earth, possibly belched out as stellar winds (plasma streaming outward from stars) from the young stars that orbit the black hole.

A few days later, Ruth Murray-Clay and Abraham Loeb of the Harvard–Smithsonian Center for Astrophysics suggested that the newfound object may be much more closely connected to those stars. In a preprint posted to the Web site arXiv.org on December 20, Murray-Clay and Loeb say that the cloud Gillessen and his colleagues discovered could be the disrupted remnants of a planet-forming disk surrounding a star that used to orbit Sagittarius A* at a safe distance but is now plunging toward the black hole. A protoplanetary disk is the swirling pancake of gas and dust surrounding a young star, which can coalesce into planets, asteroids and comets. “This cloud of gas naturally originates from a proto-planetary disk surrounding a low-mass star, which was scattered a century ago from the observed ring of young stars orbiting Sgr A*,” they write.

The star itself would be too faint to see. But as Sagittarius A* has distorted and fried the disk with the black hole’s gravitational pull and the radiation of its environs, it has generated a debris stream around the star that telescopes can detect.

If the young stars orbiting Sagittarius A* host protoplanetary disks, that “implies that planets form in the Galactic centre,” the researchers write. But you wouldn’t want to live on one of those worlds. The galactic center is awash in intense radiation emitted by material swirling around the outside of the black hole, which gets compressed and heated as it falls inward. (It is that radiation from outside the event horizon that allows astronomers to “see” a black hole, which itself holds tight to all matter and photons and hence emits no light.)

This may be something so watch over the next couple years. That a debris stream can be detected by telescopes is very interesting as well. I'm curious as to what we may see over the next few years of watching this development.

I admit I'm surprised that suns and planets can survive near the galactic center. I would have thought the forces would have ripped everything apart...

It shows we have a lot to learn, still, about the mechanics of black holes...

PS: I wonder if they will announce they have found Reapers over there!...

reply to post by NowanKenubi

The gravity gradient of a supermassive black hole actually makes it a bit more "survivable" than one of mere stellar mass. Because the event horizon lies at a great distance from the singularity, the tidal forces are much less than those of a lesser beast. Objects can actually make it to the horizon without experiencing spaghettifcation.

I wonder how life would fare farther away in the galactic core in systems that are threatened with being torn apart by gravity? We have found microbes that can survive ridiculous quantities of radiation. What if a whole tree of life evolved from such microbes?

reply to post by Phage


Thanks!

I sure didn't know that; very interesting...