Astronomers have known for a while now that the Sagittarius Object at the center of our galaxy was a supermassive black hole. Now they know more about that big black thing, including that it has an accretion disk twenty-five times larger than our entire solar system. Excerpt:
As the most massive objects in existence, black holes usually have accretion disks, rings of gas and other materials that reach blazing hot temperatures, sometimes even emitting powerful, luminous x-rays.
Accretion disks have been spotted around other black holes before, but never around our galaxy’s own supermassive black hole, Sagittarius A*. The immense astronomical object rests at the center of the Milky Way roughly 26,000 light years from Earth and tips the scales at an estimated 4,000,000 solar masses.
On Wednesday, a team of astronomers led by Caltech astrophysicist Elena M. Murchikova announced that it had finally detected and imaged Sagittarius A’s accretion disk using the Atacama Large Millimeter Array (ALMA) in Chile. Their finding is published in Nature.
The disk is primarily composed of hydrogen gas – equal to roughly one-tenth the mass of Jupiter. It’s heated to around 18,000 degrees Fahrenheit, though it gets far hotter closer to the black hole. The disk extends out about a hundredth of a light year, about 1,000 times the distance from the Sun to the Earth. Assuming a roughly circular shape, that would give the accretion disk a diameter about 25 times longer than our solar system’s!
Sitting here on our little moist blue pearl, it’s hard to comprehend how really big the rest of the universe is. Sometimes when I’m wandering in the mountains I get the feeling of being pretty small in the face of the grandeur of the Rockies – imagine how you’d feel sitting in a little titanium can looking down at something as big as this accretion disk, probably from a light-year or two away, so you could see the whole thing. And, also, so you’d be well away from the horrific radiation and overwhelming tidal forces that would cook you and rip you apart if you got too close.
Not that it’s likely anyone from Earth will be looking at this accretion disc from such a vantage point any time soon. Given the best current technology, it would take any Earthly spacecraft thousands of years to get to the center of the galaxy; we’d need something like a generation ship, bearing a self-sustaining population of humans. The initial crew of that ship would never see their destination. Their great-great-great-and-then-some grandchildren would, and by that time, they may well not be H. sapiens any more. Isolated populations do tend to change over a span of generations.
And it’s not likely we’ll have a trans-phobic spacecraft any time soon, no matter how freely science fiction writers (like me) speculate about just such things.
That’s too bad. If someone was advertising for homesteaders to move to some unsettled wilderness world, I’d sign up in two shakes.