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I've never seen that image of our galaxy's central region, it's fascinating! Is "Sgr A" the black hole, Sagittarius A*? If yes, why would it be bright? I though

by DeepDuh 14y ago

I've never seen that image of our galaxy's central region, it's fascinating! Is "Sgr A" the black hole, Sagittarius A*? If yes, why would it be bright? I thought it's inactive.

pkrein 14y ago
Sgr A is the black hole Sagittarius A* as far as I know. The black hole itself isn't bright. As far as I understand, the swirling gas around it (outside the event horizon) is what's sending out all the light. What do you mean by inactive?
- DeepDuh 14y ago
  By inactive I meant that it's not swallowing anything currently, but I guess if it has attracted a gas cloud this is simply not true. Must be quite a sight. Imagine there's a civilization on one of the central stars (if that's even possible considering the bursts of radiation they must get there) - I wonder what the night sky would look like.
  - privong 14y ago
    The activity level (in terms of how much material is falling into it) is fairly low, such that it doesn't qualify as being an "active galactic nucleus". However, a gas cloud (called "G2") will be passing close enough to the supermassive black hole that it will be tidally disrupted and part of the cloud will fall into the black hole. This will give us a chance to see enhanced accretion, though still not of the level for it to be considered "active".
- privong 14y ago
  Technically Sgr A* is a component of the Sgr A region. There is also Sgr A East and Sgr A West, in addition to Sgr A*.
wasnotwas 14y ago
As I have understood, "Black Hole" is something of a misnomer, as the singularity is in fact an intensely compact ball of matter/energy radiating x rays, etc. Matter releases energy as light in various wavelengths, including x, gamma, etc, but once inside the heart of the "hole" it is unable to emit ANYTHING. The net effect, however, is a surrounding veil of electromagnetic spectral emissions. Matter/energy can't escape once inside, but on the way in it puts on a hell of a show.

by DeepDuh 14y ago

I've never seen that image of our galaxy's central region, it's fascinating! Is "Sgr A" the black hole, Sagittarius A*? If yes, why would it be bright? I thought it's inactive.

pkrein 14y ago

Sgr A is the black hole Sagittarius A* as far as I know. The black hole itself isn't bright. As far as I understand, the swirling gas around it (outside the event horizon) is what's sending out all the light. What do you mean by inactive?

DeepDuh 14y ago
By inactive I meant that it's not swallowing anything currently, but I guess if it has attracted a gas cloud this is simply not true. Must be quite a sight. Imagine there's a civilization on one of the central stars (if that's even possible considering the bursts of radiation they must get there) - I wonder what the night sky would look like.
- privong 14y ago
  The activity level (in terms of how much material is falling into it) is fairly low, such that it doesn't qualify as being an "active galactic nucleus". However, a gas cloud (called "G2") will be passing close enough to the supermassive black hole that it will be tidally disrupted and part of the cloud will fall into the black hole. This will give us a chance to see enhanced accretion, though still not of the level for it to be considered "active".
privong 14y ago
Technically Sgr A* is a component of the Sgr A region. There is also Sgr A East and Sgr A West, in addition to Sgr A*.

wasnotwas 14y ago

As I have understood, "Black Hole" is something of a misnomer, as the singularity is in fact an intensely compact ball of matter/energy radiating x rays, etc. Matter releases energy as light in various wavelengths, including x, gamma, etc, but once inside the heart of the "hole" it is unable to emit ANYTHING. The net effect, however, is a surrounding veil of electromagnetic spectral emissions. Matter/energy can't escape once inside, but on the way in it puts on a hell of a show.