Unraveling the Mystery of Sagittarius A and A*

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In summary, Sagittarius A* is the location of a super massive black hole and it is located at the Sagittarius constellation.
  • #1
shounakbhatta
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Hello,

Reading through internet I came across that Sagittarius A*, located at the center of our galaxy, is the location of super massive black hole. On the other hand, Sagittarius A is located at the Sagittarius constellation.

Where is the link?

Thanks,

-- Shounak
 
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  • #2


Constellations are collections of stars and other objects that are at more or less the same inclination and declination. Distance is not a part of the equation. Example: The Andromeda galaxy lies within the Andromeda constellation. The only connection between that galaxy and the stars in our galaxy that comprise the constellation is that all of those objects lie in the same patch of sky from our Earthly perspective.

Similarly, the only connection between Sagittarius A and the stars that comprise the Sagittarius constellation is direction from our Earthly perspective. There is a connection between Sagittarius A and Sagittarius A*. All three features that comprise Sagittarius A, Sagittarius A East, Sagittarius A West, and Sagittarius A*, lie at the center of the galaxy.
 
  • #3


Like when I drive my car around and around a tree, the tree might be said to be located in a certain window of my car, just becasue that's where I always see it. But in fact, it's nowhere near my window at all.
 
  • #4


Ok. Thanks for all the help. Sagittarius A* contains the super massive black holes right?

-- Shounak
 
  • #5


One more thing. Galaxy is the super set and within that comes the stars right? So any galaxy G, should have constellations within G, right?
 
  • #6


shounakbhatta said:
One more thing. Galaxy is the super set and within that comes the stars right? So any galaxy G, should have constellations within G, right?

A galaxy is made up of stars, gas, dust, and other material. I don't understand your question about the constellations however. The constellations are purely random patterns formed by the stars in the sky. If we move about a hundred or so light years in any direction practically all the constellations will no longer be the same.
 
  • #7


Shounakbhatta, you've piqued my curiosity with Saggitarius A*, I had no idea what it was till now, thanks. And the info I found says that teh black hole at the centre of our galaxy is just located pretty much where Saggitarius A* is.
 
  • #8


you need to realize than when you look in the direction of Saggitarius, you are actually looking towards the centre of our galaxy.

that is the link :)

We cannot optically "see" the centre of our galaxy from our location, as there is too much intervening dust and gas etc. but using infrared scopes and radio telescopes we can "see" deep into that region

Dave
 
  • #9
Hello P_I,

Sagittarius A*(Sgr A*) is the seat for a super massive black hole and it is at the heart of our Galaxy, the Milky Way. If I am not wrong, on October '2012, Sgr A* erupted. Source 2, S2 is the star, closest to Sgr A* and have been seen changing position, which gives the proof of the existence of a super massive black hole.
 
  • #10
shounakbhatta said:
Hello P_I,

Sagittarius A*(Sgr A*) is the seat for a super massive black hole and it is at the heart of our Galaxy, the Milky Way. If I am not wrong, on October '2012, Sgr A* erupted. Source 2, S2 is the star, closest to Sgr A* and have been seen changing position, which gives the proof of the existence of a super massive black hole.

Hello shounakbhatta,

The stellar motion of multiple stars around the ''center Black Hole" of our galaxy has been tracked for quite some time now (more than 10 years); a list is on the wiki site http://en.wikipedia.org/wiki/Sagittarius_A*. As an afternote, in the current day, we in this field consider that every galaxy hosts a super massive black hole (SMBH) at its center.
But concerning the statement you used
shounakbhatta said:
which gives the proof of the existence of a super massive black hole.
Currently this is considered only as an indirect proof of a very massive object there with mass compatible of being a SMBH, however, a 'proof' of a black hole relies on the actual imaging of the black holes event horizon, which is an ongoing project for both Sgr A* and M87 (an elliptical galaxy with a black hole >100 times more massive than in our galaxy)
 
  • #11
Hello Astrofan,

Thank you very much for informing. Does that mean, a BH or a SMBH has not actually been SIGHTED as yet?
 
  • #12
shounakbhatta said:
Hello Astrofan,

Thank you very much for informing. Does that mean, a BH or a SMBH has not actually been SIGHTED as yet?

As far as i know it, there is to this day no direct sighting of a BH/SMBH yet.

They are getting close though, refer to this article for a bit of info: (but don't take the whole thing too seriously, lots of it is still uncertain)
http://www.sciencemag.org/content/early/2012/09/28/science.1224768.full?explicitversion=true
 
  • #13
Hello Astrofan,

Thank you for the reply. Yes, I also think in that way. We haven't viewed BH or SMBH, we are just speculating...
 
  • #14
shounakbhatta said:
We haven't viewed BH or SMBH, we are just speculating...
Nonsense. Think of what you said along the lines of "we haven't viewed the iron core at the center of the Earth, we are just speculating."

We will *never* see the black hole at the center of the galaxy; it's black. Everything we can see, including huge velocities of stars at periapsis, an accretion disc, infalling material, gravitational lensing, etc. is indirect. That does not mean it's speculation. There is surprisingly little stuff that we can "see" directly.
 
  • #15
Right, thanks.
 

1. What is Sagittarius A*?

Sagittarius A* (pronounced "Sagittarius A-star") is a supermassive black hole located at the center of our Milky Way galaxy. It is estimated to have a mass equivalent to about 4 million suns.

2. What makes Sagittarius A* a mystery?

Sagittarius A* is a mystery because it is difficult to observe due to its location in the center of our galaxy and the presence of dust and gas that obstruct our view. Additionally, its behavior and characteristics are still not fully understood by scientists.

3. How do scientists study Sagittarius A*?

Scientists study Sagittarius A* using various telescopes and instruments, including radio telescopes, infrared telescopes, and X-ray telescopes. They also use computer simulations and mathematical models to better understand its behavior.

4. What have scientists learned about Sagittarius A* so far?

Scientists have learned that Sagittarius A* is an active supermassive black hole, meaning it is currently swallowing matter and emitting powerful jets of radiation. They have also been able to map its structure and track its movements, which has helped to better understand its behavior.

5. Why is studying Sagittarius A* important?

Studying Sagittarius A* is important because it can provide insights into the formation and evolution of galaxies, as well as the role of black holes in shaping the universe. It can also help us better understand the fundamental laws of physics and gravity. Additionally, understanding the behavior of Sagittarius A* can help us better predict and prepare for potential future interactions with other black holes in our galaxy.

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