Second Black Hole at the Center of the Milky Way 61
Tsalg pastes "A second black hole lurks at the centre of our Galaxy, according to astronomers who have watched a cluster of stars spinning around it. Just three years ago, astronomers confirmed that the Milky Way revolves around a supermassive black hole, called Sagittarius A*, which is about 2.6 million times more massive than the Sun. But now a much smaller black hole, just 1,300 times our Sun's mass, has been found orbiting about three light years away from its supermassive cousin. placing it intermediate between the relatively small (stellar mass) black holes in the Milky way Galaxy and the supermassive black holes found in the nuclei of galaxies."
i read.... (Score:2, Funny)
Tithing (Score:5, Funny)
So, if you give money to a church, it goes to God; and if you pay taxes to government, it goes down a black hole?
Contradictory? (Score:3, Interesting)
- dshaw
Re:Contradictory? (Score:5, Informative)
Re:Contradictory? (Score:2)
Stars in the spiral arms don't collide and if they did they would be far from elastic.
The arms rotate only because the stars that form them rotate, there's no wave propagating through some medium.
Re:Contradictory? (Score:4, Informative)
If the arms rotated because of the stellar orbits, you can easily see that the arms would be wound up beyond recognition by now. So that clearly doesn't work. (It's referred to as the "winding problem" in astrophysics.)
By the way, I'm pretty sure that sound waves aren't consider "density waves". The latter are driven by gravity, sound waves are pressure waves.
Re:Contradictory? (Score:4, Insightful)
In a galaxy, gravity is the binding force. Imagine every star in the galaxy as a physical ball. And for simplicity's sake, imagine that it's connected to all it's neighbors by a spring. That spring is gravity. Now, move the sheet of interconnected stars that you've just made. Bingo, you have density waves.
Re:Contradictory? (Score:2)
Also these [nap.edu] fascinating pages [astronomynotes.com].
Apparently we still don't know what creates the density wave in the first place, or maintains them. All we know is why they're brighter...
Re:Contradictory? (Score:2, Interesting)
If the "big bang" theory is correct, and the entire universe emanated from a point -
Where did all this rotational inertia come from???
I guess the primordial point we supposedly came from was spinning?
Is it likely that "black holes" can be spun up so much from ingesting incoming rotational inertia that they become unstable and sling themselves apart... aka, the "big bang"?
I am not a cosmologist, or even a cosmetician as far as that goes, but I ofte
Re:Contradictory? (Score:2)
* By "spin" I really mean angular momentum.
Re:Contradictory? (Score:1)
( I consider your "angular momentum" to be the same as my "rotational inertia" )
This study of cosmology is extremely interesting, yet so much a cliffhanger as we seek yet more and more data... much like a drug addiction. Every time we think we have an answer, it seems to reveal another box of questions.
I know in the end its just gotta be simple. So far things always have seemed to work that
Re:Contradictory? (Score:2)
Cosmology is like all of science. Each answer opens new questions. The questions get more d
Re:Contradictory? (Score:3, Insightful)
Do we have any way of knowing if the universe as a whole is rotating? Or if it is, in what plane and how fast?
One of the key axioms of Cosmology is that of isotropy. No matter which way you look the universe looks roughly the same. This has been a very successful conjecture and many a cosmologist wouldn't like to throw that principle away without a fight.
I'm no expert at cosmology but my immediate thought is that material would spread out along the plane of rotation like dust does with newly forming
Re:Contradictory? (Score:2)
The universe as a whole is too tenuous to be collisional. So that's not it.
Isotropy does imply conservation of angular momentum, but I'm not sure that it implies a non-rotating universe.
Re:Contradictory? (Score:4, Informative)
Re:Contradictory? (Score:1, Informative)
black hole collision (Score:5, Interesting)
Stars ripping each other apart. (Score:3, Funny)
See this link [mtv.com] for more information and pictures. I particularly like the one where Andre Agassi knocks Tiger Woods' kneecap out of the arena.
Re:black hole collision (Score:1)
is there any classification about types of black holes? if they collide will they just merge?
can black holes get bigger? if A sucks B in is A larger afterwards or has it the same 'size'!?
just some late-night thoughts. going to bed now.
Re:black hole collision (Score:3, Interesting)
Re:black hole collision (Score:5, Informative)
And some very interesting gravity waves [psc.edu] will be generated!
Re:black hole collision (Score:3, Informative)
Re:black hole collision (Score:5, Interesting)
One of the major problems is that programs crash pretty quickly when the evolution develops a singularity. A good method for avoiding this is called excision, where the singularity is removed from the grid and replaced with boundary conditions. This was recently implemented in my advisor's group and applied to the binary neutron star problem. At the end of the evolution, a black hole forms, so it doesn't seem like there are too many steps before a full black hole collision is possible.
Re:black hole collision (Score:3, Interesting)
Re:black hole collision (Score:3, Funny)
Just divide by zero......twice
Re:black hole collision (Score:1, Informative)
Re:black hole collision (Score:2)
So, is it just a coincidence (Score:2, Funny)
That's one big toilet! (Score:2)
I bet you have to wait while Lake Mead refills itself so you can re-flush to catch any floaters that didn't go down the first time!
Hole II (Score:2)
What are the odds (Score:2, Interesting)
Re:What are the odds (Score:3, Informative)
Re:What are the odds (Score:2, Insightful)
Re:What are the odds (Score:1)
awesome (Score:2, Insightful)
Re:awesome (Score:1)
Re:awesome (Score:1)
Re:awesome (Score:1)
Re:awesome (Score:1)
Scary (Score:1, Interesting)
I've allways had a fear that, despite out best efforts as intelegent beings, the universe as a whole will be fated to a cold, dark future, without any intelegent life and one big black hole. Or (almost as bad) a repetition of itself.
I think there is a phobia for that, it was on star treck once, nelix had it.
I dunno if HUMANS have the average intelegence to escape earh before extinction, but I hope some race will save the
Re:Scary (Score:2)
Re:Scary (Score:3, Interesting)
Remember, a black hole doesn't have any magical sucking power. It's just gravity. If a star collapsed into a black hole, its gravitational pull doesn't get any stronger. It's still the same mass, it's just a lot denser. Contrary to what science fiction shows will tell you, it won't start "sucking in" anything that the star it collapsed from wasn't already "sucking in".
Now consider how often you see planets and stars collide. You ever hear about it? Even when two galaxies run into
Re:Scary (Score:1)
FooAtWFU is right:
"The universe is a big place, perhaps the biggest." Kilgore Trout (Kurt Vonnegut character)
Re:Scary (Score:1)
Re:Scary (Score:1)
Sounds about right - what about this one: "The critical density corresponds to somewhere between 2 and 8 hydrogen atom per cubic yard" (Alan Guth in "The Inflationary Universe"). Let's hope that God knows his conversions to the metric system better than NASA.
Re:Unlikely - information is retained (Score:1)
.
-shpoffo
Re:Scary (Score:2)
Is this a big surprise? (Score:2)
Re:Is this a big surprise? (Score:3, Informative)
That this is a surprise depends on whom you ask. The real issue here is to understand how those huge f**off multi-billion solar mass black holes form. And so far there had not been such high-quality evidence for anything in between a stellar-mass black hole formed by a single massive star collapse, and those monsters in the middle of galaxies.
So those who think that they come from mergers of solar-mass BHs are comforted. There's also those who say that in no way those monsters had enough time to form by s
Colour? (Score:1, Funny)
Death and Taxes (Score:4, Funny)
Is it just serendipity that this object, into which everything goes and never comes back, is named after an Earthly agency [irs.gov] to which similar attributes are often ascribed?
Re:Death and Taxes (Score:2)
Na. The IRS is more like a wormhole. It takes money from the middle class and funnels it to corporations and to the military for creating mayhem and socialism in Iraq.
Re:Death and Taxes (Score:1)
You need to get up to date with your patriotic vocabulary.
A bit of math (Score:2)
Plugging in the values for these two black holes, assuming they are in a nearly circular orbit, we find that the period is about 55,000 years. That sounds like a long time until you realize that this mammoth orbit is almost 20 light years in circumference.
That means tha