Slashdot Mirror
Deep in the Core
meehawl writes "A video of what is currently thought to be the closest star to the supermassive black hole at the centre of our galaxy. The star orbits the black hole in a highly elliptical orbit with a period of 15 years or so, but at its closest approach it swings within 17 light hours of the black hole (around three times the distance between the Sun and Pluto). In the video, you can see the star ricochet past its closest approach to the black hole. This slingshot effect enabled astronomers to further pinpoint the mass of the black hole, which is confidently estimated at 2 million suns or so. The mass observation, coupled with the size constraints observed, indicates the object at the centre of the galaxy is definitely composed of some exotically dense form of matter."
this slashdot effect enabled astronomers to further pinpoint the mass of the black hole, which is confidently estimated to be somewhere in the server room
So our galaxy is like spit bubbles circling the great cosmic drain?
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really is pretty awesome. I had no idea that this "slingshot effect" was so 'graphic'...wrong word, okay, 'extreme'. Quite amazing.
meehawl: Lets link to a mpg video file on the front page of Slashdot! Nothing could go wrong! Zonk: Brilliant!
Is this a 3 year old article?? Or did we just pass too close to a black hole, bending time or something???
it looks to me that the dot just changed his mind on which direction he wanted to go. That or maybe he didnt like one of the other dots in that direction.
the object at the centre of the galaxy is definitely composed of some exotically dense form of matter.
Oh my god . . . It's full of politicians and pundits . . . !
Black holes are where God divided by zero?
Paleotechnologist and connoisseur of pretty shiny things.
As they note, there remains now the mystery of how they got so much mass to concentrate in one place. Stars don't forget all about conventional orbital dynamics just because they've spotted a black hole somewhere not too far off.
While the idea of black holes, dark matter, etc seems intringing, it is still a lot of theory. It is nice to see that people haven't given up, but that's not to say that this article is just as much speculation as the next.
With that said, wouldn't it be nice to focus all of humanities efforts on answering the questions we don't yet know the answers for ... instead of killing each other? I know that we already have the answer, but 42 only answers the ultimate question, we can't even answer the simple things like "do black holes exist?"
Ignore the "p2p is theft" trolls, they're just uninformed
The http://arxiv.org/abs/astro-ph/0210426:linkedarticl e says the "enclosed point mass" (read: black hole) has a mass of 3.7 million solar masses, +- 1.5M solar masses. Not 2M solar masses, as the article summary indicates. For most people, myself included, this is a meaningless distinction, but in the interest of scientific accuracy, I thought I'd mention it.
High-speed Road Trip (18.000KPH)
but seriously, since it is revolving around the black hole, does that mean it is slowly being sucked in?
Revolving is kind of a 2 dimensional way to look at it. Instead it is orbiting, which is actually a perpetual fall. So the short answer is..."yes, it is not being sucked in". Really, I would have no idea how to do the math (as most of the variable are too...variable). But basically, for every object that can be orbited you can figure out a minimum sustainable orbit versus one that is catastrophic.
You'd be surprised how much scientific research is sponsored by DARPA (in the States, of course). While it's likely that this particular piece of research was not, in general DARPA funds a lot more than NSF. In other words, "killing each other", to a certain extent, drives scientific research. "killing each other" gave us the IP stack of protocols, for instance ...
The Raven
A million here, a million there, and pretty soon you're talking real masses.
Da Blog
Anybody else get a plain black screen for the video?
Running Media Player Classic, I get diddly squat in the way of moving dots.
Of course, I suppose I could just be looking at the black hole itself......
"City hall" in German is "Rathaus" Kinda explains a few things......
"killing each other" gave us the IP stack of protocols
It's true, it's true! They say that the war in Iraq is supposed to give us something called IPv6!
The Voyager I is currently at a distance of 95 AU. 122 AU could be the distance from the sun to the heliopause.
According to the original paper from 2002, the star is nowhere near close enough to be "tidally disrupted", so it's just orbiting. (What it says is that even at closest approach, it's still 70x too far way.)
With all those stars whipping around, though, it wouldn't be hard to get the occasional star either entirely ejected, or potted right in. More usually, an orbit would be changed so that it approaches closely enough on each orbit to have a bit of mass (say, a trillion tons) stripped off, and gets used up over the course of a few thousand years. Of course at some point we wouldn't be able to see it any more, so there could be a bunch of those happening right now.
Probably most of the mass moving near it is non-radiating low-density plasma whose motion is controlled less by gravitation than by unimaginably intense electromagnetic fields. We see stars, but there's lots else going on in there we can't see.
Black holes don't have special sucking power... it's just normal gravity. Just as a planet can orbit a star, or a star can orbit another star, a star can orbit a black hole. It will behave exactly as if it were orbiting a planet of an equal mass, as long as it's going fast enough to maintain orbit.
The caveat is that if one gets too close to the black hole, within what is termed the 'event horizon', then there is no turning back. Not even light escapes (generally speaking -- Stephen Hawking would be a more appropriate speaker on the subject.) This star does not appear to be doing that since it's still orbiting, and we can see it.
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Take a look at the original press release, dated 16 October 2002.
The article was published in Nature at the same time, and the video isn't new either.
Remind me why this is going up on Slashdot today?
*Begins humming to himself* Deep in the Core, the galactic core, a black hole spins toniiiiight
________
Entranced by anime since late summer 2001 and loving it ^_^
What are you talking about? This is a 3D space, not a 2D plane. That star's just crossing in front of it.
Esoteric reference.
It would be a stable orbit, except this is a pretty unusual situation. It's in a pretty dense neighborhood, so the star may interact with other stars or other matter. Such collisions will often take energy out of the orbit. Also, as seen with orbiting pulsars, the star loses some energy due to gravitational radiation. There could be magnetic fields that put a brake on things over long periods of time. If the star gets too close, tidal distortion becomes significant.
There are plenty of forces that could cause the star to spiral in. The calculations are left to the reader. I am sure people will be watching for changes in the orbit.
Fiat Lux.
But basically, for every object that can be orbited you can figure out a minimum sustainable orbit versus one that is catastrophic.
Definitely, good post. I believe you refer to escape velocity, which is represented by the equation: escape velocity = sqrt(2GM/r) where G is the gravitational constant, M is the mass of the the object which the potentially escaping object orbits, and r is the distance between the center of mass in the body being orbited and the point at which escape velocity is calculated (at different points in the orbit, the necessary velocity would fluctuate). Orbits in which the object's velocity is less than escape velocity are said to be bound, and those in which it exceedes it are said to be unbound. At that point, the path of the escaping body is no longer elliptical, but rather hyperbolic.
More information at http://en.wikipedia.org/wiki/Escape_velocity
Actually, there is some recent debate as to whether or not the milky way galaxie is a spiral galaxie. Some astronomers think it has a different shape, something like a bar if i recall correctly.
It looks like all the observations, measurements, analyses and even the 'press embargo' are over three years old. Are there any updates?
Kevin Fox
17 light hours is roughly 113 AUs, if the star passes that close to the black hole, I wonder if the line of the node of the orbit will precess forward enough to measure due to the frame dragging from the spin of the black hole. That would also help prove it's a black hole. The spin of the black hole should be pretty fast since if formed by capturing matter in orbit. The Einstein "Gravity Probe B" tried to measure the same affect in earth orbit but it's so tiny in the Earth's case, a 2 Million Ms black hole would have a big frame drag effect. I guess it comes down to whether the star gets close enough and long enough to get dragged much. http://einstein.stanford.edu/ Mark
heat == infrared photon, which like optical photons,cannot escape a black hole. however, heat can be generated from the accretion disc of matter being pulled into the hole. e.g. gas being ripped off a nearby star and orbiting the hole.
If a black hole can create a gravitational force so powerful it can suck in light, doesn't that mean that when the light is being sucked in it is travelling faster than light towards the black hole?
No, as light doesn't speed up and slow down in empty space. Instead, it changes frequency. Light travelling towards a black hole (or any other gravitating object) gets blue-shifted.