Virtual Telescope Zooms In On Milky Way Black Hole

FiReaNGeL writes "An international team has obtained the closest views ever of what is believed to be a super-massive black hole at the center of the Milky Way galaxy. The astronomers used radio dishes in Hawaii, Arizona and California to create a virtual telescope more than 2,800 miles across that is capable of seeing details more than 1,000 times finer than the Hubble Space Telescope. The target of the observations was the source known as Sagittarius A* ("A-star"), long thought to mark the position of a black hole whose mass is 4 million times greater than the sun. Though Sagittarius A* was discovered 30 years ago, the new observations for the first time have an angular resolution, or ability to observe small details, that is matched to the size of the event horizon."

Re:Interferometry

[Maelwryth]

Agreed, and in the interests of an intelligent thread (to which I should not be posting) I bring you "STRUCTURE OF SAGITTARIUS A* AT 86 GHz USING VLBI CLOSURE QUANTITIES" [iop.org] which is actually worth reading if you want to get up to date on the research into Sagittarius A*.

Re:Interferometry

[jriskin]

Just out of curiosity, how far could you push something like this? If you had an array of Hubble sized telescopes in space and could put them whatever distance you'd like from each other, what sort of results could you get?

Re:Interferometry

[Maelwryth]

And this [arxiv.org] (pdf warning) might be of interest as well, as it is from S Doeleman July 2008.

Re:Interferometry

[Anonymous Coward]

Veery good ones, but putting a telescope in the sky is 10-100 times the cost of one on the earth. That's why they are building ALMA, and they play with VLA, and SKA (square kilometer array).

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[account_deleted]

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Re:obligatory

[nospam007]

>... Now this Slashdot post has really put a downer on my day.

Just follow the example of the Pierson Puppeteers and you'll be safe.

"Darwin"

[Herve5]

Indeed the European Space Agency has had such a project for years: a space optical interferometer named Darwin, with an additional twist: by using descructive interferometry instead of constructive one, they intend to switch off a star in the center of the field of view, to see the planets around (these ones being way darker you wouldn't detect them otherwise), analyse the molecules in them etc. Needless to say, this project is still in its early phases, but indeed appears, with a schedule, in ESA's plans. http://en.wikipedia.org/wiki/Darwin_(ESA) [wikipedia.org]

Re:Interferometry

[john83]

A related concept, which I find interesting, is that the diameter of telescopes on earth isn't really the limiting factor. In the ideal situation, yes, a bigger aperture gives you better resolution, but in practice, you have to compensate for atmospheric turbulence first, using something like adaptive optics (where you use a deformable mirror). I've been told that some telescopes (like the Pan Starr) now do this step digitally.

Black hole gravity

[mbone]

General relativity makes no predictions about what is happening at the center of black holes - there is a singularity in the equations there. Worse, in general relativity singularities are (probably) never "naked" - if you go in to see what is happening you can never come back out, or send a signal back out, to tell us about it.

But, yet, the gravity of the black hole, as experienced outside, does increase with time as things get sucked in.

Re:also...

[AP31R0N]

Also, the expansion takes the form of things moving away from each other, not themselves getting bigger. Black holes don't suck things in anymore than the Earth sucks in the moon. If you get close enough, yeah, you'll fall in. But it's not like water going down a drain, or a vacuum. There are black holes in the center of the galaxy that are frighteningly huge, millions of solar masses... that aren't gobbling up stars. While their gravity is strong, the distances involved quickly makes the pull very weak. That and there are other objects pulling in every other direction.

Interesting side bit - Small black holes evaporate over time. Virtual particles pop outside the event horizon and sometimes escape, becoming real. Over enough time the black hole fizzles away. How that works exactly you'd have to ask Hawking.

Any physicists on hand to clarify/correct? /long fascinated by black holes

Re:also...

[tinkerton]

If you'd replace the sun with a black hole of the same mass, the earth would remain on the same orbit as it does now. A black hole doesn't pull any harder than another object of the same mass.

It's only when you get close that things start to change. Gravity is zero if you're 3km from the center of the sun, but with its black hole replacement, it would be impossible even for light to get away from it.

Re:Interferometry

[gEvil (beta)]

So when do we get the mobile phone telescope? We just need to get thousands of people to point their cellphone cameras at the same spot in the sky, right?

Re:Interferometry

[DerekLyons]

On reflection after my answer above - it could be made to work, possibly. If the phones can receive and record the signal, and if they can tag it a close intervals with GPS position and timing data... You can subsequently analyze the data streams and form crude 'beams'. Your angular resolution is going to suck rocks however, think in terms of a couple of degrees.