A black hole unmasked

Nov 29, 2011
An optical image of the sky showing the location of the black hole, Cygnus X-1. (Right) An artist's conception of the black hole system, showing the black hole drawing material towards it from a massive, blue companion star. This material forms a disk and jets that emit radiation. Credit: Optical: DSS; Illustration: NASA/CXC/M.Weiss

Black holes are among the most amazing and bizarre predictions of Einstein's theory of gravity. A black hole is thought to be point-like in dimension, but it is surrounded by an imaginary surface, or "edge," of finite size (its "event horizon") within which anything that ventures becomes lost forever to the rest of the universe.

Despite their reputation as implacable sinks for matter and energy, the regions around are often sources of powerful emission. They can be ringed by a disk of matter, for example contributed by gas from an orbiting ; when infalling material interacts with that disk, radiation and matter can be ejected.

A black hole is so simple that it can be completely described by only three parameters: its mass, its spin, and its electric charge, but measuring these values is far from simple. The charge is usually considered to be negligibly small, leaving only two parameters. The mass can be found when the black hole has an orbiting companion, since the periodic orbital motions of the pair are precisely determined by their masses and the orbit's size. Infalling material provides a source of radiation to measure the period, but ascertaining the size of the orbit requires knowing the distance to the source.

All these difficulties have been overcome in a set of three papers appearing together this month. CfA Mark Reid, Jeff McClintock, Ramesh Narayan, Lijun Gou, James Steiner, and Jingen Xiang, together with their colleagues, used radio wavelength parallax techniques to measure the precise distance to the first discovered black hole, Cygnus X-1: it is 6060 light-years away, with an uncertainty of about 6%. The firm distance estimate enabled the scientists to infer the mass of the black hole: 14.8 with about the same uncertainty, 7%. Not least, the sole remaining parameter of a black hole -- its spin -- could now also be determined. The team calculated that the black hole is rotating at about 95% of the maximum rotation permitted in Einstein's theory, corresponding to its whirling around about 800 times per second. While these objects are still just as amazing and bizarre, these new papers are a dramatic step forward in our understanding of their basic properties.

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User comments : 26

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jsdarkdestruction
4 / 5 (6) Nov 29, 2011
no doubt oliver will try to turn this into more of his propaganda. Oliver, why is this 14.8 solar mass neutron star not shedding hydrogen from the n-n repulsive force like in our sun? why cant we see this 14.8 solar mass neutron stars like other neutron stars? where is the radiation all neutron stars must admit according to your theory?
rawa1
1 / 5 (6) Nov 29, 2011
The team calculated that the black hole is rotating at about 95% of the maximum rotation permitted in Einstein's theory
It just means, such black hole must produce jets, which are analogy of gravitational brigtnening. Such black hole will differ significantly from classical relativistic model of pin point singularity.

http://www.chalme..._576.jpg
yep
1 / 5 (3) Nov 29, 2011
This means the world is flat you just do not see it because of the long round edges.
DavidMcC
1.8 / 5 (4) Nov 29, 2011
"A black hole is thought to be point-like in dimension, but it is surrounded by an imaginary surface, or "edge," of finite size (its "event horizon") within which anything that ventures becomes lost forever to the rest of the universe."
That's a very old-fashioned view of it. In more modern times, the concept of a theory of "quantum gravity" is used to do away with the mathematical singularity version of a BH. Unfortunately, the maths turns out to be too difficult so far.
bewertow
3.5 / 5 (2) Nov 29, 2011
@ DavidMcC

We don't have an accepted theory of quantum gravity yet. Everything is still being developed and awaiting experimental tests.
rawa1
1.1 / 5 (8) Nov 29, 2011
We don't have an accepted theory of quantum gravity yet.
You can never reconcile pair of theories at the moment, when one predicts one result and the another one predicts another result for the very same phenomena or quantity (like the density of vacuum or cosmological constant). Such formal system of equations is unsolvable.
http://en.wikiped...astrophe
Of course, it can still work as a Philosopher's stone, i.e. like the salary generator for mathematicians involved.
Jonathan_Ivgi
1 / 5 (1) Nov 29, 2011
traveling at 200,000 Miles Per Hour. it would take

20,330,601 years. to reach the Black Hole.

That's a pretty long trip.
Vendicar_Decarian
3.4 / 5 (10) Nov 29, 2011
"20,330,601 years. to reach the Black Hole." - Ivqi

Ya, but in comparison you are just an arm's length away from uranus.

Relatively speaking.
CHollman82
1 / 5 (1) Nov 29, 2011
"20,330,601 years. to reach the Black Hole." - Ivqi

Ya, but in comparison you are just an arm's length away from uranus.

Relatively speaking.


Well done.
Vendicar_Decarian
2.4 / 5 (5) Nov 29, 2011
Twas barely a stretch. I plucked the fruit just above the lowest hanging berries.
Vendicar_Decarian
1 / 5 (4) Nov 29, 2011
Dingleberries are the second lowest hanging fruit.
ChuckWyatt
5 / 5 (2) Nov 29, 2011
In the constellation of Cygnus
There lurks a mysterious, invisible force
The Black Hole
Of Cygnus X-1

Six Stars of the Northern Cross
In mourning for their sister's loss
In a final flash of glory
Nevermore to grace the night...

Graeme
not rated yet Nov 30, 2011
Where is the publication for this? I would like to know how the parallax was measured. Are they measuring change of angle in the sky over 6 months?
Vendicar_Decarian
2.3 / 5 (3) Nov 30, 2011
"Are they measuring change of angle in the sky over 6 months?" - Graeme

Yes. Radio Astronomy interferometry does much better than the 1 second of arc limit to standard optical astronomy.

0.0001 seconds of arc resolution is possible with a baseline that is 8,000 miles across.

So what you do is measure that accurately now and 6 months from now and then take the difference.

1 second of arc resolution over a baseline = 1 au corresponds to 63,000 light years.

Benni
1 / 5 (1) Nov 30, 2011
In the recent past when our tiny astronomy club (6)has had it's monthly meetings, "black hole" discussions are the most frequent "off-topic" issues we have discussed.

One member brought up a possible discovery of 3 "quark stars" that astronomers think may be the building block of a BH. The unique thing about these bodies is the incredible bending of light these bodies exert on other light sources (this is what led to their discovery), something like a 15-30% bend. That's a lot of of "bending" to put a photon through, only a truly massive object can do that.

So this brought up a question: What quantity of mass must exist to bend passing starlight 100%? This entailed a discussion of how to calculate "escape velocity of a photon". I have searched the internet specifically for that topic & have found nothing. Can anyone here help us out?

Thanks, Benni.
Ethelred
3.4 / 5 (5) Dec 01, 2011
Repulsive forces between neutrons is an empirical fact [1,2].
No Oliver. The Pauli Exclusion Principle is what your chart shows. The way stability is increases in larger nuclei with increasing neutron to proton ratios also show that neutrons do not repel each other. Funny the way you pretend that reality will go away if you just keep ignoring it.

It won't go away. Time to deal with it.

Neutron repulsion causes fragmentation and/or neutron emission from the cores of neutron-rich a.) Atoms, b.) Stars, and c.) Galaxies [3]:
Which would also fragment the Earth, the Sun and the Milky Way except that the fantasy force would have stopped them from forming in the first place.

1.Radiation from a pulsar separated the d- and l- amino acids in primitive meteorites before life started here [1].
So you claim. Only the evidence shows otherwise.>>
Ethelred
3.3 / 5 (7) Dec 01, 2011
2. Fe-56, the decay product of doubly magic Ni-56, is only made near the core of a supernova.
Yes. And it can be formed in any type II Supernova. There is no need it be OUR Sun and the evidence it that more than one supernova was involved and maybe a Wolf-Rayet.

3. Fe-56 is the most abundant atom on Earth.
It isn't the most abundant in the Sun, where is much less than one percent, or the Universe as a whole, where it is even lower. Nor is there any reason to suppose it is.

Why? Earth formed as a pulsar planet!
Minimum mass of a pulsar is just a tad more than the Earth. At the time of formation it is a tad more than the Sun and not one pulsar has been found to be less massive than the formation mass.

You claim we must go on evidence. Why don't you start doing that?

Ethelred
Ethelred
3.7 / 5 (3) Dec 01, 2011
So this brought up a question: What quantity of mass must exist to bend passing starlight 100%? This entailed a discussion of how to calculate "escape velocity of a photon".
The escape velocity must be greater than 300,000 KPS for light to bend 100%, that is for there to be a black hole. This more dependent on density than the total mass assuming there are such things as primordial or quantum black holes. I think you mean for a stellar mass black hole.

Here is a discussion of this question. Heavy on math in some of the posts.
http://www.physic...?t=56143

http://en.wikiped...ar_limit

http://en.wikiped...velocity

There are General Relativity affects as the diameter of a mass in decreased due to compression. I think this lowers the amount of the original mass, or alternately the diameter of the mass, that has to be there before the gravitational compression begins.

Ethelred
Seeker2
1 / 5 (1) Dec 06, 2011
Such black hole will differ significantly from classical relativistic model of pin point singularity.

Yes note a pin point singularity would have to have infinite spin to conserve angular momentum when the BH collapsed.

Seeker2
not rated yet Dec 06, 2011
So this brought up a question: What quantity of mass must exist to bend passing starlight 100%? This entailed a discussion of how to calculate "escape velocity of a photon". I have searched the internet specifically for that topic & have found nothing. Can anyone here help us out?

I think you're referring to something like the Einstein Ring in gravitational lensing. Wiki talks about that.
Seeker2
not rated yet Dec 06, 2011
We don't have an accepted theory of quantum gravity yet. Everything is still being developed and awaiting experimental tests.

You mean like experimental tests on gravity?
DavidMcC
not rated yet Dec 06, 2011
@ DavidMcC

We don't have an accepted theory of quantum gravity yet. Everything is still being developed and awaiting experimental tests.

That's what I was saying! It may be that the reason for the lack is that the maths is beyond everyone at the moment. (Eg, loop integration in Lee Smolin's loop quantum gravity.)
Seeker2
not rated yet Dec 06, 2011
So what type of experiment would you suggest?
DavidMcC
not rated yet Dec 07, 2011
I think the maths has to come first.
Seeker2
not rated yet Dec 07, 2011
I think the maths has to come first.

Ok Lee. Go do your maths and then get back to us.
DavidMcC
not rated yet Dec 08, 2011
I think the maths has to come first.

Ok Lee. Go do your maths and then get back to us.


Absolutely! It's all Smolin's fault for suggesting a cosmology then not following through on the maths! ;)