Birth of Black Hole Possibly Being Observed

TheTXLibra writes "Robert Roy Britt reports on Space.com that we may now be witnessing the earliest stages of black hole development. Star SN 1986J, began to collapse in 1983 into a neutron star, resulting in a supernova explosion in 1986. If the mass of the neutron star reaches 1.4 times the mass of Earth's Sun, it will theoretically collapse into a black hole, if not, it will stabilize as a neutron star."

Comments

Not quite accurate.

[Eevee]

began to collapse in 1983 into a neutron star, resulting in a supernova explosion in 1986.

If you read the article, the supernova explosion happened in '83, but wasn't detected until '86.

Re:Not quite accurate.

[Hungus]

You are pissing over 3 years? Read the article and you can derive that it supposedly went nova over 31 million years ago. We are just now seeing/detecting it from 1982/3 on. Oh and the reason it wasn't "seen" was because the frequency of the emmisions.

SN 1986J was so bizarre that it was serendipitously discovered first in the radio, and afterwards in the optical. Therefore, the precise date of its explosion is not known, but on the basis of the available radio and optical data sn 1986j has been estimated to have exploded around the end of 1982, or the beginning of 1983

Re:Not quite accurate.

[beeplet]

Also, the collapse into a neutron star or black hole would have been almost instantaneous... So we're not exactly watching the NS/BH being born - more like waiting for the dust to clear so we can see what's in there.

Re:Not quite accurate.

[Anonymous Coward]

The object is 30 million light-years away -- the supernova explosion happened roughly 30 million years ago.

Re:Not quite accurate.

[Anonymous Coward]

Meaning the start is roughly 3 light years away?

Re:Not quite accurate.

[Threni]

> Bad Panda! No Bamboo for you! In matters of importance AC's will not be responded
> to. Want to say something critical, f

I think you need to work on your sig file. I guess you could save 1 byte by removing the superflous apostrophe you've felt the need to add after 'AC'.

Re:Not quite accurate.

[Hungus]

Cheers, though emailing me woiuld have saved many many more bytes :)

Holes?

[Anonymous Coward]

Aren't they really gravastars rather than holes? Why do people still call them black holes?

Re:Holes?

[Hungus]

Because "Gravastars" are still very much a new and thus fringe theory.

Re:Holes?

[Christopher Thomas]

You're promising not to reply to my posts, now please STOP DOING IT.

Fine. _I'll_ reply.

Gravastars are an interesting idea, but they:

a) Propose modifications to physics (the phase transition that gives rise to a different type of space in the interior).

and

b) Attempt to solve a problem that doesn't necessarily exist (embodiment of entropy in black holes, which string theory takes a fairly good stab at explaining).

Thus, I'm skeptical of claims that gravastars exist, barring observations supporting their existance or wider acceptance by the scientific community.

At least in the paper I've managed to dig up so far, they acknowledge many othe potential models of how black holes work, and suggest types of observations that would help determine whether their model is accurate (i.e., they don't claim it's the One True Model off the bat). This is one of the hallmarks of good science.

Observations to look for are gravity-wave signatures of resonance modes in the stiff shell surrounding the gravastar, and optical signatures of impacting matter interacting with this shell. The first should be possible when we get sufficiently sensitive gravity wave detectors online, and the second should be possible from observations of accretion disks in known black hole/other star binary pairs once Mazur and Mottola have worked through the math to figure out what the observational signatures should _be_. Thirdly, if you could get close enough to take good measurements, you'd be able to distinguish between gravastar-type black holes and Hawking-Bekenstein black holes by different radiation signatures coming off of them, but that requires being right next to the hole and having instruments sensitive enough to detect very faint, low-frequency thermal radiation.

In summary, claiming that the gravastar model _is_ what black holes are is very, very premature.

Re:Holes?

[Anonymous Coward]

I belive his sig says ACs will no be responded to, not childish arses who have yet to cease drawing on their mum's teat.

Interesting and monumental!

[Alizarin Erythrosin]

Not only is it a cool picture, but this is a pretty interesting thing to witness. In my initial reaction I thought "How can we see this in our lifetimes?" It seems that, as mentioned in the article, "[t]his collapse is extremely fast, and the core collapses into a neutron star in about one second."

The collapse into a black hole in such a short time (also in the article) is somewhat expected, because the gravity will be so strong. This should be a pretty neat and real way to verify if our view on black hole formation and the associated astro-physics that accompany it are mostly correct.

Re:Interesting and monumental!

[CodeMonkey4Hire]

Keep in mind that we are not seeing the formation of a black hole (or neutron star). That was obscured by the supernova remnants. What we [maybe] are now seeing is the youngest black hole (or neutron star) that we have ever observed. 20 years old is barely out of the womb in cosmological terms, but we missed the birth. The only reason that we are getting to see it this early is that we are fortunate enough to line up with a "crack" in the expanding shell of supernova remnants.

Still, very awesome. It will definitely help us with our understanding of supernovas and their aftermath.

It would be really incredible if we could ever find a star that was about to supernova. It would be the most outrageous luck to find it and observe it up until the instant of supernova (I am afraid that we will never get to see the first couple years after that.)

Knowing where to look...

[beeplet]

The article didn't even mention one of the most important reasons this is interesting - so far the only stellar-mass blackhole candidates are in binary systems (where you can infer the mass of an unseen object from the orbit of the visible star). Otherwise, you can't see find a black hole unless you know where to look - and now we do.

(I guess you could also theoretically look for black holes by their gravitational lensing effects, but you would have to monitor a huge number of stars and hope that a black hole intercepts your line-of-sight to one of them, so not very practical.)

Probabilistic fallacy in article

[kevinatilusa]

"The star's original mass is not known, so there's a roughly equal chance that the remaining central object is a neutron star or a black hole"

Just because you don't know whether or not an event occurs doesn't mean that it stands a "roughly equal" chance of occurring and not occurring

Re:Probabilistic fallacy in article

[ColaMan]

It depends upon the average mass of known stars, for all I know , 50% of them could be below 1.4 suns.

*Then* it would be a "roughly equal" chance of it being a black hole.

Re:Probabilistic fallacy in article

[Hoch]

They probably have more data than that, for instance our sun has no chance of even supernovaing, much more massive stars are required to do that.

Re:Probabilistic fallacy in article

[Anonymous Coward]

Well, maybe. It depends on your interpretation of quantum mechanics.

The Nature of Probability

[NSash]

Yes, it does. Probability is a construct that depends on available information.

For example, let's say someone flips a coin and you call the result in mid-air. In reality, the result of the coin toss is already determined at this point. However, as far as you're concerned the probability of either result is 50%. Or even better, let's say that you're trying to guess which of two cups holds a ball. The person who placed the ball knows with complete certainty which cup holds it, but as far as you're concerned the probability is 50% that the ball is in either cup.

Probability doesn't exist independently of observation. Probability is simply a measure of expectation.

Re:The Nature of Probability

[coast99]

How about a discussion of Bayesian vs. frequentist. I would argue that probability depends on your Baysian prior.

Re:The Nature of Probability

[logpoacher]

Ok, what you say is right, but I didn't think that that's what the original poster was complaining about.

I think he was trying to say that for "roughly equal" to apply, we must presume to know that P(black hole) ~= P(neutron star). Maybe we do know that, perhaps because that's generally the case (due to distribution of stars of different masses), or because we know something special about this particular case.

But if not, then the quote in the article is falling into the "either it'll happen or it won't" fallacy. Casino owners love this style of thinking, because it induces people to forget that the odds are against them, and to bet anyway: "either I'll win or I won't". It's common to confuse "2 outcomes" with "50% chance", and the article sounds like it has done so, but then again it's possible that it hasn't.

Unfortunately, in both your examples, each outcome is exactly as likely as the other - they're symmetrical (as long as they're fair!), so they don't illustrate the fallacy, because you were drawing attention to something else. Try this - it's similar to your examples, but it's asymmetric: Consider a (normal 6-sided) dice roll, where you're asked to guess if the result is a 4. The dice has rolled, but you haven't seen the result yet, and the chances of getting your 4 are 1/6, and 5/6 of not getting it - they're not "roughly equal". Does that work for you?

Re:The Nature of Probability

[Anonymous Coward]

In your example we assume that it's 1/6 because there are six sides on the die because the only factor we know is that it has six sides and we assume that it will land with one side facing up. We don't know if the die's mass is assymetrical so that it tends to land with the same side down. We don't know if there's something about the surface that we are using that might cause it to land one way or another. We don't know if the surface is uneven so that the die could come to rest with an edge facing up. We don't know which side is up while it's being held and we don't know if there's something about how it is released that will predispose it to land in a certain way.

Since all we know is that the die has six sides we can simplify it to say that the odds are 1 in 6. And since we believe that there are two possible outcomes for this star, we assume that the odds are 1 in 2.

Re:The Nature of Probability

[Anonymous Coward]

Since all we know is that the die has six sides we can simplify it to say that the odds are 1 in 6. And since we believe that there are two possible outcomes for this star, we assume that the odds are 1 in 2.

You're arguing what's known as "the principle of insufficient reason". It's all right to argue that if you really don't know anything else about the alternatives. But astrophysicists know more than that. (For instance, they know something about the prior ratios of black holes to neutron stars in the universe. No, I don't happen to know what they are.) So, while you might put prior odds at 1:1, an astrophysicist, with more knowledge of the problem, wouldn't.

How long until they know?

[egon]

I glanced through the article and was absolutely amazed (not knowing that much about this subject) that the collapse into a neutron star took a mere second. Considering the scale of the event, that's just astounding to me.

What I didn't see was any indication when they'll be able to determine whether the star is going to remain a stable neutron star or become a black hole. Does anybody with actual knowledge in the subject care to comment?

Re:How long until they know?

[wyldeling]

It is been approx ten years since I had astronomy, but if I remember correctly this is how stars operate:

The stellar furnace operates in several distinct stages where each stage fuses a particular element and the byproduct is the element used in the next stage. The first is hydrogen, the second is helium. The third is the Cargon - Nitrogen - Oxygen cycle (I think this is the third stage). The CNO cycle produces Silicon. This is where things get interesting ... Most stars don't get beyond the CNO cycle (they're not massive enough), but those that do start to fuse Silicon. The final stage is Iron, which is only fusable at a net cost of energy (you get less out than you put in). Once, a star starts producing Iron in its core, its death is assured. I believe (here's the part that is foggy), that once a star starts to fuse Silicon into Iron the star begins to collapse. This process only takes about 3 mins total, from starting to fuse Silicon in any great quantity to supernova!

There are a couple stages of collapse, also. The first is an electron degeneracy stage (don't know much about this stage). It provides some outward pressure, and may prevent further collapse. Stars with between 1.4 and 3 solar masses may have enough mass to push beyond the electron degeneracy stage to the neutron degeneracy stage (neutron stars). At this stage, there is enough gravitational pressure to push the electrons in the atoms into their nucleuses. The electrons and protons pair up and become neutrons in a sort of reverse neutron decay. Beyond 3 solar masses, not even the outward pressure of the neutron degeneracy can prevent the star from collapsing into a black hole.

Incedently, I had always heard that a neutron star was between 1.4 and 3 solar masses. So, the fact that the article discusses it requireing less than 1.4 is curious ...

Re:How long until they know?

[Kallahan]

this number is because a nuetron star has blow most of its mass off, if after the supernova the mass is 1.4 suns then it may become a black hole. Which if I remember correctly about 50% of a stars mass is lost in supernova making the original star approx. 3 solar masses

Re:How long until they know?

[meringuoid]

Incedently, I had always heard that a neutron star was between 1.4 and 3 solar masses. So, the fact that the article discusses it requireing less than 1.4 is curious ...

1.4 solar masses is the limit for a core supported by electron degeneracy - a white dwarf. Stellar remnants exceeding this mass will collapse to form a neutron star.

The maximum mass of neutron stars is less well known; the properties of neutronium cannot easily be tested in the laboratory! The absolute maximum, assuming that neutronium is completely incompressible by any finite force, is about five solar masses. The reason is that in neutron stars general relativity comes into play, and pressure itself has gravity. We get an asymptote at about five solar masses, and even a hypothetical incompressible neutronium core has to collapse.