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:Holes?

[Hungus]

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

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

[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: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: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 ...