ILikePluto
member
Reged: 02/17/09
|
Giant Black Hole Shreds and Swallows Helpless Star
#5201902 - 05/02/12 01:30 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Giant Black Hole Shreds and Swallows Helpless Star
by Ken Croswell
Some people seem born under an unlucky star. But some stars are equally unlucky themselves. Astronomers have spotted a star in another galaxy plunging toward a giant black hole and being ripped to shreds, sparking a flare so brilliant that observers detected it from a distance of 2.1 billion light-years. By watching the flare brighten and fade, scientists have achieved the unprecedented feat of reconstructing the life story of the doomed sun.
Full story at ScienceNOW
|
Pess
(Title)
Reged: 09/12/07
Loc: Toledo, Ohio
|
Re: Giant Black Hole Shreds and Swallows Helpless Star
[Re: ILikePluto]
#5202379 - 05/02/12 05:45 PM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Pesse (Live fast. Die young, Leave a good looking corpse) Mist
|
Ira
Carpal Tunnel
Reged: 08/22/10
Loc: Mitzpe Ramon, Israel
|
Re: Giant Black Hole Shreds and Swallows Helpless Star
[Re: ILikePluto]
#5202394 - 05/02/12 05:52 PM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
I still don't understand why a supermassive black hole gobbling a star is such a rare event (once every 10,000 years.) You'd thing an object of several million to several billion solar masses would have enough "suck" power to empty the tightly packed center of a galaxy.
/Ira
|
Pess
(Title)
Reged: 09/12/07
Loc: Toledo, Ohio
|
Re: Giant Black Hole Shreds and Swallows Helpless Star
[Re: Ira]
#5202467 - 05/02/12 06:29 PM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Quote:
I still don't understand why a supermassive black hole gobbling a star is such a rare event (once every 10,000 years.) You'd thing an object of several million to several billion solar masses would have enough "suck" power to empty the tightly packed center of a galaxy.
/Ira
Because of the inverse square law, even a super-massive black hole of the size postulated to exist at the center of our galaxy would only clear an area of a little over 3 light years around it (over time).
Most stuff beyond that would have enough radial velocity to just orbit--just as our planetary system would continue to orbit undisturbed if the sun suddenly collapsed into a black hole.
Pesse (same mass-it just went over to the darkside). Mist
|
EJN
Pooh-Bah
Reged: 11/01/05
Loc: Highway 61
|
Re: Giant Black Hole Shreds and Swallows Helpless Star
[Re: ILikePluto]
#5202569 - 05/02/12 07:15 PM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
When I read stuff like this, I can only conclude that astronomy has
now reached the anthropology mode of analysis.
"From examining the skull, anthropologists determined it belonged to
a 12-year old girl who died April 23, 284935 B.C. at 10:23 a.m. from a blow on
the skull accidentally administered by the tribal shaman who had ingested too
many hallucinogenic mushrooms and mistook her for an evil spirit."
In other words, drawing sweeping conclusions from limited data.
|
Ira
Carpal Tunnel
Reged: 08/22/10
Loc: Mitzpe Ramon, Israel
|
Re: Giant Black Hole Shreds and Swallows Helpless Star
[Re: Pess]
#5202648 - 05/02/12 07:58 PM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Quote:
Quote:
I still don't understand why a supermassive black hole gobbling a star is such a rare event (once every 10,000 years.) You'd thing an object of several million to several billion solar masses would have enough "suck" power to empty the tightly packed center of a galaxy.
/Ira
Because of the inverse square law, even a super-massive black hole of the size postulated to exist at the center of our galaxy would only clear an area of a little over 3 light years around it (over time).
Most stuff beyond that would have enough radial velocity to just orbit--just as our planetary system would continue to orbit undisturbed if the sun suddenly collapsed into a black hole.
Pesse (same mass-it just went over to the darkside). Mist
Then one must ask how such a massive object came to be. Surely not by ingesting one star every 10,000 years.
/Ira
|
deSitter
Still in Old School
Reged: 12/09/04
|
Re: Giant Black Hole Shreds and Swallows Helpless Star
[Re: Ira]
#5202678 - 05/02/12 08:20 PM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
There is basically nothing in this report that is related to reality. This is all the sort of hallucinogenic vision that is more appropriate in alt-rock from the 70s than in science. There should be some recourse as in the old days, to counteract this sort of stupidity, but there is not. We are stuck with it.
-drl
|
Ira
Carpal Tunnel
Reged: 08/22/10
Loc: Mitzpe Ramon, Israel
|
Re: Giant Black Hole Shreds and Swallows Helpless Star
[Re: deSitter]
#5202727 - 05/02/12 08:46 PM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Apparently, wandering black holes have a much bigger apetite than stationary ones.
http://phys.org/news/2011-04-newly-merged-black-hole-eagerly.html
/Ira
|
barasits
sage
Reged: 06/12/11
Loc: Chicago
|
Re: Giant Black Hole Shreds and Swallows Helpless Star
[Re: EJN]
#5203031 - 05/03/12 01:16 AM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Quote:
When I read stuff like this, I can only conclude that astronomy has
now reached the anthropology mode of analysis.
"From examining the skull, anthropologists determined it belonged to
a 12-year old girl who died April 23, 284935 B.C. at 10:23 a.m. from a blow on
the skull accidentally administered by the tribal shaman who had ingested too
many hallucinogenic mushrooms and mistook her for an evil spirit."
In other words, drawing sweeping conclusions from limited data.
|
EJN
Pooh-Bah
Reged: 11/01/05
Loc: Highway 61
|
Re: Giant Black Hole Shreds and Swallows Helpless Star
[Re: barasits]
#5203042 - 05/03/12 01:37 AM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Quote:
That's a very informative response.
|
barasits
sage
Reged: 06/12/11
Loc: Chicago
|
Re: Giant Black Hole Shreds and Swallows Helpless Star
[Re: EJN]
#5203084 - 05/03/12 02:27 AM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Quote:
Quote:
That's a very informative response.
Use the anthropological mode of analysis and draw a sweeping conclusion from limited data. 
Geoff
|
Pess
(Title)
Reged: 09/12/07
Loc: Toledo, Ohio
|
Re: Giant Black Hole Shreds and Swallows Helpless Star
[Re: Ira]
#5203475 - 05/03/12 10:29 AM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Quote:
Then one must ask how such a massive object came to be. Surely not by ingesting one star every 10,000 years.
/Ira
Who knows?
But logically you have a really dense star cluster at the center with several stars merging into super-massive stars. These eventually collapse into black holes. These black holes merge and the remaining superdense stars in the local cluster get swept up over time.
Also, at the center of the galaxy, there are constant perturbations of local giant stars altering their 0rbits enough to cross paths with the supergiant BH--further enhancing its stature among other BH's...
I am sure things are much more hectic in the early days of galaxy formation and also when galaxies collide or even pass glancing blows altering all sorts of orbital mechanics.
I think this article just has a few speculations in it that explains (some) of the observations. I seriously doubt it is the final word.
Black holes are so misunderstood...
Pesse (Maybe if they called them 'Black Knight Holes' they would be less feared? ..but then there is the problem of fitting them with a cool cape) Mist
|
sirchz
super member
Reged: 09/21/09
|
Re: Giant Black Hole Shreds and Swallows Helpless Star
[Re: deSitter]
#5203819 - 05/03/12 01:37 PM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Quote:
There is basically nothing in this report that is related to reality. This is all the sort of hallucinogenic vision that is more appropriate in alt-rock from the 70s than in science. There should be some recourse as in the old days, to counteract this sort of stupidity, but there is not. We are stuck with it.
-drl
Are you unhappy with the ScienceNow report or the underlying work reported in Nature, or both?
|
Mike Casey
Reged: 11/11/04
Loc: El Pueblo de Nuestra Señora la...
|
Re: Giant Black Hole Shreds and Swallows Helpless Star
[Re: ILikePluto]
#5204222 - 05/03/12 04:56 PM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Quote:
Giant Black Hole Shreds and Swallows Helpless Star
by Ken Croswell
Some people seem born under an unlucky star.
"Helpless Star, unlucky star"... Cloying anthropomorphism sucks, and not very well at that.
|
barasits
sage
Reged: 06/12/11
Loc: Chicago
|
Re: Giant Black Hole Shreds and Swallows Helpless Star
[Re: Mike Casey]
#5204265 - 05/03/12 05:18 PM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Jeez, this is a tough crowd.
Croswell is trying to present the material in a style that makes it more accessible to a general audience.
EJN, sorry for being overly subtle. It just struck me as a little ironic that a comment criticizing sweeping generalizations based on limited data contains a sweeping generalization based on limited data about anthropology.
Geoff
|
EJN
Pooh-Bah
Reged: 11/01/05
Loc: Highway 61
|
Re: Giant Black Hole Shreds and Swallows Helpless Star
[Re: barasits]
#5204449 - 05/03/12 07:13 PM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Quote:
It just struck me as a little ironic that a comment criticizing sweeping generalizations based on limited data contains a sweeping generalization based on limited data about anthropology.
It's called sarcasm.
I will now try to seriously critique the actual paper, which you can read at http://arxiv.org/pdf/1205.0252.pdf.
The popular accounts are, for the most part, hype and fluff.
The data consists of a set of light curves obtained in the UV, visible, and IR wavelengths. There are also spectra obtained with the MMT, and an observation obtained in the x-ray wavelength with the Chandra satellite. The spectrum is a combination of the event and the host galaxy. Since no pre-existing spectra of the host galaxy exist, that was subtracted using a computer model of what the spectrum of the host galaxy should look like. The conclusion that it was a helium core is based on matching the resulting spectrum after removal of the model galaxy spectrum to polytropic mathematical models of convective and degenerate stellar interiors. Polytropes are commonly used in stellar models and in calculating stellar evolution. The conclusion that it fell into a black hole is based on numerical simulations of what that event should look like.
The whole procedure seems more like trying to fit the data to a preconceived idea, rather than constructing a theory from the data.
From the data alone, there are only several conclusions which can be drawn:
There is an abundance of helium, the helium emission line is obvious even in the combined spectrum; the event was brighter in UV than visible wavelengths and there was insignificant brightening at x-ray wavelengths; and the light curves are different than those of typical type Ia & type II supernovae. Concluding that is was a star which fell into a black hole requires a chain of reasoning which seems rather contrived.
The total energy calculated for the event (2.1 x 10^51 ergs) does fall within the range typical for supernova. At is brightest, it was about 19th magnitude. The measured redshift is z = 0.1696
|
astroRoy
professor emeritus
Reged: 07/09/11
Loc: Southern Oregon
|
Re: Giant Black Hole Shreds and Swallows Helpless Star
[Re: EJN]
#5204466 - 05/03/12 07:29 PM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
QUOTE:[Then one must ask how such a massive object came to be. Surely not by ingesting one star every 10,000 years.}
If the BH is 13.7 billion years old, a star every 10,000 years for breakfast is, well you do the math. It's a pretty big BH if it is that old.
Roy
|
Neutrino?
sage
Reged: 12/14/09
Loc: Wasatch
|
Re: Giant Black Hole Shreds and Swallows Helpless Star
[Re: EJN]
#5204512 - 05/03/12 08:00 PM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Quote:
The whole procedure seems more like trying to fit the data to a preconceived theory, rather than constructing a theory from the data.
?
These guys(gals too!) are observational astronomers. This is what they do.
Edited by Neutrino? (05/03/12 08:05 PM)
|
deSitter
Still in Old School
Reged: 12/09/04
|
Re: Giant Black Hole Shreds and Swallows Helpless Star
[Re: Neutrino?]
#5204556 - 05/03/12 08:32 PM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
EJN's point is based on the difference between experimental vs. observational science. If you observe to a theory in astrophysics, you will surely find what you seek. The advances in astronomy are always serendipitous. One observes with an open mind, and the theory comes later.
-drl
|
astrotrf
Not at all Mundane
Reged: 09/30/07
Loc: Rodeo, NM
|
Re: Giant Black Hole Shreds and Swallows Helpless Star
[Re: EJN]
#5204562 - 05/03/12 08:37 PM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Quote:
From the data alone, there are only several conclusions which can be drawn:
There is an abundance of helium, the helium emission line is obvious even in the combined spectrum; the event was brighter in UV than visible wavelengths and there was insignificant brightening at x-ray wavelengths; and the light curves are different than those of typical type Ia & type II supernovae.
So your point is that we should just stop there, say "gee, that was odd", and walk away, rather than try to come up with an explanation that fits the anomalies you listed?
I see nothing wrong with "Hey, we saw this odd event. We did a numerical simulation of a star falling into a black hole, and it matches up pretty well with that event."
I can't think of any science that would progress very far if, when faced with an unusual observation, just shrugged and didn't try to explain it.
|
Previous
Index
Next
Threaded
