Black Hole Swallows Star 166
Thorfinn.au writes "The New Scientist writes a conjectural piece to explain the light pattern of SCP 06F6 in what was first identified as a supernova — but observations show a skewed and stretched light curve not fitting with an current theoretical explanation of exploding stars. Also, the discussion in the comments is interesting."
Re:"discussion in the comments" (Score:1, Informative)
Re:I'm not scientist (Score:2, Informative)
Re:could someone please explain (Score:5, Informative)
One possible way would be a jet of energy streaming from a rotating black hole...
Wikipedia article. [wikipedia.org]
Re:I'm not scientist (Score:4, Informative)
But wouldn't a roving black hole produce a tell-tale roving gravitational lensing?
Only if you were extremely close by or got a perfect lineup. The former, we could probably notice out to a significant fraction of a light year or so if we were watching the sky.
The latter case is rather problematic, as it would be hard to distinguish a black hole's lensing effect from noise - one frame you see a few photons, the next you don't. Was it a galaxy? A star? Nebula? Random noise?
Re:could someone please explain (Score:5, Informative)
I'm not educated in astrophysics and everytime I read something like this I wonder, how does anything manage to get "blasted away" from a black hole? I was under the impression anything that got close to it was absorbed?
Simple, black holes are very messy eaters - they radiate a significant fraction of their food as photons. Keep in mind you are accelerating much of the star to a significant fraction of c, letting it collide with itself. This goes double for stellar mass black holes - you have a million+ kilometer star getting 'swallowed' by a twenty kilometer black hole. Even a perfect landing is going to result in most of the star's mass getting flung back out into space if only because the hole is smaller than the core of the star.
Re:could someone please explain (Score:5, Informative)
Anything that crosses the event horizon is absorbed. Anything that does not interacts gravitationally with the black hole as it would with any other massive object. Black holes don't have any sort of magical ability to suck things in. All they have is gravity (Well, ok. They also have charge and spin.)
Re:could someone please explain (Score:5, Informative)
Yes, the "event horizon" (EH) is the boundary beyond which nothing can escape the gravitational pull of the black hole.
However, it's not a physical boundary (black holes do not have a physical surface), it's the mathematically-calculated boundary beyond which events inside the EH cannot affect an outside observer. As a particle gets closer to the EH, its chances of escape shrink to infinity, and once the EH is crossed, it's effectively gone from the outside world.
That being said, under certain conditions, particles can be radiated outward from a black hole:
1.) If an object inside the "photon sphere" (Schwartzchild Radius X 1.5) but still outside the EH emits photons, those photons can still escape. (Photons coming inbound are screwed, though. Approaching on a tangent, have a slim chance to "bounce off" due to rotational gain.).
2.) If the black hole is rotating, and a particle is approaching the black hole at a tangent, it may also escape via "stealing" some of the rotational energy.
3.) Rotating black holes also emit particles via Hawking radiation, which is more of a particle-antiparticle explanation that I want to get into here.
So, yeah, it's sort of an issue of semantics - if you consider the zone right outside the EH a part of the black hole, then yes, things can escape from a black hole; if you take the common (and incorrect) view that a black hole has a definite "border", and discount all the fun stuff that's going on around the black hole, then no, nothing can escape.
(Of course, this is a ridiculously simplified explanation, and I do expect at least one Slashdot astrophysicist to poke it full of holes (pun intended).)
Re:could someone please explain (Score:5, Informative)
Re:could someone please explain (Score:5, Informative)
Gaensicke and colleagues envision two scenarios that might explain the object. In one, a carbon-rich star gets too close to a middle- or heavy-weight black hole, which tears the star apart. Some of this material is absorbed by the black hole, and some is blasted away in a flare that was eventually seen from Earth as SCP 06F6.
I'm not educated in astrophysics and everytime I read something like this I wonder, how does anything manage to get "blasted away" from a black hole? I was under the impression anything that got close to it was absorbed?
Black holes gravitationally pull matter toward them like any other object with the same mass, until you're inside the event horizon, at which point there is no escape. Thus, outside the event horizon, objects will tend to orbit the black hole just as they'd orbit a star of equal mass. Over time, the orbit of gas falling into a black hole decays and the gas falls toward the singularity and its orbital velocity increases. When this happens, the volume occupied by the orbit of the gas decreases, leading to higher density gas and thus heat generated through friction and compression. This heat raises the temperature of the gas, which increases its pressure and can result in a portion of the gas being blown off into space.
Re:I'm not scientist (Score:4, Informative)
I could have sworn that something like that happened in 1919 when a guy named Arthur Eddington kinda helped confirm the theory for Einstein [wikipedia.org]. Proximity allowed us to see the lensing, which we can't easily see from a distance, but it's there on all objects of sufficient mass, not just galaxies.
Re:Because it's not interesting. (Score:5, Informative)
Same with the neutron stars, or pulsars allegedly being stars that "rotate faster than dentist drills." The impossible is far more likely than the improbable.
And... what's so improbable about a massive and extremely dense object spinning rapidly, vs an even more massive but much less dense object spinning at a rate that is proportionally slower?
I'd say that the impossible, in this case violating Conservation of Angular Momentum, is usually what is far more improbable.
Re:could someone please explain (Score:4, Informative)
Simple analogy I sometimes use to explain black hole emissions in a way most people are familiar with...
Ever flush a toilet and notice a splash that jumps above the rim? Same thing.
While the majority of the mass gets pulled into the hole, the chaotic nature of the flow means that some mass gets ejected every which way. Depending on where you are situated, the ejected material can be quite noticeable.
Bad Title (Score:4, Informative)
"These possibilities, combined with the observation that the
disrupted object be a carbon-rich star, rather than a normal
main sequence one appear to make the case for tidal disruption
somewhat contrived. Nonetheless, with only one object, and
thus an essentially unconstrained rate and space density for
such events, it remains a possibility."
So, while tidal disruption is a possibility, it is not the favored scenario.
ATTN: Slashdot Monitor, Galactic Navigators Guild (Score:2, Informative)
Quoting this for your attention just in case (once again) your filter software fails to pick up on a communication whose existence your Guild would prefer to ignore:
The thing is, they DIDN'T see a black hole swallowing a star. They saw a massive burst of radiation. But they describe NOT what they actually observed, but their interpretation of what they observed instead. Are there no other possible sources for massive bursts of radiation than black holes swallowing stars? Given the aberrant numbers of high energy particles entering our star system, I would say it's premature indeed. Same with the neutron stars, or pulsars allegedly being stars that "rotate faster than dentist drills."
Can it be any more clear that the indigenous technosavvies of this backward planet are about to see through the ruses you have been feeding them, and recognize the artifacts of your warp ship accelerations for what they are? How long do you think you can preserve that foolish fiction of a "Hubble Constant Universe" you've been encouraging them to accept?
Would it really be that costly for you to exercise a little more control over your thrust vectors? Yes, it would cut into the profits of each voyage by several tenths of a percent. But that is a pittance to pay for this unique opportunity to study a pre-Warp and pre-Contact civilization during that critical period just prior to its recognition of the bubble distortion at its heliopause. We've only had one such opportunity before. Need I remind you of how your Guild mucked up that one?