Starship Asterisk*

Massive Black Hole Shreds Passing Star

Explanation: What happens when a star gets too close to a black hole? Recent observations from Earth-orbiting observatories of an event dubbed ASASSN-14li, in a distant galactic center, appears to be giving one star's harrowing story. Although angularly unresolved, variations in high energy light indicate that some of the star became shredded and reformed into a disk swirling around the dark abyss. In the hypothesized scenario envisioned, a jet formed on the spin axis of the black hole. The innermost part of the disk, colored white, glows most strongly in X-rays and may drive a periodic wind, shown in blue. Future X-ray and ultraviolet observations of stellar disruptions by black holes -- including those in the center of our own galaxy -- hold promise of telling us about the complex dynamics of some of the hottest and highest-gravity places in the universe.

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What are the error bars on the data?

Once upon a time, there was a little star who lived with her big sister star on the edge of a starry thicket. The little star was all yellow, so her sister called her Little Yellow One. The two sisters had an even bigger sister from their starbirth cluster who lived in the middle of the stellar thicket.

One day, the biggest sister got some really nasty hiccups, so that the stellar thicket got all lit up with her convulsions. The middle sister became worried about her and gave her little sister a mighty kick, so that she would go and see their biggest sister. "Go and see our biggest sister", she said to Little Yellow One, "and don't stray off the path, so you don't get eaten by the beasts that roam the thicket."

But Little Yellow One set off, skipping and singing, and didn't pay too much attention to where she went. And then suddenly, there was a terrific explosion (not that Little Yellow One knew that it was called an explosion) and she got all confused and lost her way completely. But after a long time (Little Yellow One wasn't sure how long) she saw, or felt, or perhaps just guessed, that Something was coming her way.

"What, ho!" she called out. "Who is there?"

"I'm your Biggest Sister," came a dark, dark voice from the void.

"But Biggest Sister, the other stars form arcs around you", Little Yellow One said.

"All the better to see you with their arc-shaped eyes, my child," said the Cavern of Darkness.

"But Biggest Sister, I feel so strangely pulled towards you," said the little star.

"All the better for me to hug you," said the blackness.

"But Biggest Sister, I'm unravelling! cried Little Yellow One.

"All the better for me to eat you," replied the Black Hole, as the spaghettified Little Yellow One spiraled down its horribly transformed Biggest Sister's insatiable maw.


Ann

Nice one. Just wondering if my understanding is correct - to me, it seems the scene is a 3-D type where black hole and incoming star that gets eaten up are actually closer to each other (than everything else) and all the white objects seen around the black hole - especially in the beginning - are either distant objects (appearing closer because of we seeing it in 2-D) and some stuff around event horizon (circular edges of black hole) is distant stuff seen flashing in replicated way around black hole because of gravitational lensing effect. Correct ? Or did I misunderstand something ? Thanks.

Guest wrote:What are the error bars on the data?

You might try the preprint:
http://arxiv.org/abs/1510.06348

What is occurring at 0:16? It looks like the integrity of the star suddenly fails, like a balloon popping. Is that the core of the star being ejected? It looks almost as if the outer layers were yanked away leaving the core behind, which I doubt is occurring.

ShaileshS wrote:Nice one. Just wondering if my understanding is correct(...)

You are absolutely correct.

Scott wrote:What is occurring at 0:16? It looks like the integrity of the star suddenly fails, like a balloon popping. Is that the core of the star being ejected? It looks almost as if the outer layers were yanked away leaving the core behind, which I doubt is occurring.

That is exactly what I came to the discussion page for. I think that an answer to that one could be linked with the amount of material the black hole already has stolen from the original star. If the remaining mass is not important enough to keep the rest of the star material, it may have that exploding motion, balancing a weaker gravity with inherent repulsion of the material. At that moment, if the black hole wasn't nearby, I would tend to think that the remaining of the star would eventually form a much larger sphere but much less dense. Possibly ending up forming some kind of giant gas planet.

SergeiPoulp wrote:

ShaileshS wrote:Nice one. Just wondering if my understanding is correct(...)

You are absolutely correct.

Scott wrote:What is occurring at 0:16? It looks like the integrity of the star suddenly fails, like a balloon popping. Is that the core of the star being ejected? It looks almost as if the outer layers were yanked away leaving the core behind, which I doubt is occurring.

That is exactly what I came to the discussion page for. I think that an answer to that one could be linked with the amount of material the black hole already has stolen from the original star. If the remaining mass is not important enough to keep the rest of the star material, it may have that exploding motion, balancing a weaker gravity with inherent repulsion of the material. At that moment, if the black hole wasn't nearby, I would tend to think that the remaining of the star would eventually form a much larger sphere but much less dense. Possibly ending up forming some kind of giant gas planet.

Well, a star maintains its equilibrium by balancing its inward gravity with the proper amount of fusion, which creates an outward flow of energy that eventually reaches the photosphere of the star, making it shine.

In the video, the black hole suddenly steals a lot of matter from the star. If this mass loss happens too quickly, the star may not be able to "turn on the brakes" on its own fusion quickly enough. If it can't reduce its fusion quickly enough, its production of energy may overwhelm its rapidly shrinking gravity. The star will simply go pop.

Ann

And what is the timescale of these events? Months? Days? Seconds? Thanks.

Ann wrote:(...) If it can't reduce its fusion quickly enough, its production of energy may overwhelm its rapidly shrinking gravity. The star will simply go pop.

That's right, degenerate materials at high temperatures would be at the star core, so that would be a tremendous amount of energy just waiting to do the trick. Good point! Thanks!

isoparix wrote:And what is the timescale of these events? Months? Days? Seconds? Thanks.

Yes. My very question.

The graph in the paper shows data spanning over 220 days. I don't know how much the illustration (not a simulation, as far as I know) covers isn't totally clear but I would guess that this event occurs over a matter of months.

Stellar Vampire...siphons more than "shreds" it appears.

Odd, as a White Dwarf siphons on its companion, and then BLOWS UP... and this does not. But also, takes the star "with it".

Happy Halloween, it is SPOOKY out there.

:---[===] *

APOD Robot wrote:
Massive Black Hole
Shreds Passing Star

Tidal & centrifugal forces should cause the star to, at least, start off as a prolate spheroid (i.e., American football)

Anyone else note that the fans at the edge of the accretion disk that are being lit by the accretion disk winds are pointed in the wrong direction? Conservation of angular momentum, gravity and frame dragging all say they should be trailing, not leading.

Everything in the universe wants to kill us. I wonder if planet Earth could survive this black hole scenario? Maybe there's a minuscule chance we could be ejected before X-rays fried us or tidal forces broke us up into bite size pieces. A rouge Earth flying off with no sunlight, spinning chaotically, slowly freezing in the dark. great scene in a movie. I'm sleeping with my red flashlight tonight.

What would be the real-time period encompassed by this video?

LesB wrote:
What would be the real-time period encompassed by this video?

• . http://asterisk.apod.com/viewtopic.php? ... 97#p249683

@ REMO
I'm aghast that so many people had comments about other things, without first pointing out that obvious glaring unreality.
The video purports to be a representation of reality, by a reputable science institution.
The complete absurdity of having spiral arms out ahead of their causal conditions (rotationally) removes it from the category of being a representation of the way matter behaves, and is little more than a cartoon. It makes me think it was composed by amateurs.

redmudislander wrote:@ REMO
I'm aghast that so many people had comments about other things, without first pointing out that obvious glaring unreality.
The video purports to be a representation of reality, by a reputable science institution.
The complete absurdity of having spiral arms out ahead of their causal conditions (rotationally) removes it from the category of being a representation of the way matter behaves, and is little more than a cartoon. It makes me think it was composed by amateurs.

The video was made by NASA's Goodard Space Flight Center and CI Lab.

Conceptual Image Lab information wrote:

Located in Greenbelt Maryland at the NASA's Goddard Space Flight Center, our artists work closely with the world's leading astronomers, scientists and engineers to bring theory, design and concepts to life in a scientifically accurate and visually compelling way.

Redmudislander, what makes you think that you understand black holes and their interaction with stars better than the world's leading astronomers? What are your credentials?

Or are you aghast because the black hole behavior in the video resembles nothing you have ever come across in your own life here on Earth, in your day-to-day existence?

Ann

redmudislander wrote:@ REMO
I'm aghast that so many people had comments about other things, without first pointing out that obvious glaring unreality.
The video purports to be a representation of reality, by a reputable science institution.
The complete absurdity of having spiral arms out ahead of their causal conditions (rotationally) removes it from the category of being a representation of the way matter behaves, and is little more than a cartoon. It makes me think it was composed by amateurs.

There is no requirement that everything in the Universe operate in a way that seems intuitive to you.

Chris Peterson wrote:

redmudislander wrote:
The complete absurdity of having spiral arms out ahead of their causal conditions (rotationally) removes it from the category of being a representation of the way matter behaves. It makes me think it was composed by amateurs.

There is no requirement that everything in the Universe operate in a way that seems intuitive to you.

It's always nice to have a second opinion
from another professional NASA artist.