Black hole loses its appetite for gassy cloud

November 20, 2014
This simulation shows the possible behavior of a gas cloud (G2) that has been observed approaching the black hole at the center of the Milky Way. Graphic by ESO/MPE/Marc Schartmann

(Phys.org) —In a showdown of black hole versus G2 – a cloud of gas and dust – it looks like G2 won.

Recent research shows that G2 came within 30 billion kilometers of the super-massive black hole at the center of our galaxy, yet managed to escape from the gravitational pull of the black hole.

Initially, a supercomputer simulation prepared by two Lab physicists and a former postdoc more than two years ago suggested that some of G2 would survive, although its surviving mass would be torn apart, leaving it with a different shape and questionable fate.

The findings are the work of computational physicist Peter Anninos and astrophysicist Stephen Murray, both of AX division within the Weapons and Complex Integration Directorate (WCI), along with their former postdoc Chris Fragile, now an associate professor at the College of Charleston in South Carolina, and his student, Julia Wilson.

The team's simulations allowed the members to more efficiently follow the cloud's progression toward the black hole.

But recent observations by an outside group show that G2 managed to escape the appetite of the black hole.

"For it to have survived means that some gravity is keeping it intact," Murray said. "The mass of the by itself is far too small to hold the cloud together. If there were nothing else there, the cloud would have been torn apart, as indicated by our models and those of other researchers."

The black hole is known as Sagittarius A-star (Sgr A*). "Sgr" is the abbreviation for Sagittarius, the constellation in the direction of the center of the Milky Way. Most galaxies have a black hole at their center, some thousands of times bigger than this one, which has a mass of about 4 million times that of our sun.

Astronomers originally noticed something in the region in 2002, but the first detailed determinations of G2's size and orbit came in 2012. The dust in the cloud has been measured at about 550 degrees Kelvin, approximately twice as hot as the surface temperature on Earth. The gas, mostly hydrogen, is about 10,000 degrees Kelvin, or almost twice as hot as the surface of the sun.

"A star being present within the cloud would make sense, and was suggested by earlier workers trying to explain the origin of the G2 cloud, which is otherwise pretty mysterious," Murray said.

One idea was that the cloud might be the result of an old star losing mass. Based on the brightness of the object, the mass of the star was estimated to be pretty small (no more than about the mass of our sun), and "our models indicated that it would be insufficient to hold the cloud together against the tidal forces of the black hole," he said.

However, in the new study (link is external) appearing in the journal Astrophysical Journal Letters, the researchers found that G2 is pretty much intact after its passage near the black hole. Some of the gas does show distortion by the gravity of the black hole, but there is a core of warm gas that has remained essentially unchanged. That would indicate something significantly more massive than our sun holding it together. The authors propose that it is the result of the merger of a close binary star system (two stars in orbit around each other). Such mergers might be due to interaction with the tidal field of the black hole, and the result might be a puffed-up star whose outer atmosphere is seen as the warm core of G2 that survived passage by the black hole.

"That proposal means that we're seeing G2 very shortly after the merger of the two stars," Murray said. "While that's certainly possible, it does mean that we're seeing it at a special and relatively short-lived time. I haven't seen strong arguments that the object can't be a more typical star, somewhat more massive than our sun, undergoing normal mass loss as it nears the end of its life. Continued observations should let us determine just what's inside of G2."

Explore further: Gas cloud will collide with our galaxy's black hole in 2013

More information: Astrophysical Journal Letters, iopscience.iop.org/2041-8205/796/1/L8/article

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43 comments

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movementiseternal
Nov 20, 2014
This comment has been removed by a moderator.
cantdrive85
1.9 / 5 (14) Nov 20, 2014
Using astrophysicists own models the result didn't match prediction, hence falsification. Instead of revisiting basic assumptions more ad hoc explanations are shoveled onto the heaping pile of stinking excrement that is considered the standard theory.
Scroofinator
3.6 / 5 (7) Nov 20, 2014
hence falsification

It's not really falsification just because there predictions didn't come true, it just means they were wrong. This event just shows that mass based calculations aren't always reliable.
Da Schneib
4.3 / 5 (16) Nov 20, 2014
Gee, and instead of concluding all of astrophysics is wrong, they concluded that they had not been able to see internal details of the cloud. Fancy that. Who'd'a thunk it?

Meanwhile, kinda hard to do mass-based calculations when you don't know the mass because you can't see the internal structure.

Just sayin'.
Scroofinator
1.7 / 5 (11) Nov 20, 2014
Meanwhile, kinda hard to do mass-based calculations when you don't know the mass because you can't see the internal structure


Can we see the internal structure of the Sun? Don't make excuses for poorly conducted science. They made an assumption and it proved to be wrong, deal with it.

We now have enough data to actually calculate the mass of G2, yet they're still guessing. Large hydrogen clouds have been known to have anomalous densities, so this is just another case of "we don't know".

Da Schneib
4.1 / 5 (14) Nov 20, 2014
I'm not the one having trouble dealing with it. Snicker.

As far as having enough data to calculate its mass, where precisely? Link and quote please. They estimated the mass, but that was based on it being all gas. It's not behaving like it's all gas. Says so in the article.

This is duh.
Scroofinator
1.6 / 5 (7) Nov 20, 2014
We know the force applied to G2, we know the mass of Sag A*, and we know the distance between the two. Not that hard of a calculation.
Da Schneib
4.6 / 5 (10) Nov 20, 2014
How exactly do we know "the force applied to G2?"
Scroofinator
1.5 / 5 (8) Nov 20, 2014
Since we have SagA* mass, we can determine the mass of G2 by determining it's orbital radius and period, calculating the required centripetal force and equating this force to the force predicted by the law of universal gravitation using SagA* mass.
Da Schneib
3.8 / 5 (10) Nov 20, 2014
But they hadn't been looking at it long enough to determine its orbital radius and period, and the Galactic Center is a very complicated place, with a big accretion disk, and a bunch of other stars and gas and dust clouds all around.

So basically you're just waving your hands and saying "they oughtta."

So, does the EU "theory" make lots of predictions without any data? That's about what I figured.
barakn
5 / 5 (9) Nov 20, 2014
If it's not that hard of a calculation, then it should be easy for Scroofinator to post it here.
Scroofinator
1.5 / 5 (8) Nov 20, 2014
But they hadn't been looking at it long enough to determine its orbital radius and period, and the Galactic Center is a very complicated place, with a big accretion disk, and a bunch of other stars and gas and dust clouds all around

More excuses. We've been watching G2 since 2002, so we should have enough data to make a reasonable calculation.

Get me the data barakn, and I'll post the results of the calculations.
Da Schneib
4.3 / 5 (11) Nov 20, 2014
LOL
"We didn't have enough data" isn't an excuse. That's you making stuff up.

And you've inadvertently admitted the data weren't there, proving you're lying and trolling.

Post reported.
Scroofinator
2.3 / 5 (9) Nov 20, 2014
And you've inadvertently admitted the data weren't there, proving you're lying and trolling.

Post reported


What are you talking about? Are we having the same conversation? I explicitly said "we should have enough data to make a reasonable calculation".

Man, if I didn't know better I'd think you were a Stumpy in Schneib's clothing...
Da Schneib
3.8 / 5 (10) Nov 20, 2014
Right after you claimed not having enough data was an "excuse."

You're either lying/trolling or insane. I chose to believe the former.
Scroofinator
2.1 / 5 (7) Nov 20, 2014
not having enough data IS an "excuse."


My emphasis.
imido
Nov 20, 2014
This comment has been removed by a moderator.
Da Schneib
3.2 / 5 (10) Nov 20, 2014
Trolling reported. Bye, scroo-foid.

Back to your I-ching sticks or tea leaves or eclectic universe or whatever.
imido
Nov 20, 2014
This comment has been removed by a moderator.
Scroofinator
1.8 / 5 (5) Nov 20, 2014
So that the particles of interstellar gas around central black hole are separated each other, they do move collectively as a single body and they don't actually collapse with their gravity.


So a black hole would be like a 'dark' star flinging quantum mass ejections, but it's energy is on the quantum level. Sounds like a different take on Hawking radiation. I could see DE/DM originating this way.
imido
Nov 20, 2014
This comment has been removed by a moderator.
imido
Nov 20, 2014
This comment has been removed by a moderator.
cantdrive85
1.8 / 5 (10) Nov 21, 2014
But they hadn't been looking at it long enough to determine its orbital radius and period, and the Galactic Center is a very complicated place, with a big accretion disk, and a bunch of other stars and gas and dust clouds all around.

So basically you're just waving your hands and saying "they oughtta."

So, does the EU "theory" make lots of predictions without any data? That's about what I figured.

Oddly they figured out the path, and the timing fairly well. What wasn't very well predicted was the interaction of the "gas cloud" and the fictional BH. What they forgot to consider is that plasma that makes up this electric current doesn't care much about gravity but is more affected by the strong electric and magnetic fields in that "very complicated place".
Da Schneib
3.2 / 5 (9) Nov 21, 2014
Oddly they figured out the path, and the timing fairly well.
Not really, since they predicted it would be pulled apart.

Duh.
PS3
2.5 / 5 (12) Nov 21, 2014
Trolling reported. Bye, scroo-foid.

Back to your I-ching sticks or tea leaves or eclectic universe or whatever.


Doesn't agree with me,must be trolling!!!

That is the science crowd around here lol.
Scroofinator
1 / 5 (3) Nov 21, 2014
Hawking mechanism just says, when some event horizon appears inside of strong gravitational field, the the quantum fluctuations of vacuum would enable the evaporation of matter from it.

Right, but the evaporation of matter is constantly happening, regardless of food for the black hole. My question is does this evaporation happen dark particle to particle, or does it release in large bursts of particles?
movementiseternal
Nov 21, 2014
This comment has been removed by a moderator.
barakn
5 / 5 (8) Nov 21, 2014
We've been watching G2 since 2002, so we should have enough data to make a reasonable calculation.

Get me the data barakn, and I'll post the results of the calculations. -scroofinator
Two objects with different masses can follow exactly the same orbit around a third, much more massive object, so knowing an object's orbital parameters can't possibly give you the mass. The reason you haven't posted the calculation, or even the equation used to perform the calculation, is that there is no equation. To know G2's mass, you would have to study how it change's Sgr A*'s orbit - and good luck with that, Sgr A* is 4 million solar masses and G2 only got within 200 AU of it.
Scroofinator
1.2 / 5 (5) Nov 21, 2014
so knowing an object's orbital parameters can't possibly give you the mass

Maybe not with great accuracy, but they can be used to better approximate the mass instead of just guessing.
barakn
5 / 5 (8) Nov 21, 2014
No. Take Newton's universal law of gravitation, F=G*M1*M2/r^2. If M1 and r are known but M2 is not, we can't calculate F but we can calculate F/M2, the force per unit mass. But this is just the acceleration a because F= M* a. In other words, a = G*M1/r^2. Oh, would you look at that - the acceleration of M2 is independent of its mass. We've known this since Galileo dropped his balls (or didn't), but apparently you are a little slow.
Shitead
1 / 5 (2) Nov 21, 2014
How do astronomers know that the gas cloud came within 28 light-minutes of the gravitational anomaly? At a distance of more than 25,000 light years the cloud could easily be a light year either side of the anomaly along the line of sight and the instruments would not notice the difference.
Scroofinator
1 / 5 (4) Nov 21, 2014
No. Take Newton's universal law of gravitation, F=G*M1*M2/r^2. If M1 and r are known but M2 is not, we can't calculate F but we can calculate F/M2, the force per unit mass. But this is just the acceleration a because F= M* a. In other words, a = G*M1/r^2. Oh, would you look at that - the acceleration of M2 is independent of its mass

Good for you, you did some basic algebra. Why do we need the acceleration?

Try using Kepler's third law:
M=4*(pi^2)*(r^2)/G*T^2

Where r is the mean radius and T is the period.

We have partial orbital characteristics, which should be good enough to satisfy the necessary conditions for an approximation.

barakn
5 / 5 (9) Nov 21, 2014
Kepler's Third Law relates the period T of a small mass in orbit around a large mass M. In this case M would correspond to the mass of Sgr A*. But I should have kept my mouth shut and let you plug in the numbers. We would have fallen out of our chairs laughing as you announced that the mass of the small gas cloud is 4 million solar masses.
Scroofinator
5 / 5 (8) Nov 21, 2014
Yup, my mistake, thanks for the correction
Da Schneib
3 / 5 (6) Nov 21, 2014
How do astronomers know that the gas cloud came within 28 light-minutes of the gravitational anomaly? At a distance of more than 25,000 light years the cloud could easily be a light year either side of the anomaly along the line of sight and the instruments would not notice the difference.
This is incorrect. In fact they are accurate enough to measure this. Apparently you have no idea how telescope mounts work. And have never heard of lasers.
imido
Nov 21, 2014
This comment has been removed by a moderator.
dtxx
4.4 / 5 (7) Nov 22, 2014
They didn't measure it, with using laser the less. Don't lie. I dislike liars. Reported.


Are you sure you should be reporting anyone? Now that you had to stop spamming AWT lies, why still come here? Hmmmmm zephy?
Captain Stumpy
4 / 5 (8) Nov 23, 2014
They didn't measure it, with using laser the less. Don't lie. I dislike liars. Reported.
@ZEPHIR / imido
i hate to bust your bubble yet again... no. that is wrong
i actually enjoy it

but anyway... if you would read the ABSTRACT in the linked study
The data were obtained using the Keck II laser guide star adaptive optics system (LGSAO) and the facility near-infrared camera (NIRC2) through the K' [2.1 μm] and L' [3.8 μm] broadband filters
IOW - Da Schneib was 100% correct about their use of lasers during observation and you (Zephir) are stupid and illiterate
you should have read at LEAST the part where they say
Several results emerge from these observations
and then the part about
2) G2's L' brightness measurements are consistent with those over the last decade


you owe Da Schneib an apology
you can thank us by leaving for good and trolling elsewhere
imido
Nov 23, 2014
This comment has been removed by a moderator.
Captain Stumpy
3.4 / 5 (10) Nov 23, 2014
(as Da Schneib and you naively expect)
@ZEPHIR
and apparently you like to misinterpret arguments and ignore relevant points
you also like to provide plenty of pseudoscience with no empirical evidence
you said
How do astronomers know that the gas cloud came within 28 light-minutes of the gravitational anomaly? At a distance of more than 25,000 light years the cloud could easily be a light year either side of the anomaly along the line of sight and the instruments would not notice the difference
To which Schneib replied
This is incorrect. In fact they are accurate enough to measure this. Apparently you have no idea how telescope mounts work. And have never heard of lasers.
so, by reading this, you should have learned that:
1- you are a liar
2- you should take some literacy courses
3- the study AND Schneib BOTH refute your claims about using lasers, which was the point of the refute to you

delete yourself, TROLL

ZEPHIR=TROLL
DeliriousNeuron
2.1 / 5 (7) Nov 24, 2014
Shut up Stumpydick! Nobody here likes you. Go jump off a birdge!
imido
Nov 24, 2014
This comment has been removed by a moderator.
Da Schneib
4 / 5 (4) Nov 25, 2014
The laser guiding doesn't serve for measurement of distance
We were discussing direction, not distance.

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