We’re about to watch a star almost dive into the Milky Way’s black hole

The new GRAVITY instrument will allow scientists to closely the study the star, S2.

Read the whole story

 

[ten91]

Can we just all take a moment to appreciate astronomers' ability to name things.

Edit: And that's not sarcasm in any way. They get away with some amazing names. Like Cthulhu Regio on Pluto.

 

[linthat22]

It'd be cool to see what happens.

 

[maehara]

ten91[/url]":283r8prq]Edit: And that's not sarcasm in any way. They get away with some amazing names. Like Cthulhu Regio on Pluto.

Sadly those fun Pluto names are all unofficial ones used by the New Horizons team. I'm sure the IAU will spoil everyone's fun when they get around to settling on the official names, even though I believe the most of the unofficial ones do fit with the agreed theme.

 

[Aykernar]

ten91[/url]":1hcp2nhv]Can we just all take a moment to appreciate astronomers' ability to name things.

Edit: And that's not sarcasm in any way. They get away with some amazing names. Like Cthulhu Regio on Pluto.

As far as I can tell (and I even went so far as to check The Actual Paper describing the instrument), despite the capitalization, GRAVITY doesn't actually stand for anything. It is just... a name. Which is frankly disappointing, because it is always a laugh to see the language abuse people commit to make their acronyms sound cool, and when I saw the name I was looking forward to discovering another example.

If I'm wrong, and it actually is an acronym, please let us know!

 

[S_T_R]

A whole star traveling at .025c. The amount of energy involved is staggering.

 

[Gooberslot]

Can they predict when the star will actually fall into the black hole?

 

[lordneeko]

S_T_R[/url]":3m7p3z7a]A whole star traveling at .025c. The amount of energy involved is staggering.

For fun comparisons, our sun (solar system) is travelling about 0.000667128c

 

[pr0t0]

So we've got a star 15 times more massive than the Sun making its closest approach to a black hole that's roughly 4 million times more massive than the Sun at a distance just over 3 times the distance between Pluto and the Sun?

Break out the popcorn!

I'm wondering all kinds of things like, will S2 speed up significantly as it approaches? If so, will it stay in it's orbit or can it be thrown out?

Very, very cool!

 

[BasP]

Although I'm disappointed that GRAVITY isn't some elaborate and extremely awkward acronym, I find "Very Large Telescope" and "S2" kind of reassuring in their simplicity.

 

[juanlucasrey]

"The new GRAVITY instrument will allow scientists to closely the study the star, S2."

I think there's a "the" that should be removed there..

 

[ten91]

lordneeko[/url]":2ol7tin3]

S_T_R[/url]":2ol7tin3]A whole star traveling at .025c. The amount of energy involved is staggering.

For fun comparisons, our sun (solar system) is travelling about 0.000667128c

For even more fun.
Our sun's mass is about 1.989 x 10^30 Kg
That star is estimated to be 15x our sun's mass. So 2.9835×10^31 Kg
So that going 0.025c is going to ruin anything's day it comes across.

 

[rpresser]

pr0t0[/url]":2zlpnbhe]I'm wondering all kinds of things like, will S2 speed up significantly as it approaches?

Of course, just like all eccentric orbits.

If so, will it stay in it's orbit or can it be thrown out?

No, it will stay in its orbit.

 

[JerryLove]

ten91[/url]":185wtswf]

lordneeko[/url]":185wtswf]

S_T_R[/url]":185wtswf]A whole star traveling at .025c. The amount of energy involved is staggering.

For fun comparisons, our sun (solar system) is travelling about 0.000667128c

For even more fun.
Our sun's mass is about 1.989 x 10^30 Kg
That star is estimated to be 15x our sun's mass. So 2.9835×10^31 Kg
So that going 0.025c is going to ruin anything's day it comes across.

Well... except for a super-massive black hole.

 

[FF22]

It's not the black hole itself this star will get "almost dive into", but the black hole's event horizon. It could only "almost dive into" the black hole if it would be way past the event horizon, at which point we couldn't observe it "almost diving into" anything anymore from the outside of the former.

 

[mikedelhoo]

lordneeko[/url]":383ewn1t]

S_T_R[/url]":383ewn1t]A whole star traveling at .025c. The amount of energy involved is staggering.

For fun comparisons, our sun (solar system) is travelling about 0.000667128c

Hey man, it's all relative.

 

[DarkSkyForever]

Gooberslot[/url]":3u5q88sc]Can they predict when the star will actually fall into the black hole?

Well the article said the star will approach at a closest distance of 17 light hours, or about 3x the distance from our Sun to Pluto.

So it will just orbit the black hole in a large elliptical orbit and be flung back out again. Black holes don't just "suck" things into them like a cosmic vaccuum cleaner, they're just massive objects with gravity the same as any other object in space.

 

[ten91]

JerryLove[/url]":3k2x17ua]

ten91[/url]":3k2x17ua]

lordneeko[/url]":3k2x17ua]

S_T_R[/url]":3k2x17ua]A whole star traveling at .025c. The amount of energy involved is staggering.

For fun comparisons, our sun (solar system) is travelling about 0.000667128c

For even more fun.
Our sun's mass is about 1.989 x 10^30 Kg
That star is estimated to be 15x our sun's mass. So 2.9835×10^31 Kg
So that going 0.025c is going to ruin anything's day it comes across.

Well... except for a super-massive black hole.

Granted. But everything else.

 

[EricBerger]

Gooberslot[/url]":2ubix6zv]Can they predict when the star will actually fall into the black hole?

With the much better data provided by GRAVITY I suspect they will be able make these kind of predictions.

 

[Azethoth666]

lordneeko[/url]":nmzpnht9]

S_T_R[/url]":nmzpnht9]A whole star traveling at .025c. The amount of energy involved is staggering.

For fun comparisons, our sun (solar system) is travelling about 0.000667128c

Our local group moves at about 0.002c compared to the CMB.

As for the "energy" involved, it is just the mass of the hole and the star times c squared yes? The rest is relativistic orbital mechanics and a severe case of spacetime curvature.

 

[nickersonm]

FF22[/url]":36ln92r6]It's not the black hole itself this star will get "almost dive into", but the black hole's event horizon. It could only "almost dive into" the black hole if it would be way past the event horizon, at which point we couldn't observe it "almost diving into" anything anymore from the outside of the former.

A black hole refers to the event horizon, generally. You're looking for the term 'singularity'.

 

[Canterrain]

As scientists continued to study the phenomenon, they began to notice odd signals. Later a closer study of the signals revealed faint words being said over and over again. "Frame Shift Drive, Charging." There is some debate that these may actually be the words "Friendship drive charging."

 

[gmerrick]

So in 2018 is the star at its closet approach or is it that we will finally see the historical data of that approach?

 

[DBell]

gmerrick[/url]":dduk8y9m]So in 2018 is the star at its closet approach or is it that we will finally see the historical data of that approach?

That's when we will see the data. SAG A* is about 26,000 light years away, so since the light from S2's most recent orbit started our way, it will have completed nearly 1700 more orbits. Might even have been captured, but we won't know that for sure until the distant future...

 

[cse84]

EricBerger[/url]":tt1v62pu]

Gooberslot[/url]":tt1v62pu]Can they predict when the star will actually fall into the black hole?

With the much better data provided by GRAVITY I suspect they will be able make these kind of predictions.

We might be able to make a prediction, but I doubt it will be very precise or that the prediction will be in a realistically short time frame (I would suspect any event in the Milky Way predicted to happen after the merger of Milky Way and Andromeda to be pretty speculative). The Hulse-Taylor binary pulsar has an orbital period of less than 8 hours and already has an expected life time of 300 million years. S2 would have an orbital period of about 6 days if it orbited in a circular orbit at its current closest approach distance. And as far as I know, the expected life time increases super-linearly with the orbital period, so the expected life time would probably be at least 5 billion years.

 

[Bongle]

cse84[/url]":2mvh8veq] S2 would have an orbital period of about 6 days if it orbited in a circular orbit at its current closest approach distance.

Which is pretty fun to think about since it's at ~Pluto's distance from the sun - imagine Pluto moving 5x as far in the sky each night as the moon does. That thing is cooking.

 

[Maldoror]

S_T_R[/url]":312xs5s1]A whole star traveling at .025c. The amount of energy involved is staggering.

More interesting are the tidal forces on the star at that distance. I bet that puppy looks nothing like a sphere.

Edit: on second thought, if the closest approach is 17 hours... maybe not.

Edit 2: ninja'd by cse84

 

[cse84]

Maldoror[/url]":21lknt2z]

S_T_R[/url]":21lknt2z]A whole star traveling at .025c. The amount of energy involved is staggering.

More interesting are the tidal forces on the star at that distance. I bet that puppy looks nothing like a sphere.

They are not very strong actually. Small black holes have much larger tidal forces near their event horizon than large black holes. That means that large black holes can be "quiet", i.e. they can swallow stars without tearing them apart before they reach the event horizon. Small black holes tend to be "louder" - they tear apart their prey, squeeze them into a giant accretion disc and then eat that disc piecemeal, meanwhile producing a lot of radiation via this accretion disc.

 

[dj__jg]

Aykernar[/url]":3mrj7dkx]

ten91[/url]":3mrj7dkx]Can we just all take a moment to appreciate astronomers' ability to name things.

Edit: And that's not sarcasm in any way. They get away with some amazing names. Like Cthulhu Regio on Pluto.

As far as I can tell (and I even went so far as to check The Actual Paper describing the instrument), despite the capitalization, GRAVITY doesn't actually stand for anything. It is just... a name. Which is frankly disappointing, because it is always a laugh to see the language abuse people commit to make their acronyms sound cool, and when I saw the name I was looking forward to discovering another example.

If I'm wrong, and it actually is an acronym, please let us know!

Hmmmm... So we should probably just call it the Gravity instrument, which adheres to the "just use the most delightfully simple name you can come up with" theme. Full-Caps on non-acronym names is confusing.
Also: Dammit, I was really looking forward to discovering how they had to abuse language to make that acronym. Perhaps the comment section can come up with something?

 

[ten91]

dj__jg[/url]":27nspv9h]

Aykernar[/url]":27nspv9h]

ten91[/url]":27nspv9h]Can we just all take a moment to appreciate astronomers' ability to name things.

Edit: And that's not sarcasm in any way. They get away with some amazing names. Like Cthulhu Regio on Pluto.

As far as I can tell (and I even went so far as to check The Actual Paper describing the instrument), despite the capitalization, GRAVITY doesn't actually stand for anything. It is just... a name. Which is frankly disappointing, because it is always a laugh to see the language abuse people commit to make their acronyms sound cool, and when I saw the name I was looking forward to discovering another example.

If I'm wrong, and it actually is an acronym, please let us know!

Hmmmm... So we should probably just call it the Gravity instrument, which adheres to the "just use the most delightfully simple name you can come up with" theme. Full-Caps on non-acronym names is confusing.
Also: Dammit, I was really looking forward to discovering how they had to abuse language to make that acronym. Perhaps the comment section can come up with something?

Maybe it's GRAVITY because you have to say it in a specific tone. Like the one used when you say SCIENCE.

 

[Veritas super omens]

What happens at Sagitarrius A* stays at Sagitarrius A*.

best geek joke ever on Futurama.

 

[monkeyman.kix]

General RelAtivistic Velocity Interferometric TYmer.

There. Not so hard was it?

 

[KT421]

Veritas super omens[/url]":19zs5jk9]What happens at Sagitarrius A* stays at Sagitarrius A*.

best geek joke ever on Futurama.

It took me a second. But then I lol'd heartily.

I find that my video game life is leaking. I had to put this all in context by converting the distances to Ls (Light seconds) (about 60k) and 2.5% of c is "7.5 times faster than Mitterand Hollow," or, to use technical terminology, "really damn fast."

 

[Bengie25]

pr0t0[/url]":1qobuvjs]So we've got a star 15 times more massive than the Sun making its closest approach to a black hole that's roughly 4 million times more massive than the Sun at a distance just over 3 times the distance between Pluto and the Sun?

Break out the popcorn!

I'm wondering all kinds of things like, will S2 speed up significantly as it approaches? If so, will it stay in it's orbit or can it be thrown out?

Very, very cool!

Except in the case of two blackholes bouncing off of each-other, I don't think a normal 2 body interaction will cause one to get throw out. Of course we're talking about galactic nuclei, so the star probably interacted with other bodies along the way and could have gained extra energy pushing out its apsis.

 

[daarong]

ten91[/url]"5wljs17]

lordneeko[/url]"5wljs17]

S_T_R[/url]"5wljs17]A whole star traveling at .025c. The amount of energy involved is staggering.

For fun comparisons, our sun (solar system) is travelling about 0.000667128c

For even more fun.
Our sun's mass is about 1.989 x 10^30 Kg
That star is estimated to be 15x our sun's mass. So 2.9835×10^31 Kg
So that going 0.025c is going to ruin anything's day it comes across.

Let's step up the fun another notch,

0.025c is almost 17 million miles per hour...

Sounds like a lot, but if it was in a sci fi movie it'd be, well, boring! 17 million / hour is "only" around half the Earth's diameter per second... so by today's hyper-speed sci fi action movie standards, it'd be a relatively slow motion obliteration

 

[Dilbert]

Gooberslot[/url]":leucl6km]Can they predict when the star will actually fall into the black hole?

It won't fall in in the short term. After all, that star must be very old by human timekeeping standards and it's been orbiting this entire time. Long term, many millions or billion years the star may lose its orbital momentum due to exchange of gravity waves, or due to drag if there's gas or other matter in its path. We'd need rather precise measurements of the change in its orbit, orbit after orbit, to determine that. We just recently begun to track this star. Our instruments will no doubt get better from here, and our data more accurate. But at this time there's no way to know for sure. That's okay. We don't know everything. We can make a pretty good assumption, however, that we will keep learning more, and someone some day will find out.

 

[ridgeguy]

Would the tides (gravitational gradient) from the black hole be strong enough at the 17 light hour closest approach to distort the star? If so, do we have any way to detect that?

 

[ten91]

daarong[/url]":swt6cx5b]

ten91[/url]":swt6cx5b]

lordneeko[/url]":swt6cx5b]

S_T_R[/url]":swt6cx5b]A whole star traveling at .025c. The amount of energy involved is staggering.

For fun comparisons, our sun (solar system) is travelling about 0.000667128c

For even more fun.
Our sun's mass is about 1.989 x 10^30 Kg
That star is estimated to be 15x our sun's mass. So 2.9835×10^31 Kg
So that going 0.025c is going to ruin anything's day it comes across.

Let's step up the fun another notch,

0.025c is almost 17 million miles per hour...

Sounds like a lot, but if it was in a sci fi movie it'd be, well, boring! 17 million / hour is "only" around half the Earth's diameter per second... so by today's hyper-speed sci fi action movie standards, it'd be a relatively slow motion obliteration

The Empire's next superweapon. Death Star. Death Star II. Star Killer Base. Next this.

 

[All4vols]

Can you imagine the tidal forces that S2 must experience? What does something like that DO to the internal structure of a star? What will it do to it's life expectancy? How fast would it have to be spinning to compensate and maintain it's integrity? Just.... wow...

 

[Hat Monster]

ridgeguy[/url]":66bikntj]Would the tides (gravitational gradient) from the black hole be strong enough at the 17 light hour closest approach to distort the star? If so, do we have any way to detect that?

No. Tides around a supermassive black hole are very mild. The black hole is so big that, unlike smaller, stellar, black holes, they don't develop enormous tidal forces. A tidal force is a difference in gravity across the object in question. The gravity is not very different around a supermassive black hole, it's just enormous everywhere.

This is not to say that conditions aren't extreme. S2 will experience a maximum acceleration of 1.5 m/s^2 and a velocity (relative to Sag. A*) of over 5,100 km/s. It is 15 solar masses and is being thrown around like it's nothing.

It's now known as S0-2, there's also an S0-102, which whips around the unseen supermassive object in just 11.5 years. The mass of S0-102 isn't known well, spectra give it 10-30 solar masses, but it could also be a younger degenerate object, in which case it would be about a single solar mass.