Star Hurled Out of Centre of our Galaxy

Serendipity

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It's bad enough have comets and asteroids wandering through our Solar System (but not surprising). Now comes news that whole massive stars can come our way as well. Fortunately the one they discovered isn't on a collision course with us. But the thought does send shivers down my spine - so who's up for writing a bit of science fiction about this?

See Object spotted speeding through the universe after being thrown out by a black hole
 

Elckerlyc

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The thing I can't get my head around is the speed of the thing - 1,700km per second!
So, if you see that thing coming right at you, with its breakneck speed of 1,700km/sec, and assuming for simplicity sake this star has about the same diameter as our sun (1,393,000km), you will need to move (1,393,000/2)=696,500km aside to get out of its way (not mentioning heat or radiation). The sun will need 696,500/1,700 = 409.7 seconds to cover that distance.
Just don't wait too long is all I'm saying.
 

Brian G Turner

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so who's up for writing a bit of science fiction about this?
Not science fiction, but I am trying to write a non-fiction book about the latest discoveries in space science, and what that means for us. :)

In this example, it's simply the latest of a number of "high velocity stars" that have been recently detected. There's now a section on Wikipedia about them: Stellar kinematics - Wikipedia
 

J Riff

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It could zing right on out and start circling the galaxy, or smash into something on the way. Odds against hitting us: Unknown!! (scary music)
 

dask

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Not science fiction, but I am trying to write a non-fiction book about the latest discoveries in space science, and what that means for us. :)

In this example, it's simply the latest of a number of "high velocity stars" that have been recently detected. There's now a section on Wikipedia about them: Stellar kinematics - Wikipedia
I'd like to know when your book on space discoveries is published.
 

J Riff

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Thing is.. it would have little or no resistance... so it might not curve much. But it could affect a lot of gravitational fields on it's way, quite possibly destroy Earth on the way past. We could be dragged off and away outa the Mily Way for gosh sake, like in Space 1999 but a lot faster.
 

RJM Corbet

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A star thrown out BY a black hole? Not thrown out OF a black hole?

Black holes don't ever throw out anything? Isn't that the very nature of what a black hole is?
 

Elckerlyc

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I think I read somewhere that the star could be one of a binary system. The closer they get, the faster they orbit each other. If one of those stars get caught in the pull of a black hole, the other is suddenly freed of the binary bond and gets slung on its merry way.

*Now I await the true experts to be thoroughly refuted....*
 

Venusian Broon

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The thing I can't get my head around is the speed of the thing - 1,700km per second!
Actually reasonably slow.

Let me explain. :)

The escape velocity of an object to leave our solar system, from the vicinity of the Earth, is approximately 42 km/s.

The equations for escape velocity are proportional to the square root of the mass of the object you want to escape and the inverse of the distance.

So, Saggitarius A is about 4 million times more massive than our sun. Therefore if you were at 1 Astronomical unit from the black hole, you would need to increase your velocity by 2000 times, or ~84,000 km/s to escape the system!

This star is 'only' doing 1,700 km/s! This seems to imply that this star must at about 2,500 A.U. away from the black hole for it to be flung out. That seems a lot...but remember that 1 light year is 63,241 A.U. so it's still 'in the neighbourhood' in astronomical terms.
 

mosaix

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Actually reasonably slow.

Let me explain. :)

The escape velocity of an object to leave our solar system, from the vicinity of the Earth, is approximately 42 km/s.

The equations for escape velocity are proportional to the square root of the mass of the object you want to escape and the inverse of the distance.

So, Saggitarius A is about 4 million times more massive than our sun. Therefore if you were at 1 Astronomical unit from the black hole, you would need to increase your velocity by 2000 times, or ~84,000 km/s to escape the system!

This star is 'only' doing 1,700 km/s! This seems to imply that this star must at about 2,500 A.U. away from the black hole for it to be flung out. That seems a lot...but remember that 1 light year is 63,241 A.U. so it's still 'in the neighbourhood' in astronomical terms.
Still can't get my head around it, VB.
 

RJM Corbet

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Ok. Well this recent thread by @Daysman shows how light from the sun takes 45 minutes to reach Jupiter, travelling at 300 000 km a second. So divide that by 1700km per second -- or multiply it or whatever.

Someone do the math, just don't ask me -- how long would this rogue star take to reach Jupiter, if launched from the sun?


I get five-and-a-half days? So ... not so very fast really, in the eventual scheme of things?
 
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Venusian Broon

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Ok. Well this recent thread by @Daysman shows how light from the sun takes 45 minutes to reach Jupiter, travelling at 300 000 km a second. So divide that by 1700km per second -- or multiply it or whatever.

Someone do the math, just don't ask me -- how long would this rogue star take to reach Jupiter, if launched from the sun?


I get five-and-a-half days? So ... not so very fast really, in the eventual scheme of things?
I used Excel and some very wonky numbers, but about 130 hours.

1700 km/s is about 0.5% the speed of light, so there's a fair difference.
 
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Elckerlyc

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45 mins = 2,700 sec x 300,000km = 810,000,000 km distance Sun - Jupiter.
However, Googling tells me it is in fact. 778,547,200km.
778,547,200 / 1,700 = 457,968.9 sec = 7,632.8 mins = 127.2 hrs = 5.3 days.

Or 300,000 / 1,700 = 176.47 * 45 mins = 7,941.1 mins = 132.3 hrs = 5,5 days.

A difference of 6hrs, but I guess the 45 mins isn't exactly right, just like the 810mln km wasn't.
Not counting acceleration.
 
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