Physics Forums (http://www.physicsforums.com/index.php)
-   Astronomy & Astrophysics (http://www.physicsforums.com/forumdisplay.php?f=71)
-   -   Questions concerning hypervelocity stars (http://www.physicsforums.com/showthread.php?t=562692)

 Travito Dec25-11 12:37 PM

Questions concerning hypervelocity stars

Hey everybody, I'm new here and what better way to start then jump right in!! I have a few questions concerning hypervelocity stars for a sci fi book that I want to write.

First of all, what is the agreed upon "average" speed of a hypervelocity star? I have done a bit of googling, but I have seen a lot of different numbers. Would 1000km/s be about right?

Secondly, I have read that some hypervelocity stars are thought to have originated in the Magellanic Clouds. Which one would be more likely to produce hypervelocity stars? The LMC or the SMC?

Thirdly and finally, given the speed and the distance of the LMC/SMC, how long would it take a hypervelocity star to reach Earth? I know this would never happen, but keep in mind it's just for a sci fi novel :P

Thank you all for your help and I look forward to being a member of these forums :) Merry Christmas!!!

Travito

 DaveC426913 Dec25-11 01:36 PM

Re: Questions concerning hypervelocity stars

Quote:
 Quote by Travito (Post 3683456) Which one would be more likely to produce hypervelocity stars? The LMC or the SMC?
Can't imagine it would make any difference.

Quote:
 Quote by Travito (Post 3683456) Thirdly and finally, given the speed and the distance of the LMC/SMC, how long would it take a hypervelocity star to reach Earth?
You know the distance to LMC, and you know the velocity you've chosen, so it;s a pretty straightforward calc.

Re: Questions concerning hypervelocity stars

Why do you say it can never happen?

 qraal Dec25-11 11:46 PM

Re: Questions concerning hypervelocity stars

Quote:
 Quote by Travito (Post 3683456) Hey everybody, I'm new here and what better way to start then jump right in!! I have a few questions concerning hypervelocity stars for a sci fi book that I want to write. First of all, what is the agreed upon "average" speed of a hypervelocity star? I have done a bit of googling, but I have seen a lot of different numbers. Would 1000km/s be about right? Secondly, I have read that some hypervelocity stars are thought to have originated in the Magellanic Clouds. Which one would be more likely to produce hypervelocity stars? The LMC or the SMC? Thirdly and finally, given the speed and the distance of the LMC/SMC, how long would it take a hypervelocity star to reach Earth? I know this would never happen, but keep in mind it's just for a sci fi novel :P Thank you all for your help and I look forward to being a member of these forums :) Merry Christmas!!! Travito
From what I have read hyper velocity stars have been flung out of the Galactic core. I guess they might be easier to see in the LMC/SMC. The Magellanic Clouds are about 168,000 (LMC) & 225,000 ly (SMC) away. At 1,000 km/s you're travelling at 300 years per light-year, thus it's 56,000,000 years & 75,000,000 years flight time respectively.

Re: Questions concerning hypervelocity stars

Most HVS are thought to have been hurled out from the galactic core-not all.

 Chronos Dec30-11 08:06 PM

Re: Questions concerning hypervelocity stars

Hypervelocity stars can originate from any part of any galaxy. They are usually associated with supernova kicks. Some are also due to black hole slingshots. The ones that originate near galactic cores are typically easier to detect.

 DaveC426913 Dec31-11 06:12 PM

Re: Questions concerning hypervelocity stars

Quote:
 Quote by Radrook (Post 3683668) Why do you say it can never happen?
What? I didn't say that; I said LMC is as likely as SMC. Doesn't make a diff which one you choose.

Re: Questions concerning hypervelocity stars

Quote:
 Quote by DaveC426913 (Post 3690816) What? I didn't say that; I said LMC is as likely as SMC. Doesn't make a diff which one you choose.
Travito said that he knows a supervelocity star could never reach earth and I asked why he thinks that's impossible.

 DaveC426913 Jan8-12 10:05 PM

Re: Questions concerning hypervelocity stars

Quote:
 Quote by Radrook (Post 3702051) Travito said that he knows a supervelocity star could never reach earth and I asked why he thinks that's impossible.
Oh. Well, that's why quoting is helpful. :wink:

I guess he was just heading off the standard responses saying 'this is so fabulously unlikely that it's not a realistic scenario'.