APOD: Starburst Cluster in NGC 3603 (2016 Nov 06)

Comments and questions about the APOD on the main view screen.
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Ann
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Re: APOD: Starburst Cluster in NGC 3603 (2016 Nov 06)

Post by Ann » Sat Nov 12, 2016 6:30 am

Star cluster simulation. Credit: Adam Block.
I should add that one reason why the stars so rarely collide is that they are zipping by one another really fast. Also, bear in mind that although cluster stars are incredibly close to one another compared with the stars in the in the solar neighborhood (Alpha Centauri anyone?), the stars themselves are still incredibly small compared with the vast distances separating them. That is true even inside a dense cluster. Even inside a dense cluster, chances are that speeding stars racing along blindly will still not collide with any of its brethren (or sistren?) stars.

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neufer
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Re: APOD: Starburst Cluster in NGC 3603 (2016 Nov 06)

Post by neufer » Sat Nov 12, 2016 4:27 pm

Ann wrote:
I should add that one reason why the stars so rarely collide is that they are zipping by one another really fast.
  • Example:

    Alpha Centauri has a proper motion across the sky of ~23.3 km/s.

    The minimum angular velocity necessary to avoid colliding with the sun from that distance is just ~2 mm/sec.
https://en.wikipedia.org/wiki/Stellar_collision wrote:
<<While stellar collisions may occur very frequently in certain parts of the galaxy, the likelihood of a collision involving the Sun is very small. A probability calculation predicts the rate of stellar collisions involving the Sun is 1 in 1028 years. For comparison, the age of the universe is of the order 1010 years.

Even though our star will likely not be directly affected by such an event, the Earth may, however, be easily affected by a nearby collision. Astronomers say that if a stellar collision happens within 100 light years of the Earth, it could possibly result in Earth's destruction. This is still very unlikely though because there are no stellar clusters this close to the Solar System.>>
Last edited by neufer on Sat Nov 12, 2016 7:39 pm, edited 2 times in total.
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Re: APOD: Starburst Cluster in NGC 3603 (2016 Nov 06)

Post by geckzilla » Sat Nov 12, 2016 4:29 pm

All imagery you see of stars is also misleading in a way. In reality, those stars also aren't really as close to touching as they appear. If their light didn't spread out on the detector, they'd be completely invisible and not even take up a single pixel upon its surface.
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