Comments on: Vampires and thrillseekers rejuvenate dead stars

By: Miguel Farah

Miguel Farah — Fri, 07 Sep 2012 16:06:48 +0000

I wonder: are there any estimations at how long a star merger would take? Is there ANY chance to actually catch one in the process? Are there any known stars that are about to merge in this way in said cluster (or any other)?

By: Darren

Darren — Thu, 24 Dec 2009 22:17:09 +0000

Maybe the stars are being transported from a black hole and are just coming out of an event horizon then speeding off into space. I just cant see how that many stars can coexist without running into each other.

By: TreeHouseForRent

TreeHouseForRent — Thu, 24 Dec 2009 15:34:31 +0000

Way cool! I’m still trying to understand how light has mass. When rays of light pass by black holes, they bend. Where the gravity is really strong, the light doesn’t escape at all. Anyone?

By: andy

andy — Thu, 24 Dec 2009 15:16:30 +0000

Mass transfer does change the orbital semimajor axis. IIRC, for conservative mass transfer (no mass lost from the system), transfer from the more massive star to the less massive one causes decrease of semimajor axis, transfer from the less massive star to the more massive one causes increase of semimajor axis.

By: toasterhead

toasterhead — Thu, 24 Dec 2009 15:13:57 +0000

What does the age of a cluster refer to, exactly, and how is it determined? Is it the time at which that group of stars began aggregating around a common center of gravity, or is it determined by looking at the chemical composition and estimating how many life-cycles the stars within the cluster have been through?

By: Gary Ansorge

Gary Ansorge — Thu, 24 Dec 2009 14:59:39 +0000

25. Peter B:

I rather doubt there would be any orbital degeneration, as the total mass of this two star system would be constant but the common center of gravity would shift as mass is transferred from one star to the other.

GAry 7

By: Michael

Michael — Thu, 24 Dec 2009 14:50:37 +0000

@DrFlimmer, HB stars are blueish to yellowish, but more luminous than main sequence stars of the same color. When you look at a high-res color image of a globular cluster, you mostly see the luminous red giant and AGB stars, and then the next brightest stars are the blueish HB stars. The main sequence stars (including the rare blue stragglers) are much fainter. E.g., see the HR diagram figure in the middle of these lecture notes: http://tinyurl.com/y989emb

Oh, here’s a better color-vs.-brightness plot for the globular M13: http://tinyurl.com/y875qj8

By: Peter B

Peter B — Thu, 24 Dec 2009 14:02:17 +0000

What a fascinating pair of concepts.

I’m trying to wrap my head around the idea that one star extracts material from its binary twin. In particular I’m thinking about what happens to the siphonee – as it loses material, the relative masses of the two stars will change, which presumably must affect the orbit of the two stars around each other. Could someone explain what happens as this process continues? Would the siphoned star orbit inwards as it lost mass? Would the gas in the vicinity act like an atmosphere providing aerobraking for a spacecraft? Does this mean the siphoned star will eventually crash into its larger twin? Enquiring minds want to know!

By: Alan T

Alan T — Thu, 24 Dec 2009 13:41:53 +0000

WOW! Sorry, best i could do after retrieving my jaw from the floor.

By: Cyberdraco

Cyberdraco — Thu, 24 Dec 2009 06:40:45 +0000

I literally had goosebumps when I visualized a Cosmic vampire star…How wonderful it is to be star stuff.