Globular Clusters: remnant core of captured galaxy?

mental4astro (Alexander) · #1 15-12-2009, 12:38 AM

Hi all,

I was told on the weekend that massive GC's like Omega Centuri and 47 Tuc were likely to be the remnant core of galaxies captured by the Milky Way. Is this the case? Not casting dispersions on my learned friend on the notion, but I'd like another point of view on what for me is 'Crikey! Wow! what an opportunity'.

I had also read about the possibility of there being a black hole within these massive GC's. This could help answer a few Q's on the structural integrety of them with their tight orbits.

Is the chemical make up of GC's a clue to this?

If this is the case, how on Earth (pun intended) would the smaller GC's form?

Alex.

Lismore Bloke (Paul) · #2 15-12-2009, 07:48 AM

I put this Wikipedia link into the thread on Terzan 5. It covers the topics you mention and has some good links also. Good starting point.

http://en.wikipedia.org/wiki/Omega_Centauri

Lismore Bloke (Paul) · #3 15-12-2009, 09:15 AM

Here are a couple of the links from the Wiki article:

http://msowww.anu.edu.au/news/media_...ase_030716.php

http://www.spacetelescope.org/news/html/heic0809.html

Vanda (Ian) · #4 23-12-2009, 11:40 PM

So reading these links its possible its a galaxy remnant - yet to be proven though!

TheDecepticon · #5 24-12-2009, 11:08 PM

I don't have access to a planetarium, however, isn't there one in Sagittarius, M55??(not sure on the actual number) that is known as the Sagittarius Dwarf Galaxy? It was until recently considered a Glob, but has since been reclassified? I could be wrong, but this is what I thought, and I think it is in Wiki somewhere.

Terry B · #6 24-12-2009, 11:08 PM

Omega Cent is different to most other GCs. It has a much higher metalicity and is not entirely composed of very old stars like most GCs.
It seems more like a galaxy core.The origin of GCs is still poorly understood.

TheDecepticon · #7 24-12-2009, 11:16 PM

Ok, I was sort wrong/right. M54 is a globular cluster of the Sagittarius Dwarf, and resides at its core. So, where do dwarf elliptical galaxies get their globs from?(not really expecting an answer, more thinking aloud)

mithrandir (Andrew) · #8 24-12-2009, 11:21 PM

Quote:

Originally Posted by TheDecepticon

I don't have access to a planetarium, however, isn't there one in Sagittarius, M55??(not sure on the actual number) that is known as the Sagittarius Dwarf Galaxy? It was until recently considered a Glob, but has since been reclassified? I could be wrong, but this is what I thought, and I think it is in Wiki somewhere.

First hit I got:

Sagittarius Dwarf http://www.daviddarling.info/encyclopedia/S/SagDEG.html
A satellite galaxy of the Milky Way and the second closest external galaxy after the Canis Major Dwarf. It is populated, as is usual for a dwarf elliptical galaxy, by old yellowish stars. Obscured by large amounts of dust in the galactic plane, SagDEG was discovered as recently as 1994. It has four known globular clusters – M54, Arp 2, Terzan 7, and Terzan 8 – of which M54 is easily the brightest and was the first extragalactic globular ever found, by Charles Messier in 1778.

TheDecepticon · #9 24-12-2009, 11:37 PM

Here is another, Mental, with several generations of stars as Omega, with astronomers thinking it is a dwarf remnant also. Awesome stuff, really!

http://www.iceinspace.com.au/forum/s...ad.php?t=54515

mental4astro (Alexander) · #10 25-12-2009, 12:06 AM

Cool stuff.

It wow's me how complex things are. Truely facinating.

And to think that we are so privledged to be able to gaze upon these treasures!

Vanda (Ian) · #11 25-12-2009, 11:18 AM

Which brings me to good ole sol. Presumed part of a loose cluster when born. Read in Wikipadia somewhere that there are some 10-11 stars that are paralleling alpha centauri's course. Which makes me curious - are any paralleling sol? Has too much time elapsed for us to identify any stars born next to ours - part of sols original cluster. I assume all those billions of years has been enough time to make sol's siblings impossible to trace?

spacezebra (Petra) · #12 25-12-2009, 05:30 PM

Thank you for the posts guys, as I am currently studying GC's this is indeed very interesting!

Cheers Petra d.

mental4astro (Alexander) · #13 25-12-2009, 10:16 PM

Quote:

Originally Posted by Vanda

Which brings me to good ole sol. Presumed part of a loose cluster when born. Read in Wikipadia somewhere that there are some 10-11 stars that are paralleling alpha centauri's course. Which makes me curious - are any paralleling sol? Has too much time elapsed for us to identify any stars born next to ours - part of sols original cluster. I assume all those billions of years has been enough time to make sol's siblings impossible to trace?

I vaguely remember reading some where that there have been a few stars identified as being sibbling of Sol. Vaguely.

The chemical composition of sibbling stars is very specific by tracing the isotope signature. It's like a genetic marker.

I just cannot remember where I came across this article.