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Kullat Nunu
2005-Mar-22, 08:58 PM
ESO Press Release: Young and Exotic Stellar Zoo (http://www.eso.org/outreach/press-rel/pr-2005/pr-08-05.html)


Super star clusters are groups of hundreds of thousands of very young stars packed into an unbelievably small volume. They represent the most extreme environments in which stars and planets can form.

Until now, super star clusters were only known to exist very far away, mostly in pairs or groups of interacting galaxies. Now, however, a team of European astronomers [1] have used ESO's telescopes to uncover such a monster object within our own Galaxy, the Milky Way, almost, but not quite, in our own backyard!

The newly found massive structure is hidden behind a large cloud of dust and gas and this is why it took so long to unveil its true nature. It is known as "Westerlund 1" and is a thousand times closer than any other super star cluster known so far. It is close enough that astronomers may now probe its structure in some detail.

Westerlund 1 contains hundreds of very massive stars, some shining with a brilliance of almost one million suns and some two-thousand times larger than the Sun (as large as the orbit of Saturn)! Indeed, if the Sun were located at the heart of this remarkable cluster, our sky would be full of hundreds of stars as bright as the full Moon. Westerlund 1 is a most unique natural laboratory for the study of extreme stellar physics, helping astronomers to find out how the most massive stars in our Galaxy live and die.

From their observations, the astronomers conclude that this extreme cluster most probably contains no less than 100,000 times the mass of the Sun, and all of its stars are located within a region less than 6 light-years across. Westerlund 1 thus appears to be the most massive compact young cluster yet identified in the Milky Way Galaxy.

George
2005-Mar-22, 09:07 PM
"With so many stars in such a small volume, some of them may collide", envisages Simon Clark. "This could lead to the formation of an intermediate-mass black hole more massive than 100 solar masses. It may well be that such a monster has already formed at the core of Westerlund 1."

In a cluster like this, I wonder which comes first, the blackhole or the cluster?

Kullat Nunu
2005-Mar-22, 09:18 PM
Looks like it is a good candidate for a globular cluster progenitor. :o

Padawan
2005-Mar-22, 09:36 PM
"With so many stars in such a small volume, some of them may collide", envisages Simon Clark. "This could lead to the formation of an intermediate-mass black hole more massive than 100 solar masses. It may well be that such a monster has already formed at the core of Westerlund 1."

In a cluster like this, I wonder which comes first, the blackhole or the cluster?


I would bet on the stars, as the black hole itself must first become a star to evolve to a black hole. I dont think a black hole would have pulled all those stars to itself, unless it's extremely massive...though there is a possibility... :-k

Kullat Nunu
2005-Mar-22, 10:11 PM
I would bet on the stars, as the black hole itself must first become a star to evolve to a black hole. I dont think a black hole would have pulled all those stars to itself, unless it's extremely massive...though there is a possibility... :-k

Well, the black holes get only the stars that wander too close (inside the Roche limit), and even in that case only a small part of the star gets consumed. Most of the star just spreads into the interstellar space. And that is the case with supermassive black holes weighting millions of Suns.

Better scenario would be coalescing stellar-mass black holes. More massive the black hole is, more likely it travels into the center of the cluster, as it loses potential energy by throwing normal stars away in close encounters. If several few solar mass black holes merge in the center of the cluster, result would be a intermediate-mass black hole.

Manchurian Taikonaut
2005-Mar-29, 02:37 PM
another Galaxy type discovery

galaxy collisions to star birth: European ISO

http://www.esa.int/esaCP/SEM7SVRMD6E_index_1.html

ISO - Infrared Space Observatory ESA operating at wavelengths from 2.5 to 240 microns, could observe astronomical objects that remain hidden for optical telescopes, such as cool objects that are unable to emit in visible light. Opaque objects, those surrounded by clouds of dust, are another specialty of ISO because the longer IR wavelengths can penetrate the dust, allowing us to see deeper into such clouds.

http://www.esa.int/export/esaSC/SEMM7G1A6BD_index_0.html

Launched November 1995
I think the power of the NASA Spitzer infrared has left this one behind and we'll also have the JWST soon enough, but its good to see the ISO working away

Launch window
2005-Oct-14, 02:52 PM
ESO's Telescopes See Afterglows of Elusive Short Bursts
http://www.eso.org/outreach/press-rel/pr-2005/pr-26-05.html
Using the 1.5m Danish telescope at La Silla (Chile), they showed that these short, intense bursts of gamma-ray emission most likely originate from the violent collision of two merging neutron stars. The same team has also used ESO's Very Large Telescope to constrain the birthplace of the first ever short burst whose position could be pinpointed with high precision, GRB 050509B.

publiusr
2005-Oct-14, 05:33 PM
ESO Press Release: Young and Exotic Stellar Zoo (http://www.eso.org/outreach/press-rel/pr-2005/pr-08-05.html)

How may ly was it from us? I must have missed that part.

Kullat Nunu
2005-Oct-14, 07:01 PM
About 10,000 light years.

George
2005-Oct-17, 06:19 PM
About 10,000 light years.
Did you mean parsecs (http://aanda.u-strasbg.fr:2002/articles/aas/full/1998/03/ds6324/node5.html)instead?

IIRC, I may have been originally thinking of a blackhole progenitor where its supernova powers would trigger the resulting star formation. [Sort'a..."One star to find them; one star to bring them all and in the darkness bind them; one star to rule them all" kind'a thing.:) Sorry, too many movies.]

Is this remotely possible, and could a cloud be so dense to allow for such?

Kullat Nunu
2005-Oct-18, 05:54 AM
No, light years. Do you think they use parsecs in press releases? ;)


Because Westerlund 1 is at a distance of only about 10,000 light-years, high-resolution cameras such as NAOS/CONICA on ESO's Very Large Telescope can resolve its individual stars. Such observations are now starting to reveal smaller stars in Westerlund 1, including some that are less massive than the Sun. Astronomers will thus soon be able to study this exotic galactic zoo in great depth.

George
2005-Oct-18, 12:27 PM
No, light years. Do you think they use parsecs in press releases? ;)
Hmmm, good point. :)

It appears it is hard to determine tight cluster distances, especially when veiled, according to this (http://64.233.187.104/search?q=cache:kefeB8RjqZQJ:aanda.u-strasbg.fr:2002/articles/aa/pdf/2002/19/aa2192.pdf+Westerlund1++pc&hl=en). [See first paragraph under Introduction.]


For example, Westerlund (1987) and Piatti et al. (1998a) derived distances for Westerlund1 of 5.0 and 1.0 kpc, respectively.

My prior reference uses 1.1 kpc. I am surprised at the degree of discrepancy considering its proximity.

George
2005-Oct-18, 02:57 PM
Looks like it is a good candidate for a globular cluster progenitor. :o

L I B! Lookie here (http://www.space.com/scienceastronomy/051013_blackhole_stars.html?from=astrowire.com)

Looks like a blackhole has progenitor powers. :) Of course, I can't say it works the same for a cluster, but....

I was thinking only in terms of its supernova action. Interesting, heh?

[hmmm....this link should be another thread I suppose]

Kullat Nunu
2005-Oct-18, 03:20 PM
Looks like the weirdest stellar objects tend to cluster around each other...

For example, the star cluster 1620-20 not only include the magnetar SGR 1806-20 that caused the huge gamma ray eruption recently, but also probably the most massive star in the Milky Way galaxy, LBV 1806-20.

George
2005-Oct-18, 04:50 PM
Looks like the weirdest stellar objects tend to cluster around each other...

For example, the star cluster 1620-20 not only include the magnetar SGR 1806-20 that caused the huge gamma ray eruption recently, but also probably the most massive star in the Milky Way galaxy, LBV 1806-20.
Interesting. Do you suspect a central black hole might be stirring the pot? SGR1806-20's flare was the brightest object ever observed, or do I recall something more brilliant occuring since last December?

Kullat Nunu
2005-Oct-18, 07:29 PM
No, it was same event.

There doesn't have to be any black holes in 1806-20 cluster to stir up things. In fact, it has been theorized that extremely massive stars don't end up as black holes but -- magnetars. So the progenitor of SGR 1806-20 might have been originally a massive star like its siblings.

George
2005-Oct-18, 08:43 PM
No, it was same event.

There doesn't have to be any black holes in 1806-20 cluster to stir up things. In fact, it has been theorized that extremely massive stars don't end up as black holes but -- magnetars. So the progenitor of SGR 1806-20 might have been originally a massive star like its siblings.

I wonder if our magnetar is centrally located. Probably not, but it would be interesting if the pot could indeed be stirred but such things. A magnetar might even have an advantage with its ability to flare-up. Black holes are more intraverted (like I used to be before joining this outfit :) ).

Launch window
2006-Jan-06, 04:15 PM
ESO PR Highlights in 2005
http://www.eso.org/outreach/press-rel/pr-2006/phot-01-06.html
One of the highlights was without any doubt the confirmation of the first image of an exoplanet, around the star 2M1207 (see ESO PR 12/05). ESO's telescopes also found a Neptune-mass exoplanet around a small star (PR 30/05) - a discovery that proves crucial in the census of other planetary systems, and imaged a tiny companion in the close vicinity of the star GQ Lupi, a very young object still surrounded by a disc, with an age between 100,000 and 2 million years (PR 09/05).

other info here
http://www.bautforum.com/showthread.php?t=13270
http://www.bautforum.com/showthread.php?t=8153