Scientists find most massive star ever discovered

[Naty1]

Scientists find most massive star ever discovered,

Like Charlie on 2 1/2 men, sounds like burning the candle at both ends...

http://news.yahoo.com/s/ap/20100721/ap_on_sc/eu_most_massive_star

 

[Astronuc]

The story at ESO - http://www.eso.org/public/news/eso1030/

Tarantula nebula region (7 April 2006) - http://www.eso.org/public/news/eso0613/

 

[turbo]

It's exciting in part because it is thought that when enough mass accretes in a single body to set off fusion, the radiation from the new-born star will clear the environs and prevent further accretion. Apparently this super-massive star managed to accrete its constituent materials before radiating enough energy to sweep surrounding environs of gas and dust. Previously-accepted limits on stellar mass will have to be re-thought, as well as our understanding of the physics of star formation.

 

[OmCheeto]

It's exciting in part because it is thought that when enough mass accretes in a single body to set off fusion, the radiation from the new-born star will clear the environs and prevent further accretion.

I'm not much of a cosmologist*, but I was thinking about just that around a year ago.
I wondered why all the stars in the universe didn't all start out the same size.

Apparently this super-massive star managed to accrete its constituent materials before radiating enough energy to sweep surrounding environs of gas and dust. Previously-accepted limits on stellar mass will have to be re-thought, as well as our understanding of the physics of star formation.

Simply incredible. Hard to imagine such beasts. Only a million years old, and already it's lost a fifth of it's mass.

http://www.eso.org/public/news/eso1030/
Very massive stars produce very powerful outflows. “Unlike humans, these stars are born heavy and lose weight as they age,” says Paul Crowther. “Being a little over a million years old, the most extreme star R136a1 is already ‘middle-aged’ and has undergone an intense weight loss programme, shedding a fifth of its initial mass over that time, or more than fifty solar masses.”

Is it possible that R136a1 was created by the merging of two or three smaller stars?
It would make sense.

These super heavyweight stars are extremely rare, forming solely within the densest star clusters.

I wonder what that would look like, two stars the size of Eta Carinae merging, and how long it would take?

*Ok. I'm not a cosmologist at all. But I do like looking at the stars :)

 

[Chronos]

Stars form at fairly vast distances apart. The probability of 2 eta carinae size stars forming close enought to interact is pretty low.

 

[SpiffyKavu]

This also seems to be a young cluster. There are a dozen very high mass stars (>35 solar masses) reported in this cluster, so the age of the cluster has been estimated at maybe one million years. The chances of a merger seem very small within the time frame.

I wonder what that would look like, two stars the size of Eta Carinae merging, and how long it would take?

A merger of two Eta Car stars would be impressive, and fun to watch. However, if the stars were in a binary system, I think that such high mass stars would likely evolve and go supernova before having a chance to merge. The resulting merger would still be impressive, but would not involve nearly as much mass.

There are observed stars which may be a result of the merger of two stars, known as blue stragglers. These are observed in old and dense star clusters, though.

 

[nicksauce]

Previously-accepted limits on stellar mass will have to be re-thought, as well as our understanding of the physics of star formation.

I'm not much of a star formation guy myself, but I've talked to a few colleagues who are about this. They tell me that upper-limits on stellar mass come from probability arguments, such as - "Assuming this IMF is valid, we should see X many stars with a mass above M, but we don't see any, so M is an upper bound on the maximum stellar mass" - rather than from physical arguments. Furthermore, they say that the upper bounds have typically tended to increase in recent years. So the impression I got was that the discovery of a 300M star wouldn't really change all that much.

 

[FawkesCa]

how does this change thoughts on gamma ray bursts (when the star eventually close hypernova)? could this one be close enough to effect us at only 22,000 light years?

 

[OmCheeto]

Stars form at fairly vast distances apart. The probability of 2 eta carinae size stars forming close enought to interact is pretty low.

Then how would such stars form. It's been my understanding that once a star coalesces enough matter to start the fusion process, collection of gasses would cease, as the stellar wind would blow the gasses away.

http://www.eso.org/public/archives/releases/sciencepapers/eso1030/eso1030.pdf" (2.2 Mb pdf)
Most, if not all, stars form in groups or clusters (Lada & Lada
2003). An average star forms with an initial mass of ∼0.5 M⊙
while the relative proportion of stars of higher and lower mass
obeys an apparently universal initial mass function (IMF, Kroupa
2002). In addition, there appears to be a relationship between the
mass of a cluster and its highest-mass star

The Astrophysikalisches Institut Potsdam seems to imply merging as a source of these big stars:

High-mass http://www.aip.de/groups/starplan/"
* Origin of massive stars in clusters and in the field (in collaboration with the RAVE project of the AIP)
* Mass segregation in young clusters and dynamical interactions (ejections and runaway OB stars, stellar collisions and mergers, progenitors of gamma-ray bursters)
* The origin of massive binaries and Trapezium-type systems
* Sequential massive star formation, starbursts

Looking at the image of the region, it's hard not to imagine mergers in such a dense cluster.

The image shows the central star cluster R136 in the extragalactic giant HII region 30 Doradus in the LMC.