Scientists Discover Biggest Star 202
Hugh Pickens writes "Scientists at the University of Sheffield have discovered the most massive stellar giant, R136a1 measured at 265 solar masses, using the European Southern Observatory's Very Large Telescope in Chile and data from the Hubble Space Telescope. It's in the Tarantula Nebula in the Large Magellanic Cloud, a small 'satellite' galaxy which orbits the Milky Way. Previously, the heaviest known stars were around 150 times the mass of the Sun, known as the 'Eddington Limit,' and this was believed to be close to the cosmic size limit because as stars get larger, the amount of energy created in their cores grows faster than the force of gravity which holds them together. 'Because of their proximity to the Eddington Limit they lose mass at a pretty high rate,' says Professor Paul Crowther, the chief researcher in the Sheffield team. Hyper-stars like R136a1 are believed to be formed from several young stars merging together, and are only found in the very heart of stellar clusters. R136a1 is believed to have a surface temperature of more than 40,000 degrees Celsius, and is 10 million times brighter than the Sun. Crowther adds that R136a1 is about as big as stars can get. 'Owing to the rarity of these monsters, I think it is unlikely that this new record will be broken any time soon.'"
Re:You think that's big!?!?!? (Score:2, Interesting)
VY Canis Majoris (Score:4, Interesting)
The article states that R136a1 is 265 solar masses, however it doesn't say how big it is.
VY Canis Majoris is 2,100 times the size of the sun, and 230,000 times the size of Earth. It is so huge, that if it occupied the centre of our solar system, its boundaries would be Saturn's orbit.
If R136a1 is the heaviest star, then it must be considerably more dense than VY Canis Majoris, but I find the latter to be far more impressive.
Re:I guess it's time to update the earth to star (Score:2, Interesting)
Just you wait until some committee somewhere out there decides that the sun is too small and inconsequential to be classed as a real star. If it happened to Pluto...
Re:Anonymous Coward (Score:4, Interesting)
Well yeah, the first line of the summary says "most massive", which in astronomy is usually (usually) what "biggest" means.
Though it is admittedly ambiguous. I was watching Jeopardy (a taped episode a friend of mine was in and *won*) and one of the answers was "It's the biggest planet after Jupiter and Saturn", and the correct question was "Neptune?" (the 3rd most massive) but the contestant questioned "Uranus?" (3rd largest diameter). The judges ended up accepting it due to the ambiguity of the question.
And I know that I personally consider the Jeopardy judges to be the ultimate authority on when something is ambiguous and multiple interpretations are valid!
Ten million times brighter than the Sun? (Score:3, Interesting)
Re:You think that's big!?!?!? (Score:4, Interesting)
Owing to the size of the universe, I think it is likely that this new record will be broken sometime soon.
The record is for the largest one found, not the largest one in the universe. These things are pretty difficult to find. They're all in dense clusters in active star forming regions. The cluster R136 is so dense that prior to the launch of HST we thought that there were fewer stars in it, but each of those stars would have been several hundred solar masses. HST was able to resolve those superstars into multiple smaller (50 solar mass) stars. Except for this one, apparently.
We haven't found any equivalent star clusters in the Milkyway (yet). It's possible there aren't any. Maybe something about the composition or dynamics of Galactic gas prevents such large stars from forming. No other galaxy would be close enough that we could resolve cluster into individual stars. The SMC doesn't have active star formation. So we're stuck with the LMC as a target for finding a larger star. There's no other cluster in the LMC like R136, so to break this record we'd probably need to find a larger star in the same cluster. Or we would need to find out that R136a1 is a multiple star system containing 2 or more smaller stars rather than one star of 265 solar masses.
As far as how significant this is... I'm sure it will drive star formation theorists nuts trying to build stars that big in a cluster environment. But as a find, in and of itself, they looked for a really huge star in what is well known as the only place you're going to possibly find a really huge star. It seems kind of like "discovering" a route from your front door to the bus stop when you know where both of them are. Given how many people are interested in star forming regions, I'm kind of wondering why nobody did it earlier. I may have to read the paper to see if some interesting or difficult technique was necessary.
Re:Ten million times brighter than the Sun? (Score:5, Interesting)
I'm guessing that what it probably means is that this star is estimated at having ten million times the power output compared to the Sun. Therefore, at some fixed reference distance, it would deliver ten million times more watts of illumination per square meter. This doesn't mean that the surface brightness is ten million times greater than that of the Sun, because some of the brightness comes from the greater size of the star. If you make a lamp with one hundred light bulbs, they are not individually brighter than a single light bulb, but as an aggregate, they provide more illumination, and can be more easily seen from farther away.