VLT finds fastest rotating star

Dec 05, 2011
This view shows part of the stellar nursery called the Tarantula Nebula in the Large Magellanic Cloud, a small neighbor of the Milky Way. At the center lies the brilliant star VFTS 102 This view includes both visible-light and infrared images from the Wide Field Imager at the MPG/ESO 2.2-meter telescope at La Silla and the 4.1-metre infrared VISTA telescope at Paranal. VFTS 102 is the most rapidly rotating star ever found. Credit: ESO/M.-R. Cioni/VISTA Magellanic Cloud survey. Acknowledgment: Cambridge Astronomical Survey Unit

(PhysOrg.com) -- ESO's Very Large Telescope has picked up the fastest rotating star found so far. This massive bright young star lies in our neighbouring galaxy, the Large Magellanic Cloud, about 160 000 light-years from Earth. Astronomers think that it may have had a violent past and has been ejected from a double star system by its exploding companion.

An international team of astronomers has been using ESO's Very Large at the Paranal Observatory in Chile, to make a survey of the heaviest and brightest stars in the , in the . Among the many brilliant stars in this the team has spotted one, called VFTS 102, that is rotating at more than two million kilometres per hour — more than three hundred times faster than the Sun and very close to the point at which it would be torn apart due to centrifugal forces. VFTS 102 is the fastest rotating star known to date.

The astronomers also found that the star, which is around 25 times the mass of the Sun and about one hundred thousand times brighter, was moving through space at a significantly different speed from its neighbours.

"The remarkable rotation speed and the unusual motion compared to the surrounding stars led us to wonder if this star had had an unusual early life. We were suspicious." explains Philip Dufton (Queen's University Belfast, Northern Ireland, UK), lead author of the paper presenting the results.

This is an artist's concept of the fastest rotating star found to date. The massive, bright young star, called VFTS 102 rotates at about two million kilometres per hour. Centrifugal force from this dizzying spin rate has flattened the star into an oblate shape, and spun off a disk of hot plasma, seen edge on in this view from a hypothetical planet. The star may have "spun up" by accreting material from a binary companion star. The rapidly evolving companion later exploded as a supernova. The whirling star lies 160 000 light-years away in the Large Magellanic cloud, a satellite galaxy of the Milky Way. Credit: NASA/ESA and G. Bacon (STScI)

This difference in speed could imply that VFTS 102 is a runaway star -- a star that has been ejected from a after its companion exploded as a supernova. This idea is supported by two further clues: a pulsar and an associated supernova remnant in its vicinity.

The team has developed a possible back story for this very unusual star. It could have started life as one component of a binary . If the two stars were close, gas from the companion could have streamed over and in the process the star would have spun faster and faster. This would explain one unusual fact — why it is rotating so fast. After a short lifetime of about ten million years, the massive companion would have exploded as a supernova — which could explain the characteristic gas cloud known as a supernova remnant found nearby. The explosion would also have led to the ejection of the star and could explain the third anomaly — the difference between its speed and that of other stars in the region. As it collapsed, the massive companion would have turned into the pulsar that is observed today, and which completes the solution to the puzzle.

Although the astronomers cannot yet be sure that this is exactly what happened, Dufton concludes "This is a compelling story because it explains each of the unusual features that we've seen. This star is certainly showing us unexpected sides of the short, but dramatic lives of the heaviest ."

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kevinrtrs
1 / 5 (14) Dec 05, 2011
This view shows part of the stellar nursery called the Tarantula Nebula in the Large Magellanic Cloud,

One note on this is that the text should read "part of what is commonly believed to be the stellar nursery". Right now there's absolutely no positive confirmation that it is a stellar nursery. No one has ever observed the formation of a star from any kind of space dust anywhere. Period. The statement as it stands is sheer evolutionary story telling.
have streamed over and in the process the star would have spun faster and faster. This would explain one unusual fact why it is rotating so fast

Since this is how things tend to happen in real physical life, one is reminded that something is amiss with the accretion model for our solar system. Why? Because according to that model the sun should have most of the angular momentum but instead that is found in the planets, in particular in the gas giants, which is a tremendously ominous contradiction of the model.
barakn
5 / 5 (6) Dec 05, 2011
Since the Sun is an active star, it can easily shed angular momentum, directly by losing mass or indirectly by magnetic coupling to the solar wind. Your argument holds no water.
yyz
5 / 5 (3) Dec 05, 2011
"It could have started life as one component of a binary star system. If the two stars were close, gas from the companion could have streamed over and in the process the star would have spun faster and faster. This would explain one unusual factwhy it is rotating so fast. After a short lifetime of about ten million years, the massive companion would have exploded as a supernova which could explain the characteristic gas cloud known as a supernova remnant found nearby."

The authors present a compelling scenario which takes into account the close proximity(12pc-projected) of the young(~5000yr) xray pulsar PSR J0537-6910 and the Crab-like supernova remnant B0538-691. Noted above, ejection of VFTS 102 from a binary system could also account for a 40 kms velocity 'kick' seen wrt nearby stars.

HST is being used to gather proper motion studies to determine if the connection is likely.

A preprint of the paper can be found here: http://arxiv.org/...57v1.pdf
CHollman82
4.4 / 5 (7) Dec 05, 2011
This view shows part of the stellar nursery called the Tarantula Nebula in the Large Magellanic Cloud,

One note on this is that the text should read "part of what is commonly believed to be the stellar nursery". Right now there's absolutely no positive confirmation that it is a stellar nursery. No one has ever observed the formation of a star from any kind of space dust anywhere. Period.


Wow... just like no one has ever observed a fish turn into a mammal right?

You have brain damage.
javjav
5 / 5 (3) Dec 05, 2011
I agree with chollman82. When there are so many evidences about something it is accepted savage valid theory. It is not a dogma, but from this point it corresponds to scientists denaying it to demonstrate the opposite or at least to provide their arguments. In this case the use of "star nursery" is correct, because the article is not about that matter and it would be annoying to read "comonly believed" 20 times per scientific article, as required by such a strict style.

Meanwhile, the " brain damage" statement would probably need the "commonly believed" companion or similar.
finitesolutions
1 / 5 (1) Dec 06, 2011
Wow perfect! More and more the universe looks like a computer game with new levels , hidden levels, bonus levels and sequels.
ormondotvos
5 / 5 (1) Dec 06, 2011
Why is rotation not defined in turns per unit time, rather than distance per unit time?
SpiffyKavu
5 / 5 (4) Dec 06, 2011
Rotation usually is defined in terms of number of full rotations per unit time. But in this case, velocity is better defined. We do not know the radius of the star in question but we can easily measure the rotation speed of the surface (doppler broadening of emission lines). So velocity is very well known, but not the rotations/time.
aroc91
not rated yet Dec 07, 2011
Rotation usually is defined in terms of number of full rotations per unit time. But in this case, velocity is better defined. We do not know the radius of the star in question but we can easily measure the rotation speed of the surface (doppler broadening of emission lines). So velocity is very well known, but not the rotations/time.


Thanks for the clarification. I was curious about that as well.