Скачать или смотреть A Runaway Star

  / sciencereason   ... Hubble's Universe Unfiltered (Episode 14): A Runaway Star.

In order to get observing time on Hubble, an astronomer needs a well-thought-out plan of exactly what to observe and the science that may be learned. However, the universe is continually surprising us by providing unanticipated results. When a survey of a star-forming region found a star 90 times as massive as the Sun, located hundreds of light-years from its home, and speeding by at a quarter of a million miles per hour — well, that's a surprise that's worth investigating a bit further.

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Hubble Catches Heavyweight Runaway Star Speeding from 30 Doradus

A blue-hot star, 90 times more massive than our Sun, is hurtling across space fast enough to make a round trip from Earth to the Moon in merely two hours. Though the speed is not a record-breaker, it is unique to find a homeless star that has traveled so far from its nest. The only way the star could have been ejected from the star cluster where it was born is through a tussle with a rogue star that entered the binary system where the star lived, which ejected the star through a dynamical game of stellar pinball.

This is strong circumstantial evidence for stars as massive as 150 times our Sun's mass living in the cluster. Only a very massive star would have the gravitational energy to eject something weighing 90 solar masses. The runaway star is on the outskirts of the 30 Doradus nebula, a raucous stellar breeding ground in the nearby Large Magellanic Cloud. The finding bolsters evidence that the most massive stars in the local universe reside in 30 Doradus, making it a unique laboratory for studying heavyweight stars. 30 Doradus, also called the Tarantula Nebula, is roughly 170,000 light-years from Earth.

• http://hubblesite.org/newscenter/arch...

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Notes

• This story derives from results of the Cosmic Origins Spectrograph instrument on Hubble. While famous for its awe-inspiring pictures, astronomers learn just as much from examining Hubble's spectral observations, especially in the ultraviolet region not observable from the ground. Ultraviolet light has shorter wavelengths and higher energies than the visible light seen by our eyes. Very massive stars produce higher energy emission, which has important spectral features to study in the ultraviolet region. You may not see spectra on the covers of magazines, but many of Hubble's most important results are based on these detailed graphs of emission versus wavelelength.

• The Large Magellanic Cloud is one of the great wonders of the night sky. It is, however, located at 70 degrees south of the celestial equator and is only viewable by those in the southern hemisphere. Conversely, the stars of the Big Dipper are located about 55 degrees north of the celestial equator and are best viewed from the northern hemisphere. Although bearing the name of the explorer Magellan, this small galaxy has been a spectacular sight for anyone who has ever lived "down under." I hope to be able to travel there and see it myself one day. Even more spectacular would be the view from the stars of the LMC, looking back at our Milky Way Galaxy.

• It has always struck me as a little strange that the largest star-forming region in our Local Group of galaxies, 30 Doradus, would be found in a dwarf galaxy. One would expect that the larger galaxies, like Andromeda, Triangulum, or the Milky Way, would have much more gas and dust available to make larger star-forming regions. The fact that a dwarf galaxy can make a huge star factory shows that size alone is not the determining factor. The creation of a star-forming region is also guided by the motions of the gas and dust, as well as the time available for it to collect into a vast cloud. In that sense, perhaps the calmer environment of a dwarf galaxy makes for the best place to harbor a giant starbirth cloud.

• http://hubblesite.org/
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