Mega stellar mergers

I recently happened upon a report discussing an unusual binary star system in the Magellanic Clouds, which are prominent in the southern sky. In fact, the Large Magellanic Cloud is brighter than the Orion nebula despite being 100 times more distant, and is a tremendous star-forming region containing many massive stars, novae, and a famous supernova known as SN1987A. The binary, with the unexciting name of LH54-425, is made up two young, hot blue stars with 62 and 37 times the mass of our Sun in a close orbit. In fact, the stars revolve once around each other every 2.25 days and are almost in contact.

Due to the disparity in their masses, co-discoverer George Sonneborn of NASA's Goddard Spaceflight Center believes that in the not-too-distant future (that is, within a few million years!) the two stars may merge together, creating an even more massive star. The result may appear similar to the hyper-luminous eta Carinae (about which more in a later post) which is probably the most luminous star in our own Milky Way galaxy. Astronomers do not know exactly when or how such stars merge, but it probably occurs roughly once per century in the Milky Way for massive stars, and much more frequently in stars of lower mass.

Hot on the heels of this news from the LMC (Large Magellanic Cloud), astronomers at the telescope have been able to weigh a star about 7000 light-years away in the star cluster NGC3603 (see picture). The result: a truly enormous 114 times the mass of the Sun! This star is also a member of a binary system; its partner is a comparative lightweight at 84 solar masses! Whether these stars will eventually merge is anyone's guess; it is quite possible that the giant star will lose so much gas it will never grow large enough to absorb its companion.

Links

Star duo on New Scientist Space
Super stars create new Sun