dipper@utastro.UUCP (Debbie Byrd) (12/10/84)
There's a possible black hole in the Large Magellanic Cloud. More on LMC X-3 -- in a moment. December 10 LMC X-3 One possible black hole is Cygnus X-l -- an x-ray source -- where an invisible object massive enough to be a black hole orbits an ordinary star. Now there's another possibly strong black hole candidate in the Large Magellanic Cloud -- a satellite galaxy to our own Milky Way. This black hole candidate is called LMC X-3. Possible black holes, such as Cyg X-1 or LMC X-3, call attention to themselves by their x-ray emission. It's thought that when a black hole and a star orbit around each other, the system should emit large quantities of x-rays -- as material ripped from the ordinary star spirals toward the black hole. In the case of Cygnus X-1, there appears to be a star about 20 times as massive as our sun -- orbiting a roughly 10-solar-mass x-ray object. The 10-solar-mass object is invisible -- and really may be a black hole. But it's hard to tell -- because the possible black hole is so close to the glare of its companion. There's still a slim chance that the system may really be several stars -- with no black hole at all. In the case of LMC X-3, there's also a 10-solar-mass x-ray emitter and a companion star. But the companion in this case is only a couple of times as massive as the sun. So the x-ray object can't be hiding anything in the glare of its companion -- because the companion isn't bright enough. More work is needed, but, when the numbers are pinned down, then the LMC X-3 system may become the best candidate for being a black hole. Script by Deborah Byrd. (c) Copyright 1983, 1984 McDonald Observatory, University of Texas at Austin