Name: Gerry A Adams
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Question:
What is the latest on the most recent black hole discovery? (January 1995)
Replies:
There is lots of new data from Hubble that indicates black holes in near by
galaxies. Latest data indicates that M87 may have a very clean example. My
reading is that we will be able to get the mass and size from velocity
measurements of gas speeds. It should be very interesting. The September
1994 Physics Today magazine has a nice article.
Samuel P Bowen
There is an article entitled "Where have all the black holes gone?" in the
October 1994 issue of Astronomy magazine which you may want to read. It
says that at this time there are only about three good candidates for black
holes formed from the collapse of single stars; one of them is not even in
our galaxy, but in the Large Magellanic Cloud. Astronomers believe that
there should be 1 black hole for every 3 neutron stars; since more than 500
neutron stars are known, there should be a lot more than three black holes!
At least part of the problem, as this article describes, is the difficulty
in detecting black holes. As Sam Bowen says in his response, there was
reported (last June by a group of astronomers led by Holland Ford, using the
Hubble telescope) "conclusive evidence" of a massive (perhaps 3 billion
solar masses) black hole in the giant elliptical galaxy M87. Some astrono-
mers believe that many, perhaps most, galaxies have such massive black holes
at their centers.
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