Astronomers have found further evidence for the existence of what you might call the Goldilocks category of black holes--not too large, not too small, but intermediate in mass. They have also discovered that these elusive objects may be stranger than anyone had imagined.



Not long ago, all of the black holes known to science fell into one of two classes: the diminutive stellar variety (with a mass of up to 10 suns) and the supermassive kind (with a mass of millions to billions of suns). But in recent years, hints of midsize black holes--ones containing the mass of hundreds to tens of thousands of suns--have emerged.[...]