BLACK HOLE IN MILKY WAY'S SATELLITE DEFIES EXPLANATION

Dwarf galaxy Leo I’s giant central area seems too big for such a small host

- Tereza Pultarova

A tiny galaxy orbiting at the outskirts of the Milky Way appears to have a giant black hole at its centre, comparable to that of the much larger Milky Way itself, and scientists don’t know why. The Leo I dwarf galaxy, some 820,000 light years from Earth, is only about 2,000 light years across. Until now, astronomers thought the galaxy’s mass was about 15 to 30 million times the mass of our Sun. That’s tiny compared to the Milky Way, which is estimated to weigh as much as 1.5 trillion Suns and whose disc is over 100,000 light years wide. Unexpectedly, at the heart of little Leo I sits a black hole that’s nearly as large as the one at the heart of the Milky Way. The discovery defies expectations, as astronomers believed giant black holes grew from collisions between galaxies and should correspond with the galaxy’s size.