Black hole with "diamond necklace"

The central black hole of galaxy NGC 1097 is surrounded by a ring of some 300 star-forming regions resembling a diamond necklace. The spots looking like stars are actually regions containing many stars. The mass inside the ring, including the black hole, is estimated at half a billion solar masses.

 

Here's the press release from European Southern Observatory.

http://www.eso.org/outreach/press-rel/pr-2005/phot-33-05.html

 

Here is the scientific article:

http://arxiv.org/abs/astro-ph/0507071

which was published in the Astrophysical Journal this month.

 

The star forming regions, in two spiral arms, make a circle which is very roughly 2000 lightyears in radius.

 

Here is a larger picture:

http://www.eso.org/outreach/press-rel/pr-2005/images/phot-33a-05-normal.jpg