Google Earth Community

SDSS Galaxy/Nebula Collection


Gregg1956 Jun 10, 2012 11:21 PM
Posted in group: Sky
I'm starting a new collection of galaxies and nebulae from the SDSS imagery of Google Sky. They will be objects that are visually stunning (or just cool looking) or interesting scientifically. Feel free to add your own finds here. I'll make a new musical tour when this thread gets a lot of entries.

NGC 4395 is a Seyfert 1 galaxy[1]. It has one of the smallest supermassive black holes ever discovered at it's center.

The black hole, discovered in the center of a galaxy known as NGC 4395, has a mass less than a million times that of the Sun. That might sound like a lot, but it's many times smaller than the normal "supermassive" black holes astronomers find in galaxies' centers.

"Typically, in the centers of galaxies, we'll find black holes that are a million to a billion solar masses," said astronomer Bradley Peterson of Ohio State University. "This one is less than a million — it's somewhere around 300,000 to 400,000 solar masses."

It's not just the black hole that's unusual — its host galaxy is an oddball as well, Peterson explained. While most galaxies are disk-shaped with a bulge in the middle, NGC 4395 is essentially flat; it has no central bulge. And this unusual shape may be linked to the size of the black hole: Peterson believes the black hole has already "eaten" all the stars in the center of the galaxy. This would explain why the black hole doesn't seem to be growing as well as the galaxy's odd shape.

"The remarkable thing about the galaxy that we studied is that it does not have this central bulge," Peterson said. "It just seems to be a pure disk. And despite the fact that it's a pure disk, it does have a fairly massive black hole — although it's very small by the standards of normal galactic black holes."

The black hole at the center of NGC 4395, located some 14 million light-years from Earth, could be thought of as "the runt of the litter," Peterson said. "It's the small black hole that never got enough to eat."  Astronomy Magazine article

[1] Simbad