Wednesday, October 03, 2007

A census of nearby galaxies

In Mining the Local Volume 550 galaxies have been found within 10 million parsecs. A surprising observation was that there seems to be an absence of dark matter outside of the galaxy groups - if I understood the paper correctly. The preprint had some nice graphics too!

The Ant Nebula

The gorgeous Ant Nebula image from the .Hubble Space Telescope

Surprisingly Evolved Galaxies in the Early Universe

This astrophysics preprint describes A Population of Massive and Evolved Galaxies at z>=5, when the universe was less than a billion years old, which "... seems surpising at first sight". z is the redshift which according to the standard Big Bang models of cosmology is related to the age of the galaxy.
The galaxies found in this study are remarkable in that they contain a large stellar mass, have small physical sizes and that their main epoch of star formation occured at z >= 10. Galaxies with similar properties have, however, also been found by others.

Here's another preprint Morphologies of Two Massive Old Galaxies at z ~ 2.5 which says
Considerable observational evidence has built up over
the past few years that a substantial fraction of the mas-
sive galaxies around us today were already massive at
very early epochs.