Andromeda's Extended Clusters (2014)

Once again we are faced with objects which defy categorization. These look something like globular clusters but they’re not as compact. They’re kind of like dwarf galaxies, but not quite that, either. No one has found any of these extended clusters anywhere in the Milky Way, so it is thought that because only Andromeda has them that they represent clues to the differing histories of Milky Way and Andromeda.

Anyway, if you are feeling inquisitive, all of this information can be found in this paper which goes into plenty of detail about what they are and where they may have come from.

Using Stellarium, I made a picture showing where the four clusters are located. I knew they were in the outer halo of Andromeda but EC4 is surprisingly far away to me.

There are larger sizes available at my Flickr stream. This one got kind of squished to fit into my website format.

These data all came from this proposal:
Deep imaging of newly discovered globular clusters in the outer halo of M31

Red: ACS/WFC F814W
Green: Pseudo
Blue: ACS/WFC F606W

North is 65° clockwise for all four clusters.

Copyright information:
Hubble data is public domain, but I put a lot of work into combining it into beautiful color images. The minimal credit line should read: NASA / ESA / J. Schmidt

This work is licensed under a Creative Commons Attribution 3.0 Unported License.