Hubble flirts with the Great Attractor

Posted by Thomas Anderson

A rather busy patch of space was recently snapped by NASA's Hubble Space Telescope. Scattered with many nearby stars, the field boasts numerous galaxies in the background.

Located on the border of Triangulum Australe (The Southern Triangle) and Norma (The Carpenter’s Square), this field covers part of the Norma Cluster (Abell 3627) as well as a dense area of our own galaxy, the Milky Way.

The Norma Cluster is the closest massive galaxy cluster to the Milky Way, and lies about 220 million light-years away. The enormous mass concentrated here, as well as the consequent gravitational attraction, mean that this region of space is known to astronomers as the Great Attractor, which dominates our region of the Universe.

The largest galaxy visible in this image is ESO 137-002, a spiral galaxy seen edge on. In this image from Hubble, we can discern large regions of dust across the galaxy’s bulge. What we do not see is the tail of glowing X-rays that has been observed extending out of the galaxy - but which is invisible to an optical telescope like Hubble.

Observing the Great Attractor is somewhat difficult at optical wavelengths.

Indeed, the plane of the Milky Way - responsible for the numerous bright stars in this image - both outshines (with stars) and obscures (with dust) many of the objects behind it.

There are some methods for seeing through the dust - infrared or radio observations, for example - but the region behind the center of the Milky Way, where the dust is thickest, remains an almost complete mystery to astronomers.