Segue 1: Time Capsule of an Ancient Universe
Most people know that scientists are constantly studying fossilized specimens, looking for the evolutionary rung that connects the long-dead species to those still walking the Earth today, but did you know that astronomers have a cosmic-equivalent? Only their work is done by studying the light from very distant, ancient galaxies (they are the fossils).
The most interesting “fossil” from the early universe we’ve found is that of Segue 1: a galaxy that has all but disappeared from sight. Still yet, it provides many clues to the many generations of star formation that preceded this one: http://goo.gl/GvkD8Y
Image Credits: Sloan Digital Sky Survey (left) / M. Geha (right)
Rendering Dark Matter
The Fornax Cluster is a cluster of galaxies about 60 million lightyears (19 Mpc) away. The cluster is particularly rich, with over 50 members. Have a look at the Cluster in optical wavelengths here.
But what about the image of the post? Well this is an image of Fornax with an important ‘artistic addition’. The purple fuzz surrounding the galaxies is an artistic rendering of the dark matter halos that surround clumped galaxies. Dark matter is invisible by any known direct detection technique – however its influence can be detected through gravitational forces.
Galaxy clusters are one of the best “laboratories” for studying dark matter; as the system (in this case the cluster) can be viewed as a whole and the visible matter compared to the total gravitational forces needed to keep the cluster together.
Image: NASA/JPL-Caltech (22 May 2014)