ALMA, the Atacama Large Millimeter Array, is the newest and most advanced millimetre and sub-millimetre telescope in the world. Located on the Chajnantor Plateau in Chile, the observatory is still under construction and will not be completed until the end of 2012. It is an international collaboration between countries in Europe, North America, Eastern Asia, and the host country Chile. By observing at these wavelengths, we see the signatures of molecules in space. It's only in cold, dense environments where molecules can form, and we know these to be the sites of star formation.

The image shown above was released to the public in October, 2011, and is the first image to be released from ALMA as part of their Early Science observing cycle. It shows a well known collision between two galaxies named The Antennae observed in various parts of the electromagnetic spectrum: optical from the Hubble Space Telescope in white/pink; radio emission from the Very Large Array in blue; and millimetre emission from ALMA in orange/yellow. The ALMA data tell us that large, massive resevoirs of molecular gas (specifically carbon monoxide in this image, a proxy for observing molecular hydrogen) lie along the ridge in the bottom of the image, while more spread out molecular gas exists along the upper rim. This gas will eventually collapse due to the force of gravity and repeatedly fragment into smaller and smaller clouds until stars are eventually born.

Still under half complete, ALMA surpasses the capabilities of any other millimetre/sub-millimetre facility in the world. We eagerly wait to see what new surprises this innovative instrument has in store for us in the near future and after it is fully operational.

You may not know it, but we're on a collision course. This course will make us and our nearby neighbour galaxies in the Local Group members of the Virgo Cluster. But what happens when galaxies fall into galaxy clusters like Virgo? The process is called ram pressure stripping: cold gas in the galaxies is ripped away as the galaxies themselves slam into the hot gas that pervades the cluster (the "intracluster medium"). This cold gas is what gets used to make future generations of stars; without the gas, the galaxies become red and dead.

In studying the process of galaxies entering clusters, astronomer Tom Scott at the Instituto de Astrofísica de Andalucía in Granada, Spain has discovered two long tails of cold gas streaming behind the future cluster members. This isn't entirely unexpected, except that the galaxies themselves live in tiny groups (RSCG 42 and FGC 1287) on the very outskirts of the cluster Abell 1367. They're too far away to be interacting with the intracluster medium yet! So how is the cold gas being stripped away? And why is it happening so early before the galaxies even enter the cluster? This could be telling us something more about the importance of the cluster and group environments and how these environments affect the evolution of the individual galaxies.

Astronomers here at The University of Western Ontario are part of a large, international collaboration to study the evolution of galaxies in certain types of groups called "compact groups" (such as RSCG 42 above). Professor Sarah Gallagher and graduate students Konstantin Fedotov and Tyler Desjardins investigate the evolution of the galaxies and the group environment, from star formation to the gas content, of these systems to better understand the relationship between environment and evolution.

The full article on Tom Scott's discovery of the long gas tails can be found here. Picture: Hubble Space Telescope image of Abell 1689, one of the most massive galaxy clusters known, which lies 2.2 billion light-years away towards the constellation Virgo. (Image Credit: NASA, N. Benitez (JHU), T. Broadhurst (Racah Institute of Physics/The Hebrew University), H. Ford (JHU), M. Clampin (STScI),G. Hartig (STScI), G. Illingworth (UCO/Lick Observatory), the ACS Science Team and ESA)