Tales from the Telescope: ALMA

Pat Roche reports from his visit to the ALMA site in Chile - and asks Estelle Bayet to explain why it is such an exciting new observatory.

I was in Chile last week and was able to visit the ALMA Observatory, which is on the mountain of Chajnantor (altitude: 5200m) near the border with Bolivia and Argentina in the north of the country. It is a spectacular setting, where, even at this high altitude, there are snow-flecked mountains rising further skywards around the site. At these altitudes, it is always cold, and the snow sublimes rather than melts, producing sculpted ice and snow shapes, termed penitentes, across the landscape.

ALMA very recently started observations, but is still under construction. It will ultimately have a set of 66 antennas operating at microwave frequencies, which will be used to observe a wide range of astronomical objects, and allow investigations into topics including the formation of stars and planets in our Galaxy, and dust and molecules in distant galaxies. The observatory is scheduled to be completed by the end of 2013. Twenty four antennas are now linked together via a fiber network to produce the most sensitive telescope in the world at these frequencies, with the remainder of the dishes planned to be installed over the next couple of years. In total, they will make ALMA an enormously powerful facility that will revolutionise our view of the cool Universe. Astronomers at Oxford, along with many others around the world, are eagerly awaiting their first ALMA data.

One of these Oxford astrophysicists is Estelle Bayet. “I am really excited about this instrument, because it is going to allow us to study galaxies that are like our own Milky Way, but at a very great distance from us: so we’ll be seeing them when the Universe was much younger.” says Estelle. “We are going to be able to observe the gas in these galaxies, and hence potentially understand better how the stars at this early epoch formed.” ALMA will also enable some very interesting studies of the more local Universe. As Estelle says: “For galaxies closer to us, we will be able to locate the sites of star formation with unprecedented accuracy. This will allow us to better determine the conditions required for stars to form, in terms of the temperature and density of the gas. This is particularly exciting because we still don't know in detail how stars form in the Universe - especially the most massive ones, those which create the elements we are made of.”

You can read more about the ALMA telescope at the ESO website.