Continuing Operation of the Antarctic Submillimeter Telescope and Remote Observatory (AST/RO)

Smithsonian Institution Astrophysical Observatory, Cambridge MA

Investigators

Abstract

The Antarctic Submillimeter Telescope and Remote Observatory (AST/RO) is designed to investigate one of the least explored bands of electromagnetic radiation emitted by astronomical sources. Submillimeter-wave radiation, at frequencies from about 300 Gigahertz (billions of cycles per second) up into the Terahertz (trillions of cycles per second) range, is emitted by dense gas and dust between the stars, and submillimeter-wave observations allow us to study in unprecedented detail the galactic forces acting upon that gas and the star formation processes within it. AST/RO is a 1.7 meter diameter single-dish instrument, which has been operating for six years at South Pole station in several wave bands with arcminute resolution over regions of sky which are several square degrees in size. AST/RO's relatively large field of view allows the observation of interstellar molecular clouds throughout the fourth quadrant of the Milky Way and the Magellanic Clouds, in order to locate star-forming cores and study in detail the dynamics of dense gas in our own galaxy. Studies of molecular clouds with varying heavy element content under a variety of galactic environments shows us how molecular clouds are structured, how the newly-formed stars react back on the cloud, and how galactic forces affect cloud structure. AST/RO is recognized as the test bed and progenitor of planned instruments which will go on to study how stars form throughout the universe from the earliest times to the present. Essential to AST/RO's capabilities is its location as Amundsen-Scott South Pole Station, an exceptionally cold, dry site which has unique logistical opportunities and challenges. Most submillimeter radiation from astronomical sources is absorbed by irregular concentrations of atmospheric water vapor before it reaches the Earth's surface. The dry air over South Pole Station allows an accurate intercomparison of submillimeter-wave power levels on the scale of the Milky Way and its companion galaxies.