First results from ALMA

The Atacama Large Millimeter/submillimeter Array (ALMA) in northern Chile’s Atacama
desert at an altitude of 5,000 meters has officially released its first science data.  ALMA currently comprises 20 high-precision antennas working together at millimeter and submillimeter wavelengths. ALMA has state-of-the-art receivers that cover atmospheric windows from 84–720 GHz (3 mm – 420 μm). By 2013, ALMA will have 66 antennas working together as one telescope with a maximum baseline of 16 km. Observing at mm and sub-mm wavelengths allow astronomers to study extremely cold objects in space, including the dense clouds of cosmic dust and gas which form stars and planets, luminous galaxies undergoing starbursts, and  very distant objects in the early Universe.

The first official ALMA science data released is of the Antenna Galaxies, NGC 4038 and NGC 4039, using only 12 antennas. This galaxy pair is the merger of two disk galaxies. The merger event has produced many regions of new star formation. The image shows the cold gas regions seen by ALMA – detected via carbon monoxide molecules in giant molecular clouds – in the two disk regions and the collision area of the merger – out of which new stars will form. Subsequent observations with more antennas, with larger baselines will provide superior resolution images.

Antennae Galaxies. Left: mm and sub-mm view from ALMA. Right: optical view from ESO Very Large Telescope.

ALMA is now performing Early Science Cycle 0 observations which will span 9 months, and will use 500-700 hours of array time. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the
National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan.  For more details, see

[Post by Glen Mackie & Sarah Maddison]

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