September 2012 — Antennae Galaxies composite of ALMA and Hubble observations

Calendar Sep 2012

The Antennae Galaxies (also known as NGC 4038 and 4039) are a pair of distorted collid­ing spiral galaxies about 70 million light-years away, in the constellation of Corvus (The Crow). This view combines ALMA observations, made in two different wave­length ranges during the observatory’s early testing phase, with visible-light observations from the NASA/ESA Hubble Space Telescope.

Most of the ALMA test observations used to create this image were made using only twelve antennas working together — far fewer than will be used for the first science observations — and much closer together as well. Both of these factors make the new image just a taster of what is to come.

While visible light — shown here mainly in blue — reveals the newborn stars in the gal­axies, ALMA's view shows us something that cannot be seen at those wavelengths: the clouds of dense cold gas from which new stars form. The ALMA observations — shown here in red, pink and yellow — were made at specific wavelengths of millimetre and submillimetre light (ALMA bands 3 and 7), tuned to detect carbon monoxide mole­cules in the otherwise invisible hydrogen clouds, where new stars are forming.


ALMA (ESO/NAOJ/NRAO). Visible light image: the NASA/ESA Hubble Space Telescope

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