From AAS NOVA: “Featured Image: Interacting Galaxies” I Don’t Regularly Cover Images, but These are Special


American Astronomical Society

12 June 2017
Susanna Kohler

This beautiful image shows two galaxies, IC 2163 and NGC 2207, as they undergo a grazing collision 114 million light-years away. The image is composite, constructed from Hubble (blue), Spitzer (green), and ALMA (red) data.

NASA/ESA Hubble Telescope

NASA/Spitzer Telescope

ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

In a recent study, Debra Elmegreen (Vassar College) and collaborators used this ALMA data to trace the individual molecular clouds in the two interacting galaxies, identifying a total of over 200 clouds that each contain a mass of over a million solar masses. These clouds represent roughly half the molecular gas in the two galaxies total. Elmegreen and collaborators track the properties of these clouds and their relation to star-forming regions observed with Hubble. For more information about their observations, check out the paper linked below.

A closer look at the ALMA observations for these galaxies, with the different emission regions labeled. Most of the molecular gas emission comes from the eyelids of IC 2163, and the nuclear ring and Feature i in NGC 2207. [Elmegreen et al. 2017]


Debra Meloy Elmegreen et al 2017 ApJ 841 43. doi:10.3847/1538-4357/aa6ba5

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