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15th of March 2015
A dwarf galaxy with a giant hydrogen disk
by Bärbel Koribalski (CASS)
ESO 215-G?009 is a rather isolated, nearby dwarf irregular galaxy, somewhat obscured by Milky Way stars and dust. Its neutral hydrogen (HI) disk, as measured with the Australia Telescope Compact Array (ATCA), is six times larger than its stellar extent. The galaxy's HI mass to light ratio, MHI/LB = 22 ± 4 M/L (Warren et al. 2004) is the highest measured for any galaxy. The image above shows ESO215-G?009's HI distribution (left) and mean HI velocity field (right). The latter is used to determine the galaxy's rotation curve, vrot(r), and dark matter content.

ESO215-G?009 is one of around 80 southern galaxies studied as part of the Local Volume HI Survey (LVHIS).

More HI survey work will be presented at the 8th PHISCC Workshop, starting tomorrow at Rutgers University (PHISCC = SKA Pathfinder HI Survey Coordination Committee).

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