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10th of August 2018
LVHIS images of ESO 223-G009
The Local Volume HI Survey (LVHIS) was conducted with the Australia Telescope Compact Array (ATCA) in the 21cm band. The "Local Volume" of the Universe contains about 1000 galaxies within 30 million light years of the Milky Way. LVHIS studied galaxies previously detected with the Parkes 64-m telescope in the HI Parkes All Sky Survey (HIPASS). LVHIS mapped the distribution of neutral hydrogen with 20 times greater accuracy than LVHIS, and was also able to derive their rotation speeds, which are important for measuring the dark matter content of galaxies.

ESO 223-G009 (HIPASS J1501-48) is a Magellanic irregular galaxy at a distance of about 6.5 Mpc (21 million light years). The left-hand image above shows contours of the radio emission overlaid on an optical image of the galaxy, and the right-hand image shows the velocity distribution of material in the galaxy. Due to its low Galactic latitude, in the optical it is largely obscured by dust and foreground stars. LVHIS HI maps of ESO 223-G009 reveal a large, nearly circular gas distribution and a very peculiar velocity field. The highly twisted and warped HI velocity field is indicative of a face-on warp where the gaseous disc wobbles in and out of the plane. A neutral hydrogen mass of 1 billion solar masses is inferred from the data. More information about LVHIS is given in in this blog post by Baerbel Koribalski.




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