|6th of August 2018|
|LVHIS images of ESO 270-G017|
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 270-G017 (HIPASS J1334-45), is a highly obscured spiral galaxy seen edge-on. It is approximately 7 Mpc (23 million light years) from our Galaxy. The left-hand image above shows the 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. In this case the right-hand (western) side of the galaxy is rotating towards our line of sight, and the left-hand (eastern) side of the galaxy is rotating away from our line of sight. The LVHIS data reveal a well-resolved disc with a mostly regular rotation pattern, although some peculiar motions are discernible on the western (approaching) side, which also shows a higher velocity dispersion. The observed HI extent of ESO 270-G017 is only slightly larger than the stellar disc detected in deep optical images. A neutral hydrogen mass of 2.6 billion solar masses is inferred for the data. More information about LVHIS is given in in this blog post by Baerbel Koribalski.