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HALOGAS survey data collage

Submitter: George Heald (for the HALOGAS team)
Description: The HALOGAS survey, which is being led by a team of ASTRON astronomers, has been introduced in earlier Daily Images (6 and 7 April 2009). The goal of this project is to perform exquisitely sensitive HI observations of a sample of 22 nearby galaxies, using the WSRT. These datasets will allow us to detect cold neutral hydrogen gas which is accreting onto the nearby galaxies, significantly impacting their continuing evolution. The survey has been continuing since the earlier Daily Images, and continues to produce spectacular data!

Now that we have observed an even baker's dozen (that's 13) galaxies, at least in part, it's time to start looking at them as a collection. The image shows the neutral hydrogen distribution that we detect in all 13 of our observed targets. The images are all shown at the same angular size. In many of the targets, there is clearly detected faint gas outside of the main parts of the galaxies - this is exactly the type of HI that we are searching for! As the survey progresses, we will be carefully studying this gas to find out how much accretion takes place in the average spiral galaxy.
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