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HELGA

images of the Andromeda Galaxy at several wavelengths showing how different structures are highlighted

The other large galaxy in the Local Group of galaxies (our own, of course, being the other) is the Andromeda Galaxy or M31. It is therefore very interesting to compare how stars form in the two objects. The HELGA project, which stands for "Herschel Exploitation of Large Galaxy Andromeda" is a Herschel study of M31. Our Herschel observations, which were carried out over Christmas 2010, were the subject of an ESA press release. The Herschel image (at the top right) looks quite different to the optical image (top left). The galaxy?s bulge disappears because the old stars in the bulge do not emit infrared radiation ? instead Herschel detects the dust in the star-forming disk. We have already used the Herschel data to show that the properties of the dust grains in M31 appear to vary with the distance from the centre, which is not the case for our own galaxy. Our results also confirm that the rate at which stars are forming in Andromeda is much lower than in our own galaxy. The most exciting thing about our data is that, for the first time, we can study the formation of stars in individual giant molecular clouds in a galaxy other than our own.