Meet the Milky Way

One of my favourites

This post was chosen as an Editor's Selection for ResearchBlogging.orgBack in July I wrote about my involvement in a new Zooniverse citizen science project, the then unnamed Project IX. In the last few months, Project IX became the Milky Way Project, and today yesterday it went live! A massive congratulations to Rob and the team who did a fabulous job in getting this all together.

In the Milky Way Project, we’re showing you colour images from our galaxy, the Milky Way, which were created from three wavelength channels from instruments on board the Spitzer Space Telescope. Spitzer observes the Universe in the infrared, and is therefore sensitive to objects that are colder than those that emit visible light. This includes the dense dusty clouds, concentrated in the disk of our galaxy, in which new stars are being formed. Although Spitzer is small in size, it has opened up a new window on our own and more distant galaxies in the infrared. The hundreds of thousands of images in its science archive are rich hunting grounds – particularly for those interested in star formation studies.

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Dear Fuzzies, Why So Green?

Green fuzzies (Cyganowski et al, 2008 & De Buizer & Vacca, 2010)

ResearchBlogging.orgAmongst all the excitement over the first results from Herschel, it’s easy to forget about its comparatively tiny American cousin Spitzer. Launched in 2003 with its  3 instruments IRAC, IRS and MIPS, Spitzer covers the infrared wavelengths from around 3 to 150 microns – a region that from Earth is either totally inaccessible or severely hampered by atmospheric absorption. With its 85-cm diameter primary mirror, it’s easy to dismiss Spitzer as belonging to a former era. But new science is coming out of Spitzer data every day, and vast quantities of data remain unpublished in the archives. The big legacy surveys in particular, such as c2d (Cores to Disks) and the galactic plane surveys GLIMPSE and MIPSGAL, have released a wealth of data into the public domain, throwing light on old problems and unveiling new mysteries to solve.

One interesting phenomenon witnessed on the images from the GLIMPSE survey was a curious population on extended green objects (EGOs). Catalogued by Cyganowski et al in 2008, these “green fuzzies” appear to be associated with regions of massive star formation – many of them lie in or very near to infrared dark clouds, known to harbour the earliest forms of massive star birth, or are associated with methanol masers, strong radio emission caused by excitation of methanol molecules by infrared radiation from dust. Their green colour is in a sense incidental, arising from the way we construct 3-colour images from the Spitzer camera IRAC. IRAC takes images in 4 channels, at 3.6, 4.5, 5.8 and 8 microns, and typically an red-green-blue image uses the 8, 4.5 and 3.6 micron data, respectively. In this picture, “green” indicates that the object has an unusually high flux in the 4.5 micron band.

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