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Star formation loves infrared dark clouds
We all know and love Galaxy Zoo and the various Zooniverse projects that have sprung up in recent months – Solar Stormwatch and Moon Zoo to name a couple. And there’s more on the way. Since the start of the year I’ve been excited about getting involved in another Zooniverse startup, the yet to be named Project IX. Project IX will deal with an area of astronomy I’m particularly interested in, namely star formation.
Green fuzzies (Cyganowski et al, 2008 & De Buizer & Vacca, 2010)
Amongst 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 But new science is coming out of Spitzer data every day, and vast quantities of data remain unpublished in the archives.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.
Herschel stares into Aquila
Scientists have gathered in Madrid this week to discuss for the first time the data they have received from the new infrared telescope Herschel that was launched in May of this year. Some fantastic images have been produced as part of the first observing programmes, like the one above of an active star forming region in the constellation Aquila. The region was known as a ‘dark cloud’ – meaning that dust was blocking any visible or near-infrared radiation coming from its interior. Until Herschel came along, and switched on the lights. Observing at longer infrared wavelengths, the telescope is sensitive to radiation from cooler and dusty material, allowing it to peer into the cloud’s interior. The image, created from data from two of Herschel’s images, PACS and SPIRE, shows up to 700 dense pockets of cold and dusty material that may eventually condense into stars; around 100 of them have progressed to the protostellar stage where they begin to resemble a young forming star.
ESA has launched a new site to showcase the Herschel images. A little sparsely populated so far, but the first postings are very promising indeed.
Image credit: ESA and the SPIRE & PACS consortia, Ph. André (CEA Saclay) for the Gould’s Belt Key Programme Consortia
This beautiful picture of the Omega Nebula (M17) was released today by ESO. It’s a three-colour composite image taken with the 3.6-m New Technology Telescope at ESO’s La Silla site in Chile. The nebula is a region of active star formation, one of the youngest and nearest to our solar system. A recent paper by Matthew Povich and collaborators reported over 90 candidate newborn stars in the region at varying stages of starbirth. Energetic radiation from hot young stars is exciting and lighting up the gas in the nebula.
The Povich paper contains a complete description of this hotbed of star formation at wavelengths from the radio to X-ray and is an excellent reference if you wold like to learn more.
Image credit: ESO
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