Radiation astronomy/Molecules

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This is a graph of the global mean atmospheric water vapor superimposed on an outline of the Earth. Credit: NASA.

Molecular clouds[edit]

This image shows a colour composite of visible and near-infrared images of the dark cloud Barnard 68. Credit: ESO.

G0.253+0.016 was probed "with another network of telescopes, the Combined Array for Research in Millimeter-wave Astronomy [CARMA] in California."[1]

"G0.253+0.016, which is about 30 light-years long, defies the conventional wisdom that dense gas glouds should produce lots of stars. ... The cloud is 25 times more dense than the famous Orion Nebula, which is birthing stars at a furious rate. But only a few stars are being born in G0.253+0.016, and they're pretty much all runts."[1]

"It's a very dense cloud and it doesn't form any massive stars, which is very weird"[1].

"CARMA data showed that gas within G0.253+0.016 is zipping around 10 times faster than gas in similar clouds. G0.253+0.016 is on the verge of flying apart, with its gas churning too violently to coalesce into stars. Further, the ... cloud is full of silicon monoxide, a compound typically produced when fast-moving gas smashes into dust particles. The abnormally large amounts of silicon monoxide suggest that G0.253+0.016 may actually consist of two colliding clouds, whose impact is generating powerful shockwaves."[1]

When surveyed at 1.1 mm as part of the Bolocam Galactic Plane Survey, "[t]he only currently known starless [massive proto-cluster] MPC is G0.253+0.016, which lies within the dense central molecular zone and is subject to greater environmental stresses than similar objects in the Galactic plane (Longmore et al. 2012)."[2]

Def. a "large and relatively dense cloud of cold gas and dust in interstellar space from which new stars are formed"[3] is called a molecular cloud.

The image on the right is a composite of visible (B 440 nm and V 557 nm) and near-infrared (768 nm) of the dark cloud (absorption cloud) Barnard 68.[4]

Barnard 68 is around 500 lyrs away in the constellation Ophiuchus.[4]

"At these wavelengths, the small cloud is completely opaque because of the obscuring effect of dust particles in its interior."[4]

"It was obtained with the 8.2-m VLT ANTU telescope and the multimode FORS1 instrument in March 1999."[4]


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  2. A. Ginsburg, E. Bressert, J. Bally, C. Battersby (October 20, 2012). "There are No Starless Massive Proto-Clusters in the First Quadrant of the Galaxy". The Astrophysical Journal Letters 758 (2): L29-33. doi:10.1088/2041-8205/758/2/L29. http://arxiv.org/pdf/1208.4097.pdf. Retrieved 2013-01-15. 
  3. Lua error in Module:Citation/CS1 at line 3723: bad argument #1 to 'pairs' (table expected, got nil).
  4. 4.0 4.1 4.2 4.3 Lua error in Module:Citation/CS1 at line 3723: bad argument #1 to 'pairs' (table expected, got nil).