solar system index: the radio windowhow stars die

Where stars are born

Molecular clouds with a density of 10-20 to 10-22 grammes per cm3 and temperatures in the order of 10 Kelvin degreeglossary are the seeds from which new stars are born. In fact, in these clouds, cold gas is dense enough to collapse under the effect of a gravitational perturbation. With the increase of the compression hotter and more compact globules of condensation are created up to the point when, in the centre, nuclear combustion of hydrogenglossary.

 

Fig.1: The emission of the molecular cloud L483 at infrared wavelengths.
(
Credits: NRAO)
 

 

Fig. 2: The same molecular cloud L483 observed at 1.3 mm wavelength, which corresponds to an emission line of CO.
(
Credits: NRAO)

A part from hydrogen and helium, this gas also contains carbon monoxide (CO),  cyanogen radical (CN), methylidyne radical (CH), hydroxyl radical  (OH), water (H20), formaldehyde (H2CO), ammonia (NH3), etc. - material produced mainly by supernovae.

Fig. 3: An example of a molecular cloud in our galaxy. The false colours represent emission at 25 microns (Infrared). The black contour lines represent emission of CO (1.3 mm). The graph in the bottom left corner shows speed and emission at the H2O line in a region of the cloud.
(Credits: Brand & Wouterloot)

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