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s are scattered within a cavern-like, gaseous, interstellar cloud ( NGC 604 ). The stars irradiate the gas with energetic Ultraviolet Light stripping Electron s from Atom s and exciting them—producing a characteristic Nebula r glow.]]


CHEMICAL COMPOSITIONS


Analysing the composition of interstellar clouds is achieved by studying Electromagnetic Radiation that we receive from them. Large Radio Telescope s scan the intensity in the sky of particular Frequencies of electromagnetic radiation which are characteristic of certain Molecule s' Spectra . Some interstellar clouds are cold and tend to give out EM radiation of large Wavelength s. We can produce a map of the abundance of these molecules to produce an understanding of the varying composition of the clouds. In hot clouds, there are often ions of many Elements , whose spectra can be seen in Visible and Ultraviolet Light .

Radio Telescope s can also scan over the frequencies from one point in the map, recording the intensities of each type of molecule. Peaks of frequencies mean that an abundance of that molecule or atom is present in the cloud. The height of the peak is proportional to the relative percentage that it makes up.


UNEXPECTED CHEMICALS DETECTED IN INTERSTELLAR CLOUDS


Until recently the rates of reactions in interstellar clouds were expected to be very slow, with minimal products being produced due to the low temperature and density of the clouds. However, large Organic molecules were observed in the spectra that Scientist s would not have expected to find under these conditions. The reactions needed to create them normally occur only at much higher temperatures and pressures. The fact that they were found indicates that these Chemical Reaction s in interstellar clouds take place faster than suspected. These reactions are studied in the CRESU Experiment .


HIGH-VELOCITY CLOUD


These interstellar clouds possess a velocity higher than can be explained by the rotation of the Milky Way . They are composed primarily of neutral Hydrogen , and typically have a lower portion of heavy elements than is normal for interstellar clouds in the Milky Way.

Theories intended to explain these unusual clouds include materials left over from the formation of our galaxy, or Tidally-displaced Matter drawn away from other galaxies or members of the Local Group . An example of the latter is the Magellanic Stream .

High-velocity clouds are identified with a HVC prefix, as with HVC 127-41-330 .


SEE ALSO




EXTERNAL LINKS