View Full Version : Massive Gas Halos Surround Most Galaxies

2005-Dec-14, 08:58 PM
SUMMARY: ESA's XMM-Newton observatory has turned up hot gaseous halos around several spiral galaxies. These ghostly veils have been seen surrounding "starburst galaxies", which are going through a tremendous amount of star formation - but not around the more common kinds of galaxies. Unlike a starburst galaxies, which concentrates their halos, regular galaxies will have simmering star formation stretching across them entirely. These halos can contain up to 10 million solar masses of gas.

View full article (http://www.universetoday.com/am/publish/esa_massive_haloes.html)
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2005-Dec-16, 11:13 AM

in almost every galaxy cluster a vast halo of hydrogen gas is found in which the galaxies of the cluster are embedded, while moving through the gaseous halo at speeds of 1000 km/s. As the galaxies collide with the halo gas, that gas is heated up to some 100 million kelvin, which causes the radiation which the XMM observatory as well as other X-ray observatories detect.

When you read papers on the item, you can find there various figures about the mass of these gaseous shells. The stated estimations range from several million solar masses up to 10 times the mass of all the galaxies in the respective cluster.

Let us hope that further observations and scientific investigations will be able to provide a more reliable figure of the masses of these halos some day. Perhaps it may even solve the dark matter problem, and may even make someone win a Nobel price.



2005-Dec-16, 01:02 PM
The statistics of common gaseous halos are encouraging with respect to resolving the galactic non-Keplerian rotation curves within a consistent framework of physics. It would be interesting to see how non-Keplerian the rotation curve is ..i.e. it's shape...vs. the number of solar masses inferred in their respective halos.
One of the curiosities of large diffuse clouds is that they are the birth zones of most of the giant stars (8 solar masses and up)we see. You would think that they would form where the gas density is large, favoring massive stars, but just the opposite is true. Most giant stars form in the periphery of the galaxy, or on the edge of the spiral arms where the gas density is low. High gas density seems to favor lots of smaller ones. Alfven density waves, stimulated by supernovae are thought to be one contributing impetus to star formation, but it's exact mechanism is not incontrovertible. :shifty: Pete.