Spitzer image of the Orion nebula in the infrared overlaid with XMM-Newton X-ray data in blue

Science Daily is reporting that the discovery of the cloud most certainly suggests that hot gas from many star-forming regions leaks into the interstellar medium. For those of you who do not know what an interstellar medium is, it is the matter that exists between the stars within a galaxy. It contains ions, atoms, molecules, larger dust grains, cosmic rays and magnetic fields. The Orion nebula is the nearest star forming region to the Earth that contains stars far bigger than our Sun. This newly discovered gas cloud is composed of winds that are blowing from these particular stars. As the winds slam into the surrounding gas, they are heated to millions of degrees. According to Manuel Gudel from Paul Scherrer Institut, Switzerland, who led the research team that discovered the gas, only one of these stars particularly dominates the nebula. The star in question is theta1 Orinis C, a giant star which has a mass 40 times larger than that of our Sun with a surface temperature of about 40,000 Celsius. Gudel believes that the winds coming from this star and hitting into the surrounding gas are responsible for the newly-discovered hot gas cloud. The new observations that arrived from the XMM Newton's European Photon Imaging camera (EPIC camera) are however only showing a particular portion of the gas. The surrounding pattern of these absorbing clouds gives the newly-discovered gas a shape of a Santa Claus. His hat is outlined by the northern gas bubble. The presence of this kind of a gas in a fairly common nebula is quite surprising. Astronomers developed a theory that predicted the presence of such hot gas clouds, but previous observations suggested that massive stars shedding winds or supernova explosions are required for this to occur. These observations confirm that much smaller collections of high mass stars can produce this type of gases as well.

“This is another possible way to enrich the interstellar medium. You don’t have to wait for a sudden supernova to explode. You can do it with just one or two massive stars over millions of years,” says Güdel.

The team now plans to further research and observe how the gas flows out of Orion nebula. In particular, they would like to see a connection between the giant bubble created by supernova explosions from previous generations of massive stars. If you would like to read a copy of this research, you can find it in the November 29, 2007 version of Science Express (the online version of the journal Science) under the title "A million-degree plasma pervading the extended Orion nebula".