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APOD
Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
Hot Gas Halo Detected Around Galaxy NGC 4631
Explanation: Is our Milky Way Galaxy surrounded by a halo of hot gas? A step toward solving this long-standing mystery was taken recently with Chandra X-ray observations of nearby galaxy NGC 4631 . In the above composite picture , newly resolved diffuse X-ray emission is shown in blue, superposed on an HST image showing massive stars in red. Since NGC 4631 is similar to the Milky Way , this observation indicates that our own Galaxy is indeed surrounded by a halo of hot X-ray emitting gas, although we are too close to clearly differentiate it from more nearby extended X-ray sources. The clusters of massive stars probably heat the halo gas. Exactly how this gas gets ejected into a halo is a topic of continuing research .
| Date | July 25, 2001 |
|---|---|
| Credit | Credit: Daniel Wang ( U. Mass. ) et al., Chandra , NASA |
| Authors & editors: | Robert Nemiroff (MTU) & Jerry Bonnell (UMCP) |
| A service of: |
ASD at NASA / GSFC, NASA Science Activation & Michigan Tech. U. |