Other
Scientific paper
May 2008
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008aas...212.1806f&link_type=abstract
American Astronomical Society, AAS Meeting #212, #18.06; Bulletin of the American Astronomical Society, Vol. 40, p.213
Other
Scientific paper
Molecular clouds are important objects for studying Galactic structure. Star formation occurs in molecular clouds and through observations of other galaxies, we know that they are largely confined to spiral arms. Therefore, with precise distance measurements toward molecular clouds in our Galaxy, the spiral structure of the Milky Way can in principle be deduced. However, current distance measurements to molecular clouds are fraught with errors. Kinematic distance measurements rely on the measured radial velocity of a cloud as well as the rotation of the Milky Way, both of which are uncertain. Therefore, it is important to find new methods independent of velocity for finding distances to molecular clouds. One potential method is the use of star counts. Because molecular clouds extinct stars, stars behind the cloud appear dimmer or completely disappear. Accordingly, one would expect to find fewer stars toward a molecular cloud than in a region without clouds. A cloud nearer to the observer would have a smaller overall stellar areal density. Conversely, a more distant cloud would have more stars in front of it. Because of the large extinctions, this method will work best in the infrared. This method was tested using the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE). Star count maps were made for all four GLIMPSE bands (3.6, 4.5, 5.8, and 8.0 microns). Results show that a lack of star counts in a field does not correlate with distance to the cloud, contrary to expectation. One reason for this failure is that bright emission from many star-forming clouds artificially lowers the number of detected stars due to the difficulty of extracting point sources from regions of extended bright emission. Another reason is the superposition of multiple clouds along the same line of sight. Funding for this research was provided by NSF grant AST-0507657.
Finn Susanna C.
Jackson James M.
No associations
LandOfFree
Infrared Star Counts Do Not Indicate Distances to Galactic Molecular Clouds does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Infrared Star Counts Do Not Indicate Distances to Galactic Molecular Clouds, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Infrared Star Counts Do Not Indicate Distances to Galactic Molecular Clouds will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1395519