AAS 204th Meeting, June 2004
Session 33 Early Science Results from the Spitzer Space Telescope
Topical Session, Tuesday, June 1, 2004, 8:30-10:00am, 10:45am-12:30pm, 2:30-4:00pm, 4:15-6:00pm, 601

[Previous] | [Session 33] | [Next]

[33.16] RCW49 at Mid-IR Wavelengths: A GLIMPSE from the Spitzer Space Telescope

E. Churchwell (University of Wisconsin), GLIMPSE Team

We report early Spitzer Space Telescope observations with the Infrared Array Camera (IRAC) of the luminous HII region RCW49 (NGC3247) located in the southern Galactic plane at (l,b) = (284.3,-0.3). The final images of the nebula consists of about 360 frames at each IRAC band. The region was observed 10 times, 1.2s per frame; every pixel was exposed for a total of 12s. The images show that HII regions are quite bright in the IRAC bands. These are believed to be primarily produced by PAH emission bands at 3.3, 6.2, 7.7, and 8.6 microns. The Br alpha line is also bright in the 4.5 micron band. The dust in RCW49 is found to be composed of a complex network of thin filaments, pillars, knots, and sharp boundaries. At radii less than ~5' arc from the ionizing cluster Westerlund 2, the dust seems to be sculpted by stellar winds and radiation; beyond this distance the mean intensity decreases systematically with distance to the minus third power. The network of fine filaments and knots seen in the IRAC images suggests that the nebula may be rather porous to UV radiation. If this is the case and if most luminous HII regions have similar structure to that in RCW49, it is possible that they could provide the ionization source for the Reynolds layer.

Supprot for this work, part of the Spitzer Space Telescope Legacy Science Program, was provided by NASA through Contract Number 1224653 issued to the University of Wisconsin by the Jet Propulsion laboratory, California Institute of Technology under NASA contract 1407.

[Previous] | [Session 33] | [Next]

Bulletin of the American Astronomical Society, 36 #2
© YEAR. The American Astronomical Soceity.