NOAO >   Observing Info >   Approved Programs >   2003B-0084

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Proposal Information for 2003B-0084


PI: Nathan Smith, University of Colorado, nathans@casa.colorado.edu
Address: Center for Astrophysics and Space Astronomy, 389 UCB, Boulder, CO 80309, USA

CoI: Peter S. Conti, University of Colorado
CoI: Chris G. DePree, Agnes Scott College
CoI: James Jackson, Boston University
CoI: John Bally, University of Colorado

Title: High-resolution infrared imaging of the most powerful water maser source in our Galaxy: W49A/G

Abstract: W49A is one of the most luminous regions of very massive star formation in the Galaxy, and it contains a cluster of embedded ultra- compact (UC) H \sc ii regions oriented in a 1.6-pc diameter ring. The brightest of these, called source `G', is by far the most powerful outflowing water maser source in our Galaxy. This source has been studied intensively with high spatial resolution at radio wavelengths, showing complex structure and multiple sources, but little is known about its dust content and thermal-IR luminosity. We will use mid-IR images to measure dust temperature, opacity, mass, and luminosity of the multiple sources that constitute source G. Thus, we will be able to identify the IR counterpart of the water maser source, and we will measure the embedded protostar's IR luminosity. New mid-IR images with Gemini will improve the spatial resolution by a factor ~2.5 over our previous mid-IR images for this crowded source; the density structure and relative distribution of ionized gas and dust are critical for understanding how massive stars first break out of their cocoons. Additionally, an increase in sensitivity by a factor of 10 may allow us to measure the IR luminosity of several young UCH\sc ii regions adjacent to source G that were too faint for our previous observations.


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