Galactic Structure

We live in a galaxy filled with interstellar dust and gas. The dust, in particular, obscures our view of the Galaxy. Since the dust is more transparent to infrared radiation, infrared observations can provide an unparalleled view of our Galaxy from our perspective within it. Among the most valuable tools for reconstructing a picture of the Galaxy are evolved giant stars which are large and cool and thus extremely luminous at infrared wavelengths. These giant stars can serve as "standard candles" permitting a reconstruction of their positions in three-dimensional space. In addition, the Galaxy's structure and its rotation are intimately linked. The motions of stars can provide clues to the structure of the Galaxy. My particular interest is to use infrared spectra of evolved stars detected by 2MASS to obtain their velocities and use these velocities to feed back into models of the structure of the Galaxy. Beginning in the 1990's my group conducted a spectroscopic program using my NICMASS infrared camera at the Kitt Peak Coude Feed spectrograph to obtain velocities for hundreds of evolved stars with spectra in the near-infrared H-band (1.6 um). These measurements demonstrated the feasibility of measuring the velocities of these stars to a precision of 2 km/s.