NOAO >   Observing Info >   Approved Programs >   2001B-0002

# Proposal Information for 2001B-0002

PI: Phil Massey, Lowell Observatory, massey@lowell.edu
Address: 1400 W. Mars Hill Road, Flagstaff, AZ 86001

Title: The Wolf-Rayet Content of the Local Group Starburst Galaxy IC10

Abstract: Our detection of a \it very high surface density of Wolf-Rayet stars led to the realization that IC10 is undergoing a galaxy-wide starburst (Massey & Armandroff 1995). One of the as-yet unexplained peculiarities, though, is the apparently phenomenally high ratio of WC- type to WN-type Wolf-Rayet stars, approximately 10\times greater than that of other galaxies of similar metallicity. This may suggest that the massive star IMF is actually \it inverted in IC 10 (more 100\cal M_\odot stars than 30\cal M_\odot stars), or it could be that the burst duration was so incredibly short (<300,000 yrs) that all the massive stars happen to have evolved in lock-step to the WC stage. Either possibility would be extremely exciting, but we first have to investigate a third, more prosaic possibility, namely that that a significant number of WN stars were missed in our original survey due to high and variable extinction towards IC10. The discovery of additional WNs would imply an even higher star-formation rate than currently assumed, but would relieve us of being forced to believe that star- formation processes are so different in starbursts. We are therefore proposing to carry out a much deeper and more sensitive search for additional Wolf-Rayet stars. We also will obtain a good census of the RSG population to further diagnose what is happening in this most curious" of Local Group galaxies.

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 NOAO >   Observing Info >   Approved Programs >   2001B-0002