NOAO >   Observing Info >   Approved Programs >   2017B-0064

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Program Information for 2017B-0064


PI: Philip Massey, Lowell Observatory, phil.massey@lowell.edu
Address: 1400 W MARS HILL ROAD, FLAGSTAFF, AZ 86001 USA

CoI: Kathryn F Neugent, Lowell Observatory
CoI: Emily Levesque, U. of Washington

Title: The Wolf-Rayet Content of IC10: Probing the Nearest Starburst Galaxy

Abstract: IC10 is a Local Group galaxy rich in massive stars, as revealed by the presence of 26 Wolf-Rayet (WR) stars, leading to a surface density of WRs 7 times that of the Magellanic Clouds. Even more remarkable are the types of WR stars found, with the number of carbon-rich WC-type WRs exceeding the number of nitrogen-rich WN-types. Since WCs are descended from only the highest mass stars, this may be indicative of a top-heavy initial mass function (IMF) for this nearby starburst galaxy, with the implication that other starbursts may also have peculiar IMFs, as has long been conjectured but never proved. Alternatively, it could be that previous surveys have simply missed many WN-type WRs, as these have weaker emission and are thus harder to find. We have identified 30 new WR candidates from interference filter imaging with the KPNO 4-m, and only spectroscopy with an 8-m telescope can determine if these are WRs, and if so, if they are the missing WNs or simply more WCs. If all 30 are WNs, then the WC/WN ratio may be relatively normal, but the density of massive stars even more astonishingly large. Either way, these observations will prove valuable; as a nearby metal-poor starburst, IC10 serves as a local analog of high-redshift star-forming galaxies, and the results of this work have direct implications for our understanding of stellar populations in the early Universe.

Program Type: Standard/Galactic

Scheduled Nights:
Run 1 (2017B):  GEM-NQ/GMOSN -- 10.2hrs band 1 (GN-2017B-Q-20)


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



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