NOAO >   Observing Info >   Approved Programs >   2001B-0173

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Proposal Information for 2001B-0173


PI: Ann Bragg, Harvard University, abragg@cfa.harvard.edu
Address: 60 Garden Street, Mailstop 10, Cambridge, Massachusetts 02138, U.S.A.

CoI: Scott Kenyon, Harvard-Smithsonian Center for Astrophysics

Title: The Mass Function of h+(chi) Persei

Abstract: Knowledge of the stellar initial mass function (IMF) is critical to understanding star formation and galaxy evolution. Past studies of the IMF in open clusters have primarily used luminosity functions to determine mass functions, frequently in relatively sparse clusters. Our goal with this project is to derive a reliable, well- sampled IMF for a pair of very dense young clusters (h+(chi) Persei) with ages, 1-2 \times 10^7 yr (e.g., Vogt A&A 11:359), where stellar evolution theory is robust. We will construct the HR diagram using both photometry and spectral types to derive more accurate stellar masses and ages than are possible using photometry alone. Results from the two clusters will be compared to examine the universality of the IMF. We currently have a spectroscopic sample covering an area within 12.5 arcminutes of the center of each cluster taken with the FAST Spectrograph. The sample is complete to V=15.4 and contains ~ 1500 stars. We request 2 nights at WIYN/HYDRA to extend this sample to deeper magnitudes, allowing us to determine the IMF of the clusters to a lower limiting mass and to search for a pre-main sequence, theoretically predicted to be present for clusters of this age. Out of two nights we received for this project at WIYN/HYDRA last year, we only obtained one configuration of spectra (fig. 2), due to cloudy weather. Note that both clusters are contained within a single HYDRA field.


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