Classification and Analysis of Ophiuchus YSOs from IRS Spectra
First Author:
Melissa McClure
Email: melisma AT umich.edu
University of Michigan
830 Dennison Bldg., 500 Church St.
Ann Arbor, MI 48109-1042
Coauthors:
Watson, D. M., University of Rochester
Furlan, E., JPL
Manoj, P., University of Rochester
Luhman, K., Penn State University
Forrest, W., University of Rochester
Calvet, N., University of Michigan
Espaillat, C., University of Michigan
Hartmann, L., University of Michigan
Abstract
We present the results of our guaranteed-time IRS survey of the Ophiuchus star forming region, which includes objects in the heavily embedded core region, L1688, and a smaller subset of objects in the other clouds and off-core regions. Analysis of young stellar objects is complicated by extinction along the line of sight and the inclination of each object. Using optical depths of the silicate and ice features, as well as the n2-31 and n5.3-31 micron spectral indices, we classify these objects by evolutionary stages. To apply extinction corrections to the Stage II and III objects, we determine empirical extinction curves for Av = 5-50 based on IRS spectra of K giants behind star forming regions. For Av < 8 the curves lie close to the Mathis (1990) extinction curve, but for Av > 8, they lie closer to the Weingartner & Draine (2001) Rv = 5.5 case B curve, a result which is consistent with that of Flaherty et al. (2007). After applying extinction corrections to the Stage II and III spectra, we determine spectral indices for each stage, study other indicators of disk evolution, and discuss emergent trends.
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