A Combined Spitzer and Chandra Survey of Young Stellar Objects in the Serpens Cloud Core

Autor: Winston, E., Megeath, S. T., Wolk, S. J., Muzerolle, J., Gutermuth, R., Hora, J. L., Allen, L. E., Spitzbart, B., Myers, P., Fazio, G. G.
Rok vydání: 2007
Předmět:
Zdroj: Astrophys.J.669:493-518,2007
Druh dokumentu: Working Paper
DOI: 10.1086/521384
Popis: We present Spitzer and Chandra observations of the nearby (~260 pc) embedded stellar cluster in the Serpens Cloud Core. We observed, using Spitzer's IRAC and MIPS instruments, in six wavelength bands from 3 to 70 ${\mu}m$, to detect thermal emission from circumstellar disks and protostellar envelopes, and to classify stars using color-color diagrams and spectral energy distributions (SEDs). These data are combined with Chandra observations to examine the effects of circumstellar disks on stellar X-ray properties. Young diskless stars were also identified from their increased X-ray emission. We have identified 138 YSOs in Serpens: 22 class 0/I, 16 flat spectrum, 62 class II, 17 transition disk, and 21 class III stars; 60 of which exhibit X-ray emission. Our primary results are the following: 1.) ten protostars detected previously in the sub-millimeter are detected at lambda < 24 microns, seven at lambda < 8 microns, 2.) the protostars are more closely grouped than more evolved YSOs (median separation : ~0.024 pc, and 3.) the luminosity and temperature of the X-ray emitting plasma around these YSOs does not show any significant dependence on evolutionary class. We combine the infrared derived values of AK and X-ray values of NH for 8 class III objects and find that the column density of hydrogen gas per mag of extinctions is less than half the standard interstellar value, for AK > 1. This may be the result of grain growth through coagulation and/or the accretion of volatiles in the Serpens cloud core.
Comment: 69 pages, 16 figures, accepted to ApJ. Higher Resolution Figures at: http://www.cfa.harvard.edu/~ewinston/
Databáze: arXiv
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