A combined Spitzer and Chandra survey of young stellar objects in the serpens cloud core

We present Spitzer and Chandra observations of the nearby ( similar to 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 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 these exhibit X-ray emission. Our primary results are the following: ( 1) 10 protostars detected previously in the submillimeter are detected at lambda < 24 mu m, seven at lambda < 8 mu m; ( 2) the protostars are more closely grouped than more evolved YSOs ( median protostar separation similar to 0.024 pc); and ( 3) the luminosity and temperature of the X-ray-emitting plasma around these YSOs do not show any significant dependence on evolutionary class. We combine the infrared-derived values of A(K) and X-ray values of N-H for eight Class III objects and find that the column density of hydrogen gas per magnitude of extinctions is less than half the standard interstellar value, for A(K) > 1. This may be the result of grain growth through coagulation and/or the accretion of volatiles in the Serpens cloud core.