Crystalline silicate emission in the protostellar binary SerpensSVS 20.
CIARDI D.R., TELESCO C.M., PACKHAM C., GOMEZ MARTIN C., RADOMSKI J.T., DE BUIZER J.M., PHILLIPS C.J. and HARKER D.E.
Abstract (from CDS):
We present spatially resolved mid-infrared spectroscopy of the Class I/flat-spectrum protostellar binary system SVS 20 in the Serpens cloud core. The spectra were obtained with the mid-infrared instrument T-ReCS on Gemini South. SVS 20-South, the more luminous of the two sources, exhibits a mid-infrared emission spectrum peaking near 11.3 µm, while SVS 20-North exhibits a shallow amorphous silicate absorption spectrum with a peak optical depth of τ∼0.3. After removal of the line-of-sight extinction by the molecular common envelope, the ``protostar-only'' spectra are found to be dominated by strong amorphous olivine emission peaking near 10 µm. We also find evidence for emission from crystalline forsterite and enstatite associated with both SVS 20-S and SVS 20-N. The presence of crystalline silicate in such a young binary system indicates that the grain processing found in more evolved Herbig Ae/Be and T Tauri pre-main-sequence stars likely begins at a relatively young evolutionary stage, while mass accretion is still ongoing.