VLT-detection of two edge-on Circumstellar Disks in the rho Oph dark cloud

Abstract

Observations of the rho Ophiuchi star forming region with VLT ANTU and ISAAC under 0\farcs35 seeing conditions reveal two bipolar reflection nebulosities intersected by central dust lanes. The sources (OphE-MM3 and CRBR 2422.8-3423) can be identified as spatially resolved circumstellar disks viewed close to edge-on, similar to edge-on disk sources discovered previously in the Taurus and Orion star forming regions. Millimeter continuum fluxes yield disk masses of the order of 0.01 M_sun, i.e. about the mass deemed necessary for the minimum solar nebula. Follow-up spectroscopic observations with SUBARU and CISCO show that both disk sources exhibit featureless continua in the K-band. No accretion or outflow signatures were detected. The slightly less edge-on orientation of the disk around CRBR 2422.8-3423 compared to HH 30 leads to a dramatic difference in the flux seen in the ISOCAM 4.5 mu m to 12 mu m bands. The observations confirm theoretical predictions on the effect of disk geometry and inclination angle on the spectral energy distribution of young stellar objects with circumstellar disks. Based on observations at the European Southern Observatory, Paranal (ESO Prop ID 63.I-0691), the NAOJ SUBARU telescope at Mauna Kea, Hawai`i, the ESA Infrared Space Observatory, and the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under the NASA contract NAS5-26555.