The following document lists the file abstract/BWILKING_RADOPH.abs
from catalogue VI/111.
A plain copy of the file
(without headers/trailers) may be downloaded.
Due to the large columns of gas and dust in the core of the rho Oph cloud and the high density of sources, ground-based and spaceborne infrared observations have thus far been insensitive to two important populations of embedded stars. The first is the low-luminosity Class I objects (<1 L(sun)) which are in an early, deeply embedded phase of evolution and display strong infrared excesses. The second group is the diskless Class III sources, which are usually strong x-ray emitters, but have no near-infrared excesses and can be difficult to distinguish from background stars. Yet these diverse populations have something in common: they both emit weak radio continuum emission. We propose to use ISOCAM at 6.75 and 11.5 microns to identify the infrared counterparts to a sample of weak radio sources in the rho Oph core. These data, when combined with existing near-infrared observations, will allow us to determine the amount of circumstellar dust present and to distinguish between Class I and Class III sources. Using the microscanning mode we will reach required sensitivity levels of 1 mJy and 0.6mJy (S/N=10), respectively, which is 8 times the sensitivity achieved by the guaranteed time program of Nordh et al. at 6.75 microns. Mid-infrared wavelengths are necessary since they are much more sensitive to thermal emission from circumstellar dust than near-infrared. Our program will reveal the extents and distributions of the low luminosity Class I and Class III populations embedded throughout the depth of the cloud core. The numbers and luminosities of Class I sources with L<1 L(sun) are of critical importance to explore the age, mass function, and accretion rate in rho Oph relative to other well-studied regions of low mass star formation. There is strong evidence that the Class III sources in the core are contemporaries of the T Tauri stars but have shorter timescales for disk dissipation. Our data will allow us to determine the masses of their remnant disks for direct comparison with their ages determined from infrared spectra.