|
A majority of low-mass dense cores are starless in the sense that they do
not harbour an IRAS point source to a sensitivity of about 0.1 Lsun at the
distance of Taurus. Spitzer is able to greatly improve on this sensitivity
limit, and as part of the Spitzer c2d Legacy program we have imaged about
100 isolated dense cores and 5 large molecular clouds, in part to search for
fainter embedded sources. Within the cores we have identified a number of
candidate low luminosity objects, and to date have been able to confirm a
handful of them as associated embedded sources (e.g., L1014-IRS). Although
their luminosities are similar (~0.05 Lsun), their other properties show
marked differences. In particular, the molecular outflow of one object
looks like any other low-mass protostellar outflow, while for another is it
very compact and weak. This may suggest different accretion histories, and
it is possible that some of these sources are and will remain sub-stellar
(i.e., proto-brown-dwarfs). We will report on our progress in finding and
understanding these interesting objects.
|
