How do stars gain their mass? A JCMT/SCUBA-2 Transient Survey of
  Protostars in Nearby Star Forming Regions
  Most protostars have luminosities that are fainter than expected from steady
accretion over the protostellar lifetime. The solution to this problem may lie
in episodic mass accretion -- prolonged periods of very low accretion
punctuated by short bursts of rapid accretion. However, the timescale and
amplitude for variability at the protostellar phase is almost entirely
unconstrained. In "A JCMT/SCUBA-2 Transient Survey of Protostars in Nearby Star
Forming Regions", we are monitoring monthly with SCUBA-2 the sub-mm emission in
eight fields within nearby (<500 pc) star forming regions to measure the
accretion variability of protostars. The total survey area of ~1.6 sq.deg.
includes ~105 peaks with peaks brighter than 0.5 Jy/beam (43 associated with
embedded protostars or disks) and 237 peaks of 0.125-0.5 Jy/beam (50 with
embedded protostars or disks). Each field has enough bright peaks for flux
calibration relative to other peaks in the same field, which improves upon the
nominal flux calibration uncertainties of sub-mm observations to reach a
precision of ~2-3% rms, and also provides quantified confidence in any measured
variability. The timescales and amplitudes of any sub-mm variation will then be
converted into variations in accretion rate and subsequently used to infer the
physical causes of the variability. This survey is the first dedicated survey
for sub-mm variability and complements other transient surveys at optical and
near-IR wavelengths, which are not sensitive to accretion variability of deeply
embedded protostars.
