A SCUBA-2 850-μm survey of protoplanetary discs in the IC 348 cluster

Abstract

We present 850-µm observations of the 2–3 Myr cluster IC 348 in the Perseus molecular cloud using the SCUBA-2 camera on the James Clerk Maxwell Telescope. Our SCUBA-2 map has a diameter of 30 arcmin and contains ∼370 cluster members, including ∼200 objects with IR excesses. We detect a total of 13 discs. Assuming standard dust properties and a gas-to-dustmass ratio of 100, we derive disc masses ranging from 1.5 to 16 MJUP. We also detect six Class 0/I protostars. We find that the most massive discs (MD > 3 MJUP; 850-µm flux > 10 mJy) in IC 348 tend to be transition objects according to the characteristic ‘dip’ in their infrared spectral energy distributions (SEDs). This trend is also seen in other regions. We speculate that this could be an initial conditions effect (e.g. more massive discs tend to form giant planets that result in transition disc SEDs) and/or a disc evolution effect (the formation of one or more massive planets results in both a transition disc SED and a reduction of the accretion rate, increasing the lifetime of the outer disc). A stacking analysis of the discs that remain undetected in our SCUBA-2 observations suggests that their median 850-µm flux should be 1 mJy, corresponding to a disc mass 0.3 MJUP (gas plus dust) or 1 M⊕ of dust. While the available data are not deep enough to allow a meaningful comparison of the disc luminosity functions between IC 348 and other young stellar clusters, our results imply that disc masses exceeding the minimum-mass solar nebula are very rare (1per cent) at the age of IC 348, especially around very low-mass stars. Ke