Constraints on the Circumstellar Disk Masses in the IC 348 Cluster

Abstract

A 52 × 52 region toward the young cluster IC 348 has been imaged in the millimeter continuum at 40 × 49 resolution with the Owens Valley Radio Observatory interferometer to a rms noise level of 0.75 mJy beam-1 at 98 GHz. The data are used to constrain the circumstellar disk masses in a cluster environment at an age of ~2 Myr. The mosaic encompasses 95 known members of the IC 348 cluster, with a stellar mass distribution that peaks at 0.2–0.5 M⊙. None of the stars are detected in the millimeter continuum at an intensity level of 3 σ or greater. The mean observed flux for the ensemble of 95 stars is 0.22 ± 0.08 mJy. Assuming a dust temperature of 20 K, a mass opacity coefficient of κo = 0.02 cm2 g-1 at 1300 μm, and a power-law index of β = 1 for the particle emissivity, these observations imply that the 3 σ upper limit to the disk mass around any individual star is 0.025 M⊙ and that the average disk mass is 0.002 ± 0.001 M⊙. The absence of disks with masses in excess of 0.025 M⊙ in IC 348 is different at the ~3 σ confidence level from Taurus, where ~14% of the stars in an optically selected sample have such disk masses. Compared with the minimum mass needed to form the planets in our solar system (~0.01 M⊙), the lack of massive disks and the low mean disk mass in IC 348 suggest either that planets more massive than a few Jupiter masses will form infrequently around 0.2–0.5 M⊙ stars in IC 348 or that the process to form such planets has significantly depleted the disk of small dust grains on timescales less than the cluster age of ~2 Myr.