IC 348-SMM2E: a Class 0 proto-brown dwarf candidate forming as a scaled-down version of low-mass stars

Abstract

We report on Submillimeter Array observations of the 870 μm continuum and CO (3–2), 13CO (2–1), and C18O (2–1) line emission of a faint object, SMM2E, near the driving source of the HH 797 outflow in the IC 348 cluster. The continuum emission shows an unresolved source for which we estimate a mass of gas and dust of 30 MJup, and the CO (3–2) line reveals a compact bipolar outflow centred on SMM2E, and barely seen also in 13CO (2–1). In addition, C18O (2–1) emission reveals hints of a possible rotating envelope/disc perpendicular to the outflow, for which we infer a dynamical mass of ∼16 MJup. In order to further constrain the accreted mass of the object, we gathered data from Spitzer, Herschel, and new and archive submillimetre observations, and built the spectral energy distribution (SED). The SED can be fitted with one single-modified blackbody from 70 μm down to 2.1 cm, using a dust temperature of ∼24 K, a dust emissivity index of 0.8, and an envelope mass of ∼35 MJup. The bolometric luminosity is 0.10 L⊙, and the bolometric temperature is 35 K. Thus, SMM2E is comparable to the known Class 0 objects in the stellar domain. An estimate of the final mass indicates that SMM2E will most likely remain substellar, and the SMM2E outflow force matches the trend with luminosity known for young stellar objects. Thus, SMM2E constitutes an excellent example of a Class 0 proto-brown dwarf candidate which forms as a scaled-down version of low-mass stars. Finally, SMM2E seems to be part of a wide (∼2400 au) multiple system of Class 0 sources.