A Systemic Search for Molecular Outflows Toward Candiate Low-Luminosity Protostars

Abstract

We present a systematic single-dish search for molecular outflows toward a sample of 39 candidate low-luminosity and Very Low Luminosity Objects (VeL-LOs; L(int) ≤ 0.1 L(⊙)) identified using data from the Spitzer Space Telescope catalogued by Dunham et al. toward nearby (D < 400 pc) star forming regions. Each source was observed in ¹²CO and ¹³CO J = 2 → 1 simultaneously using the sideband separating ALMA Band-6 prototype receiver on the Heinrich Hertz Telescope at 30" resolution. Using 5-point grid maps we identify new potential outflow candidates and make on-the-fly maps of the regions surrounding sources in the dense cores B59, L1148, L1228, and L1165. Of these new outflow candidates, only the map of B59 (023) shows a distinct blue outflow lobe. We also present larger and more sensitive maps of the previously detected L673-7 and the L1251-A IRS4 outflows and analyze their properties in comparison to other outflows from VeLLOs. The accretion luminosities derived from the out- flow properties of the VeLLOs with detected CO outflows are higher than the observed internal luminosity of the protostars, indicating that these sources likely had higher accretion rates in the past. We do not detect clear, unconfused signatures of red and blue molecular wings toward the other 32 sources in the survey indicating that large-scale, distinct outflows from low-luminosity protostars and VeLLOs are rare. Several potential outflows are confused with kinematic structure in the surrounding core and cloud. Interferometric imaging is needed to disentangle large-scale molecular cloud kinematics from these potentially weak protostellar outflows.