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Episodic accretion has been proposed as a solution to the long-standingluminosity problem in star formation; however, the process remains poorlyunderstood. We present observations of line emission from N2H+ and COisotopologues using the Atacama Large Millimeter/submillimeter Array (ALMA) inthe envelopes of eight Very Low Luminosity Objects (VeLLOs). In five of thesources the spatial distribution of emission from N2H+ and CO isotopologuesshows a clear anti-correlation. It is proposed that this is tracing the CO snowline in the envelopes: N2H+ emission is depleted toward the center of thesesources in contrast to the CO isotopologue emission which exhibits a peak. Thepositions of the CO snow lines traced by the N2H+ emission are located at muchlarger radii than those calculated using the current luminosities of thecentral sources. This implies that these five sources have experienced a recentaccretion burst because the CO snow line would have been pushed outwards duringthe burst due to the increased luminosity of the central star. The N2H+ and COisotopologue emission from DCE161, one of the other three sources, is mostlikely tracing a transition disk at a later evolutionary stage. ExcludingDCE161, five out of seven sources (i.e., ~70%) show signatures of a recentaccretion burst. This fraction is larger than that of the Class 0/I sourcesstudied by J{\o}rgensen et al. (2015) and Frimann et al. (2016) suggesting thatthe interval between accretion episodes in VeLLOs is shorter than that in Class0/I sources.

Probing Episodic Accretion in Very Low Luminosity Objects