Observational evidence of episodic accretion bursts toward young embedded disks

The formation and evolution of protoplanetary disks are fundamental in the process of low-mass star formation and in setting up the conditions for planet formation. In particular, Class I sources reveal the presence of Keplerian disks while still embedded in significant envelopes of dust and gas. In addition, Class I sources present infall of material (from the envelope into the disk), accretion (from the disk onto the protostar), and ejection of material through outflows, making them the perfect candidates to study the relationship between accretion and ejection. 

In this work, I present an ALMA physico-chemical survey of 12 Class I sources in the Ophiuchus star-forming region. The observation of disk tracers and the high-angular resolution of the data allow us to detect Keplerian motions of the disk and infer the protostellar mass. We find a linear correlation between the protostellar mass and the luminosity of the source, resulting in a low value for the mass accretion rate, which favors the episodic accretion scenario. In addition, we find that warm SO₂ transitions are potentially tracing accretion shocks at the envelope-disk interface, increasing the local density and, therefore, the mass accretion rate.