Protostellar jets: A statistical view with the CALYPSO IRAM-PdBI survey

Abstract

In the context of the CALYPSO IRAM-PdBI Lai•ge Program we performed the first statistical survey of protostellar jets by analysing molecular emission in a sample of 21 protostars covering a broad range of internal luminosities (Lint from 0.035 L⊙ to 47 L⊙). We find that the outflow phenomenon is ubiquitous in our sample of protostars, with wide-angle outflows detected in CO (2 - 1) in all sources, and high-velocity collimated jets detected in SiO (5-4) in 80% of the sources with Lint > 1 L⊙. The protostellar flows have an onion-like structure, with the SiO jet (opening angle, α ~ 10°) nested into a wider angle SO (α ~ 15°) and CO (α ~ 25°) outflows. Interestingly, protostellar jets show several properties in common with the atomic jets associated with more evolved sources (106 yr), e.g. one third of the jets show velocity asymmetry of ~ 1.3-2 between the two lobes, and the mass-loss rates are ~ 1% - 50% of the mass accretion rates. This suggests that the same launching mechanism is at work and that the correlation between mass ejection and mass accretion holds along the star-formation process from 104 yr up to a few Myr.