Invited Presentation
Extremely Bright low mass protostar GSS30 IRS1: an outbursting naked protostar?
Presenter: Kazuya Saigo (NAOJ)
Formation of very low-mass stars have no widely accepted scenario about the mass determination mechanism. In theory, there are three possible scenarios: 1. Formation of low mass stars from very low mass cores, 2. Dissipation of the infalling envelope due to strong protostellar outflows, 3. Dynamical ejection from the centers of protostellar cores due to gravitational interaction among multiple objects. However, verification and understanding of these scenarios are not progressing due to lack of observational information.
We examined the detailed kinematic structure of GSS30 IRS1 (hereafter, IRS1) using ALMA archival data and found that it is a naked protostar that can only be explained by the third scenario. IRS 1 is an outbursting low mass Class-I protostar with L = 11L_sun in the Oph-A region (d ~ 137 pc), which is located 15 arcsec south from well known Class-I source, GSS30 IRS 3. ALMA high-resolution observations revealed that the protostellar disk of IRS 1 is very compact (~ a few au) and hot (~ 300K). These characteristics show IRS 1 is a very young protostar. On the other hand, other ALMA data shows that IRS 1 does not associate with a clear infalling envelpe. These contradictory features suggest that compact system of IRS 1 was ejected from the parent molecular cloud core in the early phase of protostar. IRS 1 is a key sample to understand the early evolution of protostars. In the presentation, I will also discuss the asymmetric outflow associated with IRS 1.
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