(Proposal ID) S14B-029

(PI) Takami Michihiro

(Proposal Title)
 Are FUor and EXor phenomena common for low-mass protostellar evolution?

(Abstract)
Some YSOs (FUors and EXors) exhibit optical outbursts due to episodic mass 
accretion. Such accretion phase may exist in every low-mass protostar, and be 
responsible for a large fraction of the final mass. However, the relationship 
between FUors, EXors and other low-mass protostars is not yet clear, nor are 
the details of the mechanism that triggers a sudden increase in mass accretion.
 To tackle these issues we propose a systematic survey of (1) reflection 
nebulae associated with envelopes and/or circumstellar disks, (2) outflows in 
near-infrared [Fe II] and H_2 emission, and (3) faint stellar/planetary 
companions, all close to FUors and EXors using Subaru-HiCIAO. The proposed 
approach with an unprecedented angular resolution and sensitivity will be 
powerful for (1) investigating the details of their circumstellar environments, including their similarities or differences with other low-mass protostars; 
and (2) searching for possible triggers for episodic mass accretion, such as 
gravitational fragmentation and interaction with a binary/planetary companion 
etc. in the disk.