(Proposal ID) S15B-128

(PI) Takagi, Yuhei

(Proposal Title)
Disk Evolution Timescale of PMS stars in IC 348 and NGC 1333

(Abstract)
We propose a high-resolution optical spectroscopic observation to determine 
the surface gravity and age of pre-main sequence (PMS) stars in IC 348 and NGC 
1333 star-forming regions. Estimation of these parameters are important to 
clarify the details of the stellar and the planetary formation. We established 
the age determination method of PMS stars based on the surface gravity 
determinations using equivalent width ratios (Takagi et al. 2010, 2011). 
Calculating the equivalent width ratio of nearby absorption lines allows us to 
determine the surface gravity of PMS stars with no contamination from the 
uncertainties of distance, extinction, and veiling. In our previous work, we 
derived the disk dissipation timescale in Taurus cloud, which is around 3 Myr. 
In addition, the disk dissipation timescale in the rho Oph cloud was estimated 
as 1.2 Myr, which is about half of the Taurus cloud. This result indicates 
that the disk evolution timescale varies among the star-forming regions. 
In this observation, we will determine the age of the PMS stars in the IC 348 
and NGC 1333 star-forming regions whose median age are 2-3 Myr and discuss the 
diversity of the disk evolution timescale.