Internal Motions in Starless Cores Chang Won Lee Korea Astronomy & Space Science Institute With Philip C. Myers (CfA) Magnetic Fields; Core collapse to YSOs, May 17 – 19, 2010

-Quantitative analysis of spectral asymmtry in molecular lines (CS 2-1, 3-2, HCN 1-0, and N 2 H lines from Lee et al. 1999, 2001, 2004, Sohn et al. 2007) by deriving  V = (V thick - V thin )/  V thin  V < 0 : blue (infall) asymmetry  V > 0 : red (outflow) asymmetry Introduction -To find out what kind of physical properties are directly related to contracting motions in starless cores and how the contraction in starless cores is processed toward star formation

Cores with higher column density tend to have bluer  V, indicative of higher possibility of inward motions Main Results From single pointing data toward central region of the cores

Main Results

CSCs are more numerous than other groups of cores In (a) CSCs, positions with higher column density tend to get bluer and there is certain column density over where all positions are contracting Implication of Core Evolution (c)  (b)  (a) Main Results (a) Contracting Starless Cores (CSC), (b) Oscillating Starless Cores (OSC), (c) Static Starless Cores (SSC) 18 cores6 cores7 cores

-Blue fraction increases toward core peak and large even at large radii Main Results