Internal Motions in Starless Cores

1
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
2
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

• Quantitative analysis of spectral asymmtry in
  molecular lines (CS 2-1, 3-2, HCN 1-0, and N2H
  1-0 lines from Lee et al. 1999, 2001, 2004, Sohn
  et al. 2007) by deriving
• dV (Vthick - Vthin)/ DVthin
• dV lt 0 blue (infall) asymmetry
• dV gt 0 red (outflow) asymmetry

3
Main Results
From single pointing data toward central region
of the cores
Cores with higher column density tend to have
bluer dV, indicative of higher possibility of
inward motions
4
Main Results
5
Main Results
(a) Contracting Starless Cores (CSC), (b)
Oscillating Starless Cores (OSC), (c) Static
Starless Cores (SSC)
18 cores
6 cores
7 cores

• 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)

6
Main Results
-Blue fraction increases toward core peak and
large even at large radii
7
(No Transcript)
8
(No Transcript)