The Radial Velocity Distribution of Class I and Flat-Spectrum Protostars

We analyze radial velocities for a sample of 31 Class I and flat spectrumprotostars in Taurus-Auriga, rho Ophiuchi and Serpens for evidence of theglobal dynamical state of extremely young stellar populations buried withinparental molecular clouds. Comparing the radial velocity of each protostar tothat of the local CO gas, we are able to constrain the one dimensional radialvelocity dispersion of Class I and flat spectrum objects to ~ 2.5 km/sec orbelow. This upper limit to the protostellar velocity dispersion is consistentwith the velocity dispersions of surrounding CO gas which we measure to be ~1.4 km/sec, suggesting that the motions of protostars and local CO gas aredynamically linked and dominated by the gravitational potential of themolecular cloud. However, the upper limit on the protostellar velocitydispersion could still allow for slightly inflated motions of protostarsrelative to the local molecular gas. Four of the protostars analyzed appear tohave velocities more than 3 sigma (7.5 km/sec) away from the central local COgas velocity while showing spectroscopic indicators of youth and accretion suchas H_2 emission, HI Br Gamma emission, or K band continuum veiling. Theseradial velocity outliers may represent protostellar spectroscopic binaries orejected cluster members.Comment: 9 pages in emulate ApJ format, accepted for publication in A