Kinematics and physical conditions of the innermost envelope in B335

Abstract

We made C18O (2-1) and CS (7-6) images of the protostellar envelope around B335 with a high spatial dynamic range from ∼10,000 to ∼400AU by combining the Submillimeter Array and single-dish data. The C 18O emission shows an extended (∼10,000AU) structure as well as a compact (∼1500AU) component concentrated at the protostellar position. The CS emission shows a compact (∼900AU) component surrounding the protostar, plus a halo-like (∼3000AU) structure elongated along the east-west direction. At higher velocities (|ΔV| ≳ 0.3kms-1), the CS emission is stronger and more extended than the C18O emission. Physical conditions of the envelope were examined through a Large Velocity Gradient model. At |ΔV| ≳ 0.3kms-1, the gas temperature is higher (>40K) than that at |ΔV| ≲ 0.3kms-1, whereas the gas density is lower (<106cm-3). We consider that the higher temperature and lower density gas at |ΔV| ≳ 0.3kms -1 is related to the associated outflow, while the lower temperature and higher density gas at |ΔV| ≲ 0.3kms-1 is the envelope component. From the inspection of the positional offsets in the velocity channel maps, the radial profile of the specific angular momentum of the envelope rotation in B335 was revealed at radii from ∼104 down to ∼ 102AU. The specific angular momentum decreases down to a radius of 370AU, and then appears to be conserved within that radius. A possible scenario of the evolution of envelope rotation is discussed. © 2011. The American Astronomical Society. All rights reserved..