High-Velocity Jets and Slowly Rotating Envelope in B335

TL;DR

This study reveals the presence of high-velocity jets and a slowly rotating envelope in B335, providing insights into early protostellar evolution and angular momentum transfer.

Contribution

First detection of high-velocity 12CO jets in B335 and detailed analysis of its envelope's kinematics and angular momentum properties.

Findings

Detected high-velocity 12CO jets (~900x1500 AU) in B335.

Found lower mass-loss and momentum flux compared to more luminous sources.

Observed minimal envelope rotation and very low specific angular momentum.

Abstract

We have performed detailed imaging and analyses of SMA observations in 230 GHz continuum, 12CO (2-1), 13CO (2-1), and C18O (2-1) emission toward B335, a Bok globule with an embedded Class 0 source (Lbol ~ 1.5 Lsun). We report the first discover of high-velocity 12CO jets with a size of ~ 900 AU x 1500 AU along the E-W direction in B335. The estimated mass-loss rate (~ 2.3 x 10^-7 Msun yr^-1) and the momentum flux (~ 3.7 x 10^-5 Msun yr^-1 km s^-1) of the 12CO jets in B335 are one order of magnitude lower than those of other 12CO jets in more luminous sources such as HH 211 (Lbol ~ 3.6 Lsun) and HH 212 (Lbol ~ 14 Lsun). The weaker jet activity in B335 could be due to the lower active accretion onto the central protostar. The C18O emission shows a compact (~ 1500 AU) condensation associated with the central protostar, and it likely traces the protostellar envelope around B335. The envelope exhibits a velocity gradient from the east (blueshifted) to west (redshifted) that can be interpreted as an infalling motion. The estimated central stellar mass, the mass infalling rate, and the accretion luminosity are 0.04 Msun, 6.9 x 10^-6 Msun yr^-1, and 2.1 Lsun, respectively. On the other hand, there is no clear velocity gradient perpendicular to the outflow axis in the C18O envelope, suggesting little envelope rotation on a hundred-AU scale. The upper limits of the rotational velocity and specific angular momentum were estimated to be 0.04 km s^-1 and 7.0 x 10^-5 km s^-1 pc at a radius of 370 AU, respectively. The specific angular momentum and the inferred Keplerian radius (~ 6 AU) in B335 are 1 - 2 orders of magnitude smaller than those in other more-evolved sources. Possible scenarios to explain the lower specific angular momentum in B335 are discussed.