A study of the kinematics and temperature of the high-density molecular gas surrounding L1448C

We have performed VLA ammonia (1, 1) and (2, 2) observations of the molecular core associated with the very young stellar object L1448C, the powering source of the highly collimated bipolar outflow L1448. The line broadening observed in the molecular core appears to be a consequence of the interaction between the highly collimated wind from L1448C and the ambient molecular gas. The ammonia line emission shows a velocity gradient in a direction perpendicular to the outflow axis, which is consistent with rotation in a circumstellar structure. In addition, there is also evidence of a velocity gradient along the outflow axis, suggesting that the ammonia line emission could be tracing a self-gravitating, thick, disklike structure around L1448C, which appears to be rotating and contracting. We also detect ammonia emission associated with IRS 3, the infrared source about 75″ northwest of L1448C. This emission presents a wedgelike morphology pointing away from L1448C. We propose that this ammonia structure traces the region where the leading head of the L1448C near-infrared H2 jet is carving a cavity in the northern molecular core, or alternatively, where the near-infrared H2 jet is being bent to the west by the northern high-density core. In addition, an anticorrelation between the ammonia and H2 line emissions is found. The near-infrared H2 line emission is clearly seen in the relatively low density gap between the northern (IRS 3) and southern (L1448C) molecular cores, while the high-density molecular gas surrounding L1448C completely obscures this young stellar object and its counterjet at optical and near-infrared wavelengths.