L483: A Protostar In Transition From Class 0 to Class I

TL;DR

This study investigates the molecular outflow in L483, revealing its intermediate properties between Class 0 and Class I protostars, indicating it is in transition from the earliest to a more evolved stage.

Contribution

It provides detailed molecular-line observations showing the transitional nature of L483's outflow, highlighting chemical and physical properties that bridge Class 0 and Class I protostars.

Findings

Outflow is well collimated and asymmetric with warmer gas.

H2CO shows high-velocity wings and abundance enhancement.

L483's properties are intermediate between Class 0 and I sources.

Abstract

We present molecular-line observations toward the dense core in L483 and its bipolar outflow powered by the Class 0 object IRAS 18148-0440. CO (carbon monoxide) maps show that the outflow is well collimated and asymmetric, and that its gas is warmer than the surrounding cloud by at least a factor of 2. H2CO (formaldehyde) lines toward the outflow show prominent high-velocity wings and evidence for an H2CO abundance enhancement of a factor of 20. At ambient velocities, these lines show strong self-absorption and a brighter blue peak, a characteristic signature of inward motions. Finally, and in contrast with the outflows from other Class 0 objects, the CH3OH (methanol) lines in L483 do not show high velocity wings, and no evidence for abundance enhancement is found in this molecule or in SiO (silicon monoxide). Comparing the physical and chemical properties of the outflow in L483 with those of other outflows from Class 0 and Class I sources, we find that the L483 outflow is somewhat intermediate between these types. This suggests that the L483 central source has already started its transition between Class 0 and Class I, and that its mixed properties illustrate how this transition occurs.