High-Resolution Molecular Line Observations of the Environment of the Class 0 Source B1-IRS

• Published in: The Astrophysical journal Vol. 628; no. 2; pp. 789 - 799
• Main Authors: de Gregorio-Monsalvo, Itziar, Chandler, Claire J, Gómez, José F, Kuiper, Thomas B. H, Torrelles, José M, Anglada, Guillem
• Format: Journal Article
• Language: English
• Published: Chicago, IL IOP Publishing 01-08-2005; University of Chicago Press
• Subjects: stars: formation; ISM: jets and outflows; Star formation; Dynamics; Pre-main-sequence stars; ISM: molecules; Kinematics; ISM: individual (Bl-IRS); ISM: kinematics and dynamics; Jets; stars: pre-main-sequence
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1086/430773

In this work we present VLA observations of the NH sub(3), CCS, and H sub(2)O maser emission at 1 cm from the star-forming region B1-IRS (IRAS 03301+3057) with 5" (=1750 AU) of angular resolution. The CCS emission is distributed in three clumps around the central source. These clumps exhibit a velocity gradient from red- to blueshifted velocities toward B1-IRS, probably due to an interaction with the outflow from an embedded protostar. The outflow and its powering source are traced by a reflection nebula and an associated infrared point source detected in a 2MASS K-band image. We find that this infrared point source is associated with water maser emission distributed in an elongated structure ( 450 AU) along the major axis of the reflection nebula and tracing the base of the outflow of the region. Ammonia emission is extended and is spatially anticorrelated with CCS. This is the first time that this kind of anticorrelation is observed in a star-forming region with such a high angular resolution, and it illustrates the importance of time-dependent chemistry on small spatial scales. The relatively large abundance of CCS with respect to ammonia, compared with that in other star-forming regions, suggests an extreme youth for the B1-IRS object (,10 super(5) yr). We suggest the possibility that CCS abundance is enhanced via shock-induced chemistry.