AAS 199th meeting, Washington, DC, January 2002
Session 60. Star Formation - Accretion and Outflow
Display, Tuesday, January 8, 2002, 9:20am-6:30pm, Exhibit Hall

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[60.02] Gas Kinematics Around the Youngest Protostars and Jets: The Ammonia Core Encompassing IRAM04191

A. Wootten (National Radio Astronomy Observatory), J. Wiseman (Johns Hopkins University), G. Fuller (UMIST, Manchester, UK)

IRAM 04191+1523 powers a highly collimated CO outflow and is associated with a weak VLA 3.6 cm radio continuum source (André, Motte, and Bacmann 1999). Molecular line observations show evidence of infall. But high resolution continuum measurements fail to detect evidence of significant dust concentrated at the the center of the core, indicating that this source has not yet developed a large accretion disk. Our VLA observations, reported here, of the envelope gas thus characterize the system kinematics at the very beginning of central accretion and outflow production.

The ammonia (1,1) distribution covers two morphologically similar regions symmetrically placed about the position of the millimeter source. In a region of diameter 15" (2100 AU) about this source, there is a void of ammonia emission. The ~50" major axis of the structure aligns very well with the morphology of the dust continuum imaged by André et al. (1999). From their submillimeter map we judge a position angle of 130o for the major axis of that structure. The outflow is approximately perpendicular to this at a position angle of 30o. A velocity gradient occurs in the emission along a ESE-WNW line, varying from just below 6.4 km/s at the WNW to about 7.2 km/s at the ESE end, 50" (7000 AU) away at a position angle of 130o. This suggests a gradient of ~25 km s-1 pc-1, somewhat larger than quoted by André et al (1999) (~11 km s-1 pc-1) from their lower resolution (30") resolution maps, though in the same sense. The flattened double core structure shows some flaring at its extremities, reiniscent of the structure of the HH212 core. Broadest lines tend to occur closest to the continuum source.

The NH3(2,2) emission lies in a more compact structure at similar position angle. Along the major axis, the velocity of emission varies in agreement with the more extensive (1,1) emission.

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