AAS 205th Meeting, 9-13 January 2005
Session 98 High Mass Star Formation and Deeply Embedded Star Formation
Poster, Wednesday, January 12, 2005, 9:20am-6:30pm, Exhibit Hall

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[98.09] High Resolution Imaging of Three Starless Cores Using N2H+

J.M. Grcevich (University of Wisconsin - Madison/ NRAO), Y.L. Shirley (NRAO)

Pre-protostellar cores are dense, cold regions in molecular cloud complexes, but do not show signs of an internal source of luminosity. It is thought that pre-protostellar cores represent the evolutionary stage just prior to low-mass star formation. Diazenylium (N2H+) provides an excellent density tracer for late stage pre-protostellar cores because it is resistant to depletion, and its hyperfine structure can yield useful information about optical depths. We present high resolution BEARS maps of the N2H+ 1-0 hyperfine transition for three pre-protostellar cores, Lynds 1498, Lynds 1512, and Lynds 1544.

A more detailed analysis of the L1498 N2H+ 1-0 hyperfine line ratios indicates that this transition is optically thick over much of the map. The peak column density of L1498 was found to be (8.3 ±3.4) X 1012 cm-2 after optical depth correction. N2H+ abundance in L1498 is fairly constant to a radius of 15,000 AU. The width of the N2H+ 1-0 lines in L1498 are also constant to the maximum radii sampled in these observations.

In addition, we present CSO observations of the N2H+ 3-2 transition. The N2H+ 3-2 transition was detected in L1512 and L1544, the more centrally condensed cores. This work was supported by a NSF-REU site grant to Associated Universities, Inc./National Radio Astronomy Observatory.

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© 2004. The American Astronomical Society.