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[71.17] The Velocity Structures in Protostellar Cores

J.-E. Lee, C. H. Young (University of Texas at Austin), J. Di Francesco (University of California at Berkeley), H. Jacobson, N. J. Evans II (University of Texas at Austin)

Stars form through the gravitational collapse of dense molecular cores, and protostellar cores in the earliest stages are surrounded by envelopes of infalling material. Infall has been detected by blue asymmetries of optically thick molecular lines. However, such line profiles toward some sources show more complicated features because of other coherent motions related to star formation, such as outflow or rotational motions. Therefore, we need to use appropriate molecular lines to distinguish each kinematic motion.

We have observed L1251B and CB244 to study velocity structures in star forming cores. We observed the CO J=2-1 and HCO⁺ J=3-2 lines at the CSO, H¹³CO⁺ J=1-0 line with the BIMA array, and N₂H⁺ J=1-0 line with the OVRO array. HCO⁺ J=3-2 line profile has been known as a good tracer of infall motion, but its efficacy can be compromised if outflow or rotational motions are present. We can distinguish outflow and rotation from infall using lines that are more (CO J=2-1) and less (H¹³CO⁺ J=1-0 and N₂H⁺ J=1-0) opaque than HCO⁺ line.

We present the results from these observations showing the velocity structures from the outer envelope to the very dense inner envelope in the two protostellar cores. These results will be compared to radiative transfer calculations of each molecular line using the Monte Carlo method to simulate the observed molecular line profiles. For the distributions of density and temperature in these cores, the simulations of molecular line profiles will adopt the results of radiative transfer calculations of dust emission observed with SCUBA on the JCMT at submillimeter wavelengths.

The author(s) of this abstract have provided an email address for comments about the abstract: jelee@astro.as.utexas.edu

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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.