HCN(1-0) OBSERVATIONS OF STARLESS CORES

다국어 초록 (Multilingual Abstract)

We present a progress report on HCN(1-0) line observations toward starless cores to probe inwardmotions. We have made a single pointing survey toward the central regions of 85 starless cores andperformed mapping observations of 6 infall candidate starless cores. The distributions of the velocitydierence between HCN(1-0) hyperne lines and the optically thin tracer N2H+ (1-0) are signicantlyskewed to the blue, meaning that HCN(1-0) frequently detects inward motions. Their skewness to theblue is even greater than that of CS(2-1) Lee et al., possibly implying more infall occurrence thanCS(1-0). We identify 19 infall candidates by using several characteristics illustrating spectral infallasymmetry seen in HCN(1-0) hyperne lines, CS(3-2), CS(2-1), DCO+ (2-1) and N2H+ observations.The HCN(1-0) F(0-1) with the least optical depth usually shows a similar intensity distribution to thatof N2H+ which closely traces the density distribution of the cores, indicating that HCN(1-0) is lesschemically aected and so believed to reect kinematics occurring in rather inner regions of the cores.Detailed radiative transfer model ts of the spectra are underway to analyze central infall kinematicsin starless cores.

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