Internal Motions in Starless Dense Cores

Abstract

This paper discusses the statistics of internal motions in starless dense cores and the relation of these motions to core density and evolution. Four spectral lines from three molecular species are analyzed from single-pointing and mapped observations of several tens of starless cores. Blue asymmetric profiles are dominant, indicating that inward motions are prevalent in sufficiently dense starless cores. These blue profiles are found to be more abundant, and their asymmetry is bluer, at core positions with stronger ${\mathrm{N}}_2{\mathrm{H}}^{+}$ line emission or higher column density. Thirty three starless cores are classified into four types according to the blue and red shifts of the lines in their molecular line maps. Among these cores, contracting motions dominate: 19 are classified as contracting, 3 as oscillating, 3 as expanding, and 8 as static. Contracting cores have inward motions all over the core with predominance of those motions near the region of peak density. Cores with the bluest asymmetry tend to have greater column density than other cores and all five cores with peak column density $>6\times 10^{21}\mathrm{c}{\mathrm{m}}^{-2}$ are found to be contracting. This suggests that starless cores are likely to have contracting motions if they are sufficiently condensed. Our classification of the starless cores may indicate a sequence of core evolution in the sense that column density increases from static to contracting cores: the static cores in the earliest stage, the expanding and/or the oscillating cores in the next, and the contracting cores in the latest stage.

Accepted for publication in The Astrophysical Journal, 34 pages, and 14 figures

References in corpus (5)

• Identifying the Low Luminosity Population of Embedded Protostars in the c2d Observations of Clouds and Cores
• On the internal structure of starless cores. II. A molecular survey of L1498 and L1517B
• Probing Inward Motions in Starless Cores Using The HCN J = 1-0 Hyperfine Transitions : A Pointing Survey Toward Central Regions
• The Dynamical State fo the Starless Dense Core FeSt 1-457: A Pulsating Globule?
• The Dynamical State of the Starless Dense Core FeSt 1-457: A Pulsating Globule?

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