Physical and chemical characteristics of l1689-smm16, an oscillating prestellar core in Ophiuchus

From National Research Council Canada

DOI	Resolve DOI: https://doi.org/10.1088/0004-637X/790/2/129
Author	Search for: Chitsazzadeh, S.¹; Search for: Di Francesco, J.¹; Search for: Schnee, S.; Search for: Friesen, R. K.; Search for: Shimajiri, Y.; Search for: Langston, G. I.; Search for: Sadavoy, S. I.¹; Search for: Bourke, T. L.; Search for: Keto, E. R.; Search for: Pineda, J. E.; Search for: Takakuwa, S.; Search for: Tatematsu, K.
Affiliation	National Research Council of Canada. National Science Infrastructure
Format	Text, Article
Subject	ISM: kinematics and dynamics; ISM: molecules; ISM: structure; radio lines: ISM; stars: formation
Abstract	We present single-dish observations of the L1689-SMM16 core in the Ophiuchus molecular cloud in NH3 (1, 1) and (2, 2) emission using the Green Bank Telescope, in N2H+ (1-0) emission using the Nobeyama Radio Observatory, and in NH2D (), HCN (1-0), HNC (1-0), H 13CO+ (1-0), and HCO+ (1-0) emission using the Mopra telescope. The morphologies of the integrated NH3 (1, 1) and N2H+ (1-0) emission well match that of 250 μm continuum emission. Line widths of NH3 (1, 1) and N2H+ (1-0) show the presence of transonic turbulence across the core. Jeans and virial analyses made using updated measurements of core mass and size confirm that L1689-SMM16 is prestellar, i.e., gravitationally bound. It also has accumulated more mass compared to its corresponding Jeans mass in the absence of magnetic fields and therefore is a "super-Jeans" core. The high levels of X(NH 3)/X(N2H+) and deuterium fractionation reinforce the idea that the core has not yet formed a protostar. Comparing the physical parameters of the core with those of a Bonnor-Ebert sphere reveals the advanced evolutionary stage of L1689-SMM16 and shows that it might be unstable to collapse. We do not detect any evidence of infall motions toward the core. Instead, red asymmetry in the line profiles of HCN (1-0) and HNC (1-0) indicates the expansion of the outer layers of the core at a speed of 0.2 km s -1 to 0.3 km s-1. For a gravitationally bound core, expansion in the outer layers might indicate that the core is experiencing oscillations.
Publication date	2014-07-15
Publisher	American Astronomical Society IOP Publishing
In	The Astrophysical Journal 790, no. 2, 129: 1–21.
Language	English
Peer reviewed	Yes
NPARC number	21272720
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Record identifier	112c4e5c-4693-42f1-86b1-f6f17c34aa26
Record created	2014-12-03
Record modified	2020-04-22

Date modified:: 2024-06-30