Massive Quiescent Cores in Orion: Dynamical State Revealed by High-Resolution Ammonia Maps

Abstract

We present combined VLA and Green Bank Telescope images of \ammonia\ inversion transitions (1,1) and (2,2) toward OMC2 and OMC3. We focus on the relatively quiescent Orion cores, which are away from the Trapezium cluster and have no sign of massive protostars nor evolved star formation, such as IRAS source, water maser, and methanol maser. The 5\arcsec\ angular resolution and $0.6\mathrm{km}{\mathrm{s}}^{-1}$ velocity resolution of these data enable us to study the thermal and dynamic state of these cores at $\sim 0.02\mathrm{pc}$ scales, comparable to or smaller than those of the current dust continuum surveys. We measure temperatures for a total of 30 cores, with average masses of $11\,\Ms$, radii of $0.039\mathrm{pc}$, virial mass ratio $\overline{R_{vir}}$ = 3.9, and critical mass ratio $\overline{R_C}$ = 1.5. Twelve sources contain \textit{Spitzer} protostars. The thus defined starless and protostellar subsamples have similar temperature, line width, but different masses, with an average of $7.3\,\Ms$ for the former and $16\,\Ms$ for the latter. Compared to others Gould Belt dense cores, mores Orion cores have a high gravitational-to kinetic energy ratio and more cores have a larger thant unity critical mass ratio. Orion dense cores have velocity dispersion similar to those of cores in low-mass star-forming regions but larger masses for fiven size. Some cores appear to have truly supercritical gravitational-to-kinetic energy ratios, even when considering significant observational uncertainties: thermal and non-thermal gas mothins alone cannot prevent collapse.

Accepted by ApJ, ApJ2013...768...L5

References in corpus (8)

• The distance to the Orion Nebula
• MAMBO Mapping of Spitzer c2d Small Clouds and Cores
• The Spitzer Space Telescope Survey of the Orion A & B Molecular Clouds - Part I: A Census of Dusty Young Stellar Objects and a Study of their Mid-IR Variability
• A SCUBA survey of Orion, the low-mass end of the core mass function
• Dynamics of Dense Cores in the Perseus Molecular Cloud
• Millimeter- and Submillimeter-Wave Observations of the OMC-2/3 Region. III. An Extensive Survey for Molecular Outflows
• Massive Quiescent Cores in Orion. -- II. Core Mass Function
• Dichotomy in the Dynamical Status of Massive Cores in Orion

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