An Ammonia Spectral Map of the L1495-B218 Filaments in the Taurus Molecular Cloud : I. Physical Properties of Filaments and Dense cores

Abstract

We present deep NH${}_3$ observations of the L1495-B218 filaments in the Taurus molecular cloud covering over a 3 degree angular range using the K-band focal plane array on the 100m Green Bank Telescope. The L1495-B218 filaments form an interconnected, nearby, large complex extending over 8 pc. We observed NH${}_3$ (1,1) and (2,2) with a spectral resolution of 0.038 km/s and a spatial resolution of 31$"$. Most of the ammonia peaks coincide with intensity peaks in dust continuum maps at 350 $\mu$m and 500 $\mu$m. We deduced physical properties by fitting a model to the observed spectra. We find gas kinetic temperatures of 8 $-$ 15 K, velocity dispersions of 0.05 $-$ 0.25 km/s, and NH${}_3$ column densities of 5$\times$10${}^{12}$ $-$ 1$\times$10${}^{14}$ cm${}^{-2}$. The CSAR algorithm, which is a hybrid of seeded-watershed and binary dendrogram algorithms, identifies a total of 55 NH${}_3$ structures including 39 leaves and 16 branches. The masses of the NH${}_3$ sources range from 0.05 M${}_{\odot }$ to 9.5 M${}_{\odot }$. The masses of NH${}_3$ leaves are mostly smaller than their corresponding virial mass estimated from their internal and gravitational energies, which suggests these leaves are gravitationally unbound structures. 9 out of 39 NH${}_3$ leaves are gravitationally bound and 7 out of 9 gravitationally bound NH${}_3$ leaves are associated with star formation. We also found that 12 out of 30 gravitationally unbound leaves are pressure-confined. Our data suggest that a dense core may form as a pressure-confined structure, evolve to a gravitationally bound core, and undergo collapse to form a protostar.

ApJ Accepted

References in corpus (16)

• The Critical Density and the Effective Excitation Density of Commonly Observed Molecular Dense Gas Tracers
• The relation between gas and dust in the Taurus Molecular Cloud
• The Nature of the Dense Core Population in the Pipe Nebula: Thermal Cores Under Pressure
• 2MASS wide field extinction maps - I. The Pipe nebula
• An Ammonia Spectral Atlas of Dense Cores in Perseus
• Magnetically Regulated Star Formation in 3D: The Case of Taurus Molecular Cloud Complex
• VLBA determination of the distance to nearby star-forming regions I. The distance to T Tauri with 0.4% accuracy
• Unfolding the Laws of Star Formation: The Density Distribution of Molecular Clouds
• The Five College Radio Astronomy Observatory CO Mapping Survey of the Taurus Molecular Cloud
• Spatial mapping of ices in the Oph-F core: A direct measurement of CO depletion and the formation of CO2
• Formation of Magnetized Prestellar Cores with Ambipolar Diffusion and Turbulence
• Fragmentation of Shocked Flows: Gravity, Turbulence and Cooling
• The abundances of nitrogen-containing molecules during pre-protostellar collapse
• Protostar Formation in Supersonic Flows: Growth and Collapse of Spherical Cores
• Formation and Collapse of Quiescent Cloud Cores Induced by Dynamic Compressions
• The COMPLETE Nature of the Warm Dust Ring in Perseus

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