Emission from a Young Protostellar Object I. Signatures of Young Embedded Outflows

Abstract

We examine emission from a young protostellar object (YPO) with three-dimensional ideal MHD simulations and three-dimensional non-local thermodynamic equilibrium (non-LTE) line transfer calculations, and show the first results. To calculate the emission field, we employed a snapshot result of an MHD simulation having young bipolar outflows and a dense protostellar disk (a young circumstellar disk) embedded in an infalling envelope. Synthesized line emission of two molecular species (CO and SiO) show that subthermally excited SiO lines as a high density tracer can provide a better probe of the complex velocity field of a YPO, compared to fully thermalized CO lines. In a YPO at the earliest stage when the outflows are still embedded in the collapsing envelope, infall, rotation and outflow motions have similar speeds. We find that the combined velocity field of these components introduces a great complexity in the line emissions through varying optical thickness and emissivity, such as asymmetric double-horn profiles. We show that the rotation of the outflows, one of the features that characterizes an outflow driven by magneto-centrifugal forces, appears clearly in velocity channel maps and intensity-weighted mean velocity (first moment of velocity) maps. The somewhat irregular morphology of the line emission at this youngest stage is dissimilar to a more evolved object such as young Class 0. High angular resolution observation by e.g., the Atacama Large Millimeter/submillimeter Array (ALMA) telescope can reveal these features.

46 pages, 19 figures: accepted for publication in ApJ. High resolution figures are available at https://www.asiaa.sinica.edu.tw/~masako/preprints/ms_of_final.pdf

References in corpus (17)

• An atomic and molecular database for analysis of submillimetre line observations
• Magnetic processes in a collapsing dense core. I Accretion and Ejection
• Outflows and Jets from Collapsing Magnetized Cloud Cores
• The Spitzer c2d Survey of Nearby Dense Cores: II: Discovery of a Low Luminosity Object in the "Evolved Starless Core" L1521F
• Second Core Formation and High Speed Jets: Resistive MHD Nested Grid Simulations
• SiO J=5--4 in the HH211 Protostellar Jet Imaged with the SMA
• Molecular freeze-out as a tracer of the thermal and dynamical evolution of pre- and protostellar cores
• The HCO+ emission excess in bipolar outflows
• Rotating molecular outflows: the young T Tauri star in CB26
• Discovery of a Low Mass Bipolar Molecular Outflow from L1014-IRS with the Submillimeter Array
• Freeze-out and coagulation in pre-protostellar collapse
• Infall and Outflow around the HH 212 protostellar system
• Molecular gas structure around an AGN with nuclear starburst: 3-D Non-LTE calculations of CO lines
• HCN to HCO^+ Millimeter Line Diagnostics of AGN Molecular Torus I : Radiative Transfer Modeling
• Observational Characteristics of the First Protostellar Cores
• Molecular Emission Line Formation in Prestellar Cores
• Molecular line profiles as diagnostics of protostellar collapse: modelling the `blue asymmetry' in inside-out infall

Cited by in corpus (6)

• Radiation Magnetohydrodynamic Simulations of Protostellar Collapse: Protostellar Core Formation
• Synthetic observations of first hydrostatic cores in collapsing low-mass dense cores. I. Spectral energy distributions and evolutionary sequence
• The massive protostar W43-MM1 as seen by Herschel-HIFI water spectra: high turbulence and accretion luminosity
• Gas Kinematics in FIRE Simulated Galaxies Compared to Spatially Unresolved HI Observations
• A cluster of outflows in the Vulpecula Rift
• Insights into the first and second hydrostatic core stages from numerical simulations