Molecular Evolution in Collapsing Prestellar Cores

Abstract

We have investigated the evolution and distribution of molecules in collapsing prestellar cores via numerical chemical models, adopting the Larson-Penston solution and its delayed analogues to study collapse. Molecular abundances and distributions in a collapsing core are determined by the balance among the dynamical, chemical and adsorption time scales. When the central density n_H of a prestellar core with the Larson-Penston flow rises to 3 10^6 cm^{-3}, the CCS and CO column densities are calculated to show central holes of radius 7000 AU and 4000 AU, respectively, while the column density of N2H+ is centrally peaked. These predictions are consistent with observations of L1544. If the dynamical time scale of the core is larger than that of the Larson-Penston solution owing to magnetic fields, rotation, or turbulence, the column densities of CO and CCS are smaller, and their holes are larger than in the Larson-Penston core with the same central gas density. On the other hand, N2H+ and NH3 are more abundant in the more slowly collapsing core. Therefore, molecular distributions can probe the collapse time scale of prestellar cores. Deuterium fractionation has also been studied via numerical calculations. The deuterium fraction in molecules increases as a core evolves and molecular depletion onto grains proceeds. When the central density of the core is n_H=3 10^6 cm^{-3}, the ratio DCO+/HCO+ at the center is in the range 0.06-0.27, depending on the collapse time scale and adsorption energy; this range is in reasonable agreement with the observed value in L1544.

21 pages, 17 figures

Cited by in corpus (138)

• Control of star formation by supersonic turbulence
• Cold Dark Clouds: The Initial Conditions for Star Formation
• Dense Cores in Dark Clouds. XIV. N2H+(1-0) maps of dense cloud cores
• Systematic Molecular Differentiation in Starless Cores
• Probing the evolutionary status of starless cores through N2H+ and N2D+ observations
• Molecular ions in L1544. II. The ionization degree
• N2H+ and C18O Depletion in a Cold Dark Cloud
• A Survey for Infall Motions toward Starless Cores. II. $CS(2-1)$ and $N_2{H}^{+}(1-0)$ Mapping Observations
• Molecular Evolution and Star Formation: From Prestellar Cores to Protostellar Cores
• Molecular Evolution in Collapsing Prestellar Cores III: Contraction of A Bonnor-Ebert Sphere
• Abundant H2D+ in the pre-stellar core L1544
• On the internal structure of starless cores. II. A molecular survey of L1498 and L1517B
• Evolution of Chemistry and Molecular Line Profile during Protostellar Collapse
• The H_2O southern Galactic Plane Survey (HOPS): I. Techniques and H_2O maser data
• Dynamics and Depletion in Thermally Supercritical Starless Cores
• Survey of ortho-H2D+(1_{1,0}-1_{1,1}) in dense cloud cores
• From Prestellar to Protostellar Cores II. Time Dependence and Deuterium Fractionation
• The chemical history of molecules in circumstellar disks. II. Gas-phase species
• Multilayer formation and evaporation of deuterated ices in prestellar and protostellar cores
• Collapse and Fragmentation of Rotating Magnetized Clouds. I. Magnetic Flux - Spin Relation
• The Different Structures of the Two Classes of Starless Cores
• Complex Structure in Class 0 Protostellar Envelopes II: Kinematic Structure from Single-Dish and Interferometric Molecular Line Mapping
• Molecular Evolution in Collapsing Prestellar Cores II: The Effect of Grain-surface Reactions
• Probing the Early Stages of Low-Mass Star Formation in LDN 1689N: Dust and Water in IRAS 16293-2422A, B, and E
• Observations of L1521F: a highly evolved starless core
• Chemistry and Dynamics in Pre-Protostellar Cores
• Robustness of N2H+ as tracer of the CO snowline
• Chemical differentiation in a prestellar core traces non-uniform illumination
• Chemical Evolution in High-Mass Star-Forming Regions: Results from the MALT90 Survey
• Exclusion of Cosmic Rays in Protoplanetary Disks. II. Chemical Gradients and Observational Signatures
• The Distribution of Ortho-H_2D+(1_1,0 - 1_1,1) in L1544: Tracing the Deuteration Factory in Prestellar Cores
• The observed chemical structure of L1544
• The abundances of nitrogen-containing molecules during pre-protostellar collapse
• A Molecular Line Observation toward Massive Clumps Associated with Infrared Dark Clouds
• OVRO N2H+ Observations of Class 0 Protostars: Constraints on the Formation of Binary Stars
• A Search for Carbon-Chain-Rich Cores in Dark Clouds
• Disappearance of N2H+ from the Gas Phase in the Class 0 Protostar IRAM 04191
• Deuterated molecules as a probe of ionization fraction in dense interstellar clouds
• Relative Alignment Between the Magnetic Field and Molecular Gas Structure in the Vela C Giant Molecular Cloud using Low and High Density Tracers
• Freeze-out and coagulation in pre-protostellar collapse
• Radiative Transfer and Starless Cores
• Effect of Grain Size on Differential Desorption of Volatile Species and on Non-ideal MHD Diffusivity
• N2H+ and HC3N Observations of the Orion A Cloud
• Dark cloud cores and gravitational decoupling from turbulent flows
• IRAM-PdBI Observations of Binary Protostars I: The Hierarchical System SVS13 in NGC1333
• On the Influence of Uncertainties in Chemical Reaction Rates on Results of the Astrochemical Modelling
• Dense gas kinematics and a narrow filament in the Orion A OMC1 region using NH3
• Analytical Formulas of Molecular Ion Abundances and N2H+ Ring in Protoplanetary Disks
• TMC-1C: an accreting starless core
• A Coupled Dynamical and Chemical Model of Starless Cores of Magnetized Molecular Clouds: I. Formulation and Initial Results
• Oscillations of starless cores
• ATCA and Spitzer Observations of the Binary Protostellar Systems CG30 and BHR71
• A survey of H${}_2$O, CO${}_2$ and CO ice features towards background stars and low mass YSOs using AKARI
• An Early Transition to Magnetic Supercriticality in Star Formation
• Chemical Variation among Protostellar Cores: Dependence on Prestellar Core Conditions
• Molecular Line Observations of Infrared Dark Clouds II: Physical Conditions
• DNC/HNC Ratio of Massive Clumps in Early Evolutionary Stages of High-Mass Star Formation
• Characterizing the line emission from molecular clouds. Stratified random sampling of the Perseus cloud
• Angular Momentum of the N2H+ Cores in the Orion A Cloud
• Astrochemical Properties of Planck Cold Clumps
• N2H+ Observations of Molecular Cloud Cores in Taurus
• Understanding the origin of the magnetic field morphology in the wide-binary protostellar system BHR 71
• The depletion of NO in pre-protostellar cores
• Ice chemistry in massive Young Stellar Objects: the role of metallicity
• Molecular-Cloud-Scale Chemical Composition I: Mapping Spectral Line Survey toward W51 in the 3 mm Band
• The Initial Conditions for Gravitational Collapse of a Core: An Extremely Young Low-Mass Class 0 Protostar GF9-2
• Molecular-Cloud-Scale Chemical Composition II: Mapping Spectral Line Survey toward W3(OH) in the 3 mm Band
• Mapping Observations of DNC and HN^13C in Dark Cloud Cores
• Phosphorous chemistry in the shocked region L1157 B1
• Gravitationally unstable condensations revealed by ALMA in the TUKH122 prestellar core in the Orion A cloud
• Efficient diffusive mechanisms of O atoms at very low temperatures on surfaces of astrophysical interest
• Non-Equilibrium Chemistry of Dynamically Evolving Prestellar Cores: I. Basic Magnetic and Non-Magnetic Models and Parameter Studies
• C18O Depletion in Starless Cores in Taurus
• Multitransitional observations of the CS core of L673
• Flow of gas detected from beyond the filaments to protostellar scales in Barnard 5
• Precise observations of the 12C/13C ratios of HC3N in the low-mass star-forming region L1527
• Evolutionary view through the starless cores in Taurus: deuteration in TMC 1-C and TMC 1-CP
• An Ammonia Spectral Map of the L1495-B218 Filaments in the Taurus Molecular Cloud: II CCS & HC${}_7$N Chemistry and Three Modes of Star Formation in the Filaments
• Characterizing the line emission from molecular clouds. II. A comparative study of California, Perseus, and Orion A
• Molecular Cloud Cores with High Deuterium Fraction: Nobeyama Single-Pointing Survey
• The dynamical influence of cooling in the envelope of prestellar and protostellar cores
• Carbon Chain Molecules Toward Embedded Low-Mass Protostars
• The molecular distribution of the IRDC G351.77-0.51
• Modeling the chemical evolution of a collapsing prestellar core in two spatial dimensions
• Multi-generation massive star-formation in NGC3576
• Chemical Differentiation toward the Pipe Nebula Starless Cores
• Chemical evolution along the circumnuclear ring of M83
• Physical and chemical modeling of the starless core L1512
• Astrochemical Correlations in Molecular Clouds
• Probing the structure of a massive filament: ArTeMiS 350 and 450 micron mapping of the integral-shaped filament in Orion A
• Interaction between the Outflow and the Core in IRAM 04191+1522
• Molecular Line Observations of the Small Protostellar Group L1251B
• Modeling chemistry during star formation: Water deuteration in dynamic star-forming regions
• Physical and Chemical Conditions of the Protostellar Envelope and the Protoplanetary Disk in HL Tau
• The connection between warm carbon chain chemistry and interstellar irradiation of star-forming cores
• Chemical Variation in Molecular Cloud Cores in the Orion A Cloud. II
• C2H N=1-0 and N2H+ J=1-0 observations of Planck Galactic cold clumps
• Molecular abundance ratios as a tracer of accelerated collapse in regions of high mass star formation?
• Tracing the evolutionary stage of Bok globules: CCS and NH3
• An efficient method for determining the chemical evolution of gravitationally collapsing prestellar cores
• Mapping the prestellar core Ophiuchus D (L1696A) in ammonia
• Far-infrared/sub-millimetre properties of pre-stellar cores L1521E, L1521F and L1689B as revealed by the Herschel SPIRE instrument -- I. Central positions
• New detections of HC${}_5$N toward hot cores associated with 6.7 GHz methanol masers
• Chemical Variation in Molecular Cloud Cores in the Orion A Cloud
• Ambipolar diffusion and the molecular abundances in prestellar cores
• Chemistry as a diagnostic of prestellar core geometry
• Thermal Starless Ammonia Core Surrounded by CCS in the Orion A Cloud
• CS Depletion in Prestellar Cores
• Depletion of CCS in a Candidate Warm-Carbon-Chain-Chemistry Source L483
• TIMES I: a Systematic Observation in Multiple Molecular Lines Toward the Orion A and Ophiuchus Clouds
• Three dimensional projection effects on chemistry in a Planck galactic cold clump
• Early-stage star forming cloud cores in GLIMPSE Extended Green Objects (EGOs) as traced by organic species
• Carbon-Chain and Organic Molecules around Very Low-Luminosity Protostellar Objects of L1521F-IRS and IRAM 04191+1522
• Time-dependent CO depletion during the formation of protoplanetary disks
• Chemical evolution of the HC3N and N2H+ molecules in dense cores of the Vela C giant molecular cloud complex
• Radiative cooling of H3O+ and its deuterated isotopologues
• Dynamical timescale of precollapse evolution inferred from chemical distribution in the Taurus Molecular Cloud-1 (TMC-1) filament
• Detection of Two Carbon-Chain-Rich Cores; CB130-3 and L673-SMM4
• Detection of a turbulent gas component associated with a starless core with subthermal turbulence in the Orion A cloud
• Carbon Isotope Fractionation of Complex Organic Molecules in Star-Forming Cores
• Deuterium chemistry and D/H ratios in Class 0/I proto-brown dwarfs
• Chemical variations across the TMC-1 boundary: molecular tracers from translucent phase to dense phase
• Nobeyama Survey of Inward Motions toward Cores in Orion Identified by SCUBA-2
• Independent Core Rotation in Massive Filaments in Orion
• Imaging of the CCS 22.3 GHz emission in the Taurus Molecular Cloud complex
• Disappearance of N2H+ from the Gas Phase in the Class 0 Protostar IRAM 04191
• Velocity-Coherent Substructure in TMC-1: Inflow and Fragmentation
• Interferometric observations of nitrogen-bearing molecular species in the star-forming core ahead of HH 80N
• Emission from a Young Protostellar Object I. Signatures of Young Embedded Outflows
• Spectroscopic Evidence for Gas Infall in GF9-2
• Star formation timescale in the molecular filament WB 673
• Studying the chemical and kinematical structures of dense cores TMC-1C, L1544, and TMC-1 in the Taurus molecular cloud using the CCS and NH3 observations
• Chemical properties of two dense cores in a Planck Galactic Cold Clump G168.72-15.48
• Deuterium fractionation of a distant cold dark cloud along the line of sight of W51
• Water abundance in four of the brightest water sources in the southern sky
• Isotopomer-Specific Carbon Isotope Ratio of Complex Organic Molecules in Star-Forming Cores
• The TMRT K Band Observations towards 26 Infrared Dark Clouds: NH${}_3$, CCS, and HC${}_3$N
• The evolution of C4H and c-C3H2 in molecular cores