Which Part of Dense Cores Feeds Material to Protostars?: The Case of L1489 IRS

Abstract

We have conducted mapping observations ($\sim 2^{\prime }\times 2^{\prime }$) of the Class I protostar L1489 IRS using the 7-m array of the Atacama Compact Array (ACA) and the IRAM-30m telescope in the ${\mathrm{C}}^{18}\mathrm{O}$ 2-1 emission to investigate the gas kinematics on 1000-10,000 au scales. The ${\mathrm{C}}^{18}\mathrm{O}$ emission shows a velocity gradient across the protostar in a direction almost perpendicular to the outflow. The radial profile of the peak velocity was measured from a ${\mathrm{C}}^{18}\mathrm{O}$ position-velocity diagram cut along the disk major axis. The measured peak velocity decreases with radius at a radii of $\sim$1400-2900 au, but increases slightly or is almost constant at radii of $r\gtrsim$2900 au. Disk-and-envelope models were compared with the observations to understand the nature of the radial profile of the peak velocity. The measured peak velocities are best explained by a model where the specific angular momentum is constant within a radius of 2900 au but increases with radius outside 2900 au. We calculated the radial profile of the specific angular momentum from the measured peak velocities, and compared it to analytic models of core collapse. The analytic models reproduce well the observed radial profile of the specific angular momentum and suggest that material within a radius of $\sim$4000-6000 au in the initial dense core has accreted to the central protostar. Because dense cores are typically $\sim$10,000-20,000 au in radius, and as L1489 IRS is close to the end of mass accretion phase, our result suggests that only a fraction of a dense core eventually forms a star.

arXiv comment23 pages, 11 figures, accepted for publication in The Astrophysical Journal

References in corpus (60)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Astropy: A Community Python Package for Astronomy
• The NumPy array: a structure for efficient numerical computation
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• Theory of Star Formation
• The Spitzer c2d Legacy Results: Star Formation Rates and Efficiencies; Evolution and Lifetimes
• From filamentary clouds to prestellar cores to the stellar IMF: Initial highlights from the Herschel Gould Belt survey
• MAMBO Mapping of Spitzer c2d Small Clouds and Cores
• Dense Cores in Dark Clouds. XIV. N2H+(1-0) maps of dense cloud cores
• Rosseland and Planck Mean Opacities for Protoplanetary Discs
• Molecular ions in L1544. II. The ionization degree
• Magnetic Fields in the Formation of Sun-Like Stars
• N2H+ and C18O Depletion in a Cold Dark Cloud
• Physical structure and CO abundance of low-mass protostellar envelopes
• Young Stellar Objects in the Gould Belt
• A Large Catalog of Accurate Distances to Local Molecular Clouds: The Gaia DR2 Edition
• A Keplerian disk around a Class 0 source: ALMA observations of VLA1623A
• The initial conditions of isolated star formation - VI. SCUBA mapping of prestellar cores
• Formation of a Keplerian disk in the infalling envelope around L1527 IRS: transformation from infalling motions to Kepler motions
• A protostellar system fed by a streamer of 10,500 au length
• The NIKA2 large field-of-view millimeter continuum camera for the 30-m IRAM telescope
• Signs of Early-Stage Disk Growth Revealed with ALMA
• Turbulent Molecular Cloud Cores: Rotational Properties
• Rotationally-supported disks around Class I sources in Taurus: disk formation constraints
• The influence of turbulence during magnetized core collapse and its consequences on low-mass star formation
• ALMA Observations of the Transition from Infall Motion to Keplerian Rotation around the Late-phase Protostar TMC-1A
• Testing envelope models of young stellar objects with submillimeter continuum and molecular-line observation
• Embedded Protostars in the Dust, Ice, and Gas In Time (DIGIT) Key Program: Continuum SEDs, and an Inventory of Characteristic Far-Infrared Lines from PACS Spectroscopy
• IRAS 16293: A "Magnetic" Tale of Two Cores
• Decoupling of Magnetic Fields in Collapsing Protostellar Envelopes and Disk Formation and Fragmentation
• ALMA Observations of Infalling Flows toward the Keplerian Disk around the Class I Protostar L1489 IRS
• The Magnetic Field Morphology of the Class 0 Protostar L1157-mm
• ALMA Results of the Pseudodisk, Rotating disk, and Jet in Continuum and HCO+ in the Protostellar System HH 212
• Unveiling the Evolutionary Sequence from Infalling Envelopes to Keplerian Disks around Low-Mass Protostars
• Calibration and Performance of the NIKA2 camera at the IRAM 30-meter Telescope
• The masses of young stars: CN as a probe of dynamical masses
• Magnetic Field Strength Maps for Molecular Clouds: A New Method Based on a Polarization - Intensity Gradient Relation
• From infall to rotation around young stellar objects: A transitional phase with a 2000 AU radius contracting disk?
• ALMA Observations of the Protostar L1527 IRS: Probing Details of the Disk and the Envelope Structures
• Circumstellar disks and outflows in turbulent molecular cloud cores: possible formation mechanism for misaligned systems
• Transition from the Infalling Envelope to the Keplerian Disk around L1551 IRS 5
• Stringent limits on the magnetic field strength in the disc of TW Hya: ALMA observations of CN polarisation
• Dynamical Masses of Low Mass Stars in the Taurus and Ophiuchus Star Forming Regions
• Disk Masses for Embedded Class I Protostars in the Taurus Molecular Cloud
• Hierarchical fragmentation in the Perseus molecular cloud: From the cloud scale to protostellar objects
• A deeply embedded young protoplanetary disk around L1489 IRS observed by the submillimeter array
• Angular momentum profiles of Class 0 protostellar envelopes
• Searching for kinematic evidence of Keplerian disks around Class 0 protostars with CALYPSO
• Analytical Formulas of Molecular Ion Abundances and N2H+ Ring in Protoplanetary Disks
• Kinematics and Physical Conditions of the Innermost Envelope in B335
• Observation of rotation in star forming regions: clouds, cores, disks, and jets
• A highly collimated, extremely high velocity outflow in Taurus
• Angular Momentum of the N2H+ Cores in the Orion A Cloud
• Disk structure around the Class I protostar L1489 IRS revealed by ALMA: a warped disk system
• The specific angular momentum radial profile in dense cores: improved initial conditions for disk formation
• Disk Masses at the end of the main accretion phase: CARMA Observations and Multi-Wavelength Modeling of Class I Protostars
• Protostellar half-life: new methodology and estimates
• A Change of Rotation Profile in the Envelope in the HH 111 Protostellar System: A Transition to a Disk?
• The Origin of the Rotation Profiles in Star Forming Clouds
• A particular carbon-chain-producing region: L1489 starless core

Cited by in corpus (7)

• Early Planet Formation in Embedded Disks (eDisk). IV. The Ringed and Warped Structure of the Disk around the Class I Protostar L1489 IRS
• Anatomy of the Class I protostar L1489 IRS with NOEMA -- I. Disk, streamers, outflow(s) and bubbles at 3mm
• Increasing mass-to-flux ratio from the dense core to the protostellar envelope around the Class 0 protostar HH 211
• Planetesimal formation via the streaming instability in simulations of infall dominated young disks
• Synthetic Observations of the Infalling Rotating Envelope: Links between the Physical Structure and Observational Features
• Anatomy of the Class I protostar L1489 IRS with NOEMA - II. A disk replenished by a massive streamer
• Sulfur oxides tracing streamers and shocks at low mass protostellar disk-envelope interfaces