ALMA detections of the youngest protostars in Ophiuchus

Abstract

We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of 1.1 mm dust continuum and CO 2-1 emission toward six dense cores within the Ophiuchus molecular cloud. We detect compact, sub-arcsecond continuum structures toward three targets, two of which (Oph A N6 and SM1) are located in the Ophiuchus A ridge. Two targets, SM1 and GSS 30, contain two compact sources within the ALMA primary beam. We argue that several of the compact structures are small ($R\lesssim 80$ au) accretion disks around young protostars, due to their resolved, elongated structures, coincident radio and x-ray detections, or bipolar outflow detections. While CO line wings extend to $\pm 10-20$ km s${}^{-1}$ for the more evolved sources GSS 30 IRS3 and IRS1, CO emission toward other sources, where detected, only extends a few km s${}^{-1}$ from the cloud $v_{\mathrm{LSR}}$. The dust spectral index toward the compact objects suggests that the disks are either optically thick at 1.1 mm, or that significant grain growth has already occurred. We identify, for the first time, a single compact continuum source ($R\sim 100$ au) toward N6 embedded within a larger continuum structure. SM1N is extended in the continuum but is highly centrally concentrated, with a density profile that follows a $r^{-1.3}$ power law within 200 au, and additional structure suggested by the uv-data. Both N6 and SM1N show no clear bipolar outflows with velocities greater than a few km s${}^{-1}$ from the cloud velocity. These sources are candidates to be the youngest protostars or first hydrostatic cores in the Ophiuchus molecular cloud.

arXiv comment19 pages, 10 figures, accepted to ApJ

References in corpus (59)

• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• The Spitzer c2d Legacy Results: Star Formation Rates and Efficiencies; Evolution and Lifetimes
• From Molecular Cores to Planet-forming Disks: A SIRTF Legacy Program
• BANYAN. XI. The BANYAN $\Sigma$ multivariate Bayesian algorithm to identify members of young associations within 150 pc
• Dust and Gas in the disc of HL Tauri: Surface density, dust settling, and dust-to-gas ratio
• Properties of the Youngest Protostars in Perseus, Serpens, and Ophiuchus
• Young Stellar Objects in the Gould Belt
• Identifying the Low Luminosity Population of Embedded Protostars in the c2d Observations of Clouds and Cores
• ISOCAM observations of the rho Ophiuchi cloud: Luminosity and mass functions of the pre-main sequence embedded cluster
• PROSAC: A Submillimeter Array Survey of Low-Mass Protostars. I. Overview of Program: Envelopes, Disks, Outflows and Hot Cores
• PROSAC: A Submillimeter Array survey of low-mass protostars. II. The mass evolution of envelopes, disks, and stars from the Class 0 through I stages
• Collapse of a Molecular Cloud Core to Stellar Densities: The First Three-Dimensional Calculations
• A Keplerian disk around a Class 0 source: ALMA observations of VLA1623A
• Infall, Outflow, Rotation, and Turbulent Motions of Dense Gas within NGC 1333 IRAS 4
• Dynamics and Depletion in Thermally Supercritical Starless Cores
• The Gould's Belt Distances Survey (GOBELINS) I. Trigonometric parallax distances and depth of the Ophiuchus complex
• A Herschel and APEX Census of the Reddest Sources in Orion: Searching for the Youngest Protostars
• Formation Process of the Circumstellar Disk: Long-term Simulations in the Main Accretion Phase of Star Formation
• The Green Bank Ammonia Survey (GAS): First Results of NH3 mapping the Gould Belt
• The JCMT Gould Belt Survey: First results from the SCUBA-2 observations of the Ophiuchus molecular cloud and a virial analysis of its prestellar core population
• Collapse of a molecular cloud core to stellar densities: stellar core and outflow formation in radiation magnetohydrodynamics simulations
• Current Star Formation in the Ophiuchus and Perseus Molecular Clouds: Constraints and Comparisons from Unbiased Submillimeter and Mid-Infrared Surveys. II
• The first ALMA view of IRAS 16293-2422: Direct detection of infall onto source B and high-resolution kinematics of source A
• 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
• Herschel observations of B1-bS and B1-bN: two first hydrostatic core candidates in the Perseus star-forming cloud
• The Initial Conditions of Clustered Star Formation I: NH3 Observations of Dense Cores in Ophiuchus
• The dynamics of collapsing cores and star formation
• The enigmatic core L1451-mm: a first hydrostatic core? or a hidden VeLLO?
• Radiation Magnetohydrodynamics Simulation of Proto-Stellar Collapse: Two-Component Molecular Outflow
• A Candidate Detection of the First Hydrostatic Core
• Modeling the Resolved Disk Around the Class 0 Protostar L1527
• The Spitzer c2d Survey of Large, Nearby, Interstellar Clouds: VII. Ophiuchus Observed with MIPS
• L1448 IRS2E: A candidate first hydrostatic core
• Detection of Infall in the Protostar B335 with ALMA
• Disentangling the entangled: Observations and analysis of the triple non-coeval protostellar system VLA1623
• On the reliability of protostellar disc mass measurements and the existence of fragmenting discs
• Collimated jets from the first core
• Simultaneous Chandra and VLA Observations of Young Stars and Protostars in rho Ophiuchus Cloud Core A
• Quiescent Dense Gas in Protostellar Clusters: the Ophiuchus A Core
• Faint disks around classical T Tauri stars: small but dense enough to form planets?
• HD depletion in starless cores
• Synthetic observations of first hydrostatic cores in collapsing low-mass dense cores. I. Spectral energy distributions and evolutionary sequence
• An ALMA Search for Substructure, Fragmentation, and Hidden Protostars in Starless Cores in Chamaeleon I
• Revealing H2D+ depletion and compact structure in starless and protostellar cores with ALMA
• The JCMT Legacy Survey of the Gould Belt: a molecular line study of the Ophiuchus molecular cloud
• Evidence for Large Grains in the Star-forming Filament OMC-2/3
• ALMA Observations of Starless Core Substructure in Ophiuchus
• SMA and Spitzer Observations of Bok Glouble CB17: A Candidate First Hydrostatic Core?
• Observational Characteristics of the First Protostellar Cores
• Chemistry in the First Hydrostatic Core Stage By Adopting Three-Dimensional Radiation Hydrodynamic Simulations
• Characterizing the Youngest Herschel-detected Protostars I. Envelope Structure Revealed by CARMA Dust Continuum Observations
• Herschel survey of brown dwarf disks in Rho Ophiuchi
• Initial conditions for star formation in clusters: physical and kinematical structure of the starless core Oph A-N6
• Synthetic observations of first hydrostatic cores in collapsing low-mass dense cores II. Simulated ALMA dust emission maps
• Extremely Dense Cores associated with Chandra Sources in Ophiuchus A: Forming Brown Dwarfs Unveiled?
• Kinematics of a young low-mass star forming core: Understanding the evolutionary state of the First Core Candidate L1451-mm
• Gravitational instabilities in a protosolar-like disc II: continuum emission and mass estimates
• Submillimeter Observations of the Quiescent Core - Ophiuchus A-N6

Cited by in corpus (21)

• Dust Polarization Toward Embedded Protostars in Ophiuchus with ALMA. III. Survey Overview
• The central 1000 AU of a pre-stellar core revealed with ALMA. I. 1.3 mm continuum observations
• Density profile evolution during prestellar core collapse: Collapse starts at the large scale
• The JCMT BISTRO survey: alignment between outflows and magnetic fields in dense cores/clumps
• The Green Bank Ammonia Survey: A Virial Analysis of Gould Belt Clouds in Data Release 1
• Missing water in Class I protostellar disks
• ALMA observations of envelopes around first hydrostatic core candidates
• VLA cm-wave survey of young stellar objects in the Oph A cluster: constraining extreme UV- and X-ray-driven disk photo-evaporation -- A pathfinder for Square Kilometre Array studies
• Synthetic molecular line observations of the first hydrostatic core from chemical calculations
• CO Outflow Candidates Toward the W3/4/5 Complex I: The Sample and its Spatial Distribution
• FAUST. XVIII. Evidence for annular substructure in a very young Class 0 disk
• Mapping the H${}_2$D${}^{+}$ and N${}_2$H${}^{+}$ emission towards prestellar cores. Testing dynamical models of the collapse using gas tracers
• Early Planet Formation in Embedded Disks (eDisk) XVI: An asymmetric dust disk driving a multi-component molecular outflow in the young Class 0 protostar GSS30 IRS3
• The distribution of ionized, atomic and PDR gas around S1 in Rho Ophiuchus
• VLA and NOEMA view of the Bok Globule CB 17: the starless nature of a proposed FHSC candidate
• UV-irradiated outflows from low-mass protostars in Ophiuchus with JWST/MIRI
• Insights into the first and second hydrostatic core stages from numerical simulations
• FAUST. XXVIII. High-Resolution ALMA Observations of Class 0/I Disks: Structure, Optical Depths, and Temperatures
• Modeling Two First Hydrostatic Core Candidates Barnard 1b-N and 1b-S
• Millimetre continuum from LBV stars and their environs. NIKA2 observations and Virtual Observatory data
• Exploring the 100 au Scale Structure of the Protobinary System NGC 2264 CMM3 with ALMA