Physical properties of accretion shocks toward the Class I protostellar system Oph-IRS 44

Abstract

(Abridged) Physical processes such as accretion shocks are thought to be common in the protostellar phase, where the envelope component is still present, and they can release molecules from the dust to the gas phase, altering the original chemical composition of the disk. Consequently, the study of accretion shocks is essential for a better understanding of the physical processes at disk scales and their chemical output. The purpose of this work is to assess the characteristics of accretion shocks traced by sulfur-related species. We present ALMA high angular resolution observations (0.1") of the Class I protostar Oph-IRS 44. The continuum emission at 0.87 mm is observed, together with sulfur-related species such as SO, SO${}_2$, and ${}^{34}$SO${}_2$. Six lines of SO${}_2$, two lines of ${}^{34}$SO${}_2$, and one line of SO are detected toward IRS 44. The emission of all the detected lines peaks at ~0.1" (~14 au) from the continuum peak and we find infalling-rotating motions inside 30 au. However, only redshifted emission is seen between 50 and 30 au. Colder and more quiescent material is seen toward an offset region located at a distance of ~400 au from the protostar, and we do not find evidence of a Keplerian profile in these data. Accretion shocks are the most plausible explanation for the high temperatures, high densities, and velocities found for the SO${}_2$ emission. When material enters the disk--envelope system, it generates accretion shocks that increase the dust temperature and desorb SO${}_2$ molecules from dust grains. High-energy SO${}_2$ transitions (~200 K) seem to be the best tracers of accretion shocks that can be followed up by future higher angular resolution ALMA observations and compared to other species to assess their importance in releasing molecules from the dust to the gas phase.

arXiv comment16 pages, 16 figures

References in corpus (55)

• A computer program for fast non-LTE analysis of interstellar line spectra
• The Spitzer c2d Legacy Results: Star Formation Rates and Efficiencies; Evolution and Lifetimes
• Interpreting Spectral Energy Distributions from Young Stellar Objects. I. A grid of 200,000 YSO model SEDs
• Tracing the Mass during Low-Mass Star Formation. II. Modelling the Submillimeter Emission from Pre-Protostellar 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
• TADPOL: A 1.3 mm Survey of Dust Polarization in Star-forming Cores and Regions
• Dust masses of young disks: constraining the initial solid reservoir for planet formation
• Nonideal MHD Effects and Magnetic Braking Catastrophe in Protostellar Disk Formation
• A molecular survey of outflow gas: velocity-dependent shock chemistry and the peculiar composition of the EHV gas
• Compression and ablation of the photo-irradiated cloud the Orion Bar
• Current Star Formation in the Ophiuchus and Perseus Molecular Clouds: Constraints and Comparisons from Unbiased Submillimeter and Mid-Infrared Surveys. II
• Rotationally-supported disks around Class I sources in Taurus: disk formation constraints
• The structure and stability of molecular cloud cores in external radiation fields
• ALMA discovery of a rotating SO/SO${}_2$ flow in HH212. A possible MHD disk wind?
• Molecule survival in magnetized protostellar disk winds. I. Chemical model and first results
• Sensitivity analysis of grain surface chemistry to binding energies of ice species
• Spitzer IRS Observations of Class I/II Objects in Taurus: Composition and Thermal History of the Circumstellar Ices
• Multiple protostellar systems. II. A high resolution near-infrared imaging survey in nearby star-forming regions
• ALMA chemical survey of disk-outflow sources in Taurus (ALMA-DOT) VI: Accretion shocks in the disk of DG Tau and HL Tau
• Evidence for the start of planet formation in a young circumstellar disk
• Self-similar Collapse of Rotating Magnetic Molecular Cloud Cores
• ALMA Results of the Pseudodisk, Rotating disk, and Jet in Continuum and HCO+ in the Protostellar System HH 212
• ALMA Observations of the HH 46/47 Molecular Outflow
• A new study of an old sink of sulfur in hot molecular cores: the sulfur residue
• HST/NICMOS Imaging Survey of the Ophiuchus (Lynds 1688) Cluster
• Cloudlet capture by Transitional Disk and FU Orionis stars
• Observations of Infalling and Rotational Motions on a 1,000-AU Scale around 17 Class 0 and 0/I Protostars: Hints of Disk Growth and Magnetic Braking?
• On the reliability of protostellar disc mass measurements and the existence of fragmenting discs
• Subarcsecond resolution observations of warm water towards three deeply embedded low-mass protostars
• A Substellar-Mass Protostar and its Outflow of IRAS 15398-3359 Revealed by Subarcsecond-Resolution Observations of H${}_2$CO and CCH
• Dust Polarization Toward Embedded Protostars in Ophiuchus with ALMA. III. Survey Overview
• The Herschel-PACS legacy of low-mass protostars: Properties of warm and hot gas and its origin in far-UV illuminated shocks
• Outflow forces of low mass embedded objects in Ophiuchus: a quantitative comparison of analysis methods
• Molecular outflow launched beyond the disk edge
• The Hall effect in star formation
• A deeply embedded young protoplanetary disk around L1489 IRS observed by the submillimeter array
• ALMA observations of the kinematics and chemistry of disc formation
• Physical and chemical fingerprint of protostellar disc formation
• Revealing the dynamics of Class 0 protostellar discs with ALMA
• Water and methanol in low-mass protostellar outflows: gas-phase synthesis, ice sputtering and destruction
• Modeling accretion shocks at the disk-envelope interface -- Sulfur chemistry
• Subarcsecond Analysis of Infalling-Rotating Envelope around the Class I Protostar IRAS 04365+2535
• A census of $\rho$ Oph candidate members from Gaia DR2
• Disk structure around the Class I protostar L1489 IRS revealed by ALMA: a warped disk system
• Observational evidence for dissociative shocks in the inner 100 AU of low-mass protostars using Herschel-HIFI
• Synthetic Observations of Magnetic Fields in Protostellar Cores
• Origin of Misalignments: Protostellar Jet, Outflow, Circumstellar Disc, and Magnetic Field
• Chemistry of a newly detected circumbinary disk in Ophiuchus
• A young bipolar outflow from IRAS 15398-3359
• Importance of source structure on complex organics emission. I. Observations of CH${}_3$OH from low-mass to high-mass protostars
• Importance of source structure on complex organics emission II. Can disks explain lack of methanol emission from some low-mass protostars?
• Sub-arcsecond Kinematic Structure of the Outflow in the Vicinity of the Protostar in L483
• Resolved molecular line observations reveal an inherited molecular layer in the young disk around TMC1A
• Externally heated protostellar cores in the Ophiuchus star-forming region
• Cloudlet Capture Model for Asymmetric Molecular Emission Lines Observed in TMC-1A with ALMA

Cited by in corpus (7)

• JWST Observations of Young protoStars (JOYS): overview of program and early results
• The Perseus ALMA Chemical Survey (PEACHES). III. Sulfur-bearing species tracing accretion and ejection processes in young protostars
• Molecular Mapping of DR Tau's Protoplanetary Disk, Envelope, Outflow, and Large-Scale Spiral Arm
• Anatomy of the Class I protostar L1489 IRS with NOEMA -- I. Disk, streamers, outflow(s) and bubbles at 3mm
• PRODIGE VI -- Envelope to Disk with NOEMA: VI. The Missing Sulfur Problem
• Sulfur oxides tracing streamers and shocks at low mass protostellar disk-envelope interfaces
• The environmental imprint on molecular layering in the dusty streamer of M512