Dancing on the Grain: Variety of CO and its isotopologue fluxes as a result of surface chemistry and T Tauri disk properties

Abstract

At the moment, one of the main ways to infer the disk mass is to use a combination of CO isotopologue line observations. A number of theoretical studies have concluded that CO must be a reliable gas tracer as its relative abundance depends on disk parameters only weakly. However, the observed line fluxes cannot always be easily used to infer the column density, much less the abundance of CO. The aim of this work is to study the dependence of the CO isotopologue millimeter line fluxes on the astrochemical model parameters of a standard protoplanetary disk around a T Tauri star and to conclude whether they or their combinations can be reliably used to determine disk parameters. Our case is set apart from earlier studies in the literature by the usage of a comprehensive chemical network with grain surface chemistry together with line radiative transfer. We use the astrochemical model ANDES together with the radiative transfer code RADMC-3D to simulate CO isotopologue line fluxes from a set of disks with varying key parameters (disk mass, disk radius, stellar mass, and inclination). We study how these values change with one parameter varying and others fixed and approximate the dependences log-linearly. We describe the dependences of CO isotopologue fluxes on all chosen disk parameters. Physical and chemical processes responsible for these dependences are analyzed and explained for each parameter. We show that using a combination of the ${}^{13}$CO and C${}^{18}$O line fluxes, the mass can be estimated only within two orders of magnitude uncertainty and characteristic radius within one order of magnitude uncertainty. We find that inclusion of grain surface chemistry reduces ${}^{13}$CO and C${}^{18}$O fluxes which can explain the underestimation of disk mass in the previous studies.

arXiv comment17 pages, 12 figures, 3 tables. Accepted to A&A

References in corpus (42)

• An atomic and molecular database for analysis of submillimetre line observations
• Protoplanetary Disks and Their Evolution
• Circumstellar Dust Disks in Taurus-Auriga: The Submillimeter Perspective
• ALMA Survey of Lupus Protoplanetary Disks I: Dust and Gas Masses
• The photodissociation and chemistry of CO isotopologues: applications to interstellar clouds and circumstellar disks
• The 2014 KIDA network for interstellar chemistry
• An Old Disk That Can Still Form a Planetary System
• Extrasolar planet population synthesis IV. Correlations with disk metallicity, mass and lifetime
• An ALMA Survey of Protoplanetary Disks in the $\sigma$ Orionis Cluster
• A Parametric Modeling Approach to Measuring the Gas Masses of Circumstellar Disks
• Protoplanetary disk masses from CO isotopologues line emission
• A Significantly Low CO Abundance Toward the TW Hya Protoplanetary Disk: A Path to Active Carbon Chemistry?
• Chemical evolution of turbulent protoplanetary disks and the Solar nebula
• Cosmic-ray ionisation in circumstellar discs
• Mass measurements in protoplanetary disks from hydrogen deuteride
• Setting the volatile composition of (exo)planet-building material. Does chemical evolution in disk midplanes matter?
• Physical properties of dusty protoplanetary disks in Lupus: evidence for viscous evolution?
• Determining protoplanetary disk gas masses from CO isotopologues line observations
• CO Depletion in Protoplanetary Disks: A Unified Picture Combining Physical Sequestration and Chemical Processing
• CO destruction in protoplanetary disk midplanes: inside versus outside the CO snow surface
• Systematic Variations of CO Gas Abundance with Radius in Gas-rich Protoplanetary Disks
• ALMA Observations of a Gap and a Ring in the Protoplanetary Disk around TW Hya
• Protoplanetary Disk Structure With Grain Evolution: the ANDES Model
• Volatile snowlines in embedded disks around low-mass protostars
• HD far infrared emission as a measure of protoplanetary disk mass
• Herschel-PACS observation of the 10 Myr old T Tauri disk TW Hya: Constraining the disk gas mass
• Chemical Modelling of Young Stellar Objects, I. Method and Benchmarks
• Probing CO and N${}_2$ Snow Surfaces in Protoplanetary Disks with N${}_2$H${}^{+}$ Emission
• Chemical Signatures of the FU Ori Outbursts
• Mass constraints for 15 protoplanetary disks from HD 1-0
• Chemically tracing the water snowline in protoplanetary disks with HCO${}^{+}$
• A novel way of measuring the gas disk mass of protoplanetary disks using N2H+ and C18O
• Gas mass tracers in protoplanetary disks: CO is still the best
• An ALMA Survey of Protoplanetary Disks in Lynds 1641
• Chemical Feedbacks of Pebble Growth: Impacts on CO depletion and C/O ratios
• C${}^{18}$O emission as an effective measure of gas masses of protoplanetary disks
• Depletion of gaseous CO in protoplanetary disks by surface-energy-regulated ice formation
• An ALMA Survey of Chemistry in Disks around M4-M5 Stars
• ALMA reveals thermal and non-thermal desorption of methanol ice in the HD 100546 protoplanetary disk
• Weighing protoplanetary discs with kinematics: physical model, method and benchmark
• PRODIGE -- Planet-forming disks in Taurus with NOEMA. I. Overview and first results for 12CO, 13CO, and C18O
• Evidence for a Sharp CO Snowline Transition in a Protoplanetary Disk and Implications for Millimeter-wave Observations of CO Isotopologues

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