On the incidence of episodic accretion in Class I YSOs from VVV

Abstract

Episodic accretion is one of the competing models to explain the observed luminosity spread in young stellar clusters. These short-lived high accretion events could also have a strong impact on planet formation. Observations of high-amplitude variability in young stellar objects (YSOs) due to large changes in the accretion rate provide direct observational evidence for episodic accretion. However, there are still uncertainties in the frequency of these events and if episodic accretion is universal among YSOs. To determine the frequency of outbursts in Class I YSOs, we built a large and robust sample of objects at this evolutionary stage, and searched for high-amplitude near-infrared ($\Delta K_{\mathrm{S}}>2$~mag) variability in the VIRAC2 database of the Vista Variables in the Via Lactea (VVV) survey. By complementing with near-IR (2MASS and DENIS) and mid-IR (WISE/Neo-WISE) data, we find that from $\sim$ 7000 Class I YSOs, 97 objects can be classified as eruptive variable YSOs. The duration of the outbursts vary from a few months to longer than 9 years, and cover a similar range of amplitudes. Values of $\Delta K_{\mathrm{S}}>5$~mag, however, are only observed in outbursts with duration longer than 9 years. When considering different effects of completeness and contamination we estimate that the incidence of episodic accretion in Class I YSOs is between 2\% and 3\%. Finally, we determine a recurrence timescale of long-term outbursts (a.k.a FUors) of $\tau =1.75_{-0.87}^{+1.12}$~kyr. The latter value agrees with previous estimates and is in line with the expectations of higher frequency of FUor outbursts during younger stages of evolution.

17 pages, 12 figures. Accepted for publication at MNRAS

References in corpus (40)

• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• A Spitzer Survey of Young Stellar Clusters within One Kiloparsec of the Sun: Cluster Core Extraction and Basic Structural Analysis
• The UKIDSS Galactic Plane Survey
• The Optical to Mid-Infrared Extinction Law Based on the APOGEE, Gaia DR2, Pan-STARRS1, SDSS, APASS, 2MASS and WISE Surveys
• Intrinsically Red Sources observed by Spitzer in the Galactic Mid-Plane
• Imaging the water-snow line during a protostellar outburst
• Variable protostellar accretion with episodic bursts
• Accretion to Magnetized Stars through the Rayleigh-Taylor Instability: Global Three-Dimensional Simulations
• A Classification Scheme for Young Stellar Objects Using the WIDE-FIELD INFRARED SURVEY EXPLORER AllWISE Catalog: Revealing Low-Density Star Formation in the Outer Galaxy
• VIRAC: The VVV Infrared Astrometric Catalogue
• A 24 Micron Point Source Catalog of the Galactic Plane from Spitzer/MIPSGAL
• Accretion Outbursts in Self-gravitating Protoplanetary Disks
• SPICY: The Spitzer/IRAC Candidate YSO Catalog for the Inner Galactic Midplane
• Molecule sublimation as a tracer of protostellar accretion: Evidence for accretion bursts from high angular resolution C18O images
• Quantifying Variability of YSOs in the Mid-IR Over Six Years with NEOWISE
• The ALMA early science view of FUor/EXor objects - V: continuum disc masses and sizes
• A continuum of accretion burst behavior in young stars observed by K2
• Self-consistent evolution of accreting low-mass stars and brown dwarfs
• Physical and chemical fingerprint of protostellar disc formation
• Determining the recurrence timescale of long-lasting YSO outbursts
• Constraining the Rate of Protostellar Accretion Outbursts in the Orion Molecular Clouds
• JWST/MIRI Spectroscopy of the Disk of the Young Eruptive Star EX Lup in Quiescence
• Outbursts in Global Protoplanetary Disk Simulations
• The Rate, Amplitude and Duration of Outbursts from Class 0 Protostars in Orion
• A likely flyby of binary protostar Z CMa caught in action
• Young Faithful: The Eruptions of EC 53 as It Cycles through Filling and Draining the Inner Disk
• Massive compact disks around FU Orionis-type young eruptive stars revealed by ALMA
• Extreme infrared variables from UKIDSS - II. an end-of-survey catalogue of eruptive YSOs and unusual stars
• Short and long term near-infrared spectroscopic variability of eruptive protostars from VVV
• Analysis of physical processes in eruptive YSOs with near infrared spectra and multi-wavelength light curves
• A Differential Measurement of Circumstellar Extinction for AA Tau's 2011 Dimming Event
• Protoplanetary dust porosity and FU Orionis Outbursts: Solving the mystery of Earth's missing volatiles
• Spectral evolution and radial dust transport in the prototype young eruptive system EX Lup
• Large amplitude periodic outbursts and long period variables in the VVV VIRAC2-$\beta$ database
• Embedded Stellar Populations towards Young Massive Star Formation Regions I. G305.2+0.2
• YSO jets in the Galactic Plane from UWISH2: IV - Jets and outflows in Cygnus-X
• YSO jets in the Galactic Plane from UWISH2: III - Jets and Outflows in Cassiopeia and Auriga
• Migrating Planets into Ultra-Short-Period Orbits during Episodic Accretion Events
• Turbulence and its connection to episodic accretion in binary YSOs
• The Accretion History of EX Lup: A Century of Bursts, Outbursts, and Quiescence

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• Multi-wavelength detection of an ongoing FUOr-type outburst on a low-mass YSO
• The Role of Thermal Instability in Accretion Outbursts in High-Mass Stars
• Gaia20bdk -- a new FUor in Sh 2-301 Star Forming Region
• The youngest of hot jupiters in action: episodic accretion outbursts in Gaia20eae
• VVV-WIT-13: an eruptive young star with cool molecular features