Characterizing and spectrally modeling embedded FUor eruptions in the near-infrared

Abstract

Context. Episodic accretion in young stellar objects (YSOs) is thought to play a critical role in addressing the "luminosity problem" associated with star formation. However, optical surveys tend to bias against sources that are heavily obscured. Infrared time-domain surveys, such as unTimely WISE, facilitate the identification of such sources within the dense star formation regions of our Galaxy. Aims. We aim to systematically identify and characterize FUor outbursts in infrared-selected YSOs using high-resolution spectroscopy and detailed disk modeling. Methods. We conducted follow-up high-resolution spectroscopy with Gemini South/IGRINS for four FUor candidates discovered in infrared time-domain surveys. Using a combination of photometric and spectroscopic observations, we constructed spectral energy distributions and fit them with a disk model that incorporates an actively accreting inner disk together with a passively irradiated outer disk. Results. All objects show CO and H${}_2$O absorption bands at 2.3$\mu$m, and their positions in the Na + Ca versus CO equivalent width diagram further corroborate their classification as FUors. The best-fitting model spectra closely match both the observed spectral features and the overall continuum, providing additional confirmation of the FUor classification. The best-fit models reveal high extinction values ($A_V$ = 10-20 mag), with $M_{\ast }\dot{M}$ comparable to those of classical FUors such as FU Orionis. Among 18 sources initially selected via infrared light curves, $6-$7 out of 8 with available spectra exhibit FUor characteristics, implying a high selection efficiency.

arXiv comment18 pages, 15 figures; accepted for publication in A&A

References in corpus (41)

• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• Gaia Data Release 3: Summary of the content and survey properties
• Correcting for the Effects of Interstellar Extinction
• The Spitzer Space Telescope Mission
• The SIMBAD astronomical database
• The Spitzer c2d Legacy Results: Star Formation Rates and Efficiencies; Evolution and Lifetimes
• Trigonometric Parallaxes of High Mass Star Forming Regions: the Structure and Kinematics of the Milky Way
• VISTA Variables in the Via Lactea (VVV): The public ESO near-IR variability survey of the Milky Way
• Preliminary Results from NEOWISE: An Enhancement to the Wide-field Infrared Survey Explorer for Solar System Science
• Interpreting Spectral Energy Distributions from Young Stellar Objects. I. A grid of 200,000 YSO model SEDs
• Initial Performance of the NEOWISE Reactivation Mission
• The ASAS-SN Catalog of Variable Stars I: The Serendipitous Survey
• The unWISE Catalog: Two Billion Infrared Sources from Five Years of WISE Imaging
• The Burst Mode of Protostellar Accretion
• The APOGEE-2 Survey of the Orion Star Forming Complex II: Six-dimensional structure
• YSOVAR: the first sensitive, wide-area, mid-IR photometric monitoring of the ONC
• Evolutionary Signatures in the Formation of Low-Mass Protostars. II. Towards Reconciling Models and Observations
• A Near-IR Spectroscopic Survey of FU Orionis Objects
• The Hot Inner Disk of FU Ori
• A modular set of synthetic spectral energy distributions for young stellar objects
• Accretion Outbursts in Self-gravitating Protoplanetary Disks
• Kinematic Distances: A Monte Carlo Method
• Milky Way Mid-Infrared Spitzer Spectroscopic Extinction Curves: Continuum and Silicate Features
• A population of eruptive variable protostars in VVV
• Quantifying Variability of YSOs in the Mid-IR Over Six Years with NEOWISE
• Gaia 17bpi: An FU Ori Type Outburst
• Global 3-D Radiation Magnetohydrodynamic Simulations for FU Ori's Accretion Disk and Observational Signatures of Magnetic Fields
• unTimely: a Full-sky, Time-Domain unWISE Catalog
• Resolving the FU Ori System with ALMA: Interacting Twin Disks?
• Disk-Related Bursts and Fades in Young Stars
• Diagnosing FUor-like Sources: The Parameter Space of Viscously Heated Disks in the Optical and Near-IR
• Analysis of physical processes in eruptive YSOs with near infrared spectra and multi-wavelength light curves
• The SPHEREx Satellite Mission
• Application of a Steady-State Accretion Disk Model to Spectrophotometry and High-Resolution Spectra of Two Recent FU Ori Outbursts
• Discovery of a mid-infrared protostellar outburst of exceptional amplitude
• Spectroscopic confirmation of high-amplitude eruptive YSOs and dipping giants from the VVV survey
• Modeling the Multiwavelength Evolution of the V960 Mon System
• The most variable VVV sources: eruptive protostars, dipping giants in the Nuclear Disc and others
• Multi-wavelength detection of an ongoing FUOr-type outburst on a low-mass YSO
• 10 Years of Archival High-Resolution NIR Spectra: The Raw and Reduced IGRINS Spectral Archive (RRISA)
• Gaia20bdk -- a new FUor in Sh 2-301 Star Forming Region