Sudden extreme obscuration of a Sun-like main-sequence star: evolution of the circumstellar dust around ASASSN-21qj

Abstract

ASASSN-21qj is a distant Sun-like star that recently began an episode of deep dimming events after no prior recorded variability. Here we examine archival and newly obtained optical and near-infrared data of this star. The deep aperiodic dimming and absence of previous infrared excess are reminiscent of KIC 8462852 (``Boyajian's Star''). The observed occultations are consistent with a circumstellar cloud of sub-micron-sized dust grains composed of amorphous pyroxene, with a minimum mass of $1.50\pm 0.04\times 10^{-9}{M}_{\oplus }$ derived from the deepest occultations, and a minimum grain size of $0.29_{-0.18}^{+0.01}\mu$m assuming a power law size distribution. We further identify the first evidence of near-infrared excess in this system from NEOWISE 3.4 and 4.6~$\mu$m observations. The excess emission implies a total circumstellar dust mass of around $10^{-6}{M}_{\oplus }$, comparable to the extreme, variable discs associated with terrestrial planet formation around young stars. The quasiperiodic recurrence of deep dips and the inferred dust temperature (ranging from 1800 to 700~K across the span of observations) independently point to an orbital distance of $\simeq$0.2~au for the dust, supporting the occulting material and excess emission being causally linked. The origin of this extended, opaque cloud is surmised to be the breakup of one or more exocometary bodies.

arXiv comment14 pages, 6 figures, 1 table, published in ApJ

References in corpus (62)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• Astropy: A Community Python Package for Astronomy
• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• The Man Behind the Curtain: X-rays Drive the UV through NIR Variability in the 2013 AGN Outburst in NGC 2617
• Disk Frequencies and Lifetimes in Young Clusters
• ATLAS: A High-Cadence All-Sky Survey System
• Las Cumbres Observatory Global Telescope Network
• The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0
• Initial Performance of the NEOWISE Reactivation Mission
• Scattering by Interstellar Dust Grains: Optical and Ultraviolet
• A First Catalog of Variable Stars Measured by the Asteroid Terrestrial-impact Last Alert System (ATLAS)
• Debris Disks: Structure, Composition, and Variability
• Planet Hunters X. KIC 8462852 - Where's the Flux?
• Protoplanetary disk lifetimes vs stellar mass and possible implications for giant planet populations
• Real-time processing of the imaging data from the network of Las Cumbres Observatory Telescopes using BANZAI
• YSOVAR: the first sensitive, wide-area, mid-IR photometric monitoring of the ONC
• HYPERION: An open-source parallelized three-dimensional dust continuum radiative transfer code
• Spitzer observations of the Orion OB1 association: disk census in the low mass stars
• Debris Disks: Seeing Dust, Thinking of Planetesimals and Planets
• Accretion dynamics and disk evolution in NGC 2264: a study based on the Corot photometric observations
• Circumstellar material in the Vega inner system revealed by CHARA/FLUOR
• A near-infrared interferometric survey of debris disc stars. III. First statistics based on 42 stars observed with CHARA/FLUOR
• Five steps in the evolution from protoplanetary to debris disk
• A near-infrared interferometric survey of debris-disc stars. IV. An unbiased sample of 92 southern stars observed in H-band with VLTI/PIONIER
• KIC 8462852: Transit of a Large Comet Family
• Planetary Collisions outside the Solar System: Time Domain Characterization of Extreme Debris Disks
• Are Inner Disc Misalignments Common? ALMA Reveals an Isotropic Outer Disc Inclination Distribution for Young Dipper Stars
• A near-infrared interferometric survey of debris-disc stars. V. PIONIER search for variability
• Families of Plausible Solutions to the Puzzle of Boyajian's Star
• The First Post-Kepler Brightness Dips of KIC 8462852
• KIC 8462852 Faded Throughout the Kepler Mission
• Dipper disks not inclined towards edge-on orbits
• Identification of Young Stellar Variables with KELT for K2 I: Campaign 13 Taurus Dippers and Rotators
• Extreme Debris Disk Variability -- Exploring the Diverse Outcomes of Large Asteroid Impacts During the Era of Terrestrial Planet Formation
• Exocomets from a Solar System Perspective
• Modelling the KIC8462852 light curves: compatibility of the dips and secular dimming with an exocomet interpretation
• Accurate parameters for HD 209458 and its planet from HST spectrophotometry
• Testing Models of Stellar Structure and Evolution I. Comparison with Detached Eclipsing Binaries
• KIC 8462852: Will the Trojans return in 2021?
• New exocomets of $\beta$ Pic
• Constraints on the structure of hot exozodiacal dust belts
• Deep Long Asymmetric Occultation in EPIC 204376071
• Extinction and the Dimming of KIC 8462852
• The peculiar dipping events in the disk-bearing young-stellar object EPIC 204278916
• An automated search for transiting exocomets
• The Random Transiter -- EPIC 249706694/HD 139139
• The Mysterious Dimmings of the T Tauri Star V1334 Tau
• Mid-infrared Studies of HD 113766 and HD 172555: Assessing Variability in the Terrestrial Zone of Young Exoplanetary Systems
• A near-infrared interferometric survey of debris-disk stars. VII. The hot/warm dust connection
• Detection of a repeated transit signature in the light curve of the enigma star KIC 8462852: a 928-day period?
• The Little Dippers: Transits of Star-grazing Exocomets?
• The ASAS-SN Catalog of Variable Stars VIII: "Dipper" Stars in the Lupus Star-Forming Region
• A Population of Dipper Stars from the Transiting Exoplanet Survey Satellite Mission
• A Star-sized Impact-Produced Dust Clump in the Terrestrial Zone of the HD 166191 System
• Non-grey dimming events of KIC 8462852 from GTC spectrophotometry
• Highly structured inner planetary system debris around the intermediate age Sun-like star TYC 8830 410 1
• Recent Photometric Monitoring of KIC 8462852, the Detection of a Potential Repeat of the Kepler Day 1540 Dip and a Plausible Model
• Non-gray, Month-long Brightening of KIC 8462852 in the Immediate Aftermath of a Deep Dip

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