First direct detection of a polarized companion outside of a resolved circumbinary disk around CS Cha

Abstract

In the present study we aim to investigate the circumstellar environment of the spectroscopic binary T Tauri star CS Cha. From unresolved mid- to far-infrared photometry it is predicted that CS Cha hosts a disk with a large cavity. In addition, SED modeling suggests significant dust settling, pointing towards an evolved disk that may show signs of ongoing or completed planet formation. We observed CS Cha with the high contrast imager VLT/SPHERE in polarimetric differential imaging mode to resolve the circumbinary disk in near infrared scattered light. These observations were followed-up by VLT/NACO L-band observations and complemented by archival VLT/NACO K-band and HST/WFPC2 I-band data. We resolve the compact circumbinary disk around CS Cha for the first time in scattered light. We find a smooth, low inclination disk with an outer radius of $\sim$55 au (at 165 pc). We do not detect the inner cavity but find an upper limit for the cavity size of $\sim$15 au. Furthermore, we find a faint co-moving companion with a projected separation of 210 au from the central binary outside of the circumbinary disk. The companion is detected in polarized light and shows an extreme degree of polarization (13.7$\pm$0.4 \% in J-band). The companion's J- and H-band magnitudes are compatible with masses of a few M${}_{\mathrm{Jup}}$. However, K-, L- and I-band data draw this conclusion into question. We explore with radiative transfer modeling whether an unresolved circum-companion disk can be responsible for the high polarization and complex photometry. We find that the set of observations is best explained by a heavily extincted low mass ($\sim 20{\mathrm{M}}_{\mathrm{Jup}}$) brown dwarf or high mass planet with an unresolved disk and dust envelope.

arXiv comment19 pages, 15 figures, accepted for publication in A&A as of 27.04.2018

References in corpus (63)

• Dust Grain Size Distributions and Extinction in the Milky Way, LMC, and SMC
• Disk Frequencies and Lifetimes in Young Clusters
• Evolutionary models for very-low-mass stars and brown dwarfs with dusty atmospheres
• First Results from High Angular Resolution ALMA Observations Toward the HL Tau Region
• The Limiting Effects of Dust in Brown Dwarf Model Atmospheres
• Star counts in the Galaxy. Simulating from very deep to very shallow photometric surveys with the TRILEGAL code
• Ringed Substructure and a Gap at 1 AU in the Nearest Protoplanetary Disk
• Stellar, brown dwarf and multiple star properties from a radiation hydrodynamical simulation of star cluster formation
• Analysis of isoplanatic high resolution stellar fields by Starfinder code
• Spiral Density Waves in a Young Protoplanetary Disk
• On the diversity and statistical properties of protostellar discs
• Asymmetric features in the protoplanetary disk MWC758
• Spiral Arms in the Asymmetrically Illuminated Disk of MWC 758 and Constraints on Giant Planets
• Three radial gaps in the disk of TW Hydrae imaged with SPHERE
• Shadows and spirals in the protoplanetary disk HD 100453
• The Disk Population of the Chamaeleon I Star-Forming Region
• Discovery of a warm, dusty giant planet around HIP65426
• A Spitzer IRS Study of Infrared Variability in Transitional and Pre-Transitional Disks around T Tauri Stars
• Close Companions to Young Stars. I. A Large Spectroscopic Survey in Chamaeleon I and Taurus-Auriga
• HD 106906 b: A planetary-mass companion outside a massive debris disk
• On the gas content of transitional disks: a VLT/X-Shooter study of accretion and winds
• A library of near-infrared integral field spectra of young M-L dwarfs
• Consistent simulations of substellar atmospheres and non-equilibrium dust-cloud formation
• Imaging Polarimetric Observations of a New Circumstellar Disk System
• HD 203030B: an Unusually Cool Young Sub-Stellar Companion near the L/T Transition
• Direct detection of scattered light gaps in the transitional disk around HD 97048 with VLT/SPHERE
• High Orbital Eccentricities of Extrasolar Planets Induced by the Kozai Mechanism
• Three Wide Planetary-Mass Companions to FW Tau, ROXs 12, and ROXs 42B
• Planetary Construction Zones in Occultation: Discovery of an Extrasolar Ring System Transiting a Young Sun-like Star and Future Prospects for Detecting Eclipses by Circumsecondary and Circumplanetary Disks
• The Southern Proper Motion Program IV. The SPM4 Catalog
• Probing the Dust and Gas in the Transitional Disk of CS Cha with Spitzer
• Misaligned Disks in the Binary Protostar IRS 43
• Pre-main sequence spectroscopic binaries suitable for VLTI observations
• Multiplicity in transiting planet host stars. A Lucky Imaging study of Kepler candidates
• Direct evidence of a sub-stellar companion around CT Cha
• A cavity and further radial substructures in the disk around HD~97048
• Discovery of a Two-Armed Spiral Structure in the Gapped Disk in HD 100453
• Design, analysis and test of a microdots apodizer for the Apodized Pupil Lyot Coronagraph
• SPHERE IRDIS and IFS astrometric strategy and calibration
• Non-azimuthal linear polarization in protoplanetary disks
• Astrometric follow-up observations of directly imaged sub-stellar companions to young stars and brown dwarfs
• Variable dynamics in the inner disk of HD 135344B revealed with multi-epoch scattered light imaging
• Optical Linear Polarization of Late M- and L-Type Dwarfs
• ALMA reveals the anatomy of the mm-sized dust and molecular gas in the HD 97048 disk
• An ALMA Search for Substructure, Fragmentation, and Hidden Protostars in Starless Cores in Chamaeleon I
• An ALMA Disk Mass for the Candidate Protoplanetary Companion to FW Tau
• Low EUV Luminosities Impinging on Protoplanetary Disks
• Optical Linear Polarimetry of Ultra Cool Dwarfs
• Polarized scattered light from self-luminous exoplanets. Three-dimensional scattering radiative transfer with ARTES
• Probing Dust in the Atmosphere of Brown Dwarfs Through Polarization
• Resolving faint structures in the debris disk around TWA7
• A revised estimate of the distance to the clouds in the Chamaeleon complex using the Tycho-Gaia Astrometric Solution
• New constraints on the disk characteristics and companion candidates around T Cha with VLT/SPHERE
• Mass and period limits on the ringed companion transiting the young star J1407
• Point Source Polarimetry with the Gemini Planet Imager: Sensitivity Characterization with T5.5 Dwarf Companion HD 19467 B
• Linear polarization of rapidly rotating ultracool dwarfs
• New Extinction and Mass Estimates from Optical Photometry of the Very Low Mass Brown Dwarf Companion CT Chamaeleontis B with the Magellan AO System
• A survey for planetary-mass brown dwarfs in the Chamaeleon I star-forming region
• Astrometric confirmation of young low-mass binaries and multiple systems in the Chamaeleon star-forming regions
• DZ Cha: a bona fide photoevaporating disc
• Deep search for companions to probable young brown dwarfs
• Constraining the properties of transitional disks in Chamaeleon I with Herschel
• Direct Imaging discovery of a second planet candidate around the possibly transiting planet host CVSO 30

Cited by in corpus (27)

• SPHERE: the exoplanet imager for the Very Large Telescope
• The polarimetric imaging mode of VLT/SPHERE/IRDIS II: Characterization and correction of instrumental polarization effects
• Evolution of protoplanetary disks from their taxonomy in scattered light: spirals, rings, cavities, and shadows
• The Degree of Alignment Between Circumbinary Disks and Their Binary Hosts
• The Evolution of Disk Winds from a Combined Study of Optical and Infrared Forbidden Lines
• A survey of the linear polarization of directly imaged exoplanets and brown dwarf companions with SPHERE-IRDIS. First polarimetric detections revealing disks around DH Tau B and GSC 6214-210 B
• Kinematics and brightness temperatures of transition discs -- A survey of gas substructures as seen with ALMA
• Protoplanetary disks in $K_s$-band total intensity and polarized light
• The Giant Accreting Protoplanet Survey (GAPlanetS) -- Results from a Six Year Campaign to Image Accreting Protoplanets
• ALMA 0.88 mm Survey of Disks around Planetary-mass Companions
• Gemini Planet Imager Spectroscopy of the Dusty Substellar Companion HD 206893 B
• Dust Traps and the Formation of Cavities in Transition Discs: A millimetre to sub-millimetre comparison survey
• Stellar multiplicity affects the correlation between proto-planetary disc masses and accretion rates: binaries explain high-accretors in Upper Sco
• Observing the gas component of circumplanetary disks around wide-orbit planet-mass companions in the (sub)mm regime
• Colors of an Earth-like exoplanet -- Temporal flux and polarization signals of the Earth
• A faint companion around CrA-9: protoplanet or obscured binary?
• CS Cha B: A disc-obscured M-type star mimicking a polarised planetary companion
• Traces of exomoons in computed flux and polarization phase curves of starlight reflected by exoplanets
• The PDS 110 observing campaign - photometric and spectroscopic observations reveal eclipses are aperiodic
• Photoevaporation of the Jovian circumplanetary disk I. Explaining the orbit of Callisto and the lack of outer regular satellites
• Delivery of gas onto the circumplanetary disk of giant planets: Planetary-mass dependence of the source region of accreting gas and mass accretion rate
• UV Fluorescence Traces Gas and LyA Evolution in Protoplanetary Disks
• Sub-stellar companions of the young weak-line TTauri Star DoAr21
• YSES 2b is a background star: Differential astrometric M-dwarf measurements in time
• The SPHERE view of multiple star formation
• The formation of planetary systems with SPICA
• The morphology of CSCha circumbinary disk suggesting the existence of a Saturn-mass planet