On the circum(sub)stellar environment of brown dwarfs in Taurus

Abstract

Aims : We want to investigate whether brown dwarfs (BDs) form like stars or are ejected embryos. We study the presence of disks around BDs in the Taurus cloud, and discuss implications for substellar formation models. Methods : We use photometric measurements from the visible to the far infrared to determine the spectral energy distributions (SEDs) of Taurus BDs. Results: We use Spitzer color indices, Halpha as an accretion indicator, and models fit to the SEDs in order to estimate physical parameters of the disks around these BDs. We study the spatial distribution of BDs with and without disks across the Taurus aggregates, and we find that BDs with and without disks are not distributed regularly across the Taurus cloud. Conclusions: We find that 48%+/- 14% of Taurus BDs have a circumstellar disk signature, a ratio similar to recent results from previous authors in other regions. We fit the SEDs and find that none of the disks around BDs in Taurus can be fitted convincingly with a flaring index beta = 0, indicating that heating by the central object is efficient and that the disks we observe retain a significant amount of gas. We find that BDs with disks are proportionally more numerous in the northern Taurus filament, possibly the youngest filament. We do not find such a clear segregation for classical T Tauri stars (CTTS) and weak-lined T Tauri stars (WTTS), suggesting that, in addition to the effects of evolution, any segregation effects could be related to the mass of the object. A by-product of our study is to propose a recalibration of the Barrado y Navascues & Martin (2003) accretion limit in the substellar domain. The global shape of the limit fits our data points if it is raised by a factor 1.25-1.30.

11 pages, 5 figures, A&A accepted

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• The Taurus Spitzer Survey: New Candidate Taurus Members Selected Using Sensitive Mid-Infrared Photometry
• The Disk Population of the Chamaeleon I Star-Forming Region
• An Infrared/X-ray Survey for New Members of the Taurus Star-Forming Region
• A library of near-infrared integral field spectra of young M-L dwarfs
• Direct evidence of a sub-stellar companion around CT Cha
• A Comprehensive Census of Nearby Infrared Excess Stars
• Disks around Brown Dwarfs in the Sigma Orionis Cluster
• Explaining millimeter-sized particles in brown dwarf disks
• A WISE Survey of Circumstellar Disks in Taurus
• A Herschel Survey of Cold Dust in Disks Around Brown Dwarfs and Low-Mass Stars
• Substellar Objects in Nearby Young Clusters (SONYC) IV: A census of very low mass objects in NGC1333
• CARMA interferometric observations of 2MASS J044427+2512: the first spatially resolved observations of thermal emission of a brown dwarf disk
• Towards Precise Ages and Masses of Free Floating Planetary Mass Brown Dwarfs
• Structural and compositional properties of brown dwarf disks: the case of 2MASS J04442713+2512164
• New Brown Dwarf Disks in the TW Hydrae Association
• A Survey For Planetary-mass Brown Dwarfs in the Taurus and Perseus Star-forming Regions
• A Herschel Search For Cold Dust in Brown Dwarf Disks: First Results
• Molecular Outflows in the Substellar Domain: Millimeter Observations of Young Very Low Mass Objects in Taurus and rho Ophiuchi
• Hot spots and a clumpy disk: Variability of brown dwarfs and stars in the young Sigma Ori cluster
• The large-scale disk fraction of brown dwarfs in the Taurus cloud as measured with Spitzer
• Deep Near-Infrared Imaging of the rho Oph Cloud Core: Clues to the Origin of the Lowest-Mass Brown Dwarfs
• Hints for Small Disks around Very Low-Mass Stars and Brown Dwarfs
• The Taurus Boundary of Stellar/Substellar (TBOSS) Survey I: far-IR disk emission measured with Herschel
• Silicate Evolution in Brown Dwarf Disks
• Brown dwarf disks with Herschel: Linking far-infrared and (sub)-mm fluxes
• The dipper population of Taurus seen with K2
• A homogeneous analysis of disks around brown dwarfs
• Optical and near-infrared linear polarization of low and intermediate-gravity ultra-cool dwarfs
• Thermochemical modelling of brown dwarf discs
• Modeling the Protoplanetary Disks of Two Brown Dwarfs in the Taurus Molecular Cloud
• Bayesian fitting of Taurus brown dwarf spectral energy distributions
• VLA observations of the disk around the young brown dwarf 2MASS J044427+2512
• MINDS. Cha Hα 1, a brown dwarf with a hydrocarbon-rich disk
• New constraints on the presence of debris disks around G 196-3 B and VHS J125601.92-125723.9 b
• Dynamic Photometric Variability in Three Young Brown Dwarfs in Taurus: Detection of Optical Flares with TESS data