The properties of brown dwarfs and low-mass hydrogen-burning stars formed by disc fragmentation

Abstract

We suggest that a high proportion of brown dwarfs are formed by gravitational fragmentation of massive extended discs around Sun-like stars. Such discs should arise frequently, but should be observed infrequently, precisely because they fragment rapidly. By performing an ensemble of radiation-hydrodynamic simulations, we show that such discs fragment within a few thousand years, and produce mainlybrown dwarf (BDs) stars, but also planetary mass (PM) stars and very low-mass hydrogen-burning (HB) stars. Most of the the PM stars and BDs are ejected by mutual interactions. We analyse the statistical properties of these stars, and compare them with observations. After a few hundred thousand years the Sun-like primary is typically left with a close low-mass HB companion, and two much wider companions: a low-mass HB star and a BD star, or a BD-BD binary. There is a BD desert extending out to at least ~100 AU; this is because BDs tend to be formed further out than low-mass HB stars, and then they tend to be scattered even further out, or even into the field. BDs form with discs of a few Mj and radii of a few tens of AU, and they are more likely to retain these discs if they remain bound to the primary star. Binaries form by pairing of the newly-formed stars in the disc, giving a low-mass binary fraction of ~0.16. These binaries include close and wide BD/BD binaries and BD/PM binaries. BDs that remain as companions to Sun-like stars are more likely to be in BD/BD binaries than are BDs ejected into the field. Disc fragmentation is a robust mechanism; even if only a small fraction of Sun-like stars host the required massive extended discs,this mechanism can produce all the PM stars observed, most of the BD stars, and a significant proportion of the very low-mass HB stars.

Accepted by MNRAS, high-res (recommended) can be download at http://www.astro.cf.ac.uk/pub/Dimitrios.Stamatellos/publications/

References in corpus (18)

• UV excess measures of accretion onto young very low-mass stars and brown dwarfs
• The Gemini Deep Planet Survey -- GDPS
• Exploring brown dwarf disks: A 1.3 mm survey in Taurus
• Brown dwarf formation by gravitational fragmentation of massive, extended protostellar discs
• The Thermal Regulation of Gravitational Instabilities in Protoplanetary Disks III. Simulations with Radiative Cooling and Realistic Opacities
• The minimum mass for star formation, and the origin of binary brown dwarfs
• Radiative transfer and the energy equation in SPH simulations of star formation
• Can giant planets form by gravitational fragmentation of discs?
• Relative velocities among accreting planetesimals in binary systems: the circumprimary case
• The potential for Earth-mass planet formation around brown dwarfs
• Proplyds and Massive Disks in the Orion Nebula Cluster Imaged with CARMA and SMA
• Multiplicity and Optical Excess Across the Substellar Boundary in Taurus
• The Thermal Regulation of Gravitational Instabilities in Protoplanetary Disks. IV. Simulations with Envelope Irradiation
• A survey for low mass spectroscopic binary stars in the young clusters around sigma Orionis and lambda Orionis
• New Brown Dwarf Disks in the TW Hydrae Association
• Brown dwarf formation by binary disruption
• Star formation in molecular cores III. The effect of the turbulent power spectrum
• Radial and rotational velocities of young brown dwarfs and very low-mass stars in the Upper Scorpius OB association and the rho Ophiuchi cloud core

Cited by in corpus (102)

• The VLA/ALMA Nascent Disk and Multiplicity (VANDAM) Survey of Orion Protostars. A Statistical Characterization of Class 0 and I Protostellar Disks
• The Effects of Radiative Transfer on Low-Mass Star Formation
• The Two Modes of Gas Giant Planet Formation
• Planets Around Low-Mass Stars (PALMS). IV. The Outer Architecture of M Dwarf Planetary Systems
• A Statistical Analysis of SEEDS and Other High-Contrast Exoplanet Surveys: Massive Planets or Low-Mass Brown Dwarfs?
• SpeX Spectroscopy of Unresolved Very Low Mass Binaries. II. Identification of Fourteen Candidate Binaries with Late-M/Early-L and T Dwarf Components
• Discovery of a wide planetary-mass companion to the young M3 star GU Psc
• Brown dwarf disks with ALMA: evidence for truncated dust disks in Ophiuchus
• Towards a population synthesis model of self-gravitating disc fragmentation and tidal downsizing II: The effect of fragment-fragment interactions
• Forming spectroscopic massive proto-binaries by disk fragmentation
• Brown dwarf disks with ALMA
• Tidally induced brown dwarf and planet formation in circumstellar discs
• IC348-SMM2E: a Class 0 proto-brown dwarf candidate forming as a scaled-down version of low-mass stars
• The Formation and Evolution of Wide-Orbit Stellar Multiples In Magnetized Clouds
• Substellar Objects in Nearby Young Clusters (SONYC): The bottom of the Initial Mass Function in NGC1333
• Effects of radiation transfer on the structure of self-gravitating disks, their fragmentation and evolution of the fragments
• The properties of discs around planets and brown dwarfs as evidence for disc fragmentation
• 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
• Rotation Periods, Inclinations, and Obliquities of Cool Stars Hosting Directly Imaged Substellar Companions: Spin-Orbit Misalignments are Common
• Characterizing the Brown Dwarf Formation Channels from the Initial Mass Function and Binary-star Dynamics
• SOPHIE velocimetry of Kepler transit candidates. VIII. KOI-205 b: a brown-dwarf companion to a K-type dwarf
• Discovery of Seven Companions to Intermediate Mass Stars with Extreme Mass Ratios in the Scorpius-Centaurus Association
• The Young L Dwarf 2MASS J11193254-1137466 is a Planetary-Mass Binary
• The fragmentation criteria in local vertically stratified self-gravitating disk simulations
• Planet formation around M dwarfs via disc instability: Fragmentation conditions and protoplanet properties
• An ALMA and MagAO Study of the Substellar Companion GQ Lup B
• The Dynamical Fate of Self-Gravitating Disc Fragments After Tidal Downsizing
• Accretion Phase of Star Formation in Clouds with Different Metallicities
• On the Masses, Age, and Architecture of the VHS J1256-1257AB b System
• Disc formation and fragmentation using radiative non-ideal magnetohydrodynamics
• The effect of radiative feedback on disc fragmentation
• Eccentric Companions to Kepler-448b and Kepler-693b: Clues to the Formation of Warm Jupiters
• Simulations of star formation in Ophiuchus, II: Multiplicity
• Exploring the Brown Dwarf Desert: New Substellar Companions from the SDSS-III MARVELS Survey
• Brown Dwarf Binaries from Disintegrating Triple Systems
• WISEA J083011.95+283716.0: A Missing Link Planetary-Mass Object
• Characterizing gravito-turbulence in 3D: turbulent properties and stability against fragmentation
• Characterizing the protolunar disk of the accreting companion GQ Lupi B
• Tracking Advanced Planetary Systems with HARPS-N (TAPAS). I. A multiple planetary system around the red giant star TYC 1422-614-1
• The VAST Survey - IV. A wide brown dwarf companion to the A3V star $\zeta$ Delphini
• The cool brown dwarf Gliese 229 B is a close binary
• A new take on the low-mass brown dwarf companions on wide-orbits in Upper-Scorpius
• Formation of freely floating sub-stellar objects via close encounters
• The search for disks or planetary objects around directly imaged companions: A candidate around DH Tau B
• A transiting brown dwarf in a 2 hour orbit
• Youth analysis of near infrared spectra of young low-mass stars and brown dwarfs
• Isochronal age-mass discrepancy of young stars: SCExAO/CHARIS integral field spectroscopy of the HIP 79124 triple system
• Kinematic Analysis of a Protostellar Multiple System: Measuring the Protostar Masses and Assessing Gravitational Instability in the Disks of L1448 IRS3B and L1448 IRS3A
• The dynamical evolution of low-mass hydrogen-burning stars, brown dwarfs and planetary-mass objects formed through disc fragmentation
• On the effects of solenoidal and compressive turbulence in prestellar cores
• The ESO SupJup Survey II: The 12C/13C ratios of three young brown dwarfs with CRIRES${}^{+}$
• HST survey of the Orion Nebula Cluster in the H${}_2$O 1.4 $\mu$m absorption band: II. The substellar IMF down to planetary masses
• Pebble accretion in class 0/I YSOs as a possible pathway for early planet formation
• The Late-Type Extension to MoVeRS (LaTE-MoVeRS): Proper motion verified low-mass stars and brown dwarfs from SDSS, 2MASS, and WISE
• Fragmentation favoured in discs around higher mass stars
• Binary companions triggering fragmentation in self-gravitating discs
• Disk Masses and Dust Evolution of Protoplanetary Disks Around Brown Dwarfs
• The ESO SupJup Survey IV. Unveiling the carbon isotope ratio of GQ Lup B and its host star
• Precise radial velocities of giant stars. XI. Two brown dwarfs in 6:1 mean motion resonance around the K giant star $\nu$ Ophiuchi
• Very Low-Mass Stars and Brown Dwarfs in Upper Scorpius using Gaia DR1: Mass Function, Disks and Kinematics
• Improving the thin-disk models of circumstellar disk evolution. The 2+1-dimensional model
• TOI-179: a young system with a transiting compact Neptune-mass planet and a low-mass companion in outer orbit
• Chemical abundances of stars with brown-dwarf companions
• ALMA reveals a pseudo-disc in a proto-brown dwarf
• USco1621 B and USco1556 B: Two wide companions at the deuterium-burning mass limit in Upper Scorpius
• Episodic accretion and mergers during growth of massive protostars
• VLTI/GRAVITY Observations and Characterization of the Brown Dwarf Companion HD 72946 B
• Modeling the Protoplanetary Disks of Two Brown Dwarfs in the Taurus Molecular Cloud
• OGLE-2016-BLG-1469L: Microlensing Binary Composed of Brown Dwarfs
• Spectroscopic substellar initial mass function of NGC 2244
• BiPoS1 -- a computer programme for the dynamical processing of the initial binary star population
• Linear Stability Analysis of a Magnetic Rotating Disk with Ohmic Dissipation and Ambipolar Diffusion
• A multi-wavelength characterization of proto-brown dwarf candidates in Serpens
• Search for Brown Dwarfs in IC 1396 with Subaru HSC: Interpreting the Impact of Environmental Factors on Sub-stellar Population
• ALMA observations of the early stages of substellar formation in the Lupus 1 and 3 molecular clouds
• Bipolar molecular outflow of the very low-mass star Par-Lup3-4
• Gravito-turbulence in local disk simulations with an adaptive moving mesh
• On the origin of planetary-mass objects in NGC1333
• The gas disk: Evolution and chemistry
• DIPSY: A new Disc Instability Population SYnthesis, II. The Populations of Companions Formed Through Disc Instability
• Using binary statistics in Taurus-Auriga to distinguish between brown dwarf formation processes
• The structure of young embedded protostellar discs
• Complex structure of a proto-brown dwarf
• Millimeter Dust Emission and Planetary Dynamics in the HD 106906 System
• NICMOS Kernel-Phase Interferometry II: Demographics of Nearby Brown Dwarfs
• Double cyclic variations in orbital period of the eclipsing cataclysmic variable EX Dra
• On fragmentation of turbulent self-gravitating discs in the long cooling time regime
• On the survivability of a population of gas giant planets on wide orbits
• The brown dwarf population in the star forming region NGC2264
• Wide-binary eccentricity distribution in young star clusters: dependence on the binary separation and mass
• Where to find over-massive brown dwarfs: new benchmark systems for binary evolution
• On the potential origin of the circumbinary planet Delorme 1 (AB)b
• Synthetic observations of protostellar multiple systems
• Low-resolution near-infrared spectroscopic signatures of unresolved ultracool companions to M dwarfs
• Occurrence rates of accreting companions from a new method for computing emission-line survey sensitivity: application to the H-alpha Giant Accreting Protoplanet Survey
• The 3D structure of disc-instability protoplanets
• Using the Modified Lognormal Power Law Distribution to Model the Mass Function of NGC 1711
• Dust growth and planet formation by disc fragmentation
• Detection and characterisation of two VLM binaries: LP 1033-31 and LP 877-72
• Planet migration in massive circumbinary discs
• The nature of ASASSN-24fw's occultation: modelling the event as dimming by optically thick rings around a sub-stellar companion
• The VLA/ALMA Nascent Disk and Multiplicity (VANDAM) Survey of Orion Protostars VI. Insights from Radiative Transfer Modeling