The dynamical evolution of low-mass hydrogen-burning stars, brown dwarfs and planetary-mass objects formed through disc fragmentation

Abstract

Theory and simulations suggest that it is possible to form low-mass hydrogen-burning stars, brown dwarfs and planetary-mass objects via disc fragmentation. As disc fragmentation results in the formation of several bodies at comparable distances to the host star, their orbits are generally unstable. Here, we study the dynamical evolution of these objects. We set up the initial conditions based on the outcomes of the SPH simulations of Stamatellos & Whitworth, and for comparison we also study the evolution of systems resulting from lower-mass fragmenting discs. We refer to these two sets of simulations as set 1 and set 2. At 10 Myr, approximately half of the host stars have one companion left, and approximately 22% (set 1) to 9.8% (set 2) of the host stars are single. Systems with multiple secondaries in relatively stable configurations are common (about 30% and 44%, respectively). The majority of the companions are ejected within 1 Myr with velocities mostly below 5 km/s, with some runaway escapers with velocities over 30 km/s. About 6% (set 1) and 2% (set 2) of the companions pair up into very low-mass binary systems. The majority of these pairs escape as very low-mass binaries, while others remain bound to the host star in hierarchical configurations (often with retrograde inner orbits). Physical collisions with the host star (0.43 and 0.18 events per host star for set 1 and set 2) and between companions (0.08 and 0.04 events per host star for set 1 and set 2) are relatively common and their frequency increases with increasing disc mass. Our study predicts observable properties of very low-mass binaries, low-mass hierarchical systems, the brown dwarf desert, and free-floating brown dwarfs and planetary-mass objects in and near young stellar groupings, which can be used to distinguish between different formation scenarios of very low-mass stars, brown dwarfs and planetary-mass objects.

arXiv comment38 pages, 15 figures

References in corpus (95)

• Galactic Stellar and Substellar Initial Mass Function
• On the variation of the Initial Mass Function
• A Survey of Stellar Families: Multiplicity of Solar-Type Stars
• Direct Imaging of Multiple Planets Orbiting the Star HR 8799
• Stellar Multiplicity
• Unbound or Distant Planetary Mass Population Detected by Gravitational Microlensing
• Tertiary companions to close spectroscopic binaries
• Stellar, Brown Dwarf, and Multiple Star Properties from Hydrodynamical Simulations of Star Cluster Formation
• How Dry is the Brown Dwarf Desert?: Quantifying the Relative Number of Planets, Brown Dwarfs and Stellar Companions around Nearby Sun-like Stars
• A Catalog of Multiplicity among Bright Stellar Systems
• The properties of brown dwarfs and low-mass hydrogen-burning stars formed by disc fragmentation
• From binaries to multiples II: hierarchical multiplicity of F and G dwarfs
• The Spatial Distribution of Star Formation in the Solar Neighbourhood: Do all stars form in clusters?
• Multiplicity of Nearby Free-floating Ultra-cool Dwarfs: a HST-WFPC2 search for companions
• Mapping the Shores of the Brown Dwarf Desert II: Multiple Star Formation in Taurus-Auriga
• A 0.2 solar mass protostar with a Keplerian disk in the very young L1527 IRS system
• Toward Complete Statistics of Massive Binary Stars: Penultimate Results from the Cygnus OB2 Radial Velocity Survey
• Dynamical mass segregation on a very short timescale
• The effects of fly-bys on planetary systems
• The Formation and Early Evolution of Low-mass Stars and Brown Dwarfs
• Multi-physics simulations using a hierarchical interchangeable software interface
• Low-Mass Tertiary Companions to Spectroscopic Binaries I: Common Proper Motion Survey for Wide Companions using 2MASS
• The Astrophysical Multipurpose Software Environment
• Simulating star formation in molecular cloud cores I. The influence of low levels of turbulence on fragmentation and multiplicity
• Mapping the Shores of the Brown Dwarf Desert I.: Upper Scorpius
• Search for brown-dwarf companions of stars
• From binaries to multiples I: Data on F and G dwarfs within 67 pc of the Sun
• Formation of the Widest Binaries from Dynamical Unfolding of Triple Systems
• The formation of very wide binaries during the star cluster dissolution phase
• Brown dwarf formation by gravitational fragmentation of massive, extended protostellar discs
• The Primordial Binary Population - I: A near-infrared adaptive optics search for close visual companions to A star members of Scorpius OB2
• Dynamical evolution of star forming regions
• The Evolution of Wide Binary Stars
• 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
• Dynamics of Planetary Systems in Star Clusters
• High Precision Dynamical Masses of Very Low Mass Binaries
• Substellar Companions to Main Sequence Stars: No Brown Dwarf Desert at Wide Separations
• A VLT/NACO Survey for Triple and Quadruple Systems among Visual Pre-Main Sequence Binaries
• Three Wide Planetary-Mass Companions to FW Tau, ROXs 12, and ROXs 42B
• The mass ratio distribution of B-type visual binaries in the Sco OB2 association
• Sloan Low-Mass Wide Pairs of Kinematically Equivalent Stars (SLoWPoKES): A Catalog of Very Wide, Low-mass Pairs
• SpeX Spectroscopy of Unresolved Very Low Mass Binaries. II. Identification of Fourteen Candidate Binaries with Late-M/Early-L and T Dwarf Components
• Towards a Population Synthesis Model of Objects formed by Self-Gravitating Disc Fragmentation and Tidal Downsizing
• Formation, Survival, and Detectability of Planets Beyond 100 AU
• Simulating star formation in molecular cores II. The effects of different levels of turbulence
• Multiplicity Amongst Wide Brown Dwarf Companions to Nearby Stars: Gliese 337CD
• On the origin of planets at very wide orbits from the re-capture of free floating planets
• The Evolution of the Multiplicity of Embedded Protostars I: Sample Properties and Binary Detections
• Lucky Imaging survey for southern M dwarf binaries
• The importance of episodic accretion for low-mass star formation
• The dynamical evolution of multi-planet systems in open clusters
• The effects of dynamical interactions on planets in young substructured star clusters
• On the Distribution of Orbital Eccentricities for Very Low-Mass Binaries
• The Evolution of the Multiplicity of Embedded Protostars II: Binary Separation Distribution & Analysis
• The Solar Neighborhood XXVIII: The Multiplicity Fraction of Nearby Stars from 5 to 70 AU and the Brown Dwarf Desert Around M Dwarfs
• Exploring the consequences of pairing algorithms for binary stars
• SEREN - A new SPH code for star and planet formation simulations
• The formation of permanent soft binaries in dispersing clusters
• Spectroscopic Confirmation of Young Planetary-Mass Companions on Wide Orbits
• Tidally induced brown dwarf and planet formation in circumstellar discs
• Mapping the Shores of the Brown Dwarf Desert III: Young Moving Groups
• Introducing a Hybrid Method of Radiative Transfer for Smoothed Particle Hydrodynamics
• A discontinuity in the low-mass initial mass function
• The role of thermodynamics in disc fragmentation
• Encounter-Triggered Disc Mass Loss in the ONC
• The relationship between the prestellar core mass function and the stellar initial mass function
• On the frequency of close binary systems among very low-mass stars and brown dwarfs
• Dynamical population synthesis: Constructing the stellar single and binary contents of galactic field populations
• Binary frequency of very young brown dwarfs at separations smaller than 3 AU
• The Decay of Accreting Triple Systems as Brown Dwarf Formation Scenario
• Characterizing the Brown Dwarf Formation Channels from the Initial Mass Function and Binary-star Dynamics
• SDSS J080531.84+481233.0: An Unresolved L Dwarf/T Dwarf Binary
• The High-Order-Multiplicity of Unusually Wide M-dwarf Binaries: Eleven New Triple and Quadruple Systems
• Testing the universality of star formation - II. Comparing separation distributions of nearby star-forming regions and the field
• Binary star formation from ring fragmentation
• A discontinuity in the low-mass IMF - the case of high multiplicity
• The Dynamical Fate of Self-Gravitating Disc Fragments After Tidal Downsizing
• Discovery of a Very Low Mass Triple with Late-M and T Dwarf Components: LP 704-48/SDSS J0006-0852AB
• Identification of a Wide, Low-Mass Multiple System Containing the Brown Dwarf 2MASS J0850359+105716
• Formation, orbital and thermal evolution, and survival of planetary-mass clumps in the early phase of circumstellar disk evolution
• Simulations of star formation in Ophiuchus, II: Multiplicity
• Induced planet formation in stellar clusters - a parameter study of star-disk encounters
• Substellar multiplicity in the Hyades cluster
• Simulating star formation in molecular cloud cores IV. The role of turbulence and thermodynamics
• A Substellar Companion to the Dusty Pleiades Star HD 23514
• Mapping the core mass function onto the stellar IMF: multiplicity matters
• Encounters in the ONC - observing imprints of star-disc interactions
• Shaping the Brown Dwarf Desert: Predicting the Primordial Brown Dwarf Binary Distributions from Turbulent Fragmentation
• USco1606-1935: An Unusually Wide Low-Mass Triple System?
• What does a universal IMF imply about star formation?
• Dynamical structure of the inner 100 AU of the deeply embedded protostar IRAS 16293-2422
• Binarity at the L/T brown dwarf transition
• The distribution of ejected brown dwarfs in clusters
• Collisions in young triple systems

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• Towards a population synthesis model of self-gravitating disc fragmentation and tidal downsizing II: The effect of fragment-fragment interactions
• Stability of Multiplanetary Systems in Star Clusters
• The dynamical fate of planetary systems in young star clusters
• Planet formation around M dwarfs via disc instability: Fragmentation conditions and protoplanet properties
• Generating large misalignments in gapped and binary discs
• The effect of radiative feedback on disc fragmentation
• WISE2150-7520AB: A very low mass, wide co-moving brown dwarf system discovered through the citizen science project Backyard Worlds: Planet 9
• The Effect of Protoplanetary Disk Cooling Times on the Formation of Gas Giant Planets by Gravitational Instability
• Very Low-Mass Stars and Brown Dwarfs in Upper Scorpius using Gaia DR1: Mass Function, Disks and Kinematics
• The diverse lives of massive protoplanets in self-gravitating discs
• Rogue planets and brown dwarfs: Predicting the populations of free-floating planetary mass objects observable with JWST
• The long-term dynamical evolution of disc-fragmented multiple systems in the Solar Neighborhood
• M-dwarf binaries as tracers of star and brown dwarf formation
• Using binary statistics in Taurus-Auriga to distinguish between brown dwarf formation processes
• The long-term evolution of main-sequence binaries in DRAGON simulations
• On the survivability of a population of gas giant planets on wide orbits
• History of Globulettes in the Milky Way
• Low-resolution near-infrared spectroscopic signatures of unresolved ultracool companions to M dwarfs