On the thermal sensitivity of binary formation in collapsing molecular clouds

Abstract

We report the results of a numerical study on the initial formation stages of low-mass protostellar binary systems. We determine the separation of protostellar binaries formed as a function of the initial thermal state by varying the initial temperature in a slightly modified version of the Burkert and Bodenheimer collapse test. We find that the outcome is highly sensitive to both the initial temperature of the cloud and the initial amplitude of azimuthal density perturbation A. For A=10 %, variations of only 1 unit Kelvin below 10 K lead to changes of up to 100 AU ( i.e. of order 30 %) in the instantaneous separation, whereas for this small A the initial temperatures above 10 K yield, instead of a binary, a single low-mass fragment that never reaches protostellar densities. Protostellar binaries, however, do emerge when the perturbation amplitude is increased from 10 % to 25 %. We also investigate the impact of the critical density which governs the transition from isothermal to adiabatic thermodynamic behaviour of the collapsing gas. We find that the critical density not only affects the overall structural evolution of the gas envelope, but also the size of the rotating disk structures formed during collapse as well as the number of protostellar fragments resulting from the final fragmentation of the disks. This mechanism can give rise to young protostellar objects constituting bound multiple stellar systems.

arXiv commentAccepted for publication in MNRAS

References in corpus (27)

• A Survey of Stellar Families: Multiplicity of Solar-Type Stars
• SPLASH: An interactive visualisation tool for Smoothed Particle Hydrodynamics simulations
• Smoothed Particle Hydrodynamics and Magnetohydrodynamics
• An energy-conserving formalism for adaptive gravitational force softening in SPH and N-body codes
• Protostellar Collapse with Various Metallicities
• Smoothed Particle Hydrodynamics with particle splitting, applied to self-gravitating collapse
• The earliest phases of star formation - A Herschel key project. The thermal structure of low-mass molecular cloud cores
• Radiative transfer and the energy equation in SPH simulations of star formation
• Formation Scenario for Wide and Close Binary Systems
• The initial conditions of isolated star formation. V: ISOPHOT imaging and the temperature and energy balance of pre-stellar cores
• Multiple protostellar systems. II. A high resolution near-infrared imaging survey in nearby star-forming regions
• The First Discovery of a Wide Binary Brown Dwarf
• Cosmic-ray ionisation in collapsing clouds
• Discovery of a wide companion near the deuterium burning mass limit in the Upper Scorpius association
• SEREN - A new SPH code for star and planet formation simulations
• Cosmic Ray Heating of the Warm Ionized Medium
• VLA and CARMA Observations of Protostars in the Cepheus Clouds: Sub-arcsecond Proto-Binaries Formed via Disk Fragmentation
• Simulating hydromagnetic processes in star formation: introducing ambipolar diffusion into an adaptive mesh refinement code
• Protostellar collapse and fragmentation using an MHD GADGET
• A Hubble Space Telescope ACS Search for Brown Dwarf Binaries in the Pleiades Open Cluster
• Capture Formed Binaries via Encounters with Massive Protostars
• Collapse and fragmentation of Gaussian barotropic protostellar clouds
• Binary and Multiple Star Formation in Magnetic Clouds: Bar Growth and Fragmentation
• Are molecular outflows around high-mass stars driven by ionization feedback?
• A Lower Angular Momentum Limit for Self-Gravitating Protostellar Disc Fragmentation
• The Binary White Dwarf LHS 3236
• Accretion discs, low-mass protostars and planets: probing the impact of magnetic fields on stellar formation

Cited by in corpus (8)

• From large-scale to protostellar disk fragmentation into close binary stars
• The long-term dynamical evolution of disc-fragmented multiple systems in the Solar Neighborhood
• Discovery of a 500 au Protobinary in the Massive Prestellar Core G11.92-0.61 MM2
• Consistent SPH Simulations of Protostellar Collapse and Fragmentation
• Formation of multiple low mass stars, brown dwarfs and planemos via gravitational collapse
• Impetus: Consistent SPH calculations of 3D spherical Bondi accretion onto a black hole
• Episodic accretion in binary protostars emerging from self-gravitating solar mass cores
• Comparing binary systems from rotating parent gas structures with different total masses