The Role of Convection in Determining the Ejection Efficiency of Common Envelope Interactions

Abstract

A widely used method for parameterizing the outcomes of common envelopes (CEs) involves defining an ejection efficiency, ${\bar{\alpha }}_{\mathrm{eff}}$, that represents the fraction of orbital energy used to unbind the envelope as the orbit decays. Given ${\bar{\alpha }}_{\mathrm{eff}}$, a prediction for the post-CE orbital separation is possible with knowledge of the energy required to unbind the primary's envelope from its core. Unfortunately, placing observational constraints on ${\bar{\alpha }}_{\mathrm{eff}}$ is challenging as it requires knowledge of the primary's structure at the onset of the common envelope phase. Numerical simulations have also had difficulties reproducing post-CE orbital configurations as they leave extended, but still bound, envelopes. Using detailed stellar interior profiles, we calculate ${\bar{\alpha }}_{\mathrm{eff}}$ values for a matrix of primary-companion mass pairs when the primary is at maximal extent in its evolution. We find that the ejection efficiency is most sensitive to the properties of the surface-contact convective region (SCCR). In this region, the convective transport timescales are often short compared to orbital decay timescales, thereby allowing the star to effectively radiate orbital energy and thus lower ${\bar{\alpha }}_{\mathrm{eff}}$. The inclusion of convection in numerical simulations of CEs may aid ejection without the need for additional energy sources as the orbit must shrink substantially further before the requisite energy can be tapped to drive ejection. Additionally, convection leads to predicted post-CE orbital periods of less than a day in many cases, an observational result that has been difficult to reproduce in population studies where ${\bar{\alpha }}_{\mathrm{eff}}$ is taken to be constant. Finally, we provide a simple method to calculate ${\bar{\alpha }}_{\mathrm{eff}}$ if the properties of the SCCR are known.

arXiv commentAccepted to MNRAS. 10 pages, 7 figures

References in corpus (46)

• Modules for Experiments in Stellar Astrophysics (MESA)
• Modules for Experiments in Stellar Astrophysics (MESA): Convective Boundaries, Element Diffusion, and Massive Star Explosions
• Shrinking binary and planetary orbits by Kozai cycles with tidal friction
• Common Envelope Evolution: Where we stand and how we can move forward
• A Comprehensive Study of Binary Compact Objects as Gravitational Wave Sources: Evolutionary Channels, Rates, and Physical Properties
• The first gravitational-wave source from the isolated evolution of two 40-100 Msun stars
• Progenitors of gravitational wave mergers: Binary evolution with the stellar grid-based code ComBinE
• Accelerating Compact Object Mergers in Triple Systems with the Kozai Resonance: A Mechanism for "Prompt" Type Ia Supernovae, Gamma-Ray Bursts, and Other Exotica
• The Orbital Evolution of Gas Giant Planets around Giant Stars
• Post-common-envelope binaries from SDSS. IX: Constraining the common-envelope efficiency
• Theoretical uncertainties of the type Ia supernova rate
• An AMR Study of the Common Envelope Phase of Binary Evolution
• Low-Mass Binary Induced Outflows from Asymptotic Giant Branch Stars
• Simulating the Common Envelope Phase of a Red Giant Using SPH and Uniform Grid Codes
• On the alpha formalism for the common envelope interaction
• Identification of the Long-Sought Common-Envelope Events
• On the Orbits of Low-mass Companions to White Dwarfs and the Fates of the Known Exoplanets
• Hydrodynamic moving-mesh simulations of the common envelope phase in binary stellar systems
• The Mass-Loss Induced Eccentric Kozai Mechanism: A New Channel for the Production of Close Compact Object-Stellar Binaries
• Stellar Mergers Are Common
• The effect of common-envelope evolution on the visible population of post-common-envelope binaries
• Do most planetary nebulae derive from binaries? I Population synthesis model of the galactic planetary nebula population produced by singlestars and binaries
• Tides and Tidal Engulfment in Post-Main Sequence Binaries: Period Gaps for Planets and Brown Dwarfs Around White Dwarfs
• Isolated vs. Common Envelope Dynamos in Planetary Nebula Progenitors
• Accretion in common envelope evolution
• Common Envelope Wind Tunnel: Coefficients of Drag and Accretion in a Simplified Context for Studying Flows Around Objects Embedded Within Stellar Envelopes
• A comprehensive population synthesis study of post-common envelope binaries
• The formation of high-field magnetic white dwarfs from common envelopes
• Mass Transfer and Disc Formation in AGB Binary Systems
• On the role of recombination in common-envelope ejections
• Close stellar binary systems by grazing envelope evolution
• Runaway Coalescence at the Onset of Common Envelope Episodes
• Efficient common-envelope ejection through dust-driven winds
• The limited role of recombination energy in common envelope removal
• Population Synthesis Studies of Close Binary Systems Using a Variable Common Envelope Efficiency Parameter: I. Dependence upon Secondary Mass
• Considerations on the Role of Fall-Back Discs in the Final Stages of the Common Envelope Binary Interaction
• On the use of hydrogen recombination energy during common envelope events
• Energy transport by convection in the common envelope evolution
• Post-common-envelope binaries from SDSS. XIII: Mass dependencies of the orbital period distribution
• Gaseous Dynamical Friction in Presence of Black Hole Radiative Feedback
• Radiating the hydrogen recombination energy during common envelope evolution
• The population of white dwarf-main sequence binaries in the SDSS DR 12
• Tidal capture formation of Low Mass X-Ray Binaries from wide binaries in the field
• Constraints on the common-envelope evolution process from wide triple systems
• Counteracting Tidal Circularization with the Grazing Envelope Evolution
• Oxygen-neon rich merger during common envelope evolution

Cited by in corpus (37)

• Companion-launched jets and their effect on the dynamics of common envelope interaction simulations
• Common envelopes in massive stars: Towards the role of radiation pressure and recombination energy in ejecting red supergiant envelopes
• Speaking with one voice: simulations and observations discuss the common envelope $\alpha$ parameter
• Common-envelope evolution with an asymptotic giant branch star
• Binary Stars in the New Millennium
• WD 1856 b: a close giant planet around a white dwarf that could have survived a common-envelope phase
• The impact of recombination energy on simulations of the common envelope binary interaction
• Light Curve Model for Luminous Red Novae and Inferences about the Ejecta of Stellar Mergers
• Formation of sdB-stars via common envelope ejection by substellar companions
• From 3D hydrodynamic simulations of common-envelope interaction to gravitational-wave mergers
• Properties of the post in-spiral common envelope ejecta II: dust formation
• Common envelopes in massive stars II: The distinct roles of hydrogen and helium recombination
• Properties of the post in-spiral common envelope ejecta I: dynamical and thermal evolution
• Giant planet engulfment by evolved giant stars: light curves, asteroseismology, and survivability
• Convection and Spin-Up During Common Envelope Evolution: The Formation of Short-Period Double White Dwarfs
• Common Envelope Evolution on the Asymptotic Giant Branch: Unbinding within a Decade?
• Three-dimensional simulations of the jet feedback mechanism in common envelope jets supernova
• Successive common envelope events from multiple planets
• Convection Reconciles the Difference in Efficiencies Between Low-Mass and High-Mass Common Envelopes
• Post-dynamical inspiral phase of common envelope evolution: Binary orbit evolution and angular momentum transport
• Inclined jets inside a common envelope of a triple stellar system
• Observational Constraints on the Common Envelope Phase
• Hydrodynamics and survivability during post-main-sequence planetary engulfment
• Common Envelope Wind Tunnel: Range of Applicability and Self-Similarity in Realistic Stellar Envelopes
• Hydrodynamic Simulations of Disrupted Planetary Accretion Discs Inside the Core of an AGB Star
• The first catalog of candidate white dwarf-main sequence binaries in open star clusters: A new window into common envelope evolution
• Revised Stellar Parameters for V471 Tau, A Post-common Envelope Binary in the Hyades
• The Formation of Discs in the Interior of AGB Stars from the Tidal Disruption of Planets and Brown Dwarfs
• Variable jets at the termination of the common envelope evolution
• Parasite common envelope evolution by triple-star systems
• Statistics of Magrathea exoplanets beyond the Main Sequence. Simulating the long-term evolution of circumbinary giant planets with TRES
• Common envelope jets supernova with thermonuclear outburst progenitor for the enigmatic supernova remnant W49B
• Second-generation planet formation after tidal disruption from common envelope evolution
• The Energy Sharing Timescale in an Analytic Framework for Common Envelope Hydrodynamics
• Light Curve Models of Convective Common Envelopes
• Luminous Fast Blue Optical Transients and Type Ibn/Icn SNe from Wolf-Rayet/Black Hole Mergers
• Detached Shell Carbon Stars: Tracing Thermal Pulses on the Asymptotic Giant Branch