scholarly journals Common envelope: progress and transients

2016 ◽  
Vol 12 (S329) ◽  
pp. 199-206 ◽  
Author(s):  
Natalia Ivanova
Keyword(s):  
Energy Use ◽  
The Self ◽  
Orbital Energy ◽  
Recombination Energy ◽  
Common Envelope ◽  
New Class ◽  
Binary Formation ◽  
Recent Developments ◽  
The Common

AbstractWe review the fundamentals and the recent developments in understanding of common envelope physics. We report specifically on the progress that was made by the consideration of the recombination energy. This energy is found to be responsible for the complete envelope ejection in the case of a prompt binary formation, for the delayed dynamical ejections in the case of a self-regulated spiral-in, and for the steady recombination outflows during the transition between the plunge-in and the self-regulated spiral-in. Due to different ways how the recombination affects the common envelope during fast and slow spiral-ins, the apparent efficiency of the orbital energy use can be different between the two types of spiral-ins by a factor of ten. We also discuss the observational signatures of the common envelope events, their link a new class of astronomical transients, Luminous Red Novae, and to a plausible class of very luminous irregular variables.

scholarly journals WD 1856 b: a close giant planet around a white dwarf that could have survived a common envelope phase

2020 ◽  
Vol 501 (1) ◽  
pp. 676-682
Author(s):  
F Lagos ◽  
M R Schreiber ◽  
M Zorotovic ◽  
B T Gänsicke ◽  
M P Ronco ◽  
...  
Keyword(s):  
White Dwarf ◽  
Evolutionary History ◽  
Giant Planet ◽  
Asymptotic Giant Branch ◽  
Orbital Energy ◽  
Current Position ◽  
Recombination Energy ◽  
Additional Energy ◽  
Common Envelope ◽  
History Of

ABSTRACT The discovery of a giant planet candidate orbiting the white dwarf WD 1856+534 with an orbital period of 1.4 d poses the questions of how the planet reached its current position. We here reconstruct the evolutionary history of the system assuming common envelope evolution as the main mechanism that brought the planet to its current position. We find that common envelope evolution can explain the present configuration if it was initiated when the host star was on the asymptotic giant branch, the separation of the planet at the onset of mass transfer was in the range 1.69–2.35 au, and if in addition to the orbital energy of the surviving planet either recombination energy stored in the envelope or another source of additional energy contributed to expelling the envelope. We also discuss the evolution of the planet prior to and following common envelope evolution. Finally, we find that if the system formed through common envelope evolution, its total age is in agreement with its membership to the Galactic thin disc. We therefore conclude that common envelope evolution is at least as likely as alternative formation scenarios previously suggested such as planet–planet scattering or Kozai–Lidov oscillations.

scholarly journals Properties of the post-inspiral common envelope ejecta – I. Dynamical and thermal evolution

2019 ◽  
Vol 489 (3) ◽  
pp. 3334-3350 ◽  
Author(s):  
Roberto Iaconi ◽  
Keiichi Maeda ◽  
Orsola De Marco ◽  
Takaya Nozawa ◽  
Thomas Reichardt
Keyword(s):  
Thermal Evolution ◽  
Kinematic Model ◽  
Numerical Approach ◽  
Binary Interaction ◽  
Recombination Energy ◽  
Compact Binaries ◽  
Common Envelope ◽  
Type Ia ◽  
The Common ◽  
Ia Supernovae

ABSTRACT We investigate the common envelope binary interaction, that leads to the formation of compact binaries, such as the progenitors of Type Ia supernovae or of mergers that emit detectable gravitational waves. In this work, we diverge from the classic numerical approach that models the dynamic inspiral. We focus instead on the asymptotic behaviour of the common envelope expansion after the dynamic inspiral terminates. We use the SPH code phantom to simulate one of the set-ups from Passy et al., with a 0.88 M⊙, 83 R⊙ RGB primary and a 0.6 M⊙ companion, then we follow the ejecta expansion for 50 yr. Additionally, we utilize a tabulated equation of state including the envelope recombination energy in the simulation (Reichardt et al.), achieving a full unbinding. We show that, as time passes, the envelope’s radial velocities dominate over the tangential ones, hence allowing us to apply an homologous expansion kinematic model to the ejecta. The external layers of the envelope become homologous as soon as they are ejected, but it takes 5000 d (14 yr) for the bulk of the unbound gas to achieve the homologously expanding regime. We observe that the complex distribution generated by the dynamic inspiral evolves into a more ordered, shell-like shaped one in the asymptotic regime. We show that the thermodynamics of the expanding envelope are in very good agreement with those expected for an adiabatically expanding sphere under the homologous condition and give a prediction for the location and temperature of the photosphere assuming dust to be the main source of opacity. This technique ploughs the way to determining the long-term light behaviour of common envelope transients.

scholarly journals Speaking with one voice: simulations and observations discuss the common envelope α parameter

2019 ◽  
Vol 490 (2) ◽  
pp. 2550-2566 ◽  
Author(s):  
Roberto Iaconi ◽  
Orsola De Marco
Keyword(s):  
Binary Interaction ◽  
Agb Stars ◽  
Recombination Energy ◽  
Intermediate Mass ◽  
Data Set ◽  
Hydrodynamic Simulations ◽  
Common Envelope ◽  
Upper Limits ◽  
Low Mass ◽  
The Common

ABSTRACT We present a comparative study between the results of most hydrodynamic simulations of the common envelope binary interaction to date and observations of post-common envelope binaries. The goal is to evaluate whether this data set indicates the existence of a formula that may predict final separations of post-common envelope systems as a function of pre-common envelope parameters. Some of our conclusions are not surprising while others are more subtle. We find that: (i) Values of the final orbital separation derived from common envelope simulations must at this time be considered upper limits. Simulations that include recombination energy do not seem to have systematically different final separations; these and other simulations imply αCE < 0.6–1.0. At least one simulation, applicable to double-degenerate systems, implies αCE < 0.2. (ii) Despite large reconstruction errors, the post-RGB observations reconstructed parameters are in agreement with some of the simulations. The post-AGB observations behave instead as if they had a systematically lower value of αCE. The lack of common envelope simulations with low-mass AGB stars leaves us with no insight as to why this is the case. (iii) The smallest mass companion that survives the common envelope with intermediate mass giants is 0.05–0.1 M⊙. (iv) Observations of binaries with separations larger than ∼10 R⊙, tend to have high M2/M1 mass ratios and may go through a relatively long phase of unstable Roche lobe mass transfer followed by a weakened common envelope (or with no common envelope at all). (v) The effect of the spatial resolution and of the softening length on simulation results remains poorly quantified.

Modelling the Common Envelope Phase in Classical Novae

1990 ◽  
Vol 122 ◽  
pp. 297-298
Author(s):  
Anurag Shankar ◽  
James W. Truran ◽  
Andreas Burkert ◽  
Mario Livio
Keyword(s):  
Angular Momentum ◽  
Mass Loss ◽  
Orbital Plane ◽  
Orbital Energy ◽  
Classical Novae ◽  
Preliminary Results ◽  
Common Envelope ◽  
The Common

AbstractPreliminary results of 1– and 2– dimensional hydrodynamical calculations of the common envelope phase in very slow classical novae are presented. We show that frictional deposition of orbital energy and angular momentum into the envelope can potentially induce mass loss. Specifically, we find that despite rapid initial spin–up of the envelope, ejection of mass in the orbital plane continues at a substantial rate.

scholarly journals Gravitational waves from supernova mass loss and natal kicks in close binaries

2019 ◽  
Vol 490 (4) ◽  
pp. 5560-5566 ◽  
Author(s):  
A Miguel Holgado ◽  
Paul M Ricker
Keyword(s):  
Mass Loss ◽  
Gravitational Waves ◽  
Dynamical Evolution ◽  
Close Binaries ◽  
Orbital Energy ◽  
Core Collapse ◽  
Compact Binaries ◽  
Common Envelope ◽  
Binary Formation ◽  
Hubble Time

ABSTRACT Some fraction of compact binaries that merge within a Hubble time may have formed from two massive stars in isolation. For this isolated-binary formation channel, binaries need to survive two supernova (SN) explosions in addition to surviving common-envelope evolution. For the SN explosions, both the mass loss and natal kicks change the orbital characteristics, producing either a bound or unbound binary. We show that gravitational waves (GWs) may be produced not only from the core-collapse SN process, but also from the SN mass loss and SN natal kick during the pre-SN to post-SN binary transition. We model the dynamical evolution of a binary at the time of the second SN explosion with an equation of motion that accounts for the finite time-scales of the SN mass loss and the SN natal kick. From the dynamical evolution of the binary, we calculate the GW burst signals associated with the SN natal kicks. We find that such GW bursts may be of interest to future mid-band GW detectors like DECIGO. We also find that the energy radiated away from the GWs emitted due to the SN mass loss and natal kick may be a significant fraction, ${\gtrsim }10{\,{\rm {per\, cent}}}$, of the post-SN binary’s orbital energy. For unbound post-SN binaries, the energy radiated away in GWs tends to be higher than that of bound binaries.

scholarly journals Energy and Angular Momentum Deposition During Common Envelope Evolution

2004 ◽  
Vol 194 ◽  
pp. 30-32
Author(s):  
Noam Soker
Keyword(s):  
Angular Momentum ◽  
Mass Loss ◽  
Orbital Angular Momentum ◽  
White Dwarf ◽  
Early Stage ◽  
Mass Loss Rate ◽  
Orbital Energy ◽  
Giant Star ◽  
Common Envelope ◽  
The Common

AbstractI consider three processes which enhance mass loss rate from a common envelope of a giant star with a main sequence or a white dwarf companion spiraling-in inside its envelope. I consider deposition of orbital energy and orbital angular momentum to the giant's envelope, and the formation of jets by an accreting companion and their propagation in the envelope. I find that in many cases the deposition of orbital angular momentum to the envelope may be more important to the mass loss process than the deposition of orbital energy. Jets blown by an accreting companion, in particular a white dwarf, orbiting inside the outer regions of the giant's envelope may also dominate over orbital energy deposition at early stage of the common envelope evolution. These imply that, studies which ignore the deposition of angular momentum to the envelope and the effects of the accreting companion may reach wrong conclusions.

scholarly journals The impact of recombination energy on simulations of the common-envelope binary interaction

2020 ◽  
Vol 494 (4) ◽  
pp. 5333-5349 ◽  
Author(s):  
Thomas A Reichardt ◽  
Orsola De Marco ◽  
Roberto Iaconi ◽  
Luke Chamandy ◽  
Daniel J Price
Keyword(s):  
Equation Of State ◽  
Comparative Study ◽  
Binary Interaction ◽  
Recombination Energy ◽  
Common Envelope ◽  
Hydrogen Recombination ◽  
The Common ◽  
The Impact

ABSTRACT During the common-envelope binary interaction, the expanding layers of the gaseous common envelope recombine and the resulting recombination energy has been suggested as a contributing factor to the ejection of the envelope. In this paper, we perform a comparative study between simulations with and without the inclusion of recombination energy. We use two distinct setups, comprising a 0.88- and 1.8-M⊙ giants, that have been studied before and can serve as benchmarks. In so doing, we conclude that (i) the final orbital separation is not affected by the choice of equation of state (EoS). In other words, simulations that unbind but a small fraction of the envelope result in similar final separations to those that, thanks to recombination energy, unbind a far larger fraction. (ii) The adoption of a tabulated EoS results in a much greater fraction of unbound envelope and we demonstrate the cause of this to be the release of recombination energy. (iii) The fraction of hydrogen recombination energy that is allowed to do work should be about half of that which our adiabatic simulations use. (iv) However, for the heavier star simulation, we conclude that it is helium and not hydrogen recombination energy that unbinds the gas and we determine that all helium recombination energy is thermalized in the envelope and does work. (v) The outer regions of the expanding common envelope are likely to see the formation of dust. This dust would promote additional unbinding and shaping of the ejected envelope into axisymmetric morphologies.

Theory and Method and the Stakes of a Fragmented Discipline: Or, What Economics Taught Me About the Study of Religion

2020 ◽  
Author(s):  
Thomas A Lewis
Keyword(s):  
Religious Studies ◽  
The Public ◽  
Global Pandemic ◽  
Recent Developments ◽  
The Common ◽  
The Impact ◽  
Academic Study

Abstract As a discipline, the academic study of religion is strikingly fragmented, with little engagement or shared criteria of excellence across subfields. Although important recent developments have expanded the traditions and peoples studied as well as the methods used, the current extent of fragmentation limits the impact of this diversification and pluralization. At a moment when the global pandemic is catalyzing profound pressures on our universities and disciplines, this fragmentation makes it difficult to articulate to the public, to non-religious studies colleagues, and to students why the study of religion matters. We therefore too often fall back on platitudes. I argue for a revitalized methods and theories conversation that connects us even as it bears our arguments and disagreements about what we do and how. Courses in methods and theories in the study of religion represent the most viable basis we have for bringing the academic study of religion into the common conversation or argument that constitutes a discipline without sacrificing our pluralism.

scholarly journals Business Co-operatives in Australia: “Unlikely Soil for a Co-operative Movement”

2021 ◽  
pp. 1-25
Author(s):  
Greg Patmore ◽  
Nikola Balnave ◽  
Olivera Marjanovic
Keyword(s):  
Business Model ◽  
Common Good ◽  
Business Owners ◽  
The Self ◽  
Small Business Owners ◽  
Large Database ◽  
Average Life ◽  
Direct Competition ◽  
The Common ◽  
Over Time

While co-operatives are traditionally associated with workers, consumers, and farmers, the business model, with its emphasis on democracy and community, has also been adopted by small business owners, the self-employed, and professionals. These business co-operatives are distinct phenomenon, because they primarily consist of independent organizational entities that are not co-operatives and are generally in direct competition with one another. They are unique in that they bring together separate organizations that seek to combat market threats while adopting a philosophy based on co-operative principles. This article begins with an overview of the Australian co-operative landscape. It then defines the concept of business co-operatives and then draws upon the Visual Atlas of Australian Co-operatives History Project, which has developed a large database of Australian co-operatives over time and space, to examine the development of business co-operatives in Australia. It looks at where business co-operatives formed in the economy, the motivation underlying their formation, their average life spans, and their relationships with the broader co-operative movement. The article highlights the value of business co-operatives in introducing the values of participatory democracy and working for the common good into unanticipated markets and reinforcing the co-operative movement.

Solar-Driven Sorption Chillers for Residential Space Cooling: A Review of Recent Developments and Possible Applications in Canada

2015 ◽  
Author(s):  
Daniel Bowie ◽  
Cynthia A. Cruickshank
Keyword(s):  
High Performance ◽  
Energy Use ◽  
Peak Load ◽  
Internal Heat ◽  
Electricity Grid ◽  
Residential Sector ◽  
Absorption Chillers ◽  
Space Cooling ◽  
Recent Developments ◽  
Advanced Cycles

Energy use for space cooling has increased by 156% from 1990 to 2010 in the Canadian residential sector. In many parts of the country, the increasing use of electrically driven air-conditioners has begun to shift the peak load on the electricity grid from the coldest days of winter to the hottest days of summer. Many of Canada’s major electric utilities providers rely on fossil fuels to generate the additional capacity needed to meet the peak demand, resulting in significant greenhouse gas emissions. Solar-driven sorption chillers remain one of the possible solutions for shaving the peak loads experienced by the electricity grid. This paper presents a review of the recent developments in the research of adsorption and absorption chillers, as well as a comparison of the two technologies based on the latest published experimental results found in the literature. Adsorption chillers continue to evolve in their design, including the use of new consolidated and composite adsorbents, the integration of coated adsorbers into internal heat exchangers, and newly developed advanced cycles for heat and mass recovery. While the physical design of adsorption chillers continues to be advanced, the development of absorption chillers for solar cooling applications has largely been focused on optimizing the system as a whole through improved control strategies and the implementation of newly developed high performance solar collectors. Finally, the paper aims to assess the current state of development of solar-driven sorption chillers to provide insight into their applicability in the Canadian residential sector, as well as the remaining challenges facing this technology.

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