ORCID Profile
0000-0002-1126-869X
Current Organisation
Macquarie University
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Astronomical and Space Sciences | Stellar Astronomy and Planetary Systems | Galactic Astronomy | Astronomical and Space Instrumentation | Numerical and Computational Mathematics not elsewhere classified | Turbulent Flows | Quantum Chemistry | Interdisciplinary Engineering | Nanophotonics | Cosmology and Extragalactic Astronomy
Expanding Knowledge in the Physical Sciences | Learner and Learning Achievement | Education and Training not elsewhere classified | Information and Communication Services not elsewhere classified | Scientific Instruments | Expanding Knowledge in Engineering | Expanding Knowledge in the Information and Computing Sciences | Expanding Knowledge in Technology |
Publisher: IOP Publishing
Date: 04-2009
DOI: 10.1086/597765
Publisher: Oxford University Press (OUP)
Date: 19-09-2016
Publisher: No publisher found
Date: 2011
Publisher: EDP Sciences
Date: 10-2022
DOI: 10.1051/0004-6361/202243429
Abstract: Context. In this paper, we focus on post-asymptotic giant branch (post-AGB) binaries and study the interaction between the different components of these complex systems. These components comprise the post-AGB primary, a main sequence secondary, a circumbinary disk, as well as a fast bipolar outflow (jet) launched by the companion. We obtained well-s led time series of high resolution optical spectra over the last decade and these spectra provide the basis of our study. Aims. We aim to use the time-series data to quantify the velocity and density structure of the jets in nine of these post-AGB binaries. This complements our earlier work and this amounts to the analyses of 16 jet-launching systems in total. Methods. The jet is detected in absorption, at superior conjunction, when the line of sight towards the primary goes through the bipolar cone. Our spectral time series scan the jets during orbital motion. Our spatio-kinematic model is constrained by these dynamical spectra. We complement this with a radiative-transfer model in which the Balmer series are used to derive total mass-loss rates in the jets. Results. The jets are found to be wide ( 30°) and display an angle-dependent density structure with a dense and slower outer region near the jet cone and a fast inner part along the jet symmetry axes. The deprojected outflow velocities confirm that the companions are main sequence companions. The total mass-loss rates are large (10 −8 − 10 −5 M ⊙ yr −1 ), from which we can infer that the mass-accretion rates onto the companion star must be high as well. The circumbinary disk is likely the main source for the accretion disk around the companion. All systems with full disks that start near the sublimation radius show jets, whereas for systems with evolved transition disks this lowers to a detection rate of 50%. Objects without an infrared excess do not show jets. Conclusions. We conclude that jet creation in post-AGB binaries is a mainstream process. Our geometric spatio-kinematic model is versatile enough to model the variety of spectral time series. The interaction between the circumbinary disks and the central binary provide the needed accretion flow, but the presence of a circumbinary disk does not seem to be the only prerequisite to launch a jet.
Publisher: Oxford University Press (OUP)
Date: 24-07-2020
Abstract: The morphology of bipolar planetary nebulae (PNe) can be attributed to interactions between a fast wind from the central engine and the dense toroidal-shaped ejecta left over from common envelope (CE) evolution. Here we use the 3D hydrodynamic adaptive mesh refinement (AMR) code AstroBEAR to study the possibility that bipolar PN outflows can emerge collimated even from an uncollimated spherical wind in the aftermath of a CE event. The output of a single CE simulation via the smoothed particle hydrodynamics (SPH) code phantom serves as the initial conditions. Four cases of winds, all with high enough momenta to account for observed high momenta pre-PN outflows, are injected spherically from the region of the CE binary remnant into the ejecta. We compare cases with two different momenta and cases with no radiative cooling versus application of optically thin emission via a cooling curve to the outflow. Our simulations show that in all cases highly collimated bipolar outflows result from deflection of the spherical wind via the interaction with the CE ejecta. Significant asymmetries between the top and bottom lobes are seen in all cases. The asymmetry is strongest for the lower momentum case with radiative cooling. While real post-CE winds may be aspherical, our models show that collimation via ‘inertial confinement’ will be strong enough to create jet-like outflows even beginning with maximally uncollimated drivers. Our simulations reveal detailed shock structures in the shock-focused inertial confinement (SFIC) model and develop a lens-shaped inner shock that is a new feature of SFIC-driven bipolar lobes.
Publisher: American Astronomical Society
Date: 15-09-2010
Publisher: Elsevier BV
Date: 05-2010
Publisher: Springer Science and Business Media LLC
Date: 03-01-2023
Publisher: American Astronomical Society
Date: 10-11-2002
DOI: 10.1086/342877
Publisher: Oxford University Press (OUP)
Date: 12-08-2016
Publisher: American Astronomical Society
Date: 30-04-2013
Publisher: American Astronomical Society
Date: 25-06-2013
Publisher: Oxford University Press (OUP)
Date: 09-2022
Abstract: At least one in five of all planetary nebulae are the product of a common envelope (CE) interaction, where the companion in-spirals into the envelope of an asymptotic giant branch (AGB) star ejecting the nebula and leaving behind a compact binary. In this work we carry out 3D smoothed particle hydrodynamics simulations of the CE interaction between a 1.7 M⊙ AGB star and a 0.6 M⊙ companion. We model the AGB structure using a 1D stellar model taken at the seventh thermal pulse. The interaction takes place when the giant is on the expanding phase of the seventh thermal pulse and has a radius of 250 R⊙. The post-CE orbital separations varies between 20 and 31 R⊙, with the inclusion of recombination energy resulting in wider separations. Based on the observed short in-spiral time-scales, we suggest that thermal pulses can trigger CEs, extending the ability of AGB stars to capture companions into CEs, that would lead to the prediction of a larger population of post-AGB, post-CE binaries. Simulations that include a tabulated equation of state unbind a great deal more gas, likely unbinding the entire envelope on short time-scales. The shape of the CE after the in-spiral is more spherical for AGB than red giant branch stars, and even more so if recombination energy is included. We expect that the planetary nebula formed from this CE will have different features compared to those formed from red giant branch stars.
Publisher: American Astronomical Society
Date: 16-06-2010
Publisher: SPIE
Date: 24-09-2012
DOI: 10.1117/12.925812
Publisher: Cambridge University Press (CUP)
Date: 10-2017
DOI: 10.1017/S1743921317002149
Abstract: One in 5 PN are ejected from common envelope binary interactions but Kepler results are already showing this proportion to be larger. Their properties, such as abundances can be starkly different from those of the general population, so they should be considered separately when using PN as chemical or population probes. Unfortunately post-common envelope PN cannot be discerned using only their morphologies, but this will change once we couple our new common envelope simulations with PN formation models.
Publisher: American Astronomical Society
Date: 06-2002
DOI: 10.1086/340569
Publisher: American Astronomical Society
Date: 10-04-2017
Publisher: Oxford University Press (OUP)
Date: 15-02-2016
DOI: 10.1093/MNRAS/STW331
Publisher: AIP
Date: 2005
DOI: 10.1063/1.2146276
Publisher: Springer Science and Business Media LLC
Date: 03-2007
DOI: 10.1038/NATURE05576
Abstract: Cataclysmic variables (classical novae and dwarf novae) are binary star systems in which a red dwarf transfers hydrogen-rich matter, by way of an accretion disk, to its white dwarf companion. In dwarf novae, an instability is believed to episodically dump much of the accretion disk onto the white dwarf. The liberation of gravitational potential energy then brightens these systems by up to 100-fold every few weeks or months. Thermonuclear-powered eruptions thousands of times more luminous occur in classical novae, accompanied by significant mass ejection and formation of clearly visible shells from the ejected material. Theory predicts that the white dwarfs in all dwarf novae must eventually accrete enough mass to undergo classical nova eruptions. Here we report a shell, an order of magnitude more extended than those detected around many classical novae, surrounding the prototypical dwarf nova Z Camelopardalis. The derived shell mass matches that of classical novae, and is inconsistent with the mass expected from a dwarf nova wind or a planetary nebula. The shell observationally links the prototypical dwarf nova Z Camelopardalis with an ancient nova eruption and the classical nova process.
Publisher: Springer Science and Business Media LLC
Date: 2001
Publisher: EDP Sciences
Date: 17-02-2006
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3AN01924A
Abstract: Surface-enhanced Raman spectroscopy (SERS) is a potentially important tool in the rapid and accurate detection of pathogenic bacteria in biological fluids. However, for diagnostic application of this technique, it is necessary to develop a highly sensitive, stable, biocompatible and reproducible SERS-active substrate. In this work, we have developed a silver-gold bimetallic SERS surface by a simple potentiostatic electrodeposition of a thin gold layer on an electrochemically roughened nanoscopic silver substrate. The resultant substrate was very stable under atmospheric conditions and exhibited the strong Raman enhancement with the high reproducibility of the recorded SERS spectra of bacteria (E. coli, S. enterica, S. epidermidis, and B. megaterium). The coating of the antibiotic over the SERS substrate selectively captured bacteria from blood s les and also increased the Raman signal in contrast to the bare surface. Finally, we have utilized the antibiotic-coated hybrid surface to selectively identify different pathogenic bacteria, namely E. coli, S. enterica and S. epidermidis from blood s les.
Publisher: Springer Science and Business Media LLC
Date: 08-12-2022
Publisher: Springer Berlin Heidelberg
Date: 2007
Publisher: American Astronomical Society
Date: 05-2006
DOI: 10.1086/501528
Publisher: Cambridge University Press (CUP)
Date: 2017
DOI: 10.1017/PASA.2016.52
Abstract: Astrophysicists are increasingly taking into account the effects of orbiting companions on stellar evolution. New discoveries have underlined the role of binary star interactions in a range of astrophysical events, including some that were previously interpreted as being due uniquely to single stellar evolution. We review classical binary phenomena, such as type Ia supernovae, and discuss new phenomena, such as intermediate luminosity transients, gravitational wave-producing double black holes, and the interaction between stars and their planets. Finally, we reassess well-known phenomena, such as luminous blue variables, in light of interpretations that include both single and binary stars. At the same time we contextualise the new discoveries within the framework of binary stellar evolution. The last decade has seen a revival in stellar astrophysics as the complexity of stellar observations is increasingly interpreted with an interplay of single and binary scenarios. The next decade, with the advent of massive projects such as the Square Kilometre Array , the James Webb Space Telescope , and increasingly sophisticated computational methods, will see the birth of an expanded framework of stellar evolution that will have repercussions in many other areas of astrophysics such as galactic evolution and nucleosynthesis.
Publisher: American Astronomical Society
Date: 10-12-2005
DOI: 10.1086/497262
Publisher: Oxford University Press (OUP)
Date: 25-07-2020
Abstract: We study the formation of dust in the expanding gas ejected as a result of a common envelope binary interaction. In our novel approach, we apply the dust formation model of Nozawa et al. to the outputs of the 3D hydrodynamic SPH simulation performed by Iaconi et al. that involves a giant of 0.88 M⊙ and 83 R⊙, with a companion of 0.6 M⊙ placed on the surface of the giant in circular orbit. After simulating the dynamic in-spiral phase, we follow the expansion of the ejecta for $\\simeq 18\\, 000$ d. During this period, the gas is able to cool down enough to reach dust formation temperatures. Our results show that dust forms efficiently in the window between ≃ 300 d (the end of the dynamic in-spiral) and ≃ 5000 d. The dust forms in two separate populations an outer one in the material ejected during the first few orbits of the companion inside the primary’s envelope and an inner one in the rest of the ejected material. We are able to fit the grain-size distribution at the end of the simulation with a double power law. The slope of the power law for smaller grains is flatter than that for larger grains, creating a knee-shaped distribution. The power-law indexes are, however, different from the classical values determined for the interstellar medium. We also estimate that the contribution to cosmic dust by common envelope events is not negligible and comparable to that of novae and supernovae.
Publisher: EDP Sciences
Date: 16-08-2006
Publisher: EDP Sciences
Date: 18-10-2019
DOI: 10.1051/0004-6361/201936073
Abstract: Aims. We aim to determine the geometry, density gradient, and velocity structure of jets in post-asymptotic giant branch (post-AGB) binaries. Methods. Our high cadence time series of high-resolution optical spectra of jet-creating post-AGB binary systems provide us with a unique tomography of the jet. We determine the spatio-kinematic structure of the jets based on these data by fitting the synthetic spectral line profiles created by our model to the observed, orbital phase-resolved, H α -line profiles of these systems. The fitting routine is provided with an initial spectrum and is allowed to test three configurations, derived from three specific jet launching models: a stellar jet launched by the star, an X-wind, and a disk wind configuration. We apply a Markov-chain Monte Carlo routine in order to fit our model to the observations. Our fitting code is tested on the post-AGB binary IRAS 19135+3937. Results. We find that a model using the stellar jet configuration gives a marginally better fit to our observations. The jet has a wide half-opening angle of about 76° and reaches velocities up to 870 km s −1 . Conclusions. Our methodology is successful in determining some parameters for jets in post-AGB binaries. The model for IRAS 19135+3937 includes a transparent, low density inner region (for a half-opening angle 40°). The source feeding the accretion disk around the companion is most likely the circumbinary disk. We will apply this jet fitting routine to other jet-creating post-AGB stars in order to provide a more complete description of these objects.
Publisher: Oxford University Press (OUP)
Date: 03-05-2011
Publisher: American Astronomical Society
Date: 20-10-2005
DOI: 10.1086/444372
Publisher: Springer Science and Business Media LLC
Date: 2002
Publisher: American Astronomical Society
Date: 12-08-2019
Publisher: American Astronomical Society
Date: 05-2012
Publisher: Oxford University Press (OUP)
Date: 11-03-2015
DOI: 10.1093/MNRAS/STV249
Publisher: Oxford University Press (OUP)
Date: 21-08-2019
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 erge 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.
Publisher: AIP
Date: 2005
DOI: 10.1063/1.2146264
Publisher: American Astronomical Society
Date: 07-12-2009
Publisher: Cambridge University Press (CUP)
Date: 04-2006
Publisher: Cambridge University Press (CUP)
Date: 07-2011
DOI: 10.1017/S1743921311028298
Abstract: The common envelope interaction between a giant star and a stellar or substellar companion is at the origin of several compact binary classes, including the progenitors of Type Ia SN. A common envelope is also what will happen when the Sun expands and swallows its planets as far out as Jupiter. The basic idea and physics of the common envelope interaction has been known since the 1970s. However, the outcome of a common envelope interaction - what systems survive and what their parameters are - depends sensitively on the details of the engagement. To advance our knowledge of the common envelope interaction between stars and their stellar and substellar companions, we have carried out a series of simulations with Eulerian, grid-based and Lagrangian, smoothed particle hydrodynamics codes between a 0.88-M ⊙ , 85-R ⊙ , red giant branch star and companions in the mass range 0.1-0.9 M ⊙ . In this contribution, we will discuss the reliability of the techniques, the physics that is not included in the codes but is likely important, the state of the ejected common envelope, and the final binary separation. We also carry out a comparison with the observations. Finally, we discuss the common envelope efficiency parameter, α and the survival of planets.
Publisher: American Chemical Society (ACS)
Date: 28-05-2013
DOI: 10.1021/JP4032578
Publisher: American Astronomical Society
Date: 06-05-2014
Publisher: EDP Sciences
Date: 29-04-2014
Publisher: Oxford University Press (OUP)
Date: 10-07-2012
Publisher: American Astronomical Society
Date: 21-11-2011
Publisher: Cambridge University Press (CUP)
Date: 08-2019
DOI: 10.1017/S1743921318006555
Abstract: We have discovered jets in post-AGB binaries. The orbital motion allows us to carry out tomography of the jet as light from the primary star shines through the jet cone. Jets play a major role in many astrophysical environments, from young stellar objects to galaxies. They are also used to study the energetics of accretion phenomena in systems such as red transients and stellar mergers. We use high-resolution, optical, time-series spectra to constrain theories of jet launching, and the impact of jets on the evolution of these post-AGB binaries.
Publisher: Oxford University Press (OUP)
Date: 27-04-2012
Publisher: American Astronomical Society
Date: 19-12-2008
DOI: 10.1086/523890
Publisher: American Astronomical Society
Date: 11-05-2012
Publisher: SPIE
Date: 03-01-2020
DOI: 10.1117/12.2539594
Publisher: EDP Sciences
Date: 09-2020
DOI: 10.1051/0004-6361/202038414
Abstract: Aims. In this study we determine the morphology and mass-loss rate of jets emanating from the companion in post-asymptotic giant branch (post-AGB) binary stars with a circumbinary disc. In doing so we also determine the mass-accretion rates onto the companion, and investigate the source feeding the circum-companion accretion disc. Methods. We perform a spatio-kinematic modelling of the jet of two well-s led post-AGB binaries, BD+46°442 and IRAS 19135+3937, by fitting the orbital phased time series of H α spectra. Once the jet geometry, velocity, and scaled density structure are computed, we carry out radiative transfer modelling of the jet for the first four Balmer lines to determine the jet densities, thus allowing us to compute the jet mass-loss rates and mass-accretion rates. We distinguish the origin of the accretion by comparing the computed mass-accretion rates with theoretically estimated mass-loss rates, both from the post-AGB star and from the circumbinary disc. Results. The spatio-kinematic model of the jet reproduces the observed absorption feature in the H α lines. The jets have an inner region with extremely low density in both objects. The jet model for BD+46°442 is tilted by 15° with respect to the orbital axis of the binary system. IRAS 19135+3937 has a smaller tilt of 6°. Using our radiative transfer model, we find the full 3D density structure of both jets. By combining these results, we can compute the mass-loss rates of the jets, which are of the order of 10 −7 − 10 −5 M ⊙ yr −1 . From this we estimate mass-accretion rates onto the companion of 10 −6 − 10 −4 M ⊙ yr −1 . Conclusions. Based on the mass-accretion rates found for these two objects, we conclude that the circumbinary disc is most likely the source feeding the circum-companion accretion disc. This is in agreement with the observed depletion patterns in post-AGB binaries, which is caused by re-accretion of gas from the circumbinary disc that is under-abundant in refractory elements. The high accretion rates from the circumbinary disc imply that the lifetime of the disc will be short. Mass transfer from the post-AGB star cannot be excluded in these systems, but it is unlikely to provide a sufficient mass-transfer rate to sustain the observed jet mass-loss rates.
Publisher: Cambridge University Press (CUP)
Date: 07-2011
DOI: 10.1017/S1743921312010800
Abstract: AGB stars appear to lose mass spherically, but many PNe resulting from the AGB mass-loss have non-spherical morphologies. Compact disks have been found in some bipolar PNe, but their role in the shaping process remains unknown. Compact Keplerian disks are found to be common around post-AGB binaries, however, these objects may never develop into PNe. Another group of post-AGB stars, known as pre-PNe, are surrounded by collimated nebulae shining by reflected light or shock ionisation. We are observing the inner circumstellar regions of pre-PNe at high angular resolutions with the VLTI. We seek to compare pre-PNe disks to those around other post-AGB stars and PNe. New observations of the pre-PN, IRAS 16279-4757, show evidence for a disk similar to those seen in young PNe.
Publisher: Oxford University Press (OUP)
Date: 10-2004
Publisher: American Astronomical Society
Date: 20-07-2002
DOI: 10.1086/342277
Publisher: Cambridge University Press (CUP)
Date: 04-2006
Publisher: IOP Publishing
Date: 06-2009
Publisher: IOP Publishing
Date: 04-2011
DOI: 10.1086/659846
Publisher: American Astronomical Society
Date: 20-10-2006
DOI: 10.1086/506900
Publisher: Oxford University Press (OUP)
Date: 15-06-2016
Publisher: EDP Sciences
Date: 09-2014
Publisher: Oxford University Press (OUP)
Date: 25-07-2019
Abstract: We conduct three-dimensional hydrodynamic simulations of the common envelope binary interaction and show that if the companion were to launch jets while interacting with the giant primary star’s envelope, the jets would remove a substantial fraction of the envelope’s gas. We use the set-up and numerical code of an earlier common envelope study that did not include jets, with a 0.88-M⊙, 83-R⊙ red giant star and a 0.3-M⊙ companion. The assumption is that the companion star accretes mass via an accretion disc that is responsible for launching the jets which, in the simulations, are injected numerically. For the first time we conduct simulations that include jets as well as the gravitational energy released by the inspiralling core-companion system. We find that simulations with jets unbind approximately three times as much envelope mass than identical simulations that do not include jets, though the total fraction of unbound gas remains below 50 per cent for these particular simulations. The jets generate high-velocity outflows in the polar directions. The jets also increase the final core-companion orbital separation and lead to a kick velocity of the core-companion binary system. Our results show that, if able to form, jets could play a crucial role in ejecting the envelope and in shaping the outflow.
Publisher: Cambridge University Press (CUP)
Date: 07-2011
DOI: 10.1017/S1743921312011349
Abstract: The Kepler Observatory offers unprecedented photometric precision ( mmag) and cadence for monitoring the central stars of planetary nebulae, allowing the detection of tiny periodic light curve variations, a possible signature of binarity. With this precision free from the observational gaps dictated by weather and lunar cycles, we are able to detect companions at much larger separations and with much smaller radii than ever before. We have been awarded observing time to obtain light-curves of the central stars of the six confirmed and possible planetary nebulae in the Kepler field, including the newly discovered object Kn 61, at cadences of both 30 min and 1 min. Of these six objects, we could confirm for three a periodic variability consistent with binarity. Two others are variables, but the initial data set presents only weak periodicities. For the central star of Kn 61, Kepler data will be available in the near future.
Publisher: American Astronomical Society
Date: 19-10-2012
Publisher: Oxford University Press (OUP)
Date: 21-12-2018
Publisher: American Astronomical Society
Date: 12-07-2006
DOI: 10.1086/506593
Publisher: American Astronomical Society
Date: 2002
DOI: 10.1086/324737
Publisher: IOP Publishing
Date: 06-2002
DOI: 10.1086/341691
Publisher: American Astronomical Society
Date: 10-12-2002
DOI: 10.1086/345773
Publisher: American Astronomical Society
Date: 10-02-2017
Publisher: AIP
Date: 2005
DOI: 10.1063/1.2146244
Publisher: Cambridge University Press (CUP)
Date: 12-2011
Publisher: Oxford University Press (OUP)
Date: 27-03-2018
DOI: 10.1093/MNRAS/STY794
Publisher: American Astronomical Society
Date: 09-02-2004
DOI: 10.1086/382156
Publisher: Springer Science and Business Media LLC
Date: 27-02-2013
DOI: 10.1007/S00159-013-0059-2
Abstract: This work aims to present our current best physical understanding of common-envelope evolution (CEE). We highlight areas of consensus and disagreement, and stress ideas which should point the way forward for progress in this important but long-standing and largely unconquered problem. Unusually for CEE-related work, we mostly try to avoid relying on results from population synthesis or observations, in order to avoid potentially being misled by previous misunderstandings. As far as possible we debate all the relevant issues starting from physics alone, all the way from the evolution of the binary system immediately before CEE begins to the processes which might occur just after the ejection of the envelope. In particular, we include extensive discussion about the energy sources and sinks operating in CEE, and hence examine the foundations of the standard energy formalism. Special attention is also given to comparing the results of hydrodynamic simulations from different groups and to discussing the potential effect of initial conditions on the differences in the outcomes. We compare current numerical techniques for the problem of CEE and also whether more appropriate tools could and should be produced (including new formulations of computational hydrodynamics, and attempts to include 3D processes within 1D codes). Finally we explore new ways to link CEE with observations. We compare previous simulations of CEE to the recent outburst from V1309 Sco, and discuss to what extent post-common-envelope binaries and nebulae can provide information, e.g. from binary eccentricities, which is not currently being fully exploited.
Publisher: EDP Sciences
Date: 12-2018
DOI: 10.1051/0004-6361/201833507
Abstract: The high excitation planetary nebula, NGC 6302, has been imaged in two far-ultraviolet (FUV) filters, F169M (Sapphire λ eff : 1608 Å) and F172M (Silica λ eff : 1717 Å) and two near-UV (NUV) filters, N219M (B15 λ eff : 2196 Å) and N279N (N2 λ eff : 2792 Å) with the Ultra Violet Imaging Telescope (UVIT). The FUV F169M image shows faint emission lobes that extend to about 5 arcmin on either side of the central source. Faint orthogonal collimated jet-like structures are present on either side of the FUV lobes through the central source. These structures are not present in the two NUV filters or in the FUV F172M filter. Optical and infrared (IR) images of NGC 6302 show bright emission bipolar lobes in the east-west direction with a massive torus of molecular gas and dust seen as a dark lane in the north-south direction. The FUV lobes are much more extended and oriented at a position angle of 113°. They and the jet-like structures might be remnants of an earlier evolutionary phase, prior to the dramatic explosive event that triggered the Hubble type bipolar flows approximately 2200 years ago. The source of the FUV lobe and jet emission is not known, but is likely due to fluorescent emission from H 2 molecules. The cause of the difference in orientation of optical and FUV lobes is not clear and, we speculate, could be related to two binary interactions.
Publisher: Cambridge University Press (CUP)
Date: 07-2011
DOI: 10.1017/S1743921312010794
Abstract: There is at present no viable theory whereby a single star with M MS 2.3 ± 0.3 M ⊙ can sustain a PN-forming superwind with Ṁ 3×10 −5 M ⊙ yr −1 at the tip of the AGB that can eject the last ~0.3 M ⊙ of envelope mass. We propose that a binary companion can not only result in non-spherical PN, but more importantly provide the AGB mass loss rate enhancement that is required to create a visible PN. We provide an overview of our binary population synthesis calculations of the PN formation rates from common envelope (CE) interactions, CE mergers with substellar companions, tidally synchronized systems that avoid CE, gravitationally focused winds, and double degenerate systems. The predicted number of Galactic PN with radii 0.9 pc shaped and created by a binary companion is 8,100±2,300 which is (71±20)% of the observationally-estimated total. We demonstrate that the observed close central star of PN binary fraction of 15–20% is consistent with our overall binary fraction, considering we predict two binary populations with period distributions centred at log P(days) ~0 and 4. Finally, we discuss the impact of binarity on the PN luminosity function, central star mass distribution, chemical abundances, morphologies, etc., and why these distributions predicted in the binary scenario are close to observations while the single star paradigm produces distributions which are measurably discrepant.
Publisher: Cambridge University Press (CUP)
Date: 04-2006
Publisher: EDP Sciences
Date: 04-2017
Publisher: Oxford University Press (OUP)
Date: 13-04-2020
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.
Publisher: EDP Sciences
Date: 05-2013
Publisher: Oxford University Press (OUP)
Date: 13-01-2011
Publisher: EDP Sciences
Date: 04-12-2008
Publisher: Oxford University Press (OUP)
Date: 10-02-2014
DOI: 10.1093/MNRAS/STU079
Publisher: Oxford University Press (OUP)
Date: 30-11-2015
Publisher: American Astronomical Society
Date: 13-12-2011
Publisher: EDP Sciences
Date: 09-2014
Publisher: American Astronomical Society
Date: 14-07-2011
Publisher: Oxford University Press (OUP)
Date: 22-12-2019
Publisher: American Astronomical Society
Date: 11-06-2008
Publisher: Oxford University Press (OUP)
Date: 18-10-2019
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.
Publisher: EDP Sciences
Date: 2015
DOI: 10.1051/EAS/1571085
Publisher: American Astronomical Society
Date: 20-04-2004
DOI: 10.1086/421460
Publisher: MDPI AG
Date: 26-10-2018
Abstract: The morphologies of planetary nebula have long been believed to be due to wind shaping processes in which a “fast wind” from the central star impacts a previously ejected envelope. It is assumed that asymmetries existing in the “slow wind” envelope would lead to inertial confinement, shaping the resulting interacting wind flow. We present new results demonstrating the effectiveness of Common Envelope Evolution (CEE) at producing aspherical envelopes which, when impinged upon by a spherical fast stellar wind, produce highly bipolar, jet-like outflows. We have run two simple cases using the output of a single PHANTOM SPH CEE simulation. Our work uses the Adaptive Mesh Refinement code AstroBEAR to track the interaction of the fast wind and CEE ejecta allows us to follow the morphological evolution of the outflow lobes at high resolution in 3-D. Our two models bracket low and high momentum output fast winds. We find the interaction leads to highly collimated bipolar outflows. In addition, the bipolar morphology depends on the fast wind momentum injection rate. With this dependence comes the initiation of significant symmetry breaking between the top and bottom bipolar lobes. Our simulations, though simplified, confirm the long-standing belief that CEE can plan a major role in PPN and PN shaping. These simulations are intended as an initial exploration of the post-CE/PPN flow patterns that can be expected from central source outflows and CE ejecta.
Publisher: Springer Science and Business Media LLC
Date: 04-05-2023
DOI: 10.1007/S41115-023-00017-X
Abstract: When the primary star in a close binary system evolves into a giant and engulfs its companion, its core and the companion temporarily orbit each other inside a common envelope. Drag forces transfer orbital energy and angular momentum to the envelope material. Depending on the efficiency of this process, the envelope may be ejected leaving behind a tight remnant binary system of two stellar cores, or the cores merge retaining part of the envelope material. The exact outcome of common-envelope evolution is critical for in the formation of X-ray binaries, supernova progenitors, the progenitors of compact-object mergers that emit detectable gravitational waves, and many other objects of fundamental astrophysical relevance. The wide ranges of spatial and temporal timescales that characterize common-envelope interactions and the lack of spatial symmetries present a substantial challenge to generating consistent models. Therefore, these critical phases are one of the largest sources for uncertainty in classical treatments of binary stellar evolution. Three-dimensional hydrodynamic simulations of at least part of the common-envelope interaction are the key to gain predictive power in modeling common-envelope evolution. We review the development of theoretical concepts and numerical approaches for such three-dimensional hydrodynamic simulations. The inherent multi-physics, multi-scale challenges have resulted in a wide variety of approximations and numerical techniques to be exercised on the problem. We summarize the simulations published to date and their main results. Given the recent rapid progress, a sound understanding of the physics of common-envelope interactions is within reach and thus there is hope that one of the remaining fundamental problems of stellar astrophysics may be solved before long.
Publisher: Oxford University Press (OUP)
Date: 11-06-2018
Publisher: Cambridge University Press (CUP)
Date: 08-2019
DOI: 10.1017/S1743921318007202
Abstract: One may argue that, today, proceedings articles are not useful. Results belong in refereed papers and even reviews are best in publications that are long enough to do justice to the topic reviewed. In this short review, reflecting a presentation that was given at the IAU343 symposium, Why Galaxies Care about AGB Stars , I have therefore endeavoured to include some practical snippets that, while remaining true to the presentation, also provide a quick look up reference. After a reminder of how few AGB stars actually interact with a companion, and a pictorial summary of the types of interactions that can happen, I list the rapidly growing body of 3D common envelope simulations. Next, I highlight shortfalls and successes of simulations, and then spend some time comparing the two simulations of planetary nebulae from common envelope interactions to date. Finally, I summarise a handful of results pertaining to common envelope interactions between giants and planets.
Publisher: Oxford University Press (OUP)
Date: 02-2008
Publisher: Oxford University Press (OUP)
Date: 08-2008
Publisher: Oxford University Press (OUP)
Date: 12-2001
Start Date: 01-2013
End Date: 12-2018
Amount: $676,702.00
Funder: Australian Research Council
View Funded ActivityStart Date: 12-2010
End Date: 05-2014
Amount: $278,400.00
Funder: Australian Research Council
View Funded ActivityStart Date: 04-2012
End Date: 12-2015
Amount: $315,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2014
End Date: 12-2016
Amount: $1,025,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 09-2021
End Date: 08-2024
Amount: $390,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 01-2021
End Date: 01-2022
Amount: $632,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 05-2011
End Date: 12-2014
Amount: $350,000.00
Funder: Australian Research Council
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