A5057362556- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- History and Developments in Astronomy
- Astronomical Observations and Instrumentation
- Pulsars and Gravitational Waves Research
- Spectroscopy and Laser Applications
- Solar and Space Plasma Dynamics
- Galaxies: Formation, Evolution, Phenomena
- Atmospheric Ozone and Climate
- Scientific Research and Discoveries
- Adaptive optics and wavefront sensing
- Reservoir Engineering and Simulation Methods
- Spacecraft Design and Technology
- Aeolian processes and effects
- Atomic and Molecular Physics
- Modeling, Simulation, and Optimization
- Geophysics and Gravity Measurements
- Calibration and Measurement Techniques
- Planetary Science and Exploration
- Fluid Dynamics Simulations and Interactions
- Vibration and Dynamic Analysis
Macquarie University
2015-2024
American Museum of Natural History
2002-2012
Rochester Institute of Technology
2011
Technion – Israel Institute of Technology
2011
Friedrich-Alexander-Universität Erlangen-Nürnberg
2011
Australian Astronomical Observatory
2011
European Southern Observatory
2011
Institut d'Astrophysique de Paris
2011
Vrije Universiteit Brussel
2011
Universidad Nacional Autónoma de México
2003
This work aims to present our current best physical understanding of common-envelope evolution (CEE). We highlight areas consensus and disagreement, stress ideas which should point the way forward for progress in this important but long-standing largely unconquered problem. Unusually CEE-related work, we mostly try avoid relying on results from population synthesis or observations, order potentially being misled by previous misunderstandings. As far as possible debate all relevant issues...
Planetary nebulae (PNe) are circumstellar gas ejected during an intense mass-losing phase in the lives of asymptotic giant branch stars. PNe have a stunning variety shapes, most which not spherically symmetric. The debate over what makes and shapes these evolved, intermediate mass stars has raged for two decades. Today community is reaching consensus that single cannot trivially manufacture impart to them non spherical binary companion, possibly even sub-stellar one, might be needed majority...
Abstract When the primary star in a close binary system evolves into giant and engulfs its companion, core companion temporarily orbit each other inside common envelope. Drag forces transfer orbital energy angular momentum to envelope material. Depending on efficiency of this process, may be ejected leaving behind tight remnant two stellar cores, or cores merge retaining part The exact outcome common-envelope evolution is critical for formation X-ray binaries, supernova progenitors,...
We present a quantitative classification scheme for carbon and oxygen sequence Wolf-Rayet stars. Our uses new high-quality optical A AT INT observations of 20 stars which we provide narrow-band photometry estimates interstellar reddenings. In increasing order excitation, our spectral classes range from WC11 to WC4 WolfRayet with dominant line visual spectrum, subsequently WO4 WO1 those predominantly lines. refine existing WC WO schemes incorporate higher lower excitation features. Both...
We use three-dimensional hydrodynamical simulations to study the rapid infall phase of common envelope interaction a red giant branch star mass equal 0.88 \msun and companion ranging from 0.9 down 0.1 \msun. first compare results obtained using two different numerical techniques with resolutions, find overall very good agreement. then outcomes those observed systems thought have gone through envelope. The fail reproduce in sense that most donor remains bound at end final orbital separations...
We propose a simple means for compressing optical pulses with second-harmonic generation. Aperiodic quasi-phase-matching gratings impart frequency-dependent phase shift on the pulse relative to fundamental and can be engineered correct arbitrary distortions. The mechanism is discussed, detailed analysis of compression quadratic (linear frequency) chirped presented.
We have undertaken quantitative analysis of four LMC and SMC O4--9.7 extreme supergiants using far-ultraviolet FUSE, ultraviolet IUE/HSTand optical VLT UVES spectroscopy. Extended, non-LTE model atmospheres that allow for the consistent treatment line blanketing are used to analyse wind & photospheric spectral features simultaneously. Using Halpha constrain dM/dt, HeI-II lines reveal T_eff's which systematically (5-7.5kK) substantially (15-20%) lower than previously derived from...
The {\alpha}-formalism is a common way to parametrize the envelope interaction between giant star and more compact companion. {\alpha} parameter describes fraction of orbital energy released by companion that available eject star's envelope. By using new, detailed stellar evolutionary calculations we derive user-friendly prescription for {\lambda} an improved approximation binding energy, thus revising equation. We then determine both from simulations observations in self consistent manner....
Abstract Astrophysicists are increasingly taking into account the effects of orbiting companions on stellar evolution. New discoveries have underlined role binary star interactions in a range astrophysical events, including some that were previously interpreted as being due uniquely to single We review classical phenomena, such type Ia supernovae, and discuss new intermediate luminosity transients, gravitational wave-producing double black holes, interaction between stars their planets....
We present the results of hydrodynamic simulations interaction between a 10 Jupiter mass planet and red or asymptotic giant branch stars, both with zero-age main sequence 3.5 $M_\odot$. Dynamic in-spiral timescales are order few years decades for respectively. The planets will eventually be destroyed at separation from core giants smaller than resolution our simulations, either through evaporation tidal disruption. As in-spiral, stars' envelopes somewhat puffed up. Based on relatively long...
We present hydrodynamic simulations of the common envelope binary interaction between a giant star and compact companion carried out with adaptive mesh refinement code enzo smooth particle hydrodynamics phantom. These mimic parameters one by Passy et al. but assess impact larger, more realistic initial orbital separation on simulation outcome. conclude that for both codes post-common is somewhat larger amount unbound mass slightly greater when wide enough does not yet overflow or just...
We perform 3D hydrodynamical simulations of a common-envelope event involving 12 solar mass red supergiant donor. Massive stars are expected to be qualitatively different from low-mass as their envelopes have significant support radiation pressure, which increases both the final separation and amount ejected through interaction. adiabatic that include energy equation state, results in ejecting 60 per cent more (up two thirds total envelope becoming unbound, or more) yield 10 larger compared...
We present a population synthesis calculation to derive the total number of planetary nebulae (PNs) in Galaxy that descend from single stars and binary systems. Using most recent literature results on Galactic stellar formation evolution, we predict PNs with radii <0.9 pc be (4.6 ± 1.3) × 104. do not claim this complete population, since there can visible larger than limit. However, by taking limit, make our predicted inherently comparable observationally based value Peimbert Jacoby (8000...
We present an overview of the initial results from Chandra Planetary Nebula Survey (ChanPlaNS), first systematic (volume-limited) X-ray Observatory survey planetary nebulae (PNe) in solar neighborhood. The phase ChanPlaNS targeted 21 mostly high-excitation PNe within ~1.5 kpc Earth, yielding 4 detections diffuse emission and 9 X-ray-luminous point sources at central stars (CSPNe) these objects. Combining with those obtained archival data for all (14) other that have been observed to date, we...
ABSTRACT A current issue in the study of planetary nebulae with close binary central stars (CSs) is extent to which binaries affect shaping nebulae. Recent studies have begun show a high coincidence rate between large-scale axial or point symmetries and stars. In addition, combined binary-star spatiokinematic modeling demonstrated that all systems studied date appear their axis aligned primary nebula. Here we add two more list, CSs NGC 6337 Sp 1. We both be low inclination, nearly our line...
We have simulated a common envelope interaction of 0.88-M$_{\odot}$, 90-R$_{\odot}$, red giant branch star and 0.6-M$_{\odot}$, compact companion with the smoothed particle hydrodynamics code, Phantom, from beginning Roche lobe overflow phase to self-regulated inspiral, using three different resolutions. The duration is resolution dependent would lengthen increased beyond $\sim$20 years observed, while inspiral post-common separation are largely independent resolution. Mass transfer rates...
We conduct three-dimensional hydrodynamic simulations of the common envelope binary interaction and show that if companion were to launch jets while interacting with giant primary star's envelope, would remove a substantial fraction envelope's gas. use setup numerical code an earlier study did not include jets, 0.88Mo, 83Ro red star 0.3Mo companion. The assumption is accretes mass via accretion disk responsible for launching which, in simulations, are injected numerically. For first time we...
Shaping axisymmetric planetary nebulae is easier if a companion interacts with primary at the top of asymptotic giant branch. To determine impact binarity on nebula formation and shaping, we need to central star binary fraction period distribution. The short-period has been known be 10–15% from survey ∼100 stars for photometric variability indicative irradiation effects, ellipsoidal variability, or eclipses. This technique biased against binaries long periods this fact used explain why all...
The common envelope (CE) interaction describes the swallowing of a nearby companion by growing, evolving star. CEs that take place during asymptotic giant branch phase primary may lead to formation planetary nebula (PN) with post-CE close binary in middle. We have used published observations masses and kinematics jets four PN infer physical characteristics CE interaction. In three systems studied, Abell 63, ETHOS 1 Necklace PN, indicate were launched few thousand years before we favour...
We still do not know what causes aspherical planetary nebula (PN) morphologies. A plausible hypothesis is that they are due to the presence of a close stellar or substellar companion. So far, only ∼40 binary central stars PN have been detected, almost all them with such short periods their binarity revealed by photometric variability. Here we endeavoured discover at any separation, thus determining unbiased fraction PN. This number, when compared presumed parent population, can give first...
The Rotten Egg Nebula has at its core a binary composed of Mira star and an A-type companion separation >10 au. It been hypothesized to have formed by strong interactions between the in eccentric orbit during periastron passage ~800 years ago. We performed hydrodynamic simulations asymptotic giant branch interacting with companions range masses orbits initial eccentricities separations. For reasonable values eccentricity, we find that Roche lobe overflow can take place only if periods are...
Six planetary nebulae (PN) are known in the Kepler space telescope field of view, three newly identified. Of 5 central stars PN with useful data, one, J193110888+4324577, is a short-period, post common envelope binary exhibiting relativistic beaming effects. A second, star identified Pa5, has rare O(He) spectral type and periodic variability consistent an evolved companion, where orbital axis almost aligned line sight. The third PN, NGC~6826 fast rotating star, something that can only be...
We present X-ray spectral analysis of 20 point-like sources detected in Chandra Planetary Nebula Survey observations 59 planetary nebulae (PNe) the solar neighborhood. Most these detections are associated with luminous central stars within relatively young, compact nebulae. The vast majority X-ray-emitting at PN cores display "hard" (⩾0.5 keV) emission components that unlikely to be due photospheric from hot (CSPN). Instead, we demonstrate well modeled by optically thin thermal plasmas. From...
The common envelope interaction is thought to be the gateway all evolved compact binaries and mergers. Hydrodynamic simulations of between giant stars their companions are restricted dynamical, fast, in-spiral phase. They find that lifted during this phase, but remains mostly bound system. At same time, orbital separation greatly reduced, in most it levels off at values larger than measured from observations. We conjectured post-in-spiral phase gas will return Using hydrodynamic simulations,...
We have used the tidal equations of Zahn to determine maximum orbital distance at which companions are brought into Roche lobe contact with their giant primary, when primary expands during phases. This is a key step determining rates interaction between giants and companions. Our stellar structure calculations presented as radii reached red asymptotic branch (RGB AGB, respectively) stages evolution for masses 0.8 4.0 Mo (Z=0.001 - 0.04) compared other models gauge uncertainty on deriving...