scholarly journals X-ray Shaping of Planetary Nebulae

Galaxies ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 98
Author(s):  
Martín Guerrero
Keyword(s):  
Stellar Wind ◽  
Essential Role ◽  
Planetary Nebulae ◽  
Asymptotic Giant Branch ◽  
Stellar Winds ◽  
Physical Processes ◽  
X Ray ◽  
Hot Gas ◽  
Energy And Momentum ◽  
Central Stars

The stellar winds of the central stars of planetary nebulae play an essential role in the shaping of planetary nebulae. In the interacting stellar winds model, the fast stellar wind injects energy and momentum, which are transferred to the nebular envelope through an X-ray-emitting hot bubble. Together with other physical processes, such as the ionization of the nebular envelope, the asymmetrical mass-loss in the asymptotic giant branch (AGB), and the action of collimated outflows and magnetic fields, the pressurized hot gas determines the expansion and evolution of planetary nebulae. Chandra and XMM-Newton have provided us with detailed information of this hot gas. Here in this talk I will review our current understanding of the effects of the fast stellar wind in the shaping and evolution of planetary nebulae and give some hints of the promising future of this research.

scholarly journals X-ray Shaping of Planetary Nebulae

2018 ◽  
Author(s):  
Martin A Guerrero
Keyword(s):  
Mass Loss ◽  
Stellar Wind ◽  
Essential Role ◽  
Planetary Nebulae ◽  
Stellar Winds ◽  
Physical Processes ◽  
X Ray ◽  
Hot Gas ◽  
Energy And Momentum ◽  
Central Stars

The stellar winds of the central stars of planetary nebulae play an essential role in planetary nebulae shaping. In the interacting stellar winds model, the fast stellar wind injects energy and momentum which are transfered to the nebular envelope through an X-ray-emitting hot bubble. Together with other physical processes, such as the ionization of the nebular envelope, the asymmetrical mass-loss in the AGB, and the action of collimated outflows and magnetic fields, the presurized hot gas determines the expansion and evolution of planetary nebulae. \emph{Chandra} and \emph{XMM-Newton} have provided us with detailed information of this hot gas. Here in this talk I will review our current understanding of the effects of the fast stellar wind in the shaping and evolution of planetary nebulae and give some hints of the promissing future of this research.

scholarly journals Physical Processes in Nebular Shells and the Interpretation of Nebular Spectra

1983 ◽  
Vol 103 ◽  
pp. 219-227
Author(s):  
J. Patrick Harrington
Keyword(s):  
Charge Transfer ◽  
Simple Model ◽  
Stellar Wind ◽  
High Velocity ◽  
Planetary Nebulae ◽  
Geometrical Parameters ◽  
Stellar Winds ◽  
Physical Processes ◽  
Rapid Cooling ◽  
Particle Distributions

Computed models are now recognized as useful tools for interpretation of the spectra of planetary nebulae. However, even the most detailed models need geometrical parameters such as filling factors which are poorly determined by observations. Some effects may be seen more clearly by modeling the stratification than by just using total fluxes. A simple model for NGC 6720 is presented which reproduces the behavior of (Ne III) λ3869 observed by Hawley and Miller (1977), clearly showing the effects of charge transfer. The behavior of C II λ4267 remains puzzling. Finally, we comment on the interaction of high velocity stellar winds with nebular shells. Non-equilibrium particle distributions at the contact between the shocked stellar wind and the nebula may result in the rapid cooling of the shocked gas.

scholarly journals X-ray emission from Planetary Nebulae

1997 ◽  
Vol 180 ◽  
pp. 214-215 ◽  
Author(s):  
Gail M. Conway ◽  
You-Hua Chu
Keyword(s):  
Planetary Nebulae ◽  
Point Sources ◽  
Stellar Winds ◽  
X Rays ◽  
Will Emit ◽  
X Ray ◽  
Extended Sources ◽  
Central Stars

X-ray emission from planetary nebulae (PNe) may originate from two sources: central stars which are 100,000–200,000 K will emit soft X-rays, and shocked fast stellar winds reaching 106–107 K will emit harder X-rays. The former are point sources, while the shocked winds are expected to be extended sources emitting continuously out to the inner wall of the visible nebular shell (Weaver et al. 1977; Wrigge & Wendker 1996).

scholarly journals X-ray, EUV and infrared coronal-line radiation from Planetary Nebulae

1997 ◽  
Vol 180 ◽  
pp. 293-293
Author(s):  
S. A. Zhekov ◽  
M. Perinotto
Keyword(s):  
Thermal Conduction ◽  
Extreme Ultraviolet ◽  
Planetary Nebulae ◽  
Stellar Winds ◽  
Gas Temperature ◽  
Coronal Line ◽  
Temperature Plasma ◽  
Line Radiation ◽  
X Ray ◽  
Central Stars

The interacting stellar winds (ISW) theory (Kwok, S., Purton, C. R., Fitzgerald, P. M., 1978, ApJL, 219, L125) is nowadays widely accepted in the physics of Planetary Nebulae (PNe). It received much support from the observed fast winds in the central stars of PNe (CSPN), recognized to be a quite common phenomenon (e.g., Perinotto, M., 1993, in IAU Symp. No. 155, Planetary Nebulae, eds. R. Weinberger and A. Acker, Kluwer, Dordrecht, 57). Thus, the existance of a hot bubble in the PNe structure is a cornerstone of the ISW model. The high velocities (600–3500 km s–1) of the CSPN winds, are, according to the ISW model, directly responsible for an high gas temperature in the hot bubble, which is then expected to be the source of an extended X-ray and extreme ultraviolet (EUV) radiation. The PNe should also emit infrared coronal lines (IRCL) of highly ionized species since the high temperature plasma of the hot bubble is in contact with the much colder outer shell (optical PN) and the thermal conduction will produce a region of intermediate temperatures (5 × 105–106 K). A model considering the structure of the hot bubble in PNe with taking into account the thermal conductivity effects was present by Zhekov and Perinotto (1996, A&A, 309, 648).

scholarly journals X-ray observations of central stars of planetary nebulae and their winds

2011 ◽  
Vol 7 (S283) ◽  
pp. 204-210
Author(s):  
Martín A. Guerrero
Keyword(s):  
Stellar Wind ◽  
Mechanical Energy ◽  
Planetary Nebulae ◽  
Energy Output ◽  
X Rays ◽  
Late Type ◽  
Coronal Emission ◽  
X Ray ◽  
Ob Stars ◽  
Central Stars

AbstractThe photospheric emission from the hottest central stars of planetary nebulae (CSPNe) is capable to extend into the X-ray domain, with emission peaking at 0.1-0.2 keV and vanishing above 0.4 keV. Unexpected, intriguing hard X-ray emission with energies greater than 0.5 keV has been reported for several CSPNe and for a number of white dwarfs (WDs). Different mechanisms may be responsible for the hard X-ray emission from CSPNe and WDs: coronal emission from a late-type companion, shocks in fast winds as in OB stars, leakage from underneath the star photosphere, or accretion of material from a disk, a companion star, or the circumstellar medium. Therefore, the hard X-ray emission associated with CSPNe may have significant implications for our understanding of the formation of PNe: binary companions, disks, and magnetic fields are thought to play a major role in the shaping of PNe, whereas clumping in the stellar wind may have notable effects in the PN evolution by modifying the stellar mechanical energy output. Here I present the results of different observational efforts to search for hard X-ray emission from CSPNe and discuss the different mechanisms for the production of hard X-rays.

scholarly journals Evolutionary Tracks for Central Stars of Planetary Nebulae

1989 ◽  
Vol 131 ◽  
pp. 463-472 ◽  
Author(s):  
Detlef Schönberner
Keyword(s):  
Mass Loss ◽  
White Dwarf ◽  
Planetary Nebulae ◽  
Asymptotic Giant Branch ◽  
Helium Burning ◽  
Hydrogen Burning ◽  
Stellar Envelope ◽  
Thermal Pulse ◽  
Pulse Cycle ◽  
Central Stars

Our understanding of the evolution of Central Stars of Planetary Nebulae (CPN) has made considerable progress during the last years. This was possible since consistent computations through the asymptotic giant branch (AGB), with thermal pulses and (in some cases) mass loss taken into account, became available (Schönberner, 1979, 1983; Kovetz and Harpaz, 1981; Harpaz and Kovetz, 1981; Iben, 1982, 1984; Wood and Faulkner, 1986). It turned out that the evolution depends very sensitively on the inital conditions on the AGB. More precisely, the evolution of an AGB remnant is a function of the phase of the thermal-pulse cycle during which this remnant was created on the tip of the AGB by the planetary-nebula (PN) formation process (Iben, 1984, 1987). This was first shown by Schönberner (1979), and then fully explored by Iben (1984). In short, two major modes of PAGB evolution to the white dwarf stage are possible, according to the two main phases of a thermally pulsing AGB star: the hydrogen-burning or helium-burning mode. If, for instance, the PN formation, i.e. the removal of the stellar envelope by mass loss, happens during a luminosity peak that follows a thermal pulse of the helium-burning shell, the remnant leaves the AGB while still burning helium as the main energy supplier (Härm and Schwarzschild, 1975). On the other hand, PN formation may also occur during the quiescent hydrogen-burning phase on the AGB, and the remnant continues then to burn mainly hydrogen on its way to becoming a white dwarf.

scholarly journals The role of heat conduction to the formation of [WC]-type planetary nebulae

2011 ◽  
Vol 7 (S283) ◽  
pp. 494-495
Author(s):  
Christer Sandin ◽  
Matthias Steffen ◽  
Ralf Jacob ◽  
Detlef Schönberner ◽  
Ute Rühling ◽  
...  
Keyword(s):  
Heat Conduction ◽  
Chemical Composition ◽  
Physical Properties ◽  
Planetary Nebulae ◽  
Time Dependent ◽  
Diffuse Emission ◽  
Hydrodynamic Models ◽  
X Ray ◽  
Central Stars

AbstractX-ray observations of young Planetary Nebulæ (PNe) have revealed diffuse emission in extended regions around both H-rich and H-deficient central stars. In order to also reproduce physical properties of H-deficient objects, we have, at first, extended our time-dependent radiation-hydrodynamic models with heat conduction for such conditions. Here we present some of the important physical concepts, which determine how and when a hot wind-blown bubble forms. In this study we have had to consider the, largely unknown, evolution of the CSPN, the slow (AGB) wind, the fast hot-CSPN wind, and the chemical composition. The main conclusion of our work is that heat conduction is needed to explain X-ray properties of wind-blown bubbles also in H-deficient objects.

scholarly journals X-ray Observations of Planetary Nebulae since WORKPLANS I and Beyond

Galaxies ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 24
Author(s):  
Martín A. Guerrero
Keyword(s):  
Physical Properties ◽  
Planetary Nebulae ◽  
X Ray ◽  
Central Stars

Planetary nebulae (PNe) were expected to be filled with hot pressurized gas driving their expansion. ROSAT hinted at the presence of diffuse X-ray emission from these hot bubbles and detected the first sources of hard X-ray emission from their central stars, but it was not until the advent of Chandra and XMM-Newton that we became able to study in detail their occurrence and physical properties. Here I review the progress in the X-ray observations of PNe since the first WORKshop for PLAnetary Nebulae observationS (WORKPLANS) and present the perspective for future X-ray missions with particular emphasis on eROSITA.

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