X-ray Shaping of Planetary Nebulae

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.

X-ray Shaping of Planetary Nebulae

Galaxies ◽

10.3390/galaxies6030098 ◽

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 ◽

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.

Physical Processes in Nebular Shells and the Interpretation of Nebular Spectra

10.1017/s0074180900093694 ◽

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.

X-ray emission from Planetary Nebulae

10.1017/s0074180900130360 ◽

1997 ◽

Vol 180 ◽

pp. 214-215 ◽

Cited By ~ 2

Author(s):

Gail M. Conway ◽

You-Hua Chu

Keyword(s):

Planetary Nebulae ◽

Point Sources ◽

Stellar Winds ◽

X Rays ◽

Will Emit ◽

X Ray ◽

Extended Sources ◽

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).

Colliding stellar wind modelling of the X-ray emission from WR 140

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3591 ◽

2020 ◽

Vol 500 (4) ◽

pp. 4837-4848

Author(s):

Svetozar A Zhekov

Keyword(s):

Mass Loss ◽

Effective Mass ◽

Stellar Wind ◽

Mass Loss Rate ◽

Emission Measure ◽

Strong Line ◽

Stellar Winds ◽

Line Profiles ◽

X Ray ◽

Binary Orbit

ABSTRACT We modelled the Chandra and Rossi X-ray Timing Explorer X-ray spectra of the massive binary WR 140 in the framework of the standard colliding stellar wind (CSW) picture. Models with partial electron heating at the shock fronts are a better representation of the X-ray data than those with complete temperature equalization. Emission measure of the X-ray plasma in the CSW region exhibits a considerable decrease at orbital phases near periastron. This is equivalent to variable effective mass-loss rates over the binary orbit. At orbital phases near periastron, a considerable X-ray absorption in excess to that from the stellar winds in WR 140 is present. The standard CSW model provides line profiles that in general do not match well the observed line profiles of the strong line features in the X-ray spectrum of WR 140. The variable effective mass-loss rate could be understood qualitatively in CSW picture of clumpy stellar winds where clumps are efficiently dissolved in the CSW region near apastron but not at periastron. However, future development of CSW models with non-spherically symmetric stellar winds might be needed to get a better correspondence between theory and observations.

A method for calculation of line profiles in expanding atmospheres: Application to winds from central stars of planetary nebulae

10.1017/s0074180900156888 ◽

1987 ◽

Vol 122 ◽

pp. 431-432

Author(s):

M. Cerruti-Sola ◽

H.J.G.L.M. Lamers ◽

M. Perinotto

Keyword(s):

Mass Loss ◽

Stellar Wind ◽

Planetary Nebulae ◽

Line Profiles ◽

Expanding Atmospheres ◽

Associated Mass ◽

Central Stars ◽

Uv Range

The structure of a stellar wind and its associated mass loss can be derived from the analysis of ñ Cygni-like line profiles. These do better occur in the UV range and have been extensively observed with the Copernicus (900–1450 A) and IUE Satellites (1150–3200 A).

Mass Loss from Central Stars of Planetary Nebulae

10.1017/s0074180900093864 ◽

1983 ◽

Vol 103 ◽

pp. 323-335 ◽

Cited By ~ 3

Author(s):

M. Perinotto

Keyword(s):

Mass Loss ◽

Loss Rate ◽

Mass Loss Rate ◽

Large Fraction ◽

Planetary Nebulae ◽

Stellar Winds ◽

Large Interval ◽

Ionization Structure ◽

Stellar winds have been revealed in a large fraction of central stars of planetary nebulae from P Cygni profiles observed with the IUE satellite. The relevant lines are essentially the resonance lines NV λ 1240, Si IV λ 1397, CIV λ 1549 and the subordinate lines OIV∗ λ 1342, 0V∗ λ 1371, NIV∗ λ 1579. Edge velocities are of the order of 1000-3000 km s−1, similar to the case of population I O stars. Detailed determinations of the mass loss rate have been performed for NGC 6543, NGC 2371, IC 2149 and IC 3568 with values between 4.10−9 to 7. 10−7 Mo yr−1. The accuracy of these determinations is not well known. It is however clear from the variety of observed profiles in these and in several other objects that properties of the winds (ionization structure, etc.) varies considerably from object to object and that very likely the mass loss rate will span over a large interval. Some possible consequences of these winds are discussed.

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

10.1017/s0074180900131109 ◽

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 ◽

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).

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

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312010964 ◽

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 ◽

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.

Parameters of Wolf-Rayet Stars

10.1017/s0074180900148879 ◽

1986 ◽

Vol 116 ◽

pp. 199-214

Author(s):

Peter S. Conti

Keyword(s):

Absorption Spectrum ◽

Mass Loss ◽

Stellar Wind ◽

Planetary Nebulae ◽

Emission Lines ◽

Helium Ions ◽

Strong Emission ◽

Optical Region ◽

Central Stars ◽

Intrinsic Feature

Wolf-Rayet (W-R) stars are objects with strong emission lines in the optical region due to a substantial stellar wind. They are found among the extreme Population I stars which are the topic of this Symposium and also this talk, and as central stars of planetary nebulae which I will not discuss here. The mass loss rates, Ṁ, are typically several 10−5 solar masses per year. W-R stars come in two major subtypes, the WN, in which strong lines of helium and nitrogen are seen, and the WC, in which strong lines of carbon and oxygen are found, along with the helium ions. In a few WN stars hydrogen appears to be present but the spectra of W-R stars are notable for the absence of this element. Absorption lines are generally not found in W-R stars, except in some instances due to a binary companion, or a more distant companion, or as a P-Cygni profile associated with certain emission features. An absorption spectrum appears to be an intrinsic feature in a very few WN stars.

The Central Stars of He 2–131 and He 2–138: Photometric Variations

10.1017/s0074180900172195 ◽

1993 ◽

Vol 155 ◽

pp. 486-486

Author(s):

R. G. Hutton ◽

R. H. Méndez

Keyword(s):

Mass Loss ◽

Radial Velocity ◽

Time Scales ◽

Effective Temperature ◽

Planetary Nebulae ◽

Convincing Evidence ◽

Stellar Winds ◽

Line Profiles ◽

Short Term ◽

The central stars of the planetary nebulae He 2–131 and He 2–138 show variations in their visual magnitudes, with amplitudes of about 0.1 mag. and time scales of a few hours. This behavior appears to be very similar to that exhibited by the central stars of IC 418 and IC 4593. These four central stars have several other characteristics in common: a relatively low effective temperature, between 27000 and 40000 K; clear spectroscopic evidences of mass loss, both in the ultraviolet (IUE) and visible spectral regions; and short-term spectroscopic variability, in the form of radial velocity variations and/or of substantial changes in emission and P-Cygni-type line profiles. None of these central stars has shown convincing evidence of binarity; we attribute their behavior to variations in the stellar winds.