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

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.

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X-ray emission from Planetary Nebulae

Symposium - International Astronomical Union ◽

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 ◽

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).

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Radio and X-Ray Emissions from Chemically Peculiar B- and A-Type Stars: Observations and a Model

International Astronomical Union Colloquium ◽

10.1017/s0252921100020972 ◽

1993 ◽

Vol 138 ◽

pp. 507-516 ◽

Cited By ~ 1

Author(s):

Jeffrey L. Linsky

Keyword(s):

Energy Source ◽

Stellar Wind ◽

Mechanical Energy ◽

Early Type ◽

Late Type ◽

X Ray ◽

Nonthermal Radio ◽

Chemically Peculiar ◽

Early Type Stars

AbstractConventional wisdom holds that early-type and late-type stars have very different outer atmospheres, because the early-type stars lack deep convective zones. I argue that the magnetic chemically peculiar (CP) stars hotter than about spectral type A2 display many of the activity phenomena seen in the most active late-type stars. In particular, many CP stars are luminous nonthermal radio and coronal x-ray sources like the RS CVn systems. A wind-fed magnetosphere model has been proposed to explain both the nonthermal radio and the x-ray emission. In this model the stellar wind plays the role of a mechanical energy source analogous to the role played by convection in the active late-type stars.

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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 ◽

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.

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Einstein X-ray Observations of Planetary Nebulae and their Implications

Symposium - International Astronomical Union ◽

10.1017/s0074180900138525 ◽

1989 ◽

Vol 131 ◽

pp. 304-304

Author(s):

S. P. Tarafdar ◽

K.M. V. Apparao

Keyword(s):

High Resolution ◽

Point Source ◽

Planetary Nebulae ◽

Central Star ◽

Heavy Elements ◽

X Rays ◽

X Ray ◽

Einstein Observatory ◽

Central Stars

Central stars of nineteen planetary nebulae were observed for X-ray emission using the Einstein Observatory and four of them were detected. High resolution observations with the Einstein Observatory indicates that the X-ray source in NGC 246 is a point source. These planetary nebulae with positive observations turn out to be the nearest, have the least extinction and also have the largest size of the nebulae around them. It is possible that X-ray emission is observed from these planetary nebulae with larger ages because of the smaller extinction by the nebulae and also due to the settling of heavy elements in the central star which otherwise prevents escape of X-rays by providing opacity.

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X-ray Shaping of Planetary Nebulae

10.20944/preprints201808.0019.v1 ◽

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.

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Chemical Abundances of Early Type Stars

Symposium - International Astronomical Union ◽

10.1017/s007418090011486x ◽

1998 ◽

Vol 188 ◽

pp. 224-225

Author(s):

S. Tanaka ◽

S. Kitamoto ◽

T. Suzuki ◽

K. Torii ◽

M.F. Corcoran ◽

...

Keyword(s):

Surface Layer ◽

Stellar Wind ◽

Nuclear Reactions ◽

X Rays ◽

Early Type ◽

Chemical Abundances ◽

X Ray ◽

Low Metallicity ◽

Early Type Stars

X-rays from early-type stars are emitted by the corona or the stellar wind. The materials in the surface layer of early-type stars are not contaminated by nuclear reactions in the stellar inside. Therefore, abundance study of the early-type stars provides us an information of the abundances of the original gas. However, the X-ray observations indicate low-metallicity, which is about 0.3 times of cosmic abundances. This fact raises the problem on the cosmic abundances.

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Erratum: “An Extensive Collection of Stellar Wind X‐Ray Source Region Emission Line Parameters, Temperatures, Velocities, and Their Radial Distributions as Obtained fromChandraObservations of 17 OB Stars” (ApJ, 668, 456 [2007])

The Astrophysical Journal ◽

10.1086/588041 ◽

2008 ◽

Vol 680 (2) ◽

pp. 1595-1602 ◽

Cited By ~ 3

Author(s):

W. L. Waldron ◽

J. P. Cassinelli

Keyword(s):

Emission Line ◽

Stellar Wind ◽

Source Region ◽

X Ray ◽

Ob Stars ◽

Extensive Collection

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An Empirical Analysis of the Stellar Wind and Planetary Nebulae of the [WC10] Central Stars CPD-56° 8032 and He 2-113.

Planetary Nebulae ◽

10.1007/978-94-011-5244-0_26 ◽

1997 ◽

pp. 100-101

Author(s):

Orsola De Marco ◽

M. J. Barlow ◽

P. J. Storey

Keyword(s):

Empirical Analysis ◽

Stellar Wind ◽

Planetary Nebulae ◽

Central Stars

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Testing the disk-corona interplay in radiatively-efficient broad-line AGN

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935874 ◽

2019 ◽

Vol 628 ◽

pp. A135 ◽

Cited By ~ 6

Author(s):

R. Arcodia ◽

A. Merloni ◽

K. Nandra ◽

G. Ponti

Keyword(s):

Accretion Disk ◽

Reference Sample ◽

Selection Effect ◽

Galactic Nuclei ◽

Theoretical Explanation ◽

X Rays ◽

Broad Line ◽

Coronal Emission ◽

X Ray ◽

Intrinsic Scatter

The correlation observed between monochromatic X-ray and UV luminosities in radiatively-efficient active galactic nuclei (AGN) lacks a clear theoretical explanation despite being used for many applications. Such a correlation, with its small intrinsic scatter and its slope that is smaller than unity in log space, represents the compelling evidence that a mechanism regulating the energetic interaction between the accretion disk and the X-ray corona must be in place. This ensures that going from fainter to brighter sources the coronal emission increases less than the disk emission. We discuss here a self-consistently coupled disk-corona model that can identify this regulating mechanism in terms of modified viscosity prescriptions in the accretion disk. The model predicts a lower fraction of accretion power dissipated in the corona for higher accretion states. We then present a quantitative observational test of the model using a reference sample of broad-line AGN and modeling the disk-corona emission for each source in the LX − LUV plane. We used the slope, normalization, and scatter of the observed relation to constrain the parameters of the theoretical model. For non-spinning black holes and static coronae, we find that the accretion prescriptions that match the observed slope of the LX − LUV relation produce X-rays that are too weak with respect to the normalization of the observed relation. Instead, considering moderately-outflowing Comptonizing coronae and/or a more realistic high-spinning black hole population significantly relax the tension between the strength of the observed and modeled X-ray emission, while also predicting very low intrinsic scatter in the LX − LUV relation. In particular, this latter scenario traces a known selection effect of flux-limited samples that preferentially select high-spinning, hence brighter, sources.

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Magnetic fields, winds and X-rays of massive stars in the Orion nebula cluster

Proceedings of the International Astronomical Union ◽

10.1017/s1743921311010374 ◽

2010 ◽

Vol 6 (S272) ◽

pp. 208-209 ◽

Cited By ~ 1

Author(s):

Véronique Petit ◽

Gregg A. Wade ◽

Evelyne Alecian ◽

Laurent Drissen ◽

Thierry Montmerle ◽

...

Keyword(s):

Magnetic Fields ◽

Massive Stars ◽

Theoretical Models ◽

Magnetic Star ◽

X Rays ◽

Orion Nebula ◽

X Ray ◽

Ob Stars ◽

The Impact ◽

The Relationship

AbstractIn some massive stars, magnetic fields are thought to confine the outflowing radiatively-driven wind. Although theoretical models and MHD simulations are able to illustrate the dynamics of such a magnetized wind, the impact of this wind-field interaction on the observable properties of a magnetic star - X-ray emission, photometric and spectral variability - is still unclear. The aim of this study is to examine the relationship between magnetism, stellar winds and X-ray emission of OB stars, by providing empirical observations and confronting theory. In conjunction with the COUP survey of the Orion Nebula Cluster, we carried out spectropolarimatric ESPaDOnS observations to determine the magnetic properties of massive OB stars of this cluster.

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