THE CHANDRA PLANETARY NEBULA SURVEY (ChanPlaNS). III. X-RAY EMISSION FROM THE CENTRAL STARS OF PLANETARY NEBULAE

Making use of the results from recent infrared and radio surveys of planetary nebulae, we have selected 431 nebulae to form a sample where a number of distance-independent parameters (e.g., Tb, Td, I60μm and IRE) can be constructed. In addition, we also made use of other distance-independent parameters ne and T∗ where recent measurements are available. We have investigated the relationships among these parameters in the context of a coupled evolution model of the nebula and the central star. We find that most of the observed data in fact lie within the area covered by the model tracks, therefore lending strong support to the correctness of the model. Most interestingly, we find that the evolutionary tracks for nebulae with central stars of different core masses can be separated in a Tb-T∗ plane. This implies that the core masses and ages of the central stars can be determined completely independent of distance assumptions. The core masses and ages have been obtained for 302 central stars with previously determined central-star temperatures. We find that the mass distribution of the central stars strongly peaks at 0.6 M⊙, with 66% of the sample having masses <0.64 MM⊙. The luminosities of the central stars are then derived from their positions in the HR diagram according to their core masses and central star temperatures. If this method of mass (and luminosity) determination turns out to be accurate, we can bypass the extremely unreliable estimates for distances, and will be able to derive other physical properties of planetary nebulae.

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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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Structure of selected Planetary Nebulae surrounding WR-type central stars

Symposium - International Astronomical Union ◽

10.1017/s0074180900130517 ◽

1997 ◽

Vol 180 ◽

pp. 230-230

Author(s):

S.K. Górny ◽

K. Gȩsicki ◽

A. Acker

Keyword(s):

Velocity Field ◽

Planetary Nebula ◽

Radial Direction ◽

Planetary Nebulae ◽

Late Type ◽

Computer Codes ◽

Central Stars

The main aim of this work was to confirm that expansion of planetary nebulae surrounding Wolf-Rayet type central stars is characterized by turbulent motions or strong variations of velocity in the radial direction relative to the nucleus. Such properties have already been found in Ml-25, M3-15 and Pel-1 by Gesicki & Acker (1995). We have analyzed the photoionization structure and velocity field of the NGC 40 - a planetary nebula with late type ([WC 8]) Wolf-Rayet nucleus. The spectra of Hα and [NII] lines have been obtained with the 1.5m telescope at the Observatoire de Haute-Provence. The spectrograph Aurelie with dispersion of 5Å/mm and a 3″ circular entrance was used. The method and the details of the applied computer codes are published in Gesicki et al. (1996).

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

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312012094 ◽

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.

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

Galaxies ◽

10.3390/galaxies8010024 ◽

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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Stellar wind models of central stars of planetary nebulae

Astronomy and Astrophysics ◽

10.1051/0004-6361/201937150 ◽

2020 ◽

Vol 635 ◽

pp. A173 ◽

Cited By ~ 1

Author(s):

J. Krtička ◽

J. Kubát ◽

I. Krtičková

Keyword(s):

Mass Loss ◽

White Dwarf ◽

Planetary Nebula ◽

Loss Rate ◽

Mass Loss Rate ◽

Planetary Nebulae ◽

Terminal Velocity ◽

Asymptotic Giant Branch ◽

Central Stars ◽

Loss Rates

Context. Fast line-driven stellar winds play an important role in the evolution of planetary nebulae, even though they are relatively weak. Aims. We provide global (unified) hot star wind models of central stars of planetary nebulae. The models predict wind structure including the mass-loss rates, terminal velocities, and emergent fluxes from basic stellar parameters. Methods. We applied our wind code for parameters corresponding to evolutionary stages between the asymptotic giant branch and white dwarf phases for a star with a final mass of 0.569 M⊙. We study the influence of metallicity and wind inhomogeneities (clumping) on the wind properties. Results. Line-driven winds appear very early after the star leaves the asymptotic giant branch (at the latest for Teff ≈ 10 kK) and fade away at the white dwarf cooling track (below Teff = 105 kK). Their mass-loss rate mostly scales with the stellar luminosity and, consequently, the mass-loss rate only varies slightly during the transition from the red to the blue part of the Hertzsprung–Russell diagram. There are the following two exceptions to the monotonic behavior: a bistability jump at around 20 kK, where the mass-loss rate decreases by a factor of a few (during evolution) due to a change in iron ionization, and an additional maximum at about Teff = 40−50 kK. On the other hand, the terminal velocity increases from about a few hundreds of km s−1 to a few thousands of km s−1 during the transition as a result of stellar radius decrease. The wind terminal velocity also significantly increases at the bistability jump. Derived wind parameters reasonably agree with observations. The effect of clumping is stronger at the hot side of the bistability jump than at the cool side. Conclusions. Derived fits to wind parameters can be used in evolutionary models and in studies of planetary nebula formation. A predicted bistability jump in mass-loss rates can cause the appearance of an additional shell of planetary nebula.

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X-ray emission by a shocked fast wind from the central stars of planetary nebulae

Monthly Notices of the Royal Astronomical Society ◽

10.1111/j.1365-2966.2006.10234.x ◽

2006 ◽

Vol 368 (4) ◽

pp. 1706-1716 ◽

Cited By ~ 12

Author(s):

M. Akashi ◽

N. Soker ◽

E. Behar

Keyword(s):

Planetary Nebulae ◽

X Ray ◽

Fast Wind ◽

Central Stars

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Pulsations in the Nucleus of Planetary Nebula IC 418?

International Astronomical Union Colloquium ◽

10.1017/s025292110003791x ◽

1995 ◽

Vol 155 ◽

pp. 443-444

Author(s):

E. Kuczawska ◽

S. Zola

Keyword(s):

Planetary Nebula ◽

Planetary Nebulae ◽

New Class ◽

Photometric Observations ◽

Theoretical Results ◽

Central Stars

AbstractIC 418 belongs to the group of about a dozen planetary nebulae with central stars that show irregular spectroscopic and photometric variations. Recent theoretical results provide arguments that this group may constitute a new class of pulsators. We present new photometric observations of the nucleus of IC 418 showing variations with a timescale of about 1/4 day. We discuss two possible explanations of the observed phenomena: pulsational instability and an unstable wind.

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Wind inhomogeneities in [Wc] central stars of planetary nebulae

Symposium - International Astronomical Union ◽

10.1017/s0074180900211972 ◽

2003 ◽

Vol 212 ◽

pp. 192-193

Author(s):

Yves Grosdidier ◽

Anthony F.J. Moffat ◽

Agnès Acker

Keyword(s):

Emission Line ◽

Planetary Nebula ◽

Planetary Nebulae ◽

Spectroscopic Evidence ◽

Poster Paper ◽

Central Stars ◽

Present Poster

In the present poster paper, we summarize the observational spectroscopic evidence for wind clumping originating in some [WC8-10] and [WO4] central stars of planetary nebulae. Specifically, we concentrate on the C iii λ5696 and C iv λλ5801/12 emission-line variability observed for well-known planetary nebula nuclei.

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Close Binaries and the Abundance Discrepancy Problem in Planetary Nebulae

Galaxies ◽

10.3390/galaxies6040110 ◽

2018 ◽

Vol 6 (4) ◽

pp. 110

Author(s):

R. Wesson ◽

D. Jones ◽

J. García-Rojas ◽

H. Boffin ◽

R. Corradi

Keyword(s):

Planetary Nebula ◽

Planetary Nebulae ◽

Central Star ◽

Close Binaries ◽

Problem Analysis ◽

Recombination Line ◽

Central Stars ◽

Recent Establishment

Motivated by the recent establishment of a connection between central star binarity and extreme abundance discrepancies in planetary nebulae, we have carried out a spectroscopic survey targeting planetary nebula with binary central stars and previously unmeasured recombination line abundances. We have discovered seven new extreme abundance discrepancies, confirming that binarity is key to understanding the abundance discrepancy problem. Analysis of all 15 objects with a binary central star and a measured abundance discrepancy suggests a cut-off period of about 1.15 days, below which extreme abundance discrepancies are found.

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