scholarly journals X-ray Studies of Planetary Nebulae

2016 ◽  
Vol 12 (S323) ◽  
pp. 104-108
Author(s):  
Rodolfo Montez
Keyword(s):  
Mass Transfer ◽  
Planetary Nebulae ◽  
Central Star ◽  
Electromagnetic Spectrum ◽  
Stellar Winds ◽  
X Ray ◽  
New Directions ◽  
Multi Wavelength ◽  
Formation And Evolution ◽  
Compact Sources

AbstractX-ray emission from planetary nebulae (PNe) provides unique insight on the formation and evolution of PNe. Past observations and the ongoing Chandra Planetary Nebulae Survey (ChanPlaNS) provide a consensus on the two types of X-ray emission detected from PNe: extended and compact point-like sources. Extended X-ray emission arises from a shocked “hot bubble” plasma that resides within the nebular shell. Cooler than expected hot bubble plasma temperatures spurred a number of potential solutions with one emerging as the likely dominate process. The origin of X-ray emission from compact sources at the location of the central star is less clear. These sources might arise from one or combinations of the following processes: self-shocking stellar winds, spun-up binary companions, and/or accretion, perhaps from mass transfer, PN fallback, or debris disks. In the discovery phase, X-ray studies of PNe have mainly focused on the origin of the various emission processes. New directions incorporate multi-wavelength observations to study the influence of X-ray emission on the rest of the electromagnetic spectrum.

scholarly journals A consolidated online database of Galactic planetary nebulae

2011 ◽  
Vol 7 (S283) ◽  
pp. 442-443
Author(s):  
Brent Miszalski ◽  
A. Acker ◽  
F. Ochsenbein ◽  
Q. A. Parker
Keyword(s):  
Planetary Nebulae ◽  
Central Star ◽  
Radial Velocities ◽  
Online Database ◽  
Line Intensities ◽  
Multi Wavelength

AbstractSince the issue of the unifying Strasbourg-ESO Catalogue of Galactic Planetary Nebulae (SECGPN) a large number of new discoveries have been made thanks to improved surveys and discovery techniques. The increasingly heterogeneous published population of Galactic PNe, that we have determined totals <2850 PNe, is becoming more difficult to study on the whole without a centralised repository. We introduce a consolidated and interactive online database with object classifications that reflect the latest multi-wavelength data and the most recent results. The extensible database, hosted by the Centre de Donnees astronomique de Strasbourg (CDS), will contain a wealth of observed data for large, well-defined samples of PNe including coordinates, multi-wavelength images, spectroscopy, line intensities, radial velocities and central star information. It is anticipated that the database will be publicly released early 2012.

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 Optical Low States of the Supersoft X-Ray Source RXJ0513.9–6951

1997 ◽  
Vol 163 ◽  
pp. 787-787
Author(s):  
K. Reinsch ◽  
A. van Teeseling ◽  
K. Beuermann ◽  
T.M.C. Abbott
Keyword(s):  
Mass Transfer ◽  
White Dwarf ◽  
Mass Transfer Rate ◽  
Central Star ◽  
High Mass ◽  
X Ray ◽  
Total Luminosity ◽  
Nuclear Burning ◽  
Sudden Decrease ◽  
Optical Flux

The transient luminous soft X-ray source RXJ0513.9–6951 (Schaeidt et al., 1993, A&A 270, L9) is a high-mass-transfer binary system (Cowley et al., 1993, ApJ 418, L63; Pakull et al., 1993, A&A 278, L39) with a probable orbital period of 0.76 days (Crampton et al., 1996, ApJ 456, 320). Here, we summarize the results of a quasi-simultaneous optical and X-ray monitoring (see Fig. 1). The sudden decrease of the optical flux, the accompanying reddening, and the turn-on in the soft X-ray band can be quantitatively described by variations in the irradiation of the accretion disk by the hot central star (Reinsch et al., 1996, A&A 309, L11). In this simple model, we consider a white dwarf with nuclear burning of accreted matter (van den Heuvel et al., 1992, A&A 262, 97), surrounded by a flat standard disk. In the optical high state, accretion at near-Eddington rate occurs and the white dwarf photospheric radius must be considerably expanded causing an enhanced illumination of the disk and the secondary. In the optical low state, the photosphere shrinks in response to a temporarily slightly reduced mass-transfer rate. At the same time, the effective temperature increases, and the soft X-ray flux becomes detectable with ROSAT. This model does not depend on the particular cause for the drop in the accretion rate and can describe the optical/ X-ray variability with the total luminosity changing by less than 20 %.

scholarly journals Morphology of Planetary Nebulae—Possible Effects of Rotation on Stellar Ejecta

2004 ◽  
Vol 215 ◽  
pp. 473-478
Author(s):  
Sun Kwok
Keyword(s):  
Planetary Nebulae ◽  
Central Star ◽  
Time Variable ◽  
Asymptotic Giant Branch ◽  
Stellar Winds ◽  
Spherically Symmetric ◽  
Fast Wind ◽  
Effects Of Rotation ◽  
Slow Wind ◽  
Kinematic Properties

Planetary nebulae are formed as the result of the interaction between a slow stellar wind from the asymptotic giant branch progenitor and a later-developed fast outflow from the central star. Many of the morphological and kinematic properties of planetary nebulae have been successfully explained by this interacting stellar winds model. The observed diverse morphologies of planetary nebulae can also be understood if the slow wind is not spherically symmetric. However, new observational features such as collimated outflows and multi-polar lobes suggest that the fast wind may be non-isotropic and time variable. The possible roles of magnetic fields and rotation may play in the formation of these features are discussed.

scholarly journals Extended X-Ray Emission from Planetary Nebulae

1993 ◽  
Vol 155 ◽  
pp. 197-197 ◽  
Author(s):  
H.C. Kreysing ◽  
C. Diesch ◽  
J. Zweigle ◽  
R. Staubert ◽  
M. Grewing
Keyword(s):  
Ambient Medium ◽  
Planetary Nebulae ◽  
Central Star ◽  
Boundary Region ◽  
Integration Time ◽  
X Ray ◽  
The North ◽  
Sky Survey ◽  
First Results ◽  
Pointed Observation

We present first results from the ROSAT All Sky Survey on X-ray emission of planetary nebulae (PNe). For the first time extended X-ray emission from PNe was detected. This is the case for NGC 6543, NGC 6853, A 12, NGC 4361 (and LoTr 5). X-ray emission compatible with a point source was detected from BD+30°3639, however, the spectral distribution of the X-ray photons is leading to temperatures beyond 2 106 K. Thus in all cases, with the possible exception of LoTr 5, the central star of the PNe can be excluded as the main source of the observed X-ray emission. X-ray images and ROSAT spectra for all detected PNe are presented. The best observed PN in X-ray emission is NGC 6543. Due to the close vicinity to the north ecliptic pole, this object was regularly observed, every 90 minutes during the whole half year of the ROSAT All Sky Survey, resulting in 41 ksec of integration time. In addition NGC 6543 was observed in a 50 ksec pointed observation to the north ecliptic pole, taken in June 1990 during the calibration phase (Kreysing et al. 1992). A comparison of the semi-ring-like distribution of the X-ray emission of NGC 6543 with optical CCD-images shows, that most of the X-ray emission seems to originate from the boundary region between the nebula and the halo. Neither the central star nor the hot wind from the central star wind is the main source of the X-ray emission, as proposed by the interacting stellar wind model (Kwok 1982). An alternative model employing a possible coronal heating mechanism has been discussed by Kreysing (1992); accoustic waves, travelling outward from the nebula, encounter a sudden density decline at the boundary to the halo. As a consequence the waves degenerate into shock waves, dissipating their energy in a thin region of only some 1015 cm into the ambient medium.

scholarly journals Multi-Wavelength Observations of EV Lacertae

2004 ◽  
Vol 219 ◽  
pp. 249-253
Author(s):  
Rachel A. Osten ◽  
Suzanne L. Hawley ◽  
Joel Allred ◽  
Christopher M. Johns-Krull ◽  
Christine Roark ◽  
...  
Keyword(s):  
Optical Observations ◽  
Electromagnetic Spectrum ◽  
Temperature Plasma ◽  
Optical Photometry ◽  
X Ray ◽  
Neupert Effect ◽  
Conflicting Evidence ◽  
Multi Wavelength ◽  
Flare Process ◽  
Ev Lac

We report on a large, multi-wavelength campaign to observe variability across the electromagnetic spectrum in the M dwarf flare star EV Lacertae, in 2001 September. The campaign involved X-ray (Chandra ACIS-S+HETG), UV (HST/STIS), and optical (McDonald) spectra, as well as optical photometry and multi-frequency radio (VLA) observations. EV Lac demonstrated both frequent and extreme variability during the course of the two day intensive recordings. Dispersed X-ray spectra confirm the metal underabundance seen in other active stars. The increase in continuum fluxes at short X-ray wavelengths during flare intervals compared to quiescent intervals signals the creation of high temperature plasma, a signature of the flare process. Multi-wavelength comparisons reveal interesting trends: X-ray flare frequencies are within the range predicted by optical observations, yet there is no correspondence between X-ray flares and optical flares in our data. Two UV flares occur during the rise stages of X-ray flares; a major radio flare is accompanied by a large optical flare, which has no apparent counterpart in the X-ray. The results give conflicting evidence for the applicability of the Neupert effect interpretation in stellar coronae.

scholarly journals Multi-Wavelength Studies of the GX 339-4 2010 outburst

2012 ◽  
Vol 8 (S290) ◽  
pp. 17-20
Author(s):  
Marion Cadolle Bel ◽  
S. Corbel ◽  
A. Veledina ◽  
J. Rodriguez ◽  
P. D'Avanzo ◽  
...  
Keyword(s):  
Black Hole ◽  
Optical Emission ◽  
Electromagnetic Spectrum ◽  
X Ray ◽  
Relative Contribution ◽  
Multi Wavelength

AbstractThe microquasar GX 339-4 experienced an outburst in 2010. We focus on observations that are quasi-simultaneous with those made by INTEGRAL and RXTE in March–April 2010 with radio, NIR, optical and UV data. X-ray transients are extreme systems, often harboring a black hole, known to emit throughout the whole electromagnetic spectrum in outburst. We studied the source evolution and correlated changes in all wavelengths. The bolometric flux increased from 0.8 to 2.9 × 10−8 erg cm−2 s−1 while the relative contribution of the hot medium decreased. The radio, NIR and optical emission from jets was detected and observed to fade as the source softened; reprocessing in the disc was strong at the end.

scholarly journals AE Aquarii: A Short Review

2015 ◽  
Vol 2 (1) ◽  
pp. 86-89 ◽  
Author(s):  
P. J. Meintjes ◽  
A. Odendaal ◽  
H. Van Heerden
Keyword(s):  
Mass Transfer ◽  
Short Review ◽  
High Mass ◽  
Transfer Phase ◽  
X Ray ◽  
Multi Wavelength

The nova-like variable AE Aquarii has been continuously studied since its discovery on photographic plates in 1934. In this short review the peculiar multi-wavelength properties of AE Aquarii will be reviewed and explained in context of its evolution from a high mass transfer phase, during which period it could have been a supersoft X-ray source (SSS).

scholarly journals Stellar yields and abundances: new directions from planetary nebulae

2016 ◽  
Vol 12 (S323) ◽  
pp. 86-94
Author(s):  
Maria Lugaro ◽  
Amanda I. Karakas ◽  
Marco Pignatari ◽  
Carolyn L. Doherty
Keyword(s):  
Noble Gas ◽  
Planetary Nebulae ◽  
Central Star ◽  
High Energy ◽  
Type I ◽  
Agb Stars ◽  
Capture Process ◽  
New Directions ◽  
Energy Environment ◽  
Central Stars

AbstractPlanetary nebulae retain the signature of the nucleosynthesis and mixing events that occurred during the previous AGB phase. Observational signatures complement observations of AGB and post-AGB stars and their binary companions. The abundances of the elements heavier than iron such as Kr and Xe in planetary nebulae can be used to complement abundances of Sr/Y/Zr and Ba/La/Ce in AGB stars, respectively, to determine the operation of theslowneutron-capture process (thesprocess) in AGB stars. Additionally, observations of the Rb abundance in Type I planetary nebulae may allow us to infer the initial mass of the central star. Several noble gas components present in meteoritic stardust silicon carbide (SiC) grains are associated with implantation into the dust grains in the high-energy environment connected to the fast winds from the central stars during the planetary nebulae phase.

Planetary Nebulae: Origin and Evolution

1991 ◽  
Vol 9 (1) ◽  
pp. 15-19 ◽  
Author(s):  
D. C. V. Mallik
Keyword(s):  
Planetary Nebulae ◽  
Central Star ◽  
Electromagnetic Spectrum ◽  
Origin And Evolution ◽  
The Past ◽  
Star Evolution ◽  
Lively Debate ◽  
Observational Techniques ◽  
Central Stars ◽  
Made In

AbstractThere has been a great deal of progress in our understanding of planetary nebulae and their central stars during the past decade and a half. Most of this has come about through progress in observational techniques covering almost the entire electromagnetic spectrum. Theories of planetary nebula evolution have been put to better and better tests as more and more discriminating data have become available.This review describes some of the progress made in observations and their interpretation, particularly in the context of the evolution of the nebulae and the central stars. It includes a discussion on the improved determinations of magnitudes and temperatures of the central stars, and of progress in the measurement of distances, and a reassessment of the observed mass-distribution of the central stars. The last topic has been at the centre of a lively debate for almost a decade now and has been responsible for a large number of studies of central star evolution, some this review briefly touchs upon.

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