scholarly journals Chandra observations of the planetary nebula IC 4593

2020 ◽  
Vol 494 (3) ◽  
pp. 3784-3789
Author(s):  
J A Toalá ◽  
M A Guerrero ◽  
L Bianchi ◽  
Y-H Chu ◽  
O De Marco
Keyword(s):  
Planetary Nebula ◽  
Careful Analysis ◽  
Central Star ◽  
Stellar Atmosphere ◽  
Hot Stars ◽  
Imaging Spectrometer ◽  
Ccd Imaging ◽  
X Ray ◽  
High Ionization ◽  
Thin Plasma

ABSTRACT The Advanced CCD Imaging Spectrometer (ACIS-S) camera on board the Chandra X-ray Observatory has been used to discover a hot bubble in the planetary nebula (PN) IC 4593, the most distant PN detected by Chandra so far. The data are used to study the distribution of the X-ray-emitting gas in IC 4593 and to estimate its physical properties. The hot bubble has a radius of ∼2 arcsec and is found to be confined inside the optically bright innermost cavity of IC 4593. The X-ray emission is mostly consistent with that of an optically thin plasma with temperature kT ≈ 0.15 keV (or TX ≈ 1.7 × 106 K), electron density ne ≈ 15 cm−3, and intrinsic X-ray luminosity in the 0.3–1.5 keV energy range LX = 3.4 × 1030 erg s−1. A careful analysis of the distribution of hard (E >0.8 keV) photons in IC 4593 suggests the presence of X-ray emission from a point source likely associated with its central star (CSPN). If this was the case, its estimated X-ray luminosity would be LX, CSPN = 7 × 1029 erg s−1, fulfilling the log(LX, CSPN/Lbol) ≈ −7 relation for self-shocking winds in hot stars. The X-ray detection of the CSPN helps explain the presence of high-ionization species detected in the ultraviolet spectra as predicted by stellar atmosphere models.

scholarly journals Ablation and Wind Mass-Loading in the Born-Again Planetary Nebula A 30

2011 ◽  
Vol 7 (S283) ◽  
pp. 378-379
Author(s):  
Martín A. Guerrero ◽  
You-Hua Chu ◽  
Wolf-Rainer Hamann ◽  
Lidia Oskinova ◽  
Detlef Schönberner ◽  
...  
Keyword(s):  
Stellar Wind ◽  
Planetary Nebula ◽  
Central Star ◽  
Mass Loading ◽  
Diffuse Emission ◽  
X Ray ◽  
Thermal Pulse ◽  
Born Again

AbstractWe present XMM-Newton and Chandra observations of the born-again planetary nebula A 30. These X-ray observations reveal a bright unresolved source at the position of the central star whose X-ray luminosity exceeds by far the model expectations for photospheric emission and for shocks within the stellar wind. We suggest that a “born-again hot bubble” may be responsible for this X-ray emission. Diffuse X-ray emission associated with the petal-like features and one of the H-poor knots seen in the optical is also found. The weakened emission of carbon lines in the spectrum of the diffuse emission can be interpreted as the dilution of stellar wind by mass-loading or as the detection of material ejected during a very late thermal pulse.

Using tritium and x-ray tubes as x-ray calibration sources for the AXAF CCD Imaging Spectrometer

1996 ◽  
Author(s):  
Stephen E. Jones ◽  
Mark W. Bautz ◽  
Steven E. Kissel ◽  
Michael Pivovaroff
Keyword(s):  
Imaging Spectrometer ◽  
Ccd Imaging ◽  
X Ray

scholarly journals Long-term X-ray variability of the symbiotic system RT Cru based on Chandra spectroscopy

2020 ◽  
Vol 500 (4) ◽  
pp. 4801-4817
Author(s):  
A Danehkar ◽  
M Karovska ◽  
J J Drake ◽  
V L Kashyap
Keyword(s):  
High Resolution ◽  
Thermal Plasma ◽  
High Energy ◽  
Accretion Disc ◽  
Energy Transmission ◽  
Imaging Spectrometer ◽  
Ccd Imaging ◽  
X Ray ◽  
Transmission Grating ◽  
Absorbing Material

ABSTRACT RT Cru belongs to the rare class of hard X-ray emitting symbiotics, whose origin is not yet fully understood. In this work, we have conducted a detailed spectroscopic analysis of X-ray emission from RT Cru based on observations taken by the Chandra Observatory using the Low Energy Transmission Grating (LETG) on the High-Resolution Camera Spectrometer (HRC-S) in 2015 and the High Energy Transmission Grating (HETG) on the Advanced CCD Imaging Spectrometer S-array (ACIS-S) in 2005. Our thermal plasma modelling of the time-averaged HRC-S/LETG spectrum suggests a mean temperature of kT ∼ 1.3 keV, whereas kT ∼ 9.6 keV according to the time-averaged ACIS-S/HETG. The soft thermal plasma emission component (∼1.3 keV) found in the HRC-S is heavily obscured by dense materials (>5 × 1023 cm−2). The aperiodic variability seen in its light curves could be due to changes in either absorbing material covering the hard X-ray source or intrinsic emission mechanism in the inner layers of the accretion disc. To understand the variability, we extracted the spectra in the ‘low/hard’ and ‘high/soft’ spectral states, which indicated higher plasma temperatures in the low/hard states of both the ACIS-S and HRC-S. The source also has a fluorescent iron emission line at 6.4 keV, likely emitted from reflection off an accretion disc or dense absorber, which was twice as bright in the HRC-S epoch compared to the ACIS-S. The soft thermal component identified in the HRC-S might be an indication of a jet that deserves further evaluations using high-resolution imaging observations.

X-ray CCD calibration for the AXAF CCD Imaging Spectrometer

1998 ◽  
Author(s):  
Mark W. Bautz ◽  
Michael J. Pivovaroff ◽  
F. Baganoff ◽  
Takashi Isobe ◽  
Stephen E. Jones ◽  
...  
Keyword(s):  
Imaging Spectrometer ◽  
Ccd Imaging ◽  
X Ray

Molecular Hydrogen Emission from the Cometary Globules in the Helix Nebula (NGC 7293)

2003 ◽  
Vol 209 ◽  
pp. 275-276
Author(s):  
J. R. Walsh ◽  
N. Ageorges
Keyword(s):  
Central Region ◽  
Planetary Nebula ◽  
Molecular Hydrogen ◽  
Direct Evidence ◽  
Central Star ◽  
Small Distance ◽  
Ionization Front ◽  
The Sun ◽  
Hydrogen Emission ◽  
High Ionization

The discovery of many dense, dusty condensations in the Helix Nebula, NGC 7293, by Meaburn et al. (1992) was the first direct evidence of the real inhomogeneity of the medium of a planetary nebula. On account of the small distance of the Helix nebula from the Sun (~200pc), the knots (cometary globules) can be resolved from the ground and studied in detail from HST imaging (O'Dell & Handron, 1996). The condensations typically have a projected diameter of <2″ and hence sizes of <6 x 1015 cm. The condensations consist of a dusty core, visible as absorption against the background high ionization central region of the nebula for the foreground globules, and with a bow-shaped ionization front, strong in low ionization emission. The emission is displaced in the direction towards the central star, often with an outwardly-directed radial tail.

scholarly journals HST spectrophotometric data of the central star of the Planetary Nebula LMC-N66

1997 ◽  
Vol 180 ◽  
pp. 126-127
Author(s):  
M. Peña ◽  
W.-R. Hamann ◽  
L. Koesterke ◽  
J. Maza ◽  
R.H. Méndez ◽  
...  
Keyword(s):  
Planetary Nebula ◽  
Central Star ◽  
Short Time Scale ◽  
Type I ◽  
Ionization Degree ◽  
Filamentary Structure ◽  
High Ionization ◽  
Spectrophotometric Data ◽  
History Of ◽  
Short Time

N66 (WS 35, SMP 83) is a Type I (He-N rich) PN in the LMC with a high ionization degree. It shows a bipolar morphology with a filamentary structure (Dopita et al. 1993). Its central star has shown very impressive changes, in short time scale, that have been investigated. Here we describe the history of these changes:

scholarly journals X-ray and UV Views of Hot Gas in Planetary Nebulae

2003 ◽  
Vol 209 ◽  
pp. 415-424 ◽  
Author(s):  
You-Hua Chu ◽  
Martín A. Guerrero ◽  
Robert A. Gruendl
Keyword(s):  
Planetary Nebula ◽  
Dynamical Evolution ◽  
Planetary Nebulae ◽  
Central Star ◽  
X Ray ◽  
Physical Conditions ◽  
Hot Gas ◽  
Fast Wind

The interior of a planetary nebula (PN) is expected to be filled with shocked fast wind from the central star. This hot gas plays the most important role in the dynamical evolution of the PN; however, its physical conditions are not well-known because useful X-ray and far-UV observations were not available until the advent of Chandra, XMM-Newton, and FUSE. This paper reviews X-ray observations of the hot gas in PN interiors and far-UV observations of the interfaces between the hot gas and the dense nebular shells.

scholarly journals X-Ray Evidence for Wind Instabilities

1999 ◽  
Vol 169 ◽  
pp. 201-202
Author(s):  
Joseph J. MacFarlane ◽  
Joseph P. Cassinelli ◽  
D.H. Cohen
Keyword(s):  
High Speed ◽  
Circumstellar Matter ◽  
Uv Spectra ◽  
X Rays ◽  
Hot Stars ◽  
B Stars ◽  
X Ray ◽  
High Ionization ◽  
Low Mass ◽  
Production Mechanisms

Hot stars are known to emit X-rays with LX/Lbol ~ 10−7 for O stars, falling to ~ 10−9 for B3 stars. These stars also lose mass at large rates through their high-speed winds. Over the years, several types of production mechanisms have been proposed to explain the X-ray emission from O stars, with source locations ranging from very near the stellar surface to very far from the star. A coronal X-ray source was originally proposed (Cassinelli and Olson 1979) to explain the presence of anomalously high ionization stages observed as P Cygni line profiles in the UV spectra of O stars. At the other extreme, Chlebowski (1989) suggested that the X-rays of O stars originate far from the star, and are produced by the interaction of the stellar wind with circumstellar matter. A model in which shocks forming due to instabilities in the line-driven winds of O stars was proposed by Lucy (1982), and studied in detail by Owocki et al. (1988), Cooper (1994), and Feldmeier (1996). In this case, the X-ray emission originates in a large number of shock-heated regions distributed throughout the wind. The shocked-wind model has also been shown to be consistent with the X-ray emission from early-B stars, such as τ Sco (MacFarlane and Cassinelli 1989). However, it appears difficult for shocked wind models to explain the X-ray emission from B3 and later stars because of their presumed low mass loss rates (Cohen et al.1997).

scholarly journals Advanced CCD imaging spectrometer (ACIS) instrument on the Chandra X-ray Observatory

2003 ◽  
Author(s):  
Gordon P. Garmire ◽  
Mark W. Bautz ◽  
Peter G. Ford ◽  
John A. Nousek ◽  
George R. Ricker, Jr.
Keyword(s):  
Imaging Spectrometer ◽  
Ccd Imaging ◽  
X Ray

X-ray CCD calibration for the AXAF CCD Imaging Spectrometer

1996 ◽  
Author(s):  
Mark W. Bautz ◽  
Steven E. Kissel ◽  
Gregory Y. Prigozhin ◽  
Stephen E. Jones ◽  
Takashi Isobe ◽  
...  
Keyword(s):  
Imaging Spectrometer ◽  
Ccd Imaging ◽  
X Ray ◽  
Title X
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