scholarly journals Emission Lines From Hot Astrophysical Plasmas

1990 ◽  
Vol 115 ◽  
pp. 1-10 ◽  
Author(s):  
John C. Raymond
Keyword(s):  
Spectral Lines ◽  
Emission Lines ◽  
Physical Parameters ◽  
Relative Importance ◽  
Astrophysical Plasmas ◽  
X Ray ◽  
Elemental Abundances ◽  
Computer Codes ◽  
Measurement Uncertainties ◽  
Ionization Balance

AbstractThe spectral lines which dominate the X-ray emission of hot, optically thin astrophysical plasmas reflect the elemental abundances, temperature distribution, and other physical parameters of the emitting gas. The accuracy and level of detail with which these parameters can be inferred are limited by the measurement uncertainties and uncertainties in atomic rates used to compute the model spectrum. This paper discusses the relative importance and the likely uncertainties in the various atomic rates and the likely uncertainties in the overall ionization balance and spectral line emissivities predicted by the computer codes currently used to fit X-ray spectral data.

scholarly journals The Soft X-ray Background Spectrum from DXS

1997 ◽  
Vol 166 ◽  
pp. 83-90 ◽  
Author(s):  
W.T. Sanders ◽  
R.J. Edgar ◽  
D.A. Liedahl ◽  
J.P. Morgenthaler
Keyword(s):  
Galactic Plane ◽  
Emission Lines ◽  
Background Spectrum ◽  
Local Bubble ◽  
X Ray ◽  
Hot Plasma ◽  
Solar Abundances ◽  
Ionic Emission ◽  
X Ray Background ◽  
Ionization Balance

AbstractThe Diffuse X-ray Spectrometer (DXS) obtained spectra of the low energy X-ray (44 – 83 Å) diffuse background near the galactic plane from galactic longitudes 150° ≲ l ≲ 300° with ≲ 3 Å spectral resolution and ~ 15° angular resolution. Thus, DXS measured X-ray spectra that arise almost entirely from within the Local Bubble. The DXS spectra show emission lines and emission-line blends, indicating that the source of the X-ray emission is thermal – hot plasma in the Local Bubble. The measured spectra are not consistent with those predicted by standard coronal models, either with solar abundances or depleted abundances, over the temperature range 105 – 107 K. The measured spectra are also inconsistent with the predictions of various non-equilibrium models. A nearly acceptable fit to DXS spectra can be achieved using a hybrid model that combines the Raymond & Smith ionization balance calculation with recently calculated (by DAL) ionic emission lines.

scholarly journals Non-Equilibrium Ionization X-ray Emission from Supernova Remnants

1983 ◽  
Vol 101 ◽  
pp. 99-107
Author(s):  
J. Michael Shull
Keyword(s):  
Supernova Remnants ◽  
Heavy Element ◽  
Plasma Temperature ◽  
Supernova Explosion ◽  
Theoretical Models ◽  
Astrophysical Plasmas ◽  
Ionization Equilibrium ◽  
X Ray ◽  
Elemental Abundances ◽  
Stellar Nucleosynthesis

X-ray spectra of young supernova remnants (SNR's) are perhaps the most spectacular examples of hot, line-emitting astrophysical plasmas. Heated to temperatures of 1 to 10 keV and enriched with the heavy element products of stellar nucleosynthesis, the plasma inside these SNR's emits prodigiously in lines of 0, Ne, Mg, Si, S, Ar, Ca, and Fe. Theoretical models of this emission provide measures of the plasma temperature and density, elemental abundances, and the degree of approach to ionization equilibrium. Thus, astrophysicists are offered the opportunity to test their understanding of the supernova explosion, its interaction with the interstellar medium, and the nucleo-synthetic processes which enrich our galaxy with heavy elements.

scholarly journals Plasma Emission Codes: Comparisons and Critiques

1996 ◽  
Vol 152 ◽  
pp. 561-568
Author(s):  
Helen E. Mason
Keyword(s):  
Spectral Lines ◽  
Atomic Data ◽  
Physical Parameters ◽  
Spectroscopic Techniques ◽  
Plasma Emission ◽  
Atomic Processes ◽  
Astrophysical Plasmas

A great deal of effort in recent years has gone into the development of spectroscopic techniques to probe the physical parameters of solar, stellar and other astrophysical plasmas. One aspect of this work is the calculation of plasma emission codes which are used to study EUV spectral lines. These codes require the input of a large amount of atomic data. In this paper, we present an overview of the atomic processes involved and an assessment of the accuracy of the parameters which are incorporated into different emission codes.

Solar active region physical parameters inferred from a thermal cyclotron line and soft X-ray spectral lines

1987 ◽  
Vol 322 ◽  
pp. 1044 ◽  
Author(s):  
Kenneth R. Lang ◽  
Robert F. Willson ◽  
Kermit L. Smith ◽  
Keith T. Strong
Keyword(s):  
Active Region ◽  
Spectral Lines ◽  
Solar Active Region ◽  
Physical Parameters ◽  
X Ray ◽  
Cyclotron Line

scholarly journals Spectra Due to Dielectronic Recombination

1985 ◽  
Vol 19 (2) ◽  
pp. 158-158
Author(s):  
J Dubau ◽  
F Bely-Dubau
Keyword(s):  
Excited State ◽  
Plasma Diagnostics ◽  
Dielectronic Recombination ◽  
Plasma Electron ◽  
Spectral Lines ◽  
Physical Parameters ◽  
Fusion Plasmas ◽  
Target Electron ◽  
Capture Process ◽  
X Ray

Dielectronic recombination (DR) is an electron-ion process particularly effective in high temperature plasmas such as those observed in the Solar Corona, Supernovae remnants in fusion plasmas (Tokamak and laser produced plasmas). This process is a resonant capture process of projectile electrons by a target ion as one of the target electron is excited, thereby forming an intermediate autionising state which can decay radiatively to a singly excited state. DR plays an important role on the establishment of ionisation equilibrium in the plasma and is also responsible for spectral lines appearing as satellites of the resonance lines of the target ion. The analysis and interpretation of such satellite lines in terms of plasma diagnostics has been widely used in soft X-ray spectroscopy during the last decade, and has given reliable estimates of the physical parameters of the plasma (electron and ion temperatures and densities). In the case of H-like and He-like resonance lines, high resolution spectra have been obtained in Tokamak for Z = 14 - 28 and most of the satellites have been clearly identified. To help the reader to go further we give some references of solar studies 2, 3, 4, 0, Tokamak 6, 7, laser plasma 8, 9.

scholarly journals Atomic Data Needs for X-ray Astronomy

2002 ◽  
Vol 12 ◽  
pp. 82-83
Author(s):  
Nancy S. Brickhouse
Keyword(s):  
High Resolution ◽  
Atomic Data ◽  
Ionization Mechanism ◽  
Ionization State ◽  
Astrophysical Plasmas ◽  
X Ray ◽  
Physical Conditions ◽  
Elemental Abundances ◽  
The Status ◽  
Collisional Ionization

AbstractWith the launches of the Chandra X-ray Observatory and XMM-Newton, high resolution X-ray spectra of cosmic sources are broadening our understanding of the physical conditions, such as temperature, density, ionization state, and elemental abundances. X-ray emitting astrophysical plasmas can be generally classified by their dominant ionization mechanism, either collisional ionization or X-ray photoionization. The atomic data needs are significantly different for these two cases; however, for both cases it is important that we identify robust and accurate diagnostics and that we verify completeness of the broadband models. We discuss the status of the atomic data currently used in atomic databases for X-ray astronomy, in view of theoretical and experimental atomic physics considerations.

scholarly journals Astrophysical Plasmas and Atomic Processes

1998 ◽  
Vol 188 ◽  
pp. 43-46 ◽  
Author(s):  
J.S. Kaastra
Keyword(s):  
Atomic Processes ◽  
Astrophysical Plasmas ◽  
X Ray ◽  
Ionization Balance ◽  
Smith Model ◽  
Non Equilibrium

Several plasma codes are available for the analysis of hot astrophysical plasmas. Among the oldest are the Raymond-Smith model (Raymond & Smith 1977) and Mewe-Gronenschild model (Mewe et al. 1985, 1986). Minor updates to this last code have resulted in the meka model (Kaastra 1992); major updates (most importantly the ionization balance and the treatment of the Fe-L complex) resulted in the mekal code (Mewe, Kaastra & Liedahl 1995). Here also the plasma codes of Masai (1984) and Landini & Monsignori Fossi (1990) should be mentioned. The RS, meka and mekal codes are included in the XSPEC fitting package, the latest mekal code is incorporated in the SPEX package (Kaastra et al. 1996). Both Masai's code and SPEX contain non-equilibrium ionization (NEI) modes. All these codes differ in details, see Brickhouse et al. (1995) for an overview. Most important for the analysis of X-ray data is the ionization balance that is used for iron and the treatment of the Fe-L complex.

scholarly journals How to analyze 2-D nebular spectra

1997 ◽  
Vol 180 ◽  
pp. 227-227
Author(s):  
K. Gesicki ◽  
A. Acker ◽  
A. Zijlstra
Keyword(s):  
Velocity Field ◽  
Spherical Shell ◽  
Density Distribution ◽  
Central Star ◽  
Spectral Lines ◽  
Emission Lines ◽  
Computer Codes

For a nebula we construct a model, which is a spherical shell defined by inner and outer radii, density distribution and velocity field. The Teff and the luminosity of the central star are assumed to agree with observations. Then the photoionization structure is calculated and the emission lines are integrated. Having found the density from analysis of images the deduction of velocity field in order to fit the observed shapes of spectral lines is relatively easy. A detailed description of computer codes applied for the analysis of nebular spectra is presented in our earlier paper: Gesicki et al. (1996). See also Górny et al. in this volume.

scholarly journals Spectroscopic Diagnostics for Ions Observed in Solar and Cosmic Plasmas

1990 ◽  
Vol 115 ◽  
pp. 11-20 ◽  
Author(s):  
Helen E Mason
Keyword(s):  
Solar Flares ◽  
Line Emission ◽  
Wavelength Region ◽  
Spectral Lines ◽  
Emission Lines ◽  
Atomic Processes ◽  
X Ray ◽  
Spectroscopic Diagnostics ◽  
Solar Spectral Line ◽  
Diagnostic Properties

AbstractThe X-ray wavelength region (1-200Å) is rich in spectral lines from highly ionised systems. Spectra from the solar atmosphere have been studied extensively with various instruments covering different wavelength regions. In this paper, we discuss the solar spectral line emission with particular reference to iron ions and helium like ions observed during solar flares. The atomic processes involved in the calculation of theoretical intensities for low density plasmas are outlined together with the diagnostic properties of the emission lines. Comparisons are made with available cosmic X-ray spectra and predicted spectra for future projects, such as AXAF.

scholarly journals CIELO-RGS: a catalog of soft X-ray ionized emission lines

2019 ◽  
Vol 625 ◽  
pp. A122
Author(s):  
Junjie Mao ◽  
Jelle S. Kaastra ◽  
Matteo Guainazzi ◽  
Rosario González-Riestra ◽  
Maria Santos-Lleó ◽  
...  
Keyword(s):  
Detection Algorithm ◽  
Emission Lines ◽  
Quality Data ◽  
Photon Flux ◽  
Astrophysical Plasmas ◽  
High Quality ◽  
X Ray ◽  
Spectral Diagnostics ◽  
Starting Point ◽  
Automated Line

Context. High-resolution X-ray spectroscopy has advanced our understanding of the hot Universe by revealing physical properties like kinematics, temperature, and abundances of the astrophysical plasmas. Despite technical and scientific achievements, the lack of scientific products at a level higher than count spectra is hampering complete scientific exploitation of high-quality data. This paper introduces the Catalog of Ionized Emission Lines Observed by the Reflection Grating Spectrometer (CIELO-RGS) onboard the XMM-Newton space observatory. Aims. The CIELO-RGS catalog aims to facilitate the exploitation of emission features in the public RGS spectra archive. In particular, we aim to analyze the relationship between X-ray spectral diagnostics parameters and measurements at other wavelengths. This paper focuses on the methodology of catalog generation, describing the automated line-detection algorithm. Methods. A moderate sample (∼2400 observations) of high-quality RGS spectra available at XMM-Newton Science Archive is used as our starting point. A list of potential emission lines is selected based on a multi-scale peak-detection algorithm in a uniform and automated way without prior assumption on the underlying astrophysical model. The candidate line list is validated via spectral fitting with simple continuum and line profile models. We also compare the catalog content with published literature results on a small number of exemplary sources. Results. We generate a catalog of emission lines (1.2 × 104) detected in ∼1600 observations toward stars, X-ray binaries, supernovae remnants, active galactic nuclei, and groups and clusters of galaxies. For each line, we report the observed wavelength, broadening, energy and photon flux, equivalent width, and so on.

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