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 Solar Coronal Fe XVII X-Ray Line Ratios

1984 ◽  
Vol 86 ◽  
pp. 137-140
Author(s):  
H.R. Rugge ◽  
D.L. McKenzie
Keyword(s):  
Solar Activity ◽  
Solar Flares ◽  
Accurate Determination ◽  
Wavelength Region ◽  
Emission Lines ◽  
Crystal Spectrometer ◽  
X Ray ◽  
Counting Statistics ◽  
Solar Coronal

The SOLEX bragg crystal spectrometer experiment on the P78-1 satellite (Landecker, McKenzie and Rugge, 1979) has been used to determine accurate flux ratios of several strong solar Fe XVII x-ray emission lines in the ~ 15 to ~ 17 Å wavelength region. The ratios chosen were selected because the lines used permitted an accurate determination of the ratios both from the aspect of counting statistics as well as the lack of interference from other lines of comparable strength. Observations for a variety of conditions of solar activity, ranging from quiet conditions to large solar flares, are presented. For these observations intensity variations of a factor of about 60 were observed for the Fe XVII lines. Variations of a factor of almost 800 were observed for the Fe XVIII line at 14.2 Å. The observed ratios of the Fe XVII lines are compared to the theories of Loulergue and Nussbaumer (1975) and Smith, Raymond, Mann and Cowan (1984).

scholarly journals SolpeX: the soft X-ray flare polarimeter–spectrometer for the ISS

2014 ◽  
Vol 10 (S305) ◽  
pp. 114-120
Author(s):  
Janusz Sylwester ◽  
Stefan Płocieniak ◽  
Jarosław Bakała ◽  
Żaneta Szaforz ◽  
Marek Stȩślicki ◽  
...  
Keyword(s):  
Solar Flares ◽  
Line Emission ◽  
Impulsive Phase ◽  
Particle Beams ◽  
X Ray ◽  
Hot Plasma ◽  
Spectral Imager ◽  
Polarized Bremsstrahlung ◽  
Made In ◽  
Fast Rotating

AbstractWe present the innovative soft X-ray spectro-polarimeter, SolpeX. This instrument consists of three functionally independent blocks. They are to be included into the Russian instrument KORTES, to be mounted onboard the ISS. The three SolpeX units are: a simple pin-hole X-ray spectral imager, a polarimeter, and a fast-rotating drum multiple-flat-crystal Bragg spectrometer. Such a combination of measuring blocks will offer a new opportunity to reliably measure possible X-ray polarization and spectra of solar flares, in particular during the impulsive phase. Polarized Bremsstrahlung and line emission due to the presence of directed particle beams will be detected, and measurements of the velocities of evaporated hot plasma will be made. In this paper we discuss the details of the construction of the SolpeX units. The delivery of KORTES with SolpeX to the ISS is expected to happen in 2017/2018.

Atomic physics calculations relevant to solar flare spectra

1991 ◽  
Vol 336 (1643) ◽  
pp. 471-484 ◽  
Keyword(s):  
Solar Flare ◽  
Atomic Physics ◽  
Solar Flares ◽  
Solar Maximum ◽  
Emission Lines ◽  
Atomic Data ◽  
Solar Maximum Mission ◽  
X Ray ◽  
Physical Conditions ◽  
Recombination Processes

Solar flare spectra in the ultraviolet and X-ray wavelength regions are rich in emission lines from highly ionized ions, formed at temperatures around 10 7 K. These lines can be used as valuable diagnostics for probing the physical conditions in solar flares. Such analyses require accurate atomic data for excitation, ionization and recombination processes. In this paper, we present a review of work which has already been carried out, in particular for the Solar Maximum Mission observations, and we look to future requirements for Solar-A .

scholarly journals Short and Medium Term Variability of Emission Lines in Selected Southern be Stars

1999 ◽  
Vol 169 ◽  
pp. 36-39
Author(s):  
Thomas Rivinius
Keyword(s):  
Line Emission ◽  
Spectral Lines ◽  
Emission Lines ◽  
Be Stars ◽  
Medium Term ◽  
Monitoring Period ◽  
Stellar Orbit

AbstractWe observed a sample of several southern Be stars from 1995 to 1997 typically for several months in each season using our spectrograph HEROS. One of these stars, μ Cen, was found to be in the process of continued gradual recovery of the Hydrogen emitting disk which had been lost from 1977-1989. During the monitoring period numerous line emission outbursts were observed. A generalized pattern of an outburst cycle is derived from observations of different circumstellar lines at times of various levels of emission from the disk. Relative quiescence in which mostly periodic varaibiltiy is seen, rapid decreases of emission (precursor), outburst, and subsequent relaxation can be distinguished as the main constituing phases, even though there are distinct differences between different groups of spectral lines. Based on this empirical phenomenology, a schematic picture of the associated ejection of matter into a near-stellar orbit is sketched and similarities between μ Cen and other stars will be outlined.

scholarly journals Investigation of soft X-ray emission from Ar clusters heated by ultrashort laser pulses

2002 ◽  
Vol 20 (1) ◽  
pp. 51-57 ◽  
Author(s):  
T. MOCEK ◽  
C.M. KIM ◽  
H.J. SHIN ◽  
D.G. LEE ◽  
Y.H. CHA ◽  
...  
Keyword(s):  
Line Emission ◽  
Laser Pulses ◽  
Ultrashort Laser Pulses ◽  
Spectral Lines ◽  
Gas Temperature ◽  
X Ray ◽  
Charge States ◽  
Ar Gas ◽  
Collisional Ionization ◽  
Collisional Heating

We report soft X-ray spectra (4–18 nm) produced by the interaction of 25–100-fs laser pulses at an intensity of up to 7 × 1016 W/cm2 with a cryogenically cooled Ar gas jet. New spectral lines from Ar8+, Ar9+, and Ar10+ charge states appeared with decreasing preexpansion gas temperature. A nonlinear increase of X-ray line emission from Ar7+, Ar8+, and Ar9+ was observed with cooling, which saturated below a certain temperature. The drastic change in the spectrum is attributed to efficient collisional heating and collisional ionization of growing, small- to medium-sized (102–103 atoms) Ar clusters from the cooled jet. When the laser pulse was extended from 25 to 100 fs we observed considerably stronger emission on lines from high charge states, such as Ar8+, Ar9+, and Ar10+, which suggests that the resonance absorption condition could be reached for the 100-fs pulse.

scholarly journals On the Origin of the 6.4 keV line from the GRXE

2011 ◽  
Vol 7 (S279) ◽  
pp. 329-330
Author(s):  
Romanus Eze ◽  
Kei Saitou ◽  
Ken Ebisawa
Keyword(s):  
Galactic Plane ◽  
Cataclysmic Variables ◽  
Line Emission ◽  
Emission Lines ◽  
Symbiotic Stars ◽  
Line Flux ◽  
X Ray ◽  
Fluorescence Line ◽  
Magnetic Cataclysmic Variables ◽  
Cold Matter

AbstractThe Galactic Ridge X-ray Emission (GRXE) spectrum has strong iron emission lines at 6.4, 6.7, and 7.0 keV, each corresponding to the neutral (or low-ionized), He-like, and H-like iron ions. The 6.4 keV fluorescence line is due to irradiation of neutral (or low ionized) material (iron) by hard X-ray sources, indicating uniform presence of the cold matter in the Galactic plane. In order to resolve origin of the cold fluorescent matter, we examined the contribution of the 6.4 keV line emission from white dwarf surfaces in the hard X-ray emitting symbiotic stars (hSSs) and magnetic cataclysmic variables (mCVs) to the GRXE. In our spectral analysis of 4 hSSs and 19 mCVs observed with Suzaku, we were able to resolve the three iron emission lines. We found that the equivalent-widths (EWs) of the 6.4 keV lines of hSSs are systematically higher than those of mCVs, such that the average EWs of hSSs and mCVs are 180−10+50 eV and 93−3+20 eV, respectively. The EW of hSSs compares favorably with the typical EWs of the 6.4 keV line in the GRXE of 90–300 eV depending on Galactic positions. Average 6.4 keV line luminosities of the hSSs and mCVs are 9.2 × 1039 and 1.6 × 1039 photons s−1, respectively, indicating that hSSs are intrinsically more efficient 6.4 keV line emitters than mCVs. We estimated required space densities of hSSs and mCVs to account for all the GRXE 6.4 keV line emission flux to be 2 × 10−7 pc−3 and 1 × 10−6 pc−3, respectively. We also estimated the actual 6.4 keV line contribution from the hSSs, which is as much as 30% of the observed GRXE flux, and that from the mCV is about 50%. We therefore conclude that the GRXE 6.4 keV line flux is primarily explained by hSSs and mCVs.

scholarly journals Ultraviolet Observations of Stellar Coronae: Early Results from HST

1992 ◽  
Vol 9 ◽  
pp. 657-658
Author(s):  
J.L. Linsky
Keyword(s):  
High Resolution ◽  
Spectral Resolution ◽  
Solar Flares ◽  
Extreme Ultraviolet ◽  
The Sun ◽  
X Ray ◽  
Spectroscopic Diagnostics ◽  
Early Results ◽  
Active Stars ◽  
Ultraviolet Observations

Although coronae for stars other than the Sun have previously been detected only in the X-ray and radio portions of the spectrum, the HST and future spacecraft sensitive to ultraviolet (UV) and extreme ultraviolet (ETIV) light will have the spectral resolution to study the dynamics and spectroscopic diagnostics of hot coronal plasmas. In the UV region accessible to HST, forbidden lines of FeXII at 1242 and 1349Å, of FeXXI at 1354Å, and other species seen in solar flares, are predicted to be present in the spectra of active stars. Upcoming observations with the Goddard High Resolution Spectrograph (GHRS) by S. Maran will search for these lines in the dM2e star AU Mic and other stars.

scholarly journals Features in the Soft X-ray Background

1990 ◽  
Vol 115 ◽  
pp. 146-155
Author(s):  
R. Rothenflug
Keyword(s):  
Energy Resolution ◽  
Line Emission ◽  
Spatial Variations ◽  
Emission Lines ◽  
X Ray ◽  
Hot Gas ◽  
The North ◽  
North Polar ◽  
X Ray Background ◽  
Japanese Group

AbstractThe soft X-ray background is explained in terms of emission coming from hot gas. Most of these soft X-ray data were obtained by proportional counters with a poor energy resolution. Instruments having the capability to resolve lines were only flown by two groups: a GSPC by a Japanese group and a SSD by a french-american collaboration. They both detected the 0 VII line emission coming from the soft X-ray background and so proved the thermal nature of the emission. The implications of these results on possible models for the local hot medium will be discussed. The same detectors observed part of the North Polar Spur. They detected emission lines coming from different species (0 VII,Fe XVII,Ne IX). Spatial variations of line ratios for this object could be due to non-equilibrium ionization effects.

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