scholarly journals Atomic Data and Coronal Diagnostics

1995 ◽  
Vol 10 ◽  
pp. 303-304
Author(s):  
Helen E. Mason
Keyword(s):  
Solar Wind ◽  
Recent Progress ◽  
Atomic Data ◽  
Temperature Structure ◽  
Dynamic Nature ◽  
Heliospheric Observatory ◽  
Element Abundances ◽  
Spectroscopic Diagnostics ◽  
Solar Analysis ◽  
Electron Density And Temperature

AbstractSpectroscopic diagnostics play an important role in determining the electron density and temperature structure, element abundances and dynamic nature of different features in the solar atmosphere. To ensure that these techniques are accurate it is necessary to interface solar analysis programs with the best available atomic data calculations. Recent progress in this work is presented and applications to planned space observations are discussed. In particular, the CDS and Sumer instruments, on the Solar Heliospheric Observatory, will make extensive use of spectroscopic diagnostics to study the heating processes for the solar corona and the acceleration mechanisms for the solar wind.

scholarly journals High-resolution spectroscopy of the hot Am star HR 3383

2020 ◽  
Vol 500 (2) ◽  
pp. 2451-2460
Author(s):  
G M Wahlgren ◽  
K E Nielsen ◽  
D S Leckrone
Keyword(s):  
Hubble Space Telescope ◽  
Theoretical Calculations ◽  
Current Theory ◽  
Element Distribution ◽  
Spectral Lines ◽  
High Resolution Spectroscopy ◽  
Atomic Data ◽  
Stellar Spectrum ◽  
Optical Telescope ◽  
Element Abundances

ABSTRACT We present the spectrum analysis of the hot Am star HR 3383 (A1 Vm). Hubble Space Telescope STIS and Nordic Optical Telescope SOFIN data are modelled with synthetic spectra, and abundances are investigated for 78 elements. Most light elements up through oxygen show deficiencies, compared to solar abundances, followed by the general trend of increasing abundance enhancement with atomic number that levels off at a 30-fold enhancement at the lanthanide group and heavier elements. The derived element distribution is generally consistent with what is observed in other hot Am stars. Abundances for HR 3383 are also similar to what is seen for the cooler HgMn stars, with the exception of the platinum-group elements that generally show dramatic enhancements in the HgMn stars. Current theory and calculations are able to predict most observed abundances and abundance trends through the iron group. The large number of derived element abundances in this study provides a constraint for theoretical calculations attempting to explain the heavy element abundances in chemically peculiar stars. This paper includes a comprehensive description of spectral lines useful for an abundance analysis of late B and A type stars, and comments are provided on the atomic data. New data for hyperfine structure components for three lines in Lu iii and a single line in Lu ii are presented, based on laboratory spectra. In addition to the stellar spectrum, lines from the interstellar medium are noted for several of the strongest Fe ii ultraviolet transitions.

scholarly journals Helioseismology from space, the SOHO project

1988 ◽  
Vol 123 ◽  
pp. 545-548
Author(s):  
V. Domingo
Keyword(s):  
Solar Wind ◽  
Solar Corona ◽  
European Space Agency ◽  
Science Research ◽  
Small Scale ◽  
Heliospheric Observatory ◽  
Space Agency ◽  
Cluster A ◽  
Physics Programme

As a cornerstone of its long term plan for space science research, the European Space Agency (ESA) is developing the Solar Terrestrial Physics Programme that consists of two parts: one, the Solar and Heliospheric Observatory (SOHO) for the study of the solar internal structure and the physics of the solar corona and the solar wind, and another, CLUSTER, a series of four spacecraft flying in formation to study small scale plasma phenomena in several regions of the magnetosphere and in the near Earth solar wind. The feasibility of the missions was demonstrated in Phase A studies carried out by industrial consortia under the supervision of ESA (1,2). According to the current plans an announcement of opportunity calling for instrument proposals will be issued by ESA during the first quarter of 1987. It is foreseen that the spacecraft will be launched by the end of 1994.

scholarly journals The Abundance of Boron in Disk-Metallicity Stars

2000 ◽  
Vol 198 ◽  
pp. 415-424
Author(s):  
Katia Cunha
Keyword(s):  
Linear Trend ◽  
Solar Spectrum ◽  
Atomic Data ◽  
Solar Photosphere ◽  
Halo Stars ◽  
Orion Association ◽  
Solar Metallicity ◽  
Solar Analysis ◽  
Solar Ratio

Although the behavior of boron versus metallicity has been probed in a fairly large sample of halo dwarfs with HST, it is only very recently that boron abundances have been derived systematically in solar metallicity dwarfs. This effort began with a re-analysis of the solar spectrum with modern atomic data and model atmospheres so that the Sun could be adopted as a standard for the calibration of a line list in the region of the B I transition at 2497 Â. The solar analysis indicates that boron is not depleted in the solar photosphere. From a subsequent study of a sample of 14 field F/G-dwarfs with roughly solar metallicities, it is found that the behavior of boron versus [Fe/H] follows the linear trend that is observed for the halo stars. The average B/Be obtained for solar metallicity stars is 27±5 compared to the solar ratio of 23. The determination of boron abundances in the young B-type and G-type stars of the Orion association reveals a behavior of boron and oxygen in Orion that is opposite of the positive correlation which is observed for the field stars: the boron and oxygen abundances are anticorrelated.

scholarly journals Element Abundances of Solar Energetic Particles and the Photosphere, the Corona, and the Solar Wind

Atoms ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 104 ◽  
Author(s):  
Donald V. Reames
Keyword(s):  
Solar Wind ◽  
Shock Waves ◽  
Solar Corona ◽  
Plasma Temperature ◽  
Energetic Particles ◽  
Solar Energetic Particles ◽  
Charge Ratio ◽  
Ambient Plasma ◽  
Element Abundances ◽  
Resonant Wave

From a turbulent history, the study of the abundances of elements in solar energetic particles (SEPs) has grown into an extensive field that probes the solar corona and physical processes of SEP acceleration and transport. Underlying SEPs are the abundances of the solar corona, which differ from photospheric abundances as a function of the first ionization potentials (FIPs) of the elements. The FIP-dependence of SEPs also differs from that of the solar wind; each has a different magnetic environment, where low-FIP ions and high-FIP neutral atoms rise toward the corona. Two major sources generate SEPs: The small “impulsive” SEP events are associated with magnetic reconnection in solar jets that produce 1000-fold enhancements from H to Pb as a function of mass-to-charge ratio A/Q, and also 1000-fold enhancements in 3He/4He that are produced by resonant wave-particle interactions. In large “gradual” events, SEPs are accelerated at shock waves that are driven out from the Sun by wide, fast coronal mass ejections (CMEs). A/Q dependence of ion transport allows us to estimate Q and hence the source plasma temperature T. Weaker shock waves favor the reacceleration of suprathermal ions accumulated from earlier impulsive SEP events, along with protons from the ambient plasma. In strong shocks, the ambient plasma dominates. Ions from impulsive sources have T ≈ 3 MK; those from ambient coronal plasma have T = 1 – 2 MK. These FIP- and A/Q-dependences explore complex new interactions in the corona and in SEP sources.

scholarly journals Element Abundances: A New Diagnostic for the Solar Wind

2019 ◽  
Vol 879 (2) ◽  
pp. 124 ◽  
Author(s):  
J. Martin Laming ◽  
Angelos Vourlidas ◽  
Clarence Korendyke ◽  
Damien Chua ◽  
Steven R. Cranmer ◽  
...  
Keyword(s):  
Solar Wind ◽  
Element Abundances

scholarly journals The 3D solar minimum with differential emission measure tomography

2011 ◽  
Vol 7 (S286) ◽  
pp. 123-133
Author(s):  
Alberto M. Vásquez ◽  
Richard A. Frazin ◽  
Zhenguang Huang ◽  
Ward B. Manchester ◽  
Paul Shearer
Keyword(s):  
Extreme Ultraviolet ◽  
Emission Measure ◽  
Three Dimensional ◽  
Differential Emission Measure ◽  
Height Range ◽  
Heliospheric Observatory ◽  
Temperature Distributions ◽  
Imaging Telescope ◽  
Electron Density And Temperature ◽  
Comparative Results

AbstractDifferential emission measure tomography (DEMT) makes use of extreme ultraviolet (EUV) image series to deliver two products: a) the three-dimensional (3D) reconstruction of the coronal emissivity in the instrumental bands, and b) the 3D distribution of the local differential emission measure (LDEM). The LDEM allows, in turn, construction of 3D maps of the electron density and temperature distribution. DEMT is being currently applied to the space-based EUV imagers, allowing reconstruction of the inner corona in the height range 1.00 to 1.25 R⊙. In this work we applied DEMT to different Carrington Rotations corresponding to the last two solar Cycle minima. To reconstruct the 2008 minimum we used data taken by the Extreme UltraViolet Imager (EUVI), on board the Solar TErrestrial RElations Observatory (STEREO) spacecraft, and to reconstruct the 1996 minimum we used data taken by the Extreme ultraviolet Imaging Telescope (EIT), on board the Solar and Heliospheric Observatory (SOHO). We show here comparative results, discussing the observed 3D density and temperature distributions in the context of global potential magnetic field extrapolations. We also compare the DEMT results with other observational and modeling efforts of the same periods.

scholarly journals Improved Neutron-Capture Element Abundances in Planetary Nebulae

2009 ◽  
Vol 26 (3) ◽  
pp. 339-344 ◽  
Author(s):  
N. C. Sterling ◽  
H. L. Dinerstein ◽  
S. Hwang ◽  
S. Redfield ◽  
A. Aguilar ◽  
...  
Keyword(s):  
Cross Sections ◽  
Planetary Nebulae ◽  
Asymptotic Giant Branch ◽  
Rate Coefficients ◽  
Atomic Data ◽  
Agb Stars ◽  
Iron Species ◽  
Element Abundances ◽  
Ionization Balance ◽  
Initial Results

AbstractSpectroscopy of planetary nebulae (PNe) provides the means to investigate s-process enrichments of neutron(n)-capture elements that cannot be detected in Asymptotic Giant Branch (AGB) stars. However, accurate abundance determinations of these elements present a challenge. Corrections for unobserved ions can be large and uncertain, since in many PNe only one ion of a given n-capture element has been detected. Furthermore, the atomic data governing the ionization balance of these species are not well-determined, inhibiting the derivation of accurate ionization corrections. We present initial results of a program that addresses these challenges. Deep high-resolution optical spectroscopy of ∼20 PNe has been performed to detect emission lines from trans-iron species including Se, Br, Kr, Rb and Xe. The optical spectral region provides access to multiple ions of these elements, which reduces the magnitude and importance of uncertainties in the ionization corrections. In addition, experimental and theoretical efforts are providing determinations of the photoionization cross sections and recombination rate coefficients of Se, Kr and Xe ions. These new atomic data will make it possible to derive robust ionization corrections for these elements. Together, our observational and atomic data results will enable n-capture element abundances to be determined with unprecedented accuracy in ionized nebulae.

scholarly journals SOLAR AND HELIOSPHERIC OBSERVATORY/SOLAR WIND ANISOTROPIES OBSERVATIONS OF FIVE MODERATELY BRIGHT COMETS: 1999-2002

2008 ◽  
Vol 135 (4) ◽  
pp. 1533-1550 ◽  
Author(s):  
M. R. Combi ◽  
J. T. T. Mäkinen ◽  
N. J. Henry ◽  
J.-L. Bertaux ◽  
E. Quemérais
Keyword(s):  
Solar Wind ◽  
Heliospheric Observatory
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