منابع مشابه
Collisional Plasma Models with Apec/aped: Emission Line Diagnostics of Hydrogen-like and Helium-like Ions
New X-ray observatories (Chandra and XMM-Newton) are providing a wealth of high-resolution X-ray spectra in which hydrogenand helium-like ions are usually strong features. We present results from a new collisional-radiative plasma code, the Astrophysical Plasma Emission Code (apec), which uses atomic data in the companion Astrophysical Plasma Emission Database (aped) to calculate spectral model...
متن کاملar X iv : a st ro - p h / 02 04 04 9 v 1 3 A pr 2 00 2 1 HELIUM - LIKE TRIPLET DIAGNOSTICS
The 1s 2 –1s2l lines are the most intense He-like ions lines. They are used as spectroscopic diagnostics for solar active regions as well as for different laboratory plasmas. Nowadays, it exits very high spectral resolution instruments and, for intense X-ray sources, one can do spectro-scopic diagnostics from line ratios. With XMM (RGS) and Chandra (LETGS, HETGS) spectral resolutions and for se...
متن کاملX - ray photoionized plasma diagnostics with Helium - like ions . Application to Warm Absorber - Emitter in Active
We present He-like line ratios (resonance, intercombination and forbidden lines) for totally and partially photoionized media. For solar plasmas, these line ratios are already widely used for density and temperature diagnostics of coronal (collisional) plasmas. In the case of totally and partially photoionized plasmas, He-like line ratios allow for the determination of the ionization processes ...
متن کاملThe helium singlet-to-triplet line ratio in solar prominences
The emissions of the He singlet line at 6678Å and the He triplet line at 4471Å are simultaneously observed in three solar prominences. For two of them, the line pairs HeD3/Hβ andCa8662/Hβ were also observed. Comparisonswith model calculations show that the emission line ratios require low densities (nH ≈ 3 · 1010cm−3), low gas pressures (Pg ≈ 0.02 dyn/cm2), and large physical slab widths. The r...
متن کاملDensity of Superfluid Helium Droplets
The classical integral cross sections of large superfluid 4He N droplets and the number of atoms in the droplets (N = 103 − 104) have been measured in molecular beam scattering experiments. These measurements are found to be in good agreement with the cross sections predicted from density functional calculations of the radial density distributions with a 10–90% surface thickness of 5.7Å. By usi...
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ژورنال
عنوان ژورنال: Astronomy & Astrophysics
سال: 2001
ISSN: 0004-6361,1432-0746
DOI: 10.1051/0004-6361:20000419