Search results for "Forbidden mechanism"

showing 3 items of 3 documents

Measurement and interpretation of the polarization of the x-ray line emission of heliumlike Fe XXV excited by an electron beam

1996

The linear polarization of the 1s2p${\mathrm{}}^{1}$${\mathit{P}}_{1}$\ensuremath{\rightarrow}1${\mathit{s}}^{2}$${\mathrm{}}^{1}$${\mathit{S}}_{0}$ resonance line, the 1s2p${\mathrm{}}^{3}$${\mathit{P}}_{1,2}$\ensuremath{\rightarrow}1${\mathit{s}}^{2}$${\mathrm{}}^{1}$${\mathit{S}}_{0}$ intercombination lines, and the 1s2s${\mathrm{}}^{3}$${\mathit{S}}_{1}$\ensuremath{\rightarrow}1${\mathit{s}}^{2}$${\mathrm{}}^{1}$${\mathit{S}}_{0}$ forbidden line was measured in heliumlike Fe XXV excited near threshold by a monoenergetic electron beam. The measurement was carried out with a high-resolution x-ray spectrometer employing a set of two analyzing crystals that acted as polarizers by selectivel…

PhysicsNear thresholdExcited stateCathode rayX-rayAtomic physicsAstrophysicsPolarization (waves)Forbidden mechanismResonance lineX ray spectraMicrophysicsAtomic and Molecular Physics and OpticsPhysical Review A
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X-rays from accretion shocks in T Tauri stars: The case of BP Tau

2005

We present an XMM-Newton observation of the classical T Tauri star BP Tau. In the XMM-Newton RGS spectrum the O {\sc vii} triplet is clearly detected with a very weak forbidden line indicating high plasma densities and/or a high UV flux environment. At the same time concurrent UV data point to a small hot spot filling factor suggesting an accretion funnel shock as the site of the X-ray and UV emission. Together with the X-ray data on TW Hya these new observations suggest such funnels to be a general feature in classical T Tauri stars.

Physicsbusiness.product_categoryFilling factorAstrophysics::High Energy Astrophysical PhenomenaAstrophysics (astro-ph)FOS: Physical sciencesAstronomy and AstrophysicsAstrophysicsAstrophysics::Cosmology and Extragalactic AstrophysicsAstrophysicsAccretion (astrophysics)T Tauri starSpace and Planetary ScienceHigh plasmaAstrophysics::Solar and Stellar AstrophysicsFunnelAstrophysics::Earth and Planetary AstrophysicsForbidden mechanismbusinessAstrophysics::Galaxy Astrophysics
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EBIT diagnostics using X-ray spectra of highly ionized Ne

2003

We have carried out a detailed analysis of highly ionized neon spectra collected at the NIST EBIT using an NTD germanium X-ray microcalorimeter developed at the Harvard-Smithsonian Center for Astrophysics [Nucl. Instr. and Meth. A 444 (2000) 156]. Our attention was focused especially on the Ne IX He-like triplet to check electron density diagnostics through the intercombination/forbidden line ratio. We have investigated possible effects of the ion dynamics on the plasma emission line intensities, looking at the dependence of the count-rate and the charge state distribution on the electron beam energy and current. The temperature and spatial distribution of the neon ions, and hence the overl…

X-ray spectraNuclear and High Energy PhysicsElectron densityEBITChemistrySurfaces Coatings and Filmchemistry.chemical_elementFizikai tudományokSurfaces and InterfacesPlasmaIonNeonSettore FIS/05 - Astronomia E AstrofisicaTermészettudományokIonizationAstrophysical plasmaPhysics::Atomic PhysicsEmission spectrumAtomic physicsIonization of atomForbidden mechanismInstrumentationExcitation
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