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Atomic Lines (atomic + line)

Distribution by Scientific Domains
Physics and Astronomy100%

Selected Abstracts

Spatio-temporal inhomogeneities of laser induced plasma on surface solutions

LASER PHYSICS LETTERS, Issue 11 2004
J. Ben Ahmed
Abstract A transient plasma created by focusing a nanosecond laser pulse on the surface of ionic solutions of Ca++ and Mg++ is studied spectroscopically. This kind of plasma has a properties which vary significantly with time and over its extended volume. The emissions of ionic and atomic line of calcium and magnesium are analyzed to get information on the electronic temperature, the electronic density and on the kinetics of the population of low atomic and ionic states: 4P1 of CaI, 5S1/2 of CaII, 3P1 of MgII and 3P1/2 of MgII. The temperature is maximal at the plasma center and it drops at the edges. The study of the term as a function of time, where r is the radial position, shows a continue decreasing with time, which implies that the inhomogeneity of the temperature develops with time. On the another side, the electronic density deceases exponentially with time and does not vary significantly with space. These measurements allow us to follow the kinetics of the transformation of calcium (magnesium) from Ca++Mg++ to Ca+(Mg+) to give at the end Ca (Mg) and to understand the behavior of self-absorption phenomena which is observed in the resonance line of CaII at t , 2000 ns to increase with time. The experimental results are simulated by a kinetics model of LTE laser induced plasma in its late relaxation period. (© 2004 by ASTRO, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]

Correlations between diffuse interstellar bands and atomic lines

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2004
G. A. Galazutdinov
ABSTRACT We present and discuss correlations between strengths of the well-known, strong interstellar atomic lines of K i and Ca ii, and four selected, strong unidentified diffuse interstellar bands (DIBs): 5780, 5797, 5850 and 6614. In order to analyse a homogeneous sample of echelle high-resolution spectra it has been chosen to use measurements from Terskol Observatory in Northern Caucasus plus a selected number of higher resolution observations performed using other instruments. We demonstrate that the strength of certain DIBs correlate well with neutral potassium lines and to a much lower degree with ionized calcium lines. This fact suggests that the degree of irradiation of a cloud with UV photons, capable to ionize interstellar atoms, plays a crucial role in the formation/maintenance of certain molecular species: possible carriers of DIBs. [source]

VLT-CRIRES: "Good Vibrations" Rotational-vibrational molecular spectroscopy in astronomy

ASTRONOMISCHE NACHRICHTEN, Issue 5 2010
H.U. Käufl
Abstract Near-Infrared high spectral and spatial resolution spectroscopy offers new and innovative observing opportunities for astronomy. The "traditional" benefits of IR-astronomy , strongly reduced extinction and availability of adaptive optics , more than offset for many applications the compared to CCD-based astronomy strongly reduced sensitivity. Especially in high resolution spectroscopy interferences by telluric lines can be minimized. Moreover for abundance studies many important atomic lines can be accessed in the NIR. A novel spectral feature available for quantitative spectroscopy are the molecular rotational-vibrational transitions which allow for fundamentally new studies of condensed objects and atmospheres. This is also an important complement to radio-astronomy, especially with ALMA, where molecules are generally only observed in the vibrational ground state. Rot-vib transitions also allow high precision abundance measurements , including isotopic ratios , fundamental to understand the thermo-nuclear processes in stars beyond the main sequence. Quantitative modeling of atmospheres has progressed such that the unambiguous interpretation of IR-spectra is now well established. In combination with adaptive optics spectro-astrometry is even more powerful and with VLT-CRIRES a spatial resolution of better than one milli-arcsecond has been demonstrated. Some highlights and recent results will be presented: our solar system, extrasolar planets, star- and planet formation, stellar evolution and the formation of galactic bulges (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]