LiHe spectra from brown dwarfs to helium clusters

Abstract

International audienceThe detection of Li I lines is the most decisive spectral indicator of substellarity for young brown dwarfs with masses below about 0.06 solar mass. Due to the weakness of the Li resonance lines, it is important to be able to model precisely both their core widths and their wing profiles. This allows an adequate prediction of the mass at which Li lines reappear in the spectra of brown dwarfs for a given age, or reversely an accurate determination of the age of a cluster. We report improved line profiles and the dependence of line width on temperature suitable for modeling substellar atmospheres that were determined from new LiHe molecular potential energies. Over a limited range of density and temperature, comparison with laboratory measurements was used to validate the potential energies which support the spectral line profile theory

Theoretical profiles of the Mg+resonance lines perturbed by collisions with He

“…Also, the Russel-Saunders spin-orbit coupling in the ion Mg + (∆ SO = 91.57 cm −1 ) is comparable to that of the Na atom (∆ SO = 17.20 cm −1 ) (Dell'Angelo et al 2012;Allard et al 2014b), but still roughly five times larger. However, we make the hypothesis that the effect of the value of the atomic Mg + spin-orbit coupling parameter ∆ SO only varies slowly when the Mg + ion and He atom approach one another.…”

A new fully quantum-mechanical method used to calculate the collisional broadening coefficients and shift coefficients of Rb D 1 lines perturbed by noble gases He and Ar

“…Meanwhile, the slight difference of potential will also lead to an obvious difference in the results, as depicted by Allard. [28] In some way, the implementation of the analytical function may be flawed because of the fitting error, which suggests us to use a better fitting model. Another error is the 013201-6 inevitable numerical noise in the phase propagation process of Eq.…”

Theoretical investigation of the pressure broadening D1 and D2 lines of cesium atoms colliding with ground-state helium atoms

“…In fact, the experimental measurement or theoretically simulation of the absorption-emission spectra must be a crucial tool for determining the physical and chemical properties of the environments of extrasolar giant planets and brown dwarfs. [10][11][12][13][14][15][16] Furthermore, the analysis of the collisionally induced spectral broadening of the D 1 and D 2 lines has played a very significant role in the conceptual design and manufacturing of several new type and efficient lasers, namely, the diode-pumped alkali lasers (DPAL), [7,[17][18][19][20] and the excimer-pumped alkali vapor lasers (XPAL), [21][22][23][24] which was proposed as an alternative to high-power diode-pumped solid-state lasers, and could be used not only for technological applications but also for very important medical application in magnetic resonance imaging.…”