Zobrazeno 1 - 10
of 108
pro vyhledávání: '"Allard, N. F."'
We report on our new calculations of unified line profiles of K perturbed by He using ab initio potential data for the conditions prevailing in cool substellar brown dwarfs and hot dense planetary atmospheres with temperatures from $T_\mathrm{eff}$=5
Externí odkaz:
http://arxiv.org/abs/2403.03059
Publikováno v:
A&A 674, A171 (2023)
Ultracool stellar atmospheres show absorption by alkali resonance lines severely broadened by collisions with neutral perturbers. In the coolest and densest atmospheres, such as those of T dwarfs, Na I and K I broadened by molecular hydrogen and heli
Externí odkaz:
http://arxiv.org/abs/2305.06079
In this paper we emphasize the non-Lorentzian behavior of the Balmer series in helium-dominated DBA white dwarf stars for which the decades-old problem exists for the determination of the hydrogen abundance. In a very recent work, we have shown that
Externí odkaz:
http://arxiv.org/abs/2201.03294
In order to investigate the near wing of the Lyman-alpha line, accurate line profile calculations and molecular data are both required due to the existence of a close line satellite responsible for its asymmetrical shape. Lyman-alpha lines observed w
Externí odkaz:
http://arxiv.org/abs/2201.00878
Spectral observations below Lyman-alpha are now obtained with the Cosmic Origin Spectrograph (COS) on the Hubble Space Telescope (HST). It is therefore necessary to provide an accurate treatment of the blue wing of the Lyman-alpha line that enables c
Externí odkaz:
http://arxiv.org/abs/2106.00766
The opacity of alkali atoms, most importantly of Na and K, plays a crucial role in the atmospheres of brown dwarfs and exoplanets. We present a comprehensive study of NaH2 collisional profiles at temperatures from 500 to 3000 K, the temperatures prev
Externí odkaz:
http://arxiv.org/abs/1908.01989
We present a homogeneous analysis of 1023 DBZ/DZ(A) and 319 DQ white dwarf stars taken from the Montreal White Dwarf Database. This represents a significant increase over the previous comprehensive studies on these types of objects. We use new trigon
Externí odkaz:
http://arxiv.org/abs/1907.05932
Metal-polluted white dwarfs (DZ stars) are characterized by a helium-rich atmosphere contaminated by heavy elements traces originating from accreted rocky planetesimals. As a detailed spectroscopic analysis of those objects can reveal the composition
Externí odkaz:
http://arxiv.org/abs/1903.08503
WD J2356$-$209 is a cool metal-polluted white dwarf whose visible spectrum is dominated by a strong and broad sodium feature. Although discovered nearly two decades ago, no detailed and realistic analysis of this star had yet been realized. In the ab
Externí odkaz:
http://arxiv.org/abs/1902.03219
Autor:
Allard, N. F., Kielkopf, J. F., Blouin, S., Dufour, P., Gadéa, F. X., Leininger, T., Guillon, G.
Publikováno v:
A&A 619, A152 (2018)
Line shapes of the magnesium resonance lines in white dwarf spectra are determined by the properties of magnesium atoms and the structure of the white dwarf atmosphere. Through their blanketing effect, these lines have a dominant influence on the mod
Externí odkaz:
http://arxiv.org/abs/1809.04531