Periodic Intensity Fluctuations of Balmer Lines from Single-Foil Excited Fast Hydrogen Atoms

1969 ◽  
Vol 184 (1) ◽  
pp. 56-63 ◽  
Author(s):  
I. A. Sellin ◽  
C. D. Moak ◽  
P. M. Griffin ◽  
J. A. Biggerstaff
Keyword(s):  
Hydrogen Atoms ◽  
Periodic Intensity ◽  
Balmer Lines ◽  
Intensity Fluctuations

Periodic Intensity Fluctuations in Pulsars

Nature ◽  
1969 ◽  
Vol 223 (5208) ◽  
pp. 797-799 ◽  
Author(s):  
J. H. TAYLOR ◽  
M. JURA ◽  
G. R. HUGUENIN
Keyword(s):  
Periodic Intensity ◽  
Intensity Fluctuations

Periodic intensity fluctuations in spatiotemporal mode-locked lasers

2021 ◽  
Author(s):  
Yihang Ding ◽  
Xiaosheng Xiao ◽  
Shuzheng Fan ◽  
Changxi Yang
Keyword(s):  
Periodic Intensity ◽  
Intensity Fluctuations ◽  
Mode Locked Lasers

scholarly journals Emission of Fast Hydrogen Atoms in a Low Density Gas Discharge—The Most “Natural” Mirror Laboratory

Atoms ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 81
Author(s):  
Oleksandr Marchuk ◽  
Sven Dickheuer ◽  
Stephan Ertmer ◽  
Yuri Krasikov ◽  
Philippe Mertens ◽  
...  
Keyword(s):  
Experimental Data ◽  
Cross Sections ◽  
Ground State ◽  
Low Density ◽  
Hydrogen Atoms ◽  
Time Resolved ◽  
Line Shapes ◽  
Strong Signal ◽  
Balmer Lines ◽  
The Doppler Effect

In this work, we present a new application for the line shapes of emission induced by reflected hydrogen atoms. Optical properties of the solids in contact with the plasma could be effectively measured at the wavelength of Balmer lines: time-resolved measurements of reflectance and polarization properties of mirrors are performed using the wavelength separation of the direct and reflected signals. One uses the Doppler effect of emission of atoms excited by collisions with noble gases, primarily with Ar or with Kr. In spite of a new application of line shapes, the question of the source of the strong signal in the case of Ar exists: the emission observed in the case of the excitation of H or D atoms by Ar exceeds the signal induced by collisions with Kr atoms by a factor of five, and the only available experimental data for the ground state excitation show practically equal cross-sections for both gases in the energy range of 80–200 eV.

scholarly journals Radiative transfer of hydrogen lines from supernova remnant shock waves: contributions of 2s-state hydrogen atoms

2019 ◽  
Vol 485 (4) ◽  
pp. 5453-5467 ◽  
Author(s):  
Jiro Shimoda ◽  
J Martin Laming
Keyword(s):  
Radiative Transfer ◽  
Shock Waves ◽  
Supernova Remnant ◽  
Line Emission ◽  
Balmer Line ◽  
Hydrogen Atoms ◽  
Ionization Degree ◽  
Balmer Lines ◽  
The Difference ◽  
Hydrogen Lines

Abstract Radiative transfer in hydrogen lines in supernova remnant (SNR) shock waves is studied taking into account the population of the hydrogen atom 2s-state. Measurements of Balmer line emission, especially of H α, are often relied on to derive physical conditions in the SNR shock. On the other hand, Lyman series photons, especially Ly β, are mostly absorbed by upstream hydrogen atoms. As a result, atoms are excited to the 3p state, and then emit H α by the spontaneous transition from 3p to 2s. Thus, the nature of H α depends on how many Ly β photons are converted to H α photons. Moreover, the Balmer lines can be scattered by the 2s-state hydrogen atoms, which are excited not only by collisional excitation but also by the Lyman–Balmer conversion. It is shown for example that the H α photons are scattered if the shock propagates into an H i cloud with a density of ∼30 cm−3 and a size of ∼1 pc. We find that the line profile of H α becomes asymmetric resulting from the difference between line centre frequencies among the transitions from 3s to 2p, from 3p to 2s, and from 3d to 2p. We also find that the broad-to-narrow ratio of H α, which is often used to estimate the ion-electron temperature equilibrium, varies at most ≃ 10 per cent depending on the ionization degree of the upstream medium because of incomplete conversion of Lyman lines to Balmer lines.

scholarly journals Detection of the hydrogen Balmer lines in the ultra-hot Jupiter WASP-33b

2020 ◽  
Vol 645 ◽  
pp. A22
Author(s):  
F. Yan ◽  
A. Wyttenbach ◽  
N. Casasayas-Barris ◽  
A. Reiners ◽  
E. Pallé ◽  
...  
Keyword(s):  
Mass Loss ◽  
Transmission Spectrum ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Thermal Dissociation ◽  
Neutral Hydrogen ◽  
High Mass ◽  
Hydrogen Atoms ◽  
Near Ultraviolet ◽  
Balmer Lines

Ultra-hot Jupiters (UHJs) are highly irradiated giant exoplanets with extremely high day-side temperatures, which lead to thermal dissociation of most molecular species. It is expected that the neutral hydrogen atom is one of the main species in the upper atmospheres of UHJs. Neutral hydrogen has been detected in several UHJs by observing their Balmer line absorption. In this work, we report four transit observations of the UHJ WASP-33b, performed with the CARMENES and HARPS-North spectrographs, and the detection of the Hα, Hβ, and Hγ lines in the planetary transmission spectrum. The combined Hα transmission spectrum of the four transits has an absorption depth of 0.99 ± 0.05%, which corresponds to an effective radius of 1.31 ± 0.01 Rp. The strong Hα absorption indicates that the line probes the high-altitude thermosphere. We further fitted the three Balmer lines using the PAWN model, assuming that the atmosphere is hydrodynamic and in local thermodynamic equilibrium. We retrieved a thermosphere temperature 12 200−1000+1300 K and a mass-loss rate Ṁ = 1011.8−0.5+0.6 g s−1. The retrieved high mass-loss rate is compatible with the “Balmer-driven” atmospheric escape scenario, in which the stellar Balmer continua radiation in the near-ultraviolet is substantially absorbed by excited hydrogen atoms in the planetary thermosphere.

Remarks on the diffuse interstellar lines

1967 ◽  
Vol 31 ◽  
pp. 91-93 ◽  
Author(s):  
G. Herzberg
Keyword(s):  
Hydrogen Atoms ◽  
Interstellar Gas

It is suggested that the diffuse interstellar lines are produced in the interstellar gas by molecules consisting of a few hydrogen atoms and one other atom, such as CH4+ or NH4. Diffuseness of the lines is assumed to result from predissociation of these molecules.

Periodic Variations in the Coronal Green Line Intensity and their Connection with the White-light Coronal Structures

2000 ◽  
Vol 179 ◽  
pp. 197-200
Author(s):  
Milan Minarovjech ◽  
Milan Rybanský ◽  
Vojtech Rušin
Keyword(s):  
Time Resolution ◽  
White Light ◽  
Short Time Scale ◽  
High Time Resolution ◽  
Green Line ◽  
Periodic Intensity ◽  
Coronal Green Line ◽  
Significant Intensity ◽  
Short Time ◽  
Coronal Structures

AbstractWe present an analysis of short time-scale intensity variations in the coronal green line as obtained with high time resolution observations. The observed data can be divided into two groups. The first one shows periodic intensity variations with a period of 5 min. the second one does not show any significant intensity variations. We studied the relation between regions of coronal intensity oscillations and the shape of white-light coronal structures. We found that the coronal green-line oscillations occur mainly in regions where open white-light coronal structures are located.

Polarimetric Observations of Red Variables: A Study of Gas and Particle Interactions

1979 ◽  
Vol 46 ◽  
pp. 386-408 ◽  
Author(s):  
G. V. Coyne ◽  
I. S. McLean
Keyword(s):  
Wavelength Dependence ◽  
Stellar Atmosphere ◽  
Molecular Absorption ◽  
Absorption Bands ◽  
Absorption And Emission ◽  
Mira Variables ◽  
Stellar Photosphere ◽  
Regular Variable ◽  
Red Supergiants ◽  
Balmer Lines

AbstractIn recent years the wavelength, dependence of the polarization in a number of Mira variables, semi-regular variables and red supergiants has been measured with resolutions between 0.3 and 300 A over the range 3300 to 11000 A. Variations are seen across molecular absorption bands, especially TiO bands, and across atomic absorption and emission lines, especially the Balmer lines. In most cases one can ignore or it is possible to eliminate the effects due to interstellar polarization, so that one can study the polarization mechanisms operating in the stellar atmosphere and environment. The stars Omicron Ceti. (Mira), V CVn (semi-regular variable) and Mu Cephei (M2 la), in addition to other stars similar to them, will be discussed in some detail.Models to explain the observed polarization consider that the continuum flux is polarized either by electron, molecular and/or grain scattering or by temperature variations and/or geometrical asymmetries over the stellar photosphere. This polarized radiation is affected by atomic and molecular absorption and emission processes at various geometric depths in the stellar atmosphere and envelope. High resolution spectropolarimetry promises, therefore, to be a power-rul tool for studying stratification effects in these stars.

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