Hydrogen Lines in DA White Dwarfs: Improved Stark Broadening

There is presented an overview of the latest advances in the analytical theory of Stark broadening of hydrogenic spectral lines in various types of laboratory and astrophysical plasmas. They include: (1) advanced analytical treatment of the Stark broadening of hydrogenic spectral lines by plasma electrons; (2) center-of-mass effects for hydrogen atoms in a nonuniform electric field: applications to magnetic fusion, radiofrequency discharges, and flare stars; (3) penetrating-ions-caused shift of hydrogenic spectral lines in plasmas; (4) improvement of the method for measuring the electron density based on the asymmetry of hydrogenic spectral lines in dense plasmas; (5) Lorentz–Doppler broadening of hydrogen/deuterium spectral lines: analytical solution for any angle of observation and any magnetic field strength, and its applications to magnetic fusion and solar physics; (6) Revision of the Inglis-Teller diagnostic method; (7) Stark broadening of hydrogen/deuterium spectral lines by a relativistic electron beam: analytical results and applications to magnetic fusion; (8) Influence of magnetic-field-caused modifications of the trajectories of plasma electrons on shifts and relative intensities of Zeeman components of hydrogen/deuterium spectral lines: applications to magnetic fusion and white dwarfs; (9) Influence of magnetic-field-caused modifications of trajectories of plasma electrons on the width of hydrogen/deuterium spectral lines: applications to white dwarfs; (10) Stark broadening of hydrogen lines in plasmas of electron densities up to or more than Ne~1020 cm−3; and, (11) The shape of spectral lines of two-electron Rydberg atoms/ions: a peculiar Stark broadening.

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Opacities in Strong Magnetic Helds

Highlights of Astronomy ◽

10.1017/s1539299600012181 ◽

1995 ◽

Vol 10 ◽

pp. 588-590

Author(s):

Dayal T. Wickramasinghe

Keyword(s):

Entire Range ◽

White Dwarfs ◽

Specific Problem ◽

Transition Probabilities ◽

Strong Field ◽

Energy Levels ◽

Dipolar Field ◽

Origin And Evolution ◽

End Products ◽

Hydrogen Lines

White dwarfs are one of the most readily studied end products of stellarevolution. Their observed properties have provided and continue to provide important constraints for the theory of stellar evolution. Likewise, a study of magnetism in white dwarfs provides unique insights into the origin and evolution of magnetic fields in stars.Spectacular progress has been made on the specific problem of the structure of the hydrogen atom in strong fields. Energy levels and transition probabilities are now known for all low lying states of hydrogen for the entire range of field strengths appropriate to white dwarfs and neutron stars (104-1013G) (Rosner et al 1984, Forster et al 1984 and Henry and O’Connell 1984). These calculations resulted in the identification of spectral features in the magnetic white dwarf Grw+70°8247 which had remained unidentified for over 50 years (Minkowski 1938), with Zeeman shifted hydrogen lines in a magnetic field of 100 -320 MG ((eg Wickamasinghe and Ferrano 1989). Several other strong field magnetic white dwarfs have since been discovered through hydrogen Zeeman spectroscopy. The data presently at hand show that most hydrogen rich magnetic white dwarfs have complex non-dipolar field structures with strong evidence for higher order multipole components.

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Stark Broadening of Hydrogen Lines in a Plasma

Physical Review ◽

10.1103/physrev.116.4 ◽

1959 ◽

Vol 116 (1) ◽

pp. 4-16 ◽

Cited By ~ 237

Author(s):

Hans R. Griem ◽

Alan C. Kolb ◽

K. Y. Shen

Keyword(s):

Stark Broadening ◽

Hydrogen Lines

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1400. Measurement of the degree of turbulence of electrostatic oscillations in collisionless plasma by Stark broadening of spectral hydrogen lines by theeh method of high-speed electron-optical spectro-chronography

Vacuum ◽

10.1016/0042-207x(74)92252-0 ◽

1974 ◽

Vol 24 (9) ◽

pp. 413

Keyword(s):

High Speed ◽

Collisionless Plasma ◽

Stark Broadening ◽

Hydrogen Lines

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Computation of Infrared Hydrogen Lines

Symposium - International Astronomical Union ◽

10.1017/s0074180900124593 ◽

1994 ◽

Vol 154 ◽

pp. 341-346 ◽

Cited By ~ 1

Author(s):

Mats Carlsson ◽

Robert J. Rutten

Keyword(s):

Solar Atmosphere ◽

Heavy Ion ◽

Stark Broadening ◽

Diagnostic Applications ◽

Hydrogen Lines

We compare infrared hydrogen lines observed with ATMOS with computations for two models of the solar atmosphere, one without and one with a chromosphere. The weaker H I lines are formed in the photosphere. Proper evaluation of Stark broadening is required to reproduce their profiles; the heavy ion contribution is most important. The cores of the stronger lines are sensitive to the structure of the chromosphere, but detailed NLTE modeling is needed for diagnostic applications.

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Hydrogen Stark Broadening by Model Electronic Microfields

Zeitschrift für Naturforschung A ◽

10.1515/zna-1977-1101 ◽

1977 ◽

Vol 32 (11) ◽

pp. 1195-1206 ◽

Cited By ~ 4

Author(s):

Joachim Seidel

Keyword(s):

Numerical Results ◽

Unified Theory ◽

Statistical Features ◽

Line Profiles ◽

Stark Broadening ◽

Wide Range ◽

Hydrogen Lines ◽

Good Agreement

Abstract The Method of Model Microfields proposed by Brissaud and Frisch is applied to calculate Stark broadened profiles of hydrogen lines in the static ion approximation. Numerical results for L-α, H-α, and H-β are found to be in good agreement with those derived from the unified theory by Vidal, Cooper, and Smith over a wide range of plasma densities and temperatures. This demon strates that reliable line profiles may be obtained from the microfield distribution and covariance alone, more complicated statistical features being less important in this context.

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