THE STRUCTURE OF A SHOCK FRONT IN ATOMIC HYDROGEN. I. THE EFFECTS OF PRECURSOR RADIATION IN THE LYMAN CONTINUUM

Journal Article · Mon Jul 01 04:00:00 EDT 1963 · Astrophysical Journal (U.S.)

DOI:https://doi.org/10.1086/147627· OSTI ID:4659790

Whitney, C A; Skalafuris, A J

As a step toward understanding the spectra of shock waves in stellar atmospheres, the variations of temperature, density, and electron concentration in a plane steady shock are investigated, and the effects of the Lyman continuum radiation that passes through the shock front into the preshock gas is emphasized. In order to bring out the essential physical problem, a two-stream model for the radiation field is adopted and the simplifying assumptions that the cooling behind the shock takes place by radiative recombinations and that the hot region is optically thin to all continuum radiation and very thick to all significant line radiation are made. Results obtained by neglecting the effects of precursor radiation are presented and an equation giving the photon flux through the shock front in terms of shock velocity and the preshock density and ionization is derived. It is shown that electrons produced in the preshock gas by Lyman continuum radiation cannot recombine before passing through the shock front. A mathematical treatment of the preshock fiow is presented, and it is shown that the preshock gas is significantly heated and ionized by precursor radiation, that the region ahead of the shock that is perturbed by Lyman radiation is virtually unobservable except in Lyman radiation, and that the inclusion of precursor radiation significantly raises the gas temperature behind the shock. The calculations agree qualitatively with observations in predicting intense, broad Balmer lines, a weak Balmer continuum, and virtually no emission in other features. (auth)

• Research Organization: Harvard Univ., Cambridge, Mass.
• NSA Number: NSA-17-032744
• OSTI ID: 4659790
• Journal Information: Astrophysical Journal (U.S.), Journal Name: Astrophysical Journal (U.S.) Vol. Vol: 138; ISSN ASJOA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ATMOSPHERE
ATOMS
COOLING
DENSITY
ELECTRONS
EMISSION
EQUATIONS
GAS FLOW
GASES
HEAT TRANSFER
HYDROGEN
ION RECOMBINATION
IONIZATION
LYMAN LINES
NUMERICALS
PHOTONS
PHYSICS
RADIATIONS
REGENERATION
SHOCK WAVES
SPECTRA
STARS
TEMPERATURE
ULTRAVIOLET RADIATION
VARIATIONS
VELOCITY