Spectrum formation in SN1987A

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:6160289

Xu, Yueming

Techniques were developed for modeling the spectra of Supernova 1987A. The theory of spectrum formation was applied to infer the interior properties of SN1987A from the observed spectra. It was assumed that the late-time emission of SN1987A was powered by the gamma rays resulting from Co-56 decay. An analytic method was developed to calculate the Comptonization of gamma rays in a gas with photoabsorptions. The spectra of gamma rays and x rays was calculated for a stratified envelope model of SN1987A by use of Monte Carlo simulations. The technique for calculating the energy degradation spectrum of the fast electrons resulting from gamma ray Comptonizations were improved. The Bethe approximation was used to estimate the fractions of the fast electron energies deposited to heat, excitations, and ionization of the envelope material, and the resultant source spectrum of the line emissions was derived. The detailed properties of the scattering and line trapping were analyzed by use of the Sobolev approximation. Hydrogen is photo-ionized from the n = 2 state, which is overpopulated because of the Lyman alpha trapping. The hydrogen recombination was calculated in the Case C approximation (optically thick Lyman and Balmer lines and no direct recombination to the n = 2 state). It was found that the line trapping and the charge transfer between hydrogen and heavy elements are important processes for the ionization equilibrium of the envelope material. The calculation showed that the heavy elements must be mixed macroscopically, not microscopically, into the hydrogen-rich envelope. The emergent spectrum at the wavelengths of ultraviolet to infrared was calculated by Monte Carlo simulations and showed how photons of wavelength less than 2000 A would split, redistributing their luminosity to the wavelength range is greater than or equal to approximately 3000 A.

• Research Organization: Colorado Univ., Boulder, CO (USA). Cooperative Inst. for Research in Environmental Sciences
• OSTI ID: 6160289
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BALMER LINES
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
COBALT 56
COBALT ISOTOPES
DATA
DAYS LIVING RADIOISOTOPES
ELECTROMAGNETIC RADIATION
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTARY PARTICLES
ELEMENTS
ENERGY SPECTRA
ERUPTIVE VARIABLE STARS
GAMMA RADIATION
HYDROGEN
INFORMATION
INTERMEDIATE MASS NUCLEI
IONIZATION
IONIZING RADIATIONS
ISOTOPES
LYMAN LINES
MASSLESS PARTICLES
MATHEMATICAL MODELS
MONTE CARLO METHOD
NONMETALS
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
PHOTONS
RADIATIONS
RADIOISOTOPES
RECOMBINATION
SPECTRA
STAR MODELS
STARS
SUPERNOVAE
THEORETICAL DATA
VARIABLE STARS
X RADIATION