Engineering topics

Seaton, M. J.

Publications and source records attributed to Seaton, M. J..

3 records

NASA NTRS1982

Ultraviolet observations of nova Aquila, 1982

A bright nova in Aquila was discovered with a visual magnitude of 6 to 7. A number LWR and SWP spectra of the object were obtained with the IUE. The nova has a heavily reddened spectrum, E(B-V)= 0.55 + or - 0.15, and a complex shot wavelength spectrum with both narrow emission features and broad absorption troughs, indicating terminal velocities as high as 10,000 km/s. Both the continuum flux and the absorption line profiles changed between two observations. Short period variations were also observed.

Snijders, M. A. J.↗

NASA NTRS1978

IUE observations of the interstellar medium

Results from a preliminary study of interstellar absorption lines in the spectra of the three stars HD149757, HD93521 and HD153919, observed by the IUE during its commissioning phase are presented. They demonstrate the capabilities of the IUE for interstellar research. Results from a preliminary study of the emission line spectrum of the planetary nebula NGC 7027 are outlined and used to study its interstellar reddening.

Grewing, M.↗

NASA NTRS1977

Some O I oscillator strengths and the interstellar abundance of oxygen

Calculated and experimental oscillator strengths for the O I intersystem line at 1356 A and for other O I lines of interest in interstellar absorption-line studies are discussed. Attention is given to experimental f-values for the lines at 1302, 1305, and 1306 A, previous work on the f-values for the lines at 1356 and 1359 A, wave-function expansion, and calculations for permitted as well as intercombination lines. Copernicus observations of several interstellar absorption lines due to O I, C II, P II, and Ni II toward Zeta Oph are reported, equivalent widths are determined, and a curve-of-growth analysis is performed for the O I absorption lines. Oscillator strengths are recommended for the far-UV resonance lines of O I, and it is concluded that the oxygen in the interstellar H I regions toward Zeta Oph is depleted by 45% to 69%.

Zeippen, C. J.↗