Engineering topics

Stevens, J. C.

Publications and source records attributed to Stevens, J. C..

3 records

NASA NTRS1973

X-ray spectrum of the entire Cygnus Loop.

The spectrum of the entire Cygnus Loop has been obtained using gas-filled proportional counters and filters flown on a Nike-Aerobee rocket. The results indicate an average spectral temperature of (2.8 plus or minus 0.2) x 1,000,000 K and the presence of excess emission in the energy range from 0.530 to 0.693 keV. If the excess emission originates in a single line at 0.658 keV, the intensity at the earth corresponds to 1.8 plus or minus 0.7 photons per sq cm per sec, or about 10% of the total energy received from the Loop. The spectrum of the entire Loop is found to be attenuated by an average of (4.8 plus or minus 0.2) x 10 to the 20th hydrogen atoms per sq cm.

Stevens, J. C.↗

NASA NTRS1973

The X-ray surface brightness of the Cygnus Loop.

The surface brightness of the Cygnus Loop in X rays was obtained on a scale of 0.25 sq deg. The X-ray emission shows strong limb brightening, implying a shell-like source structure. The shell exhibits several regions of enhanced emission. X-ray emission which was observed from a region near the center of the Loop may be from a remnant object. The correlation between X-ray and optical emission is not as good as the correlation between radio and optical emission.

Stevens, J. C.↗

NASA NTRS1972

Soft X-rays from Cygnus X-2 and from Cygnus X-1 /in eclipse/.

Observations of Cygnus X-1 (probably in eclipse) and Cygnus X-2 on Oct. 23, 1971, show quite low absorption in their spectrum, and yet they are thought to be in a double or multiple star system from the optical data. The lack of intrinsic absorption in their spectra may be taken to mean that they lie sufficiently far from their primaries for a reduction to virtually zero of their interaction with the atmosphere of the primaries.

Stevens, J. C.↗