Accession Number : AD0663168
Title : RADIO MEASUREMENTS OF PLANETARY NEBULAE,
Corporate Author : CALIFORNIA INST OF TECH PASADENA OWENS VALLEY RADIO OBSERVATORY
Personal Author(s) : Thompson,A. R.
Report Date : 1967
Pagination or Media Count : 14
Abstract : Sixty-eight planetary nebulae were investigated in a series of observations at 10 cm wavelength using the two 90-ft. diameter antennas of the Owens Valley Radio Observatory. Of these, fifty-two were found to have flux densities greater than a minimum detectable level of approximately 10 to the -27th power W/Hz m squared. To indicate cases of possible confusion in the radio observations, the measured radio position of each nebula was compared with an accurate optical position. For a number of the stronger nebulae angular widths in the east-west direction and flux densities in H beta were calculated. A comparison with optical data shows values of the H beta absorption delta log F sub H Beta, ranging from zero to approximately 2.0 for NGC 6537 and NGC 6369. A small number of nebulae show prominently the effects of self-absorption in their radio spectra. Two nebulae, NGC 6369 and NGC 6857, show absorption which is probably attributable to hydrogen clouds within the galaxy. No definite evidence of absorption at frequencies near the radial velocities of the nebulae was found, and an upper limit on the mass of neutral hydrogen in two nebulae is briefly discussed.
Descriptors : (*EXTRATERRESTRIAL RADIO WAVES, *NEBULAE), ABSORPTION, OPTICAL PROPERTIES, BRIGHTNESS, LINE SPECTRA, HYDROGEN
Subject Categories : Astrophysics
Distribution Statement : APPROVED FOR PUBLIC RELEASE