RADIO MEASUREMENTS OF PLANETARY NEBULAE,
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.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1967
- Accession Number
- AD0663168
Entities
People
- A. R. Thompson
Organizations
- California Institute of Technology