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Publications and source records attributed to Johnson, H. M..
Observations of about 36 regions are presented as a table of flux densities in one to four frequencies, and also as maps of selected regions, or as spectral displays. Comments are also made on most of the material, especially as it relates to previously published data in various frequencies including the infrared.
Spectral data in the 0.2-1.6 keV range are presented for the extended X-ray source in the Virgo cluster. When combined with Uhuru data, the simplest function which fits the composite spectrum from 0.2 to 10 keV is one describing bremsstrahlung from an isothermal plasma at 36 million deg K. Production of the X-rays by inverse compton scattering is also considered, and models relating the X-ray source to M87 are discussed.
Available spectrometric and photometric observations of Wolf-Rayet stars by the OAO 2 spacecraft in the UV range are discussed along with radio astronomical observations of W stars with symmetrical nebulae around them. The scanned spectrum of the WN5 star HD 50896 between 1200 and 1900 A is illustrated together with the photometered spectrum of the WN6 star HD 192163 from 1330 to 3320 A. RF observations of NGC 6888 around HD 192163 are examined relative to interpretation of the properties of a WN6 star ejecting mass into a nebular shell.
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New observations of the Crab Nebula by OAO 2 stellar photometers are reported. Processed image data of the Crab give the logarithm of the integrated relative intensity per wavelength interval, corrected for sky background, and the rms error from 11 passbands in the ultraviolet range. The data are converted to logarithms of flux density per frequency interval and plotted on logarithmic scales with corrections for interstellar extinction.
The ultraviolet continuum of the star is observed and, after standard reddening corrections are applied, it is found to be hotter than a model 05 V star. The Of star and its two companions are photometered around wavelength 4640, 4686, and 4861 A. The results confirm Westerlund's (1960) absolute visual magnitude of about -6 for the Of star and confirm his rejection of NGC 6164-5 as a planetary nebula. Peculiarities of the system of nebular shells around HD 148937, of which NGC 6164-5 are the innermost, are discussed with reference to radiofrequency data. A standard extrapolation from the optical flux density of NGC 6164-5 predicts a detectable radio source but it does not appear in the relevant surveys.
Data on the UV spectrum of the Crab nebula and on UV and radio frequency observations of Wolf-Rayet stars was analyzed. A description of TT Arietis is given. It is concluded that this object must be a double star, since it does not radiate like an ordinary photosphere or a single blackbody. Details of the spectrum are given.
The ionizing light of the supernova which produced the Gum nebula is now fossilized in the still live, though failing, H II region. The main body of the nebula suggests a hollow center or shell form, with a characteristic radius of about half the distance to the outlying fragments. The edges of the main body patches are typically sharp and often bright. The structure of the Gum nebula appears to be dependent on the event of ionization and possibly on the details of heating. It is not now an unstructured ambient medium, as it may have been before the recent ionization. Several hypotheses are presented for a structured ambient medium.
Symmetrically distributed nebulae around Wolf- Rayet stars, detailing Ngc 7635 and associated star BD plus 60 deg 2522
Observations of W stars in the ultraviolet by OAO 2 and at 750 and 1400 MHz with the Green Bank telescopes are discussed. The emphasis is on the Green Bank observations of W stars with symmetric nebulae around them, their interpretation, and comparisons with other data. The implications regarding mass distribution, internal motion, flux density, ejected mass, velocity dispersion, and expanding envelopes are considered in detail.
Observations of the Crab nebula are described, which were made under the OAO 2/NASA guest-investigator program with WEP stellar photometers. The 10 foot-diameter focal plane diaphragm was ample enough to accept the 4 ft X 6 ft image. The logarithm of the integrated relative intensity per wavelength interval, corrected for sky background, and the rms error, from 11 passbands in the range 4250 to 1380 A, are given. No correction was given for polarization of light. The data were converted to logarithm of the flux density per frequency interval and plotted on scales of log nu (Hz) and of reciprocal microns with two adjustments.
Eight discrete cosmic X-ray sources observed by rocket techniques