The Galactic Continuum Spurs and Neutral Hydrogen

So far no association has been found between the features of the galactic continuum radiation known as the spurs and the distribution of neutral hydrogen. McGee, Murray and Milton 1 give contour maps of the peak brightness temperature of profiles of low velocity neutral hydrogen, and if the position of the steep outer gradient of the continuum radiation from the North Polar Spur, obtained from the best data at present available 2–4 , is plotted on these maps (Fig. 1), a correlation is immediately apparent. The line of outer gradient coincides with a spur feature in the neutral hydrogen distribution. Also plotted on Fig. 1 is the outer gradient of the continuum ridge at +10° declination, taken from ref. 4. The ridges P and U from ref. 5 are included up to the limit of that survey at R.A. = 16 h. All these ridges are in close coincidence with similar hydrogen features. A section through the neutral hydrogen and continuum distributions for the North Polar Spur edge at b II = +45° is shown in Fig. 2.