The Association of Gas and Dust from 21-CM Hydrogen Radio Observations.

Dust clouds in Taurus, Orion, and Perseus have been observed by means of the 21-cm hyperfine emission line of interstellar hydrogen. Dust clouds at intermediate galactic latitudes are strong 21-cm emitters when compared to adjacent, less dusty regions. Coincident values of gas and dust optical depths show a good correlation for these clouds. Assuming similar distributions in distance for the gas and dust, a determination follows for the average interstellar spatial density ratio of gas to dust. The individual observed values of the gas-to-dust density ratio range from 250 and have a mean value of 100. A minimum mass of 21,000 Mo is obtained for the H I the dust complex. The results indicate the dust content to be approximately 200 Mo, 1 per cent of the gas content. The gas and dust data, when compared with stellar-distribution data, suggest similar distributions of gas, dust, and stars in the anticenter.