For 10 points, name these phenomena in which molecules like silicon monoxide, formaldehyde, and water emit radiation with a wavelength longer than infrared light.
One type of these phenomena is described by the Boland-de Jong model, while another is found in "broken ring" structures. Taylor et al. created the standard classification of these phenomena, for which Menegozzi and Lamb developed coupled radiative transfer equations. Measurements of one type of these phenomena in galaxies like NGC 4258 currently provide the most accurate reference for calibrating the (*) cosmic distance ladder and constraining the value of the Hubble constant. Another type of these phenomena can be used to map the magnetic field distribution of the interstellar medium, because the Zeeman effect causes splitting of spectral lines in populations of hydroxyl radicals. For 10 points, name these phenomena in which molecules like silicon monoxide, formaldehyde, and water emit radiation with a wavelength longer than infrared light.
One type of these phenomena is described by the Boland-de Jong model, while another is found in "broken ring" structures.
masers [accept specific types]