text: Absolute magnitude is correlated with a certain properties of one of these objects in the Wilson-Bappu effect.
full_question: Absolute magnitude is correlated with a certain properties of one of these objects in the Wilson-Bappu effect. The Abbe number is determined by observing three of these objects. The splitting of the 3p energy level into states with j=3/2 and j=½ is responsible a well known pair of these entities. The namesake of these objects also names far field diffraction. D1 and D2, the sodium doublet, are an example of these objects. William Wollaston was the first person to observe these dark objects on the sun, but their namesake was the first to measure their wavelengths. For 10 points, name these absorption lines found in the Sun absorption.
first_sentence: Absolute magnitude is correlated with a certain properties of one of these objects in the Wilson-Bappu effect.