With his advisor, Walter Baade, he used Cepheid variables to show that the Andromeda galaxy was at a different distance than originally believed, leading him to revise the estimate for a certain constant.
With Loeb, this man names a test that measures the Ly-alpha forest redshifts at two different times as a probe of the universe's expansion. In a review article, this man called his field the "search for two numbers," one of which is the deceleration parameter, q. This man is the last namesake of a top-down model of galaxy formation in which a cloud collapses into a disk, named for him, Eggen, and Lynden-Bell. He showed that the color-magnitude diagram of globular clusters can be used to interpret the ages of their constituents. He's not de Vaucouleurs, but this scientist added lenticular galaxies to the (*) Hubble Tuning Fork classification scheme. With his advisor, Walter Baade, he used Cepheid variables to show that the Andromeda galaxy was at a different distance than originally believed, leading him to revise the estimate for a certain constant. For 10 points, name this longtime member of the Carnegie Observatory, an American astrophysicist who revised the measurement of Hubble's constant to around 75 kilometers per second per megaparsec.
With Loeb, this man names a test that measures the Ly-alpha forest redshifts at two different times as a probe of the universe's expansion.
Allan Sandage