chronographic (age) map tagged posts

Age structure of the Milky Way’s halo

Using colors to identify the approximate ages of >130,000 stars in the Milky Way’s halo, Notre Dame astronomers have produced the clearest picture yet of how the galaxy formed more than 13.5 billion years ago. The chronographic (age) map supports a hierarchical model of galaxy formation. That model, developed by theoreticians over the past few decades, suggests that the Milky Way formed by merging and accretion of small mini-halos containing stars and gas, and that the oldest of the Milky Way’s stars are at the center of the galaxy and younger stars and galaxies merged with the Milky Way, drawn in by gravity over billions of years...