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The first stellar age map of the Milky Way and beyond

Melissa Ness

The mass of a star is arguably its most fundamental parameter and for red giant stars it implies a stellar evolution age. Stellar masses and ages have never been derived directly from spectra of red giants. However, using the APOGEE Kepler sample of stars (the APOKASC sample), with high-quality spectra and asteroseismic masses, we have built a data-driven spectral model using THE CANNON (arXiv:1501.07604), to infer stellar age from spectra. THE CANNON constrains the ages from spectral regions with elements whose surface abundances reflect mass dependent dredge-up. We deliver a catalogue of ages for 75,000 red giants, which span the Milky Way disk, from the Galactic centre out to 20kpc. I will demonstrate the new avenues we are pursuing in Galactic archeology with these ages, and beyond.