Dennis Stello

The Kepler Ultra Deep Field

Over the past decade, the Kepler mission has been revolutionising our knowledge about stars in the Galactic disk. This is because Kepler’s photometric data of unprecedented quality, can reveal tiny variations in stellar brightness caused by standing sound wave oscillations inside stars. Every half hour over 4 years, Kepler recorded images of its fixed field of view, which were downlinked to Earth. Photometric data from the images was initially produced only for the 200,000 mission targets, mostly bright near-by disk stars. This left all non-targeted stars in the images unutilized. Crucially though, NASA created in late 2023 the photometric data for all 400,000 non-target stars that were serendipitously observed; with the same quality as the original targets. These new ‘Kepler-Bonus’ data are dominated by much fainter – hence more distant – stars. In this presentation I will show that the data will give us detections to measure oscillations in red giant stars out to hundreds of kilo parsec – essentially to the ‘edge’ of the Galaxy – making this the only data in the foreseeable future to investigate the most pristine part of the Galaxy with such high fidelity.