English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The existence of a vertical age gradient in the Milky Way disc has beenindirectly known for long. Here, we measure it directly for the first time withseismic ages, using red giants observed by Kepler. We use Stroemgren photometryto gauge the selection function of asteroseismic targets, and derive colour andmagnitude limits where giants with measured oscillations are representative ofthe underlying population in the field. Limits in the 2MASS system are alsoderived. We lay out a method to assess and correct for target selection effectsindependent of Galaxy models. We find that low mass, i.e. old red giantsdominate at increasing Galactic heights, whereas closer to the Galactic planethey exhibit a wide range of ages and metallicities. Parametrizing this as avertical gradient returns approximately 4 Gyr/kpc for the disc we probe,although with a large dispersion of ages at all heights. The ages of stars showa smooth distribution over the last 10 Gyr, consistent with a mostly quiescentevolution for the Milky Way disc since a redshift of about 2. We also find aflat age-metallicity relation for disc stars. Finally, we show how to usesecondary clump stars to estimate the present-day intrinsic metallicity spread,and suggest using their number count as a new proxy for tracing the ageing ofthe disc. This work highlights the power of asteroseismology for Galacticstudies; however, we also emphasize the need for better constraints on stellarmass-loss, which is a major source of systematic age uncertainties in red giantstars.

Measuring the vertical age structure of the Galactic disc using asteroseismology and SAGA