Paper

A new resonance-like feature in the outer disc of the Milky Way

Khanna, Shourya, Drimmel, Ronald, Bland-Hawthorn, Joss, Muraveva, Tatiana, Lobel, Alex, Castro-Ginard, Alfred, Blomme, Ronny, Ramos, Pau, Poggio, Eloisa, Frémat, Yves, Marshall, Douglas, Ripepi, Vincenzo, Andrae, Rene, Tepper-García, Thorsten, Romero-Gómez, Mercé, Chemin, Laurent, Cantat-Gaudin, Tristan, Fiqueras, Francesca, Clementini, Gisella, D'Onghia, Elena, Morgan Fouesneau

2023

Overview

Modern astrometric and spectroscopic surveys have revealed a wealth of structure in the phase space of stars in the Milky Way, with evidence of resonance features and non-equilibrium processes. Using Gaia's third data release, we present evidence of a new resonance-like feature in the outer disc of the Milky Way. The feature is most evident in the angular momentum distribution of the young Classical Cepheids, a population for which we can derive accurate distances over much of the Galactic disc. We then search for similar features in the outer disc using a much larger sample of red giant stars, as well as a compiled list of over 31 million stars with spectroscopic line-of-sight velocity measurements. While much less evident in these two older samples, the distribution of stars in action-configuration space suggests that resonance features are present here as well. The position of the feature in action-configuration space suggests that the new feature may be related to the Galactic bar, but other possibilities are discussed.

• Publisher: Cornell University Library, arXiv.org
• Subject: Angular momentum / Cepheid variables / Configurations / Red giant stars / Resonance