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

published in Astronomy & Astrophysics, 670, pp. A10 (13pp) (2023)

Abstract: 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 DR3, we present evidence of a new resonance-like feature in the outer disc of the MilkyWay. 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.

Keyword(s): Galaxy: kinematics and dynamics ; Galaxy: structure ; Galaxy: disc ; Stars: variables: Cepheids
DOI: 10.1051/0004-6361/202244605
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