Semczuk, Marcin;
Dehnen, Walter;
Schönrich, Ralph;
Athanassoula, E;
(2023)
Spiral arms and the angular momentum gap in Milky Way Cepheids.
Monthly Notices of the Royal Astronomical Society
, 519
(1)
pp. 902-908.
10.1093/mnras/stac3528.
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Abstract
The angular-momentum distribution of classical Cepheids in the outer Milky Way disc is bi-modal with a gap at Lgap = 2950 km s−1kpc, corresponding to R = 13 kpc, while no similar feature has been found in the general population of disc stars. We show that star formation in multiple spiral arm segments at the same azimuth leads to such multi-modality which quickly dissolves and only shows in young stars. Unlike other explanations, such as a 1:1 orbital resonance with the Galactic bar, this also accounts for the observed steepening of the stellar warp at Lgap, since the adjacent spiral arms represent different parts of the warped gas disc, and for the predominance of the gap at negative Galactic longitude (ℓ < 0○), since for complex spiral structure this mechanism is limited in azimuth. In this scenario the gap is clearly present only in young stars, as observed, while most purely stellar dynamical origins would affect all disc populations, including older disc stars.
Type: | Article |
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Title: | Spiral arms and the angular momentum gap in Milky Way Cepheids |
Open access status: | An open access version is available from UCL Discovery |
DOI: | 10.1093/mnras/stac3528 |
Publisher version: | https://doi.org/10.1093/mnras/stac3528 |
Language: | English |
Additional information: | © The Author(s) 2022. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. |
Keywords: | Galaxy: kinematics and dynamics, Galaxy: structure, Galaxy: disc, galaxies: spiral, stars: variables: Cepheids |
UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics |
URI: | https://discovery.ucl.ac.uk/id/eprint/10162135 |
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