# The small boxy/peanut structure of the Milky Way traced by old stars

Abstract : We analyse the positions of RR Lyrae stars in the central region of the Milky Way. In addition to the overall bar shape detected previously, we find evidence for a peanut shaped structure, in form of overdensities near ℓ = -2 and 1° at b ~ -3.5°. The corresponding physical distance between the two peaks of the peanut is $\sim 0.7\,$ kpc, significantly shorter than that found from near-IR images (3.3 kpc) and red-clump stars. Qualitatively this is expected from 'fractionation' of bar orbits, which we demonstrate to be matched in a simulation of an inside-out growing disc subsequently forming a bar.
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Journal articles

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Submitted on : Friday, May 13, 2022 - 1:55:02 PM
Last modification on : Saturday, June 25, 2022 - 3:17:12 AM

### Citation

Marcin Semczuk, Walter Dehnen, Ralph Schönrich, E. Athanassoula. The small boxy/peanut structure of the Milky Way traced by old stars. Monthly Notices of the Royal Astronomical Society, 2022, 509, pp.4532-4537. ⟨10.1093/mnras/stab3294⟩. ⟨insu-03667479⟩

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