Abstract / Description of output
We use a sample of ∼350 RR Lyrae stars with radial velocities and Gaia Data Release 2 proper motions to study orbital properties of the Hercules-Aquila Cloud (HAC) and Virgo Over-density (VOD). We demonstrate that both structures are dominated by stars on highly eccentric orbits, with pericentres around ∼1 kpc and apocentres at 15–25 kpc from the Galactic Centre. Given that the stars in the HAC and the VOD occupy very similar regions in the space spanned by integrals of motion, we conclude that these diffuse debris clouds are part of the same accretion event. More precisely, they likely represent two complementary not-fully mixed portions of an ancient massive merger, which has reshaped our Galaxy.
Original language | English |
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Journal | Monthly Notices of the Royal Astronomical Society |
Early online date | 9 Oct 2018 |
DOIs | |
Publication status | Published - 1 Jan 2019 |
Keywords / Materials (for Non-textual outputs)
- astro-ph.GA