Common origin for Hercules-Aquila and Virgo Clouds in Gaia DR2

Iulia T. Simion, Vasily Belokurov, Sergey E. Koposov

Research output: Contribution to journalArticlepeer-review

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 languageEnglish
JournalMonthly Notices of the Royal Astronomical Society
Early online date9 Oct 2018
DOIs
Publication statusPublished - 1 Jan 2019

Keywords / Materials (for Non-textual outputs)

  • astro-ph.GA

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