Discovery of magellanic stellar debris in the H3 survey

Dennis Zaritsky, Charlie Conroy, Rohan P. Naidu, Phillip A. Cargile, Mary Putman, Gurtina Besla, Ana Bonaca, Nelson Caldwell, Jiwon Jesse Han, Benjamin D. Johnson, Joshua S. Speagle, Yuan Sen Ting

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


We report the discovery of 15 stars in the H3 survey that lie, in projection, near the tip of the trailing gaseous Magellanic Stream (MS). The stars have Galactocentric velocities <−155 km s−1, Galactocentric distances of ≈40 to 80 kpc (increasing along the MS), and [Fe/H] consistent with that of stars in the Small Magellanic Cloud. These 15 stars comprise 94% (15 of 16) of the H3 observed stars to date that have RGAL > 37.5 kpc, −350 km s−1 < VGSR < −155 km s−1, and are not associated with the Sagittarius Stream. They represent a unique portion of the Milky Way's outer halo phase space distribution function and confirm that unrelaxed structure is detectable even at radii where H3 includes only a few hundred stars. Due to their statistical excess, their close association with the MS and HI compact clouds in the same region, both in position and velocity space, and their plausible correspondence with tidal debris in a published simulation, we identify these stars as debris of past Magellanic Cloud encounters. These stars are evidence for a stellar component of the tidal debris field far from the Clouds themselves and provide unique constraints on the interaction.

Original languageEnglish (US)
Article numberabcb83
JournalAstrophysical Journal Letters
Issue number1
StatePublished - Dec 10 2020

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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