Discovery of Magellanic Stellar Debris in the H3 Survey

Abstract

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 $\approx 40$ 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 $R_{GAL}>37.5$ kpc, $-$350 km s${}^{-1}<V_{GSR}<-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 H I 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.

Accepted for publication in ApJL

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Cited by in corpus (13)

• All-Sky Dynamical Response of the Galactic Halo to the Large Magellanic Cloud
• The effect of the LMC on the Milky Way system
• The Magellanic Stream at 20 kpc: A New Orbital History for the Magellanic Clouds
• Discovery of the Magellanic Stellar Stream Out to 100 Kiloparsecs
• Distant Echoes of the Milky Way's Last Major Merger
• Tidally stripped halo stars from the Large Magellanic Cloud in the Galactic North
• All-Sky Kinematics of the Distant Halo: The Reflex Response to the LMC
• Lessons from the Magellanic System and its modeling
• The Magellanic Puzzle: origin of the periphery
• Following the tidal trail: a history of modeling the Magellanic Stream
• The Pristine Survey -- XXVII. Journey to the Galactic outskirts -- Mapping the outer halo red giant stars down to the very metal-poor end
• A Search for 3-mm Molecular Absorption Line Transitions in the Magellanic Stream
• A Tilt in the Dark Matter Halo of the Galaxy