Clouds in Arms

TL;DR

This paper uses Gaia data to map low-brightness stellar features around the Magellanic Clouds, revealing spiral-arm-like streams likely caused by tidal interactions with the SMC and the Milky Way.

Contribution

It provides the first detailed astrometric mapping of Magellanic stellar streams and demonstrates their tidal origin through computer simulations.

Findings

Identification of two thin stellar streams in the LMC

Streams resemble spiral arms

Tidal interactions with SMC and Milky Way likely caused the streams

Abstract

We use astrometry and broad-band photometry from Data Release 2 of the ESA's Gaia mission to map out low surface-brightness features in the stellar density distribution around the Large and Small Magellanic Clouds. The LMC appears to have grown two thin and long stellar streams in its Northern and Southern regions, highly reminiscent of spiral arms. We use computer simulations of the Magellanic Clouds' in-fall to demonstrate that these arms were likely pulled out of the LMC's disc due to the combined influence of the SMC's most recent fly-by and the tidal field of the Milky Way.