The Magellanic Inter-Cloud Project (MAGIC) III: First spectroscopic evidence of a dwarf stripping a dwarf

TL;DR

This study provides the first spectroscopic evidence that stars in the Magellanic Bridge originate from the Small Magellanic Cloud, confirming a dwarf galaxy being tidally stripped by a larger dwarf galaxy.

Contribution

It offers the first spectroscopic confirmation of stars tidally stripped from the SMC, supporting models of dwarf-dwarf galaxy interactions.

Findings

Stars in the Magellanic Bridge are chemically and kinematically consistent with SMC origin.

Spectroscopic data confirms tidal stripping of the SMC by the LMC.

First direct spectroscopic evidence of a dwarf galaxy being tidally stripped by another dwarf.

Abstract

The Magellanic Bridge (MB) is a gaseous stream that links the Large (LMC) and Small (SMC) Magellanic Clouds. Current simulations suggest that the MB forms from a recent interaction between the Clouds. In this scenario, the MB should also have an associated stellar bridge formed by stars tidally stripped from the SMC by the LMC. There are several observational evidences for these stripped stars, from the presence of intermediate age populations in the MB and carbon stars, to the recent observation of an over-density of RR Lyrae stars offset from the MB. However, spectroscopic confirmation of stripped stars in the MB remains lacking. In this paper, we use medium resolution spectra to derive the radial velocities and metallicities of stars in two fields along the MB. We show from both their chemistry and kinematics that the bulk of these stars must have been tidally stripped from the SMC. This is the first spectroscopic evidence for a dwarf galaxy being tidally stripped by a larger dwarf.