Revealing the tidal scars of the Small Magellanic Cloud
| Autor: | Denis Erkal, Noelia E. D. Noël, Ricardo Carrera, Justin I. Read, Michele De Leo, Carme Gallart |
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| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Milky Way
FOS: Physical sciences Astrophysics Kinematics Astrophysics::Cosmology and Extragalactic Astrophysics 01 natural sciences law.invention Telescope law 0103 physical sciences Astrophysics::Solar and Stellar Astrophysics 010303 astronomy & astrophysics Spectrograph Astrophysics::Galaxy Astrophysics Physics 010308 nuclear & particles physics Astronomy and Astrophysics Astrophysics - Astrophysics of Galaxies Galaxy Statistics::Computation Red-giant branch Stars Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) Small Magellanic Cloud Astrophysics::Earth and Planetary Astrophysics |
| Popis: | Due to their close proximity, the Large and Small Magellanic Clouds (SMC/LMC) provide natural laboratories for understanding how galaxies form and evolve. With the goal of determining the structure and dynamical state of the SMC, we present new spectroscopic data for $\sim$ 3000 SMC red giant branch stars observed using the AAOmega spectrograph at the Anglo-Australian Telescope. We complement our data with further spectroscopic measurements from previous studies that used the same instrumental configuration and proper motions from the \textit{Gaia} Data Release 2 catalogue. Analysing the photometric and stellar kinematic data, we find that the SMC centre of mass presents a conspicuous offset from the velocity centre of its associated $\mbox{H\,{\sc i}}$ gas, suggesting that the SMC gas is likely to be far from dynamical equilibrium. Furthermore, we find evidence that the SMC is currently undergoing tidal disruption by the LMC within 2\,kpc of the centre of the SMC, and possibly all the way in to the very core. This is evidenced by a net outward motion of stars from the SMC centre along the direction towards the LMC and apparent tangential anisotropy at all radii. The latter is expected if the SMC is undergoing significiant tidal stripping, as we demonstrate using a suite of $N$-body simulations of the SMC/LMC system disrupting around the Milky Way. These results suggest that dynamical models for the SMC that assume a steady state will need to be revisited. Revised version submitted to MNRAS after referee report, 18 pages, 18 figures |
| Databáze: | OpenAIRE |
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