The Magellanic Puzzle: origin of the periphery

Abstract

In this paper, we analyse the metallicity structure of the Magellanic Clouds using parameters derived from the Gaia DR3 low-resolution XP spectra, astrometry and photometry. We find that the qualitative behavior of the radial metallicity gradients in the LMC and SMC are quite similar, with both of them having a metallicity plateau at intermediate radii and a second at larger radii. The LMC has a first metallicity plateau at [Fe/H]$\approx$-0.8 for 3$-$7${}^{\circ }$, while the SMC has one at [Fe/H]$\approx$-1.1 at 3$-$5${}^{\circ }$. The outer LMC periphery has a fairly constant metallicity of [Fe/H]$\approx$-1.0 (10$-$18${}^{\circ }$), while the outer SMC periphery has a value of [Fe/H]$\approx$-1.3 (6$-$10${}^{\circ }$). The sharp drop in metallicity in the LMC at $\sim$8${}^{\circ }$ and the marked difference in age distributions in these two regions suggests that there were two important evolutionary phases in the LMC. In addition, we find that the Magellanic periphery substructures, likely Magellanic debris, are mostly dominated by LMC material stripped off in old interactions with the SMC. This presents a new picture in contrast with the popular belief that the debris around the Clouds had been mostly stripped off from the SMC due to having a lower mass. We perform a detailed analysis for each known substructure and identify its potential origin based on metallicities and motions with respect to each galaxy.

11 pages, 7 figures. Accepted to MNRAS for publication. Comments welcome!

References in corpus (54)

• XGBoost: A Scalable Tree Boosting System
• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• The Gaia mission
• Correcting for the Effects of Interstellar Extinction
• Radial Mixing in Galactic Discs
• The Dark Energy Survey: more than dark energy - an overview
• Gaia Early Data Release 3: Photometric content and validation
• A distance to the Large Magellanic Cloud that is precise to one per cent
• Chemical Cartography with APOGEE: Metallicity Distribution Functions and the Chemical Structure of the Milky Way Disk
• The GALAH+ Survey: Third Data Release
• New Understanding of Large Magellanic Cloud Structure, Dynamics and Orbit from Carbon Star Kinematics
• Are the Magellanic Clouds on their First Passage about the Milky Way?
• The Dark Energy Survey Data Release 1
• The Star Formation History of the Large Magellanic Cloud
• The Role of Dwarf Galaxy Interactions in Shaping the Magellanic System and Implications for Magellanic Irregulars
• The total mass of the Large Magellanic Cloud from its perturbation on the Orphan stream
• The VMC Survey - I. Strategy and First Data
• The Origin of the Magellanic Stream and Its Leading Arm
• The disruption of nearby galaxies by the Milky Way
• Simulations of the Magellanic Stream in a First Infall Scenario
• The Tidal Origin of the Magellanic Stream and the Possibility of a Stellar Counterpart
• A general catalogue of extended objects in the Magellanic System
• The 200 Degree-Long Magellanic Stream System
• The Carnegie Hubble Program: The Distance and Structure of the SMC as Revealed by Mid-infrared Observations of Cepheids
• SMASH - Survey of the MAgellanic Stellar History
• The Lazy Giants: APOGEE Abundances Reveal Low Star Formation Efficiencies in the Magellanic Clouds
• Four-hundred Very Metal-Poor Stars Studied with LAMOST and Subaru. II. Elemental abundances
• The Proper Motion Field of the Small Magellanic Cloud: Kinematic Evidence for its Tidal Disruption
• SMASHing the LMC: A Tidally-induced Warp in the Outer LMC and a Large-scale Reddening Map
• A Tidally-Stripped Stellar Component of the Magellanic Bridge
• Low Surface Brightness Imaging of the Magellanic System: Imprints of Tidal Interactions between the Clouds in the Stellar Periphery
• Imprints of radial migration on the Milky Way's metallicity distribution functions
• A 10 kpc stellar substructure at the edge of the Large Magellanic Cloud: perturbed outer disk or evidence for tidal stripping?
• Spatially resolved LMC star formation history: I. Outside in evolution of the outer LMC disk
• The synchronised dance of the Magellanic Clouds' star formation history
• Substructures and tidal distortions in the Magellanic stellar periphery
• The recent LMC-SMC collision: Timing and impact parameter constraints from comparison of Gaia LMC disk kinematics and N-body simulations
• The Magellanic Corona and the formation of the Magellanic Stream
• The Origin of the Microlensing Events Observed Towards the LMC and the Stellar Counterpart of the Magellanic Stream
• On the dynamics of the Small Magellanic Cloud through high-resolution ASKAP HI observations
• Outside-in disk evolution in the LMC
• Clouds in Arms
• Exploring the Very Extended Low Surface Brightness Stellar Populations of the Large Magellanic Cloud with SMASH
• The Large Magellanic Cloud stellar content with SMASH: I. Assessing the stability of the Magellanic spiral arms
• The Second Data Release of the Survey of the MAgellanic Stellar History (SMASH)
• Stellar substructures in the periphery of the Magellanic Clouds with the VISTA Hemisphere Survey from the red clump and other tracers
• The Magellanic Edges Survey I. Description and First Results
• Discovery of a disrupting open cluster far into the Milky Way halo: a recent star formation event in the leading arm of the Magellanic stream?
• Deciphering the Kinematic Structure of the Small Magellanic Cloud through its Red Giant Population
• Discovery of Magellanic Stellar Debris in the H3 Survey
• The intrinsic reddening of the Magellanic Clouds as traced by background galaxies -- II. The Small Magellanic Cloud
• The Magellanic Edges Survey IV. Complex tidal debris in the SMC outskirts
• Kinematical Analysis of Substructure in the Southern Periphery of the Large Magellanic Cloud

Cited by in corpus (2)

• Strömgren photometric metallicity map of the Magellanic Cloud stars using Gaia DR3--XP spectra
• The orbital dynamics of the LMC and SMC about the Milky Way