Discovery of the Magellanic Stellar Stream Out to 100 Kiloparsecs

Abstract

The Magellanic Stream (MS) - an enormous ribbon of gas spanning $140^{\circ }$ of the southern sky trailing the Magellanic Clouds - has been exquisitely mapped in the five decades since its discovery. However, despite concerted efforts, no stellar counterpart to the MS has been conclusively identified. This stellar stream would reveal the distance and 6D kinematics of the MS, constraining its formation and the past orbital history of the Clouds. We have been conducting a spectroscopic survey of the most distant and luminous red giant stars in the Galactic outskirts. From this dataset, we have discovered a prominent population of 13 stars matching the extreme angular momentum of the Clouds, spanning up to $100^{\circ }$ along the MS at distances of $60-120$ kpc. Furthermore, these kinemetically-selected stars lie along a [$\alpha$/Fe]-deficient track in chemical space from $-2.5<[Fe/H]<-0.5$, consistent with their formation in the Clouds themselves. We identify these stars as high-confidence members of the Magellanic Stellar Stream. Half of these stars are metal-rich and closely follow the gaseous MS, whereas the other half are more scattered and metal-poor. We argue that the metal-rich stream is the recently-formed tidal counterpart to the MS, and speculate that the metal-poor population was thrown out of the SMC outskirts during an earlier interaction between the Clouds. The Magellanic Stellar Stream provides a strong set of constraints - distances, 6D kinematics, and birth locations - that will guide future simulations towards unveiling the detailed history of the Clouds.

arXiv comment21 pages, 12 figures. Submitted to ApJ

References in corpus (117)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• On the variation of the Initial Mass Function
• Gaia Data Release 3: Summary of the content and survey properties
• MESA Isochrones and Stellar Tracks (MIST). I: Solar-Scaled Models
• dynesty: A Dynamic Nested Sampling Package for Estimating Bayesian Posteriors and Evidences
• The observed properties of dwarf galaxies in and around the Local Group
• The Sloan Digital Sky Survey Photometric Camera
• Gaia Early Data Release 3: The astrometric solution
• A 2MASS All-Sky View of the Sagittarius Dwarf Galaxy: I. Morphology of the Sagittarius Core and Tidal Arms
• Detection of the gravitational redshift in the orbit of the star S2 near the Galactic centre massive black hole
• The Proper Motion of Sgr A*: II. The Mass of Sgr A*
• Initial Performance of the NEOWISE Reactivation Mission
• Are the Magellanic Clouds on their First Passage about the Milky Way?
• Third-Epoch Magellanic Cloud Proper Motions I: HST/WFC3 data and Orbit Implications
• The Star Formation History of the Small Magellanic Cloud
• Streams, substructures and the early history of the Milky Way
• The unWISE Catalog: Two Billion Infrared Sources from Five Years of WISE Imaging
• Evidence from the H3 Survey that the Stellar Halo is Entirely Comprised of Substructure
• 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
• N-body Simulations of the Small Magellanic Cloud and the Magellanic Stream
• The Proper Motion of the Large Magellanic Cloud using HST
• The Magellanic Stream, High-Velocity Clouds and the Sculptor Group
• Tango for three: Sagittarius, LMC, and the Milky Way
• Substructure revealed by RR Lyraes in SDSS Stripe 82
• The Origin of the Magellanic Stream and Its Leading Arm
• The disruption of nearby galaxies by the Milky Way
• Kraken reveals itself -- the merger history of the Milky Way reconstructed with the E-MOSAICS simulations
• Simulations of the Magellanic Stream in a First Infall Scenario
• The Parkes HI Survey of the Magellanic System
• The feeble giant. Discovery of a large and diffuse Milky Way dwarf galaxy in the constellation of Crater
• Chemical Evolution of the Magellanic Clouds: analytical models
• Light Curve Templates and Galactic Distribution of RR Lyrae Stars from Sloan Digital Sky Survey Stripe 82
• Gaia Data Release 3: Processing and validation of BP/RP low-resolution spectral data
• Gaia Universe Model Snapshot : A statistical analysis of the expected contents of the Gaia catalogue
• The Origin of the Magellanic Stream
• The Tidal Origin of the Magellanic Stream and the Possibility of a Stellar Counterpart
• Hunting for the Dark Matter Wake Induced by the Large Magellanic Cloud
• A MegaCam Survey of Outer Halo Satellites. III. Photometric and Structural Parameters
• The MagE Spectrograph
• Small Dwarf Galaxies Within Larger Dwarfs: Why Some Are Luminous While Most Go Dark
• Gaia Data Release 3: External calibration of BP/RP low-resolution spectroscopic data
• The Orbital Histories of Magellanic Satellites Using Gaia DR2 Proper Motions
• Multi-phase High-Velocity Clouds toward HE 0226-4110 and PG 0953+414
• The Magellanic Stream: Circumnavigating the Galaxy
• The 200 Degree-Long Magellanic Stream System
• And yet it moves: The dangers of artificially fixing the Milky Way center of mass in the presence of a massive Large Magellanic Cloud
• The gravitational and hydrodynamical interaction between the LMC and the Galaxy
• Machine-Learned Identification of RR Lyrae Stars from Sparse, Multi-band Data: the PS1 Sample
• The Global Dynamical Atlas of the Milky Way mergers: Constraints from Gaia EDR3 based orbits of globular clusters, stellar streams and satellite galaxies
• Reconstructing the Last Major Merger of the Milky Way with the H3 Survey
• The COS/UVES Absorption Survey of the Magellanic Stream. III: Ionization, Total Mass, and Inflow Rate onto the Milky Way
• Mapping the Stellar Halo with the H3 Spectroscopic Survey
• APOGEE Chemical Abundance Patterns of the Massive Milky Way Satellites
• N-body simulations of the Magellanic Stream
• The Chemical Enrichment History of the Small Magellanic Cloud and Its Gradients
• Phase-Space Distributions of Chemical Abundances in Milky Way-type Galaxy Halos
• Orbits of Massive Satellite Galaxies: I. A Close Look at the Large Magellanic Cloud and a New Orbital History for M33
• Quantifying the impact of the Large Magellanic Cloud on the structure of the Milky Way's dark matter halo using Basis Function Expansions
• The Lazy Giants: APOGEE Abundances Reveal Low Star Formation Efficiencies in the Magellanic Clouds
• Measuring the Mass of the Large Magellanic Cloud with Stellar Streams Observed by $S^5$
• All-Sky Dynamical Response of the Galactic Halo to the Large Magellanic Cloud
• Resolving the Metallicity Distribution of the Stellar Halo with the H3 Survey
• The Proper Motion Field of the Small Magellanic Cloud: Kinematic Evidence for its Tidal Disruption
• An HST/COS legacy survey of high-velocity ultraviolet absorption in the Milky Way's circumgalactic medium and the Local Group
• Timing the Early Assembly of the Milky Way with the H3 Survey
• Limit on the LMC mass from a census of its satellites
• The Magellanic Bridge: The Nearest Purely Tidal Stellar Population
• Clouds, Streams and Bridges. Redrawing the blueprint of the Magellanic System with Gaia DR1
• The Metallicity and Dust Content of HVC 287.5+22.5+240: Evidence for a Magellanic Clouds Origin
• Metal Abundances in the Magellanic Stream
• Detection of the LMC-induced sloshing of the Galactic halo
• Kinematics of Antlia 2 and Crater 2 from The Southern Stellar Stream Spectroscopic Survey (S5)
• Exploring the Origin and Fate of the Magellanic Stream with Ultraviolet and Optical Absorption
• The Magellanic Stream System: I. Ram-pressure tails and the relics of the collision between the Magellanic Clouds
• Fossil imprint of a powerful flare at the Galactic Centre along the Magellanic Stream
• Orbital Clustering Identifies the Origins of Galactic Stellar Streams
• The COS/UVES Absorption Survey of the Magellanic Stream: II. Evidence for a complex enrichment history of the Stream from the Fairall 9 sightline
• Stellar streams around the Magellanic Clouds
• The COS/UVES Absorption Survey of the Magellanic Stream: I. One-Tenth Solar Abundances along the Body of the Stream
• Constraining the orbital history of the Magellanic Clouds: A new bound scenario suggested by the tidal origin of the Magellanic Stream
• Mean age gradient and asymmetry in the star formation history of the Small Magellanic Cloud
• The effect of the LMC on the Milky Way system
• Equilibrium models of the Milky Way mass are biased high by the LMC
• The effect of the deforming dark matter haloes of the Milky Way and the Large Magellanic Cloud on the Orphan-Chenab stream
• Absolute V-band magnitudes and mass-to-light ratios of Galactic globular clusters
• MINESweeper: Spectrophotometric Modeling of Stars in the Gaia Era
• Red Giants in the Small Magellanic Cloud. II. Metallicity Gradient and Age-Metallicity Relation
• The Pisces Plume and the Magellanic Wake
• The Origin of the Microlensing Events Observed Towards the LMC and the Stellar Counterpart of the Magellanic Stream
• The Magellanic Corona and the formation of the Magellanic Stream
• The Magellanic Stream and the density of coronal gas in the Galactic halo
• Toward a Complete Understanding of the Magellanic Stream Formation
• The Mass Inflow and Outflow Rates of the Milky Way
• The detection of an older population in the Magellanic Bridge
• OGLE-ing the Magellanic System: Stellar populations in the Magellanic Bridge
• Accretion of the Magellanic system onto the Galaxy
• The MAGellanic Inter-Cloud project (MAGIC) I: Evidence for intermediate-age stellar populations in between the Magellanic Clouds
• A Genetic Approach to the History of the Magellanic Clouds
• Observations of a Magellanic Corona
• The Clustering of Orbital Poles Induced by the LMC: Hints for the Origin of Planes of Satellites
• Magellanic Mayhem: Metallicities and Motions
• The four leading arms of the Magellanic Cloud system
• Distant Echoes of the Milky Way's Last Major Merger
• Rotation of the Milky Way and the formation of the Magellanic Stream
• Spectroscopic Confirmation of the Pisces Overdensity
• 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?
• Identification of Sagittarius stream members in Angular Momentum space with Gaussian mixture techniques
• GASS High Velocity Clouds in the Region of the Magellanic Leading Arm
• Kinematics of the Magellanic Stream and Implications for its Ionization
• Spectroscopy of the Young Stellar Association Price-Whelan 1: Origin in the Magellanic Leading Arm and Constraints on the Milky Way Hot Halo
• Tidally stripped halo stars from the Large Magellanic Cloud in the Galactic North
• Discovery of Magellanic Stellar Debris in the H3 Survey
• An extended view of the Pisces Overdensity from the SCUSS survey
• They Might Be Giants: An Efficient Color-Based Selection of Red Giant Stars
• A history of the Magellanic Clouds and the European exploration of the Southern Hemisphere

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• UVIT Study of the MAgellanic Clouds (U-SMAC) II. A Far-UV catalog of the Small Magellanic Cloud: Morphology and Kinematics of young stellar population
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• A Galactic Transformation -- Understanding the SMC's Structural and Kinematic Disequilibrium
• Strömgren photometric metallicity map of the Magellanic Cloud stars using Gaia DR3--XP spectra
• Mapping the Distorted Dark Matter Distribution of the LMC-SMC System Prior to Milky Way Infall with Basis Function Expansions
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