Revealing the tidal scars of the Small Magellanic Cloud

Leo, M. De; Carrera, R.; Noel, Noelia E. D.; Read, Justin I.; Erkal, Denis; Gallart, Carme

doi:10.1093/mnras/staa1122

Cited by 39 publications

(14 citation statements)

References 128 publications

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“…We modelled the centre-of-mass motion of the SMC using a Bayesian approach, assuming three different positions for the centre of the galaxy that are commonly used in the literature and found the following: (μ W,H I , μ N,H I ) = (−0.800 ± 0.027, −1.195 ± 0.012) mas yr −1 for the H I centre, (μ W, optical , μ N, optical ) = (−0.743 ± 0.027, −1.233 ± 0.012) mas yr −1 for the optical centre and (μ W, Cepheid , μ N, Cepheid ) = (−0.734 ± 0.027, −1.237 ± 0.012) mas yr −1 for the Cepheid centre. Our values agree best with the recent determinations from Gaia Collaboration (2018a), Zivick et al (2018), andDe Leo et al (2020) using space-based data. We also presented spatially resolved maps of the absolute and residual PMs of likely SMC member stars and analysed the internal motions of the intermediate-age/old and young stellar populations within the SMC.…”

Section: S U M M a Ry A N D C O N C L U S I O N Ssupporting

confidence: 92%

“…Our results, for the same SMC centre, are consistent with the findings of Zivick et al (2018) and are just outside the 1σ limit of the measurements by Gaia Collaboration (2018b). Recently, De Leo et al (2020) studied in detail the kinematics within the SMC using spectroscopic data as well as PM data from Gaia DR2. The value they found for the SMC bulk motion using the position of the optical SMC centre is consistent within 2σ with our result, adopting the same centre.…”

Section: Comparison With the Literaturementioning

confidence: 99%

“…In the plane of the sky, stars also follow a non-uniform velocity structure which might indicate a stretching or tidal stripping of the SMC (e.g. van der Marel & Sahlmann 2016;Niederhofer et al 2018b;Zivick et al 2018;De Leo et al 2020). Oey et al (2018) used Gaia DR2 data to study the PMs of young O-type stars within the SMC Wing region.…”

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confidence: 99%

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The VMC survey – XLI. Stellar proper motions within the Small Magellanic Cloud

Niederhofer

Cioni

Rubele

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We used data from the near-infrared VISTA survey of the Magellanic Cloud system (VMC) to measure proper motions (PMs) of stars within the Small Magellanic Cloud (SMC). The data analysed in this study comprise 26 VMC tiles, covering a total contiguous area on the sky of ∼40 deg2. Using multi-epoch observations in the Ks band over time baselines between 13 and 38 months, we calculated absolute PMs with respect to ∼130 000 background galaxies. We selected a sample of ∼2 160 000 likely SMC member stars to model the centre-of-mass motion of the galaxy. The results found for three different choices of the SMC centre are in good agreement with recent space-based measurements. Using the systemic motion of the SMC, we constructed spatially resolved residual PM maps and analysed for the first time the internal kinematics of the intermediate-age/old and young stellar populations separately. We found outward motions that point either towards a stretching of the galaxy or stripping of its outer regions. Stellar motions towards the North might be related to the “Counter Bridge” behind the SMC. The young populations show larger PMs in the region of the SMC Wing, towards the young Magellanic Bridge. In the older populations, we further detected a coordinated motion of stars away from the SMC in the direction of the Old Bridge as well as a stream towards the SMC.

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Section: S U M M a Ry A N D C O N C L U S I O N Ssupporting

confidence: 92%

Section: Comparison With the Literaturementioning

confidence: 99%

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The VMC survey – XLI. Stellar proper motions within the Small Magellanic Cloud

Niederhofer

Cioni

Rubele

et al. 2021

Monthly Notices of the Royal Astronomical Society

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“…The lower-left panel of Figure 15 shows there to be significant dispersion in M1, precisely at the SMC edge of enhanced proper motion and at the LMC-SMC interface, where a mixture of Cloud populations is to be expected. The SMC is known to be disrupting (see, e.g., Zivick et al 2018;De Leo et al 2020) and the perturbed motions we observe here are likely a result of this, with the LMC violently dragging the eastern edge of the SMC toward it. The fact that we observe this signature in all three of the top panels indicates that the disruption is severe, penetrating through to the more centrally concentrated metalrich giants in M3.…”

Section: Slicing the Clouds By Metallicitymentioning

confidence: 80%

Magellanic Mayhem: Metallicities and Motions

Grady

Belokurov

Evans

2021

ApJ

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We assemble a catalog of Magellanic Cloud red giants from Data Release 2 of the Gaia mission and, utilizing machine-learning methods, obtain photometric metallicity estimates for them. In doing so, we are able to chemically map the entirety of the Magellanic System at once. Our maps reveal a plethora of substructure within our red giant sample, with the Large Magellanic Cloud (LMC) bar and spiral arm being readily apparent. We uncover a curious spiral-like feature in the southern portion of the LMC disk, hosting relatively metal-rich giants and likely a by-product of historic encounters with the Small Magellanic Cloud (SMC). Modeling the LMC as an inclined thin disk, we find a shallow metallicity gradient of −0.048 ± 0.001 dex kpc −1 out to ∼12°from the center of the dwarf. We see evidence that the SMC is disrupting, with its outer isodensity contours displaying the S-shape symptomatic of tidal stripping. On studying the proper motions of the SMC giants, we observe a population of them being violently dragged toward the larger Cloud. The perturbed stars predominantly lie in front of the SMC, and we interpret that they exist as a tidal tail of the dwarf, trailing in its motion and undergoing severe disruption from the LMC. We find the metallicity structure in the Magellanic Bridge region to be complex, with evidence for a composite nature in this stellar population, consisting of both LMC and SMC debris.Unified Astronomy Thesaurus concepts: Galaxies (573); Local Group (929); Large Magellanic Cloud (903); Small Magellanic Cloud (1468)

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“…Recent studies which analysed the internal proper motion structure of the SMC (e.g. Oey et al 2018;Zivick et al 2018;De Leo et al 2020);Niederhofer et al 2020) found that stars east of the main body of the galaxy move preferentially away from the SMC, towards the East. This motion has been interpreted as a signature of tidal stripping of the outer parts of the SMC.…”

Section: D Structurementioning

confidence: 99%

Gaia view of a stellar sub-structure in front of the Small Magellanic Cloud

Omkumar

Subramanian

Niederhofer

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Recent observational studies identified a foreground stellar sub-structure traced by red clump (RC) stars (∼ 12 kpc in front of the main body) in the eastern regions of the Small Magellanic Cloud (SMC) and suggested that it formed during the formation of the Magellanic Bridge (MB), due to the tidal interaction of the Magellanic Clouds. Previous studies investigated this feature only up to 4$\rlap{.}^{\circ }$0 from the centre of the SMC due to the limited spatial coverage of the data and hence could not find a physical connection with the MB. To determine the spatial extent and properties of this foreground population, we analysed data from the Gaia data release 2 (DR2) of a ∼314 deg2 region centred on the SMC, which cover the entire SMC and a significant portion of the MB. We find that the foreground population is present only between 2$\rlap{.}^{\circ }$5 to ∼ 5○–6○ from the centre of the SMC in the eastern regions, towards the MB and hence does not fully overlap with the MB in the plane of the sky. The foreground stellar population is found to be kinematically distinct from the stellar population of the main body with ∼ 35 km s−1 slower tangential velocity and moving to the North-West relative to the main body. Though the observed properties are not fully consistent with the simulations, a comparison indicates that the foreground stellar structure is most likely a tidally stripped counterpart of the gaseous MB and might have formed from the inner disc (dominated by stars) of the SMC. A chemical and 3D kinematic study of the RC stars along with improved simulations, including both tidal and hydro-dynamical effects, are required to understand the offset between the foreground structure and MB.

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Revealing the tidal scars of the Small Magellanic Cloud

Cited by 39 publications

References 128 publications

The VMC survey – XLI. Stellar proper motions within the Small Magellanic Cloud

The VMC survey – XLI. Stellar proper motions within the Small Magellanic Cloud

Magellanic Mayhem: Metallicities and Motions

Gaia view of a stellar sub-structure in front of the Small Magellanic Cloud

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