@article{NiederhoferCioniSchmidtetal.2022,
  author    = {Niederhofer, Florian and Cioni, Maria-Rosa L. and Schmidt, Thomas and Bekki, Kenji and de Grijs, Richard and Ivanov, Valentin D. and Oliveira, Joana M. and Ripepi, Vincenzo and Subramanian, Smitha and van Loon, Jacco Th},
  title     = {The VMC survey - XLVI. Stellar proper motions in the centre of the Large Magellanic Cloud},
  series = {Monthly notices of the Royal Astronomical Society},
  volume    = {512},
  journal   = {Monthly notices of the Royal Astronomical Society},
  number    = {4},
  publisher = {Oxford University Press},
  address   = {Oxford},
  issn      = {0035-8711},
  doi       = {10.1093/mnras/stac712},
  pages     = {5423 -- 5439},
  year      = {2022},
  abstract  = {We present proper motion (PM) measurements within the central region of the Large Magellanic Cloud (LMC), using near-infrared data from the VISTA survey of the Magellanic Cloud system (VMC). This work encompasses 18 VMC tiles covering a total sky area of similar to 28 deg(2). We computed absolute stellar PMs from multiepoch observations in the K-s filter over time baselines between similar to 12 and 47 months. Our final catalogue contains similar to 6322 000 likely LMC member stars with derived PMs. We employed a simple flat-rotating disc model to analyse and interpret the PM data. We found a stellar centre of rotation (alpha(0) = 79.95 degrees(+0.22)(-0.23), delta(0) = -69.31 degrees(+0.12)(-0.11)) that is in agreement with that resulting from Hubble Space Telescope data. The inferred viewing angles of the LMC disc (i = 33.5 degrees(+1.2)(-1.3), Theta = 129.8 degrees(+1.9)(-1.9)) are in good agreement with values from the literature but suggest a higher inclination of the central parts of the LMC. Our data confirm a higher rotation amplitude for the young (less than or similar to 0.5 Gyr) stars compared to the intermediate-age/old (greater than or similar to 1 Gyr) population, which can be explained by asymmetric drift. We constructed spatially resolved velocity maps of the intermediate-age/old and young populations. Intermediate-age/old stars follow elongated orbits parallel to the bar's major axis, providing first observational evidence for x(1) orbits within the LMC bar. In the innermost regions, the motions show more chaotic structures. Young stars show motions along a central filamentary bar structure.},
  language  = {en}
}
@article{SchmidtCioniNiederhoferetal.2022,
  author    = {Schmidt, Thomas and Cioni, Maria-Rosa L. and Niederhofer, Florian and Bekki, Kenji and Bell, Cameron P. M. and de Grijs, Richard and El Youssoufi, Dalal and Ivanov, Valentin D. and Oliveira, Joana M. and Ripepi, Vincenzo and van Loon, Jacco Th.},
  title     = {The VMC survey: XLV. Proper motion of the outer LMC and the impact of the SMC},
  series = {Astronomy and astrophysics},
  volume    = {663},
  journal   = {Astronomy and astrophysics},
  publisher = {EDP Sciences},
  address   = {Les Ulis},
  issn      = {0004-6361},
  doi       = {10.1051/0004-6361/202142148},
  pages     = {21},
  year      = {2022},
  abstract  = {Context. The Large Magellanic Cloud (LMC) is the most luminous satellite galaxy of the Milky Way and, owing to its companion, the Small Magellanic Cloud (SMC), represents an excellent laboratory to study the interaction of dwarf galaxies. Aims. The aim of this study is to investigate the kinematics of the outer regions of the LMC by using stellar proper motions to understand the impact of interactions, for example with the SMC about 250 Myr ago. Methods. We calculate proper motions using multi-epoch K s -band images from the VISTA survey of the Magellanic Cloud system (VMC). Observations span a time baseline of 2-5 yr. We combine the VMC data with data from the Gaia Early Data Release 3 and introduce a new method to distinguish between Magellanic and Milky Way stars based on a machine learning algorithm. This new technique enables a larger and cleaner sample selection of fainter sources as it reaches below the red clump of the LMC. Results. We investigate the impact of the SMC on the rotational field of the LMC and find hints of stripped SMC debris. The southeastern region of the LMC shows a slow rotational speed compared to the overall rotation. N-body simulations suggest that this could be caused by a fraction of stripped SMC stars located in that particular region that move opposite to the expected rotation.},
  language  = {en}
}
@article{NideverOlsenWalkeretal.2017,
  author    = {Nidever, David L. and Olsen, Knut and Walker, Alistair R. and Katherina Vivas, A. and Blum, Robert D. and Kaleida, Catherine and Choi, Yumi and Conn, Blair C. and Gruendl, Robert A. and Bell, Eric F. and Besla, Gurtina and Munoz, Ricardo R. and Gallart, Carme and Martin, Nicolas F. and Olszewski, Edward W. and Saha, Abhijit and Monachesi, Antonela and Monelli, Matteo and de Boer, Thomas J. L. and Johnson, L. Clifton and Zaritsky, Dennis and Stringfellow, Guy S. and van der Marel, Roeland P. and Cioni, Maria-Rosa L. and Jin, Shoko and Majewski, Steven R. and Martinez-Delgado, David and Monteagudo, Lara and Noel, Noelia E. D. and Bernard, Edouard J. and Kunder, Andrea and Chu, You-Hua and Bell, Cameron P. M. and Santana, Felipe and Frechem, Joshua and Medina, Gustavo E. and Parkash, Vaishali and Seron Navarrete, J. C. and Hayes, Christian},
  title     = {SMASH: Survey of the MAgellanic Stellar History},
  series = {The astronomical journal},
  volume    = {154},
  journal   = {The astronomical journal},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {0004-6256},
  doi       = {10.3847/1538-3881/aa8d1c},
  pages     = {310 -- 326},
  year      = {2017},
  abstract  = {The Large and Small Magellanic Clouds are unique local laboratories for studying the formation and evolution of small galaxies in exquisite detail. The Survey of the MAgellanic Stellar History (SMASH) is an NOAO community Dark Energy Camera (DECam) survey of the Clouds mapping 480 deg2 (distributed over similar to 2400 square degrees at similar to 20\% filling factor) to similar to 24th. mag in ugriz. The primary goals of SMASH are to identify low surface brightness stellar populations associated with the stellar halos and tidal debris of the Clouds, and to derive spatially resolved star formation histories. Here, we present a summary of the survey, its data reduction, and a description of the first public Data Release (DR1). The SMASH DECam data have been reduced with a combination of the NOAO Community Pipeline, the PHOTRED automated point-spread-function photometry pipeline, and custom calibration software. The astrometric precision is similar to 15 mas and the accuracy is similar to 2 mas with respect to the Gaia reference frame. The photometric precision is similar to 0.5\%-0.7\% in griz and similar to 1\% in u with a calibration accuracy of similar to 1.3\% in all bands. The median 5s point source depths in ugriz are 23.9, 24.8, 24.5, 24.2, and 23.5 mag. The SMASH data have already been used to discover the Hydra II Milky Way satellite, the SMASH 1 old globular cluster likely associated with the LMC, and extended stellar populations around the LMC out to R. similar to. 18.4 kpc. SMASH DR1 contains measurements of similar to 100 million objects distributed in 61 fields. A prototype version of the NOAO Data Lab provides data access and exploration tools.},
  language  = {en}
}
@article{CioniBekkiGirardietal.2016,
  author    = {Cioni, Maria-Rosa L. and Bekki, Kenji and Girardi, Leo and de Grijs, Richard and Irwin, Mike J. and Ivanov, Valentin D. and Marconi, Marcella and Oliveira, Joana M. and Piatti, Andres E. and Ripepi, Vincenzo and van Loon, Jacco Th.},
  title     = {XVII. Proper motions of the Small Magellanic Cloud and the Milky Way globular cluster 47 Tucanae},
  series = {Physical review : E, Statistical, nonlinear and soft matter physics},
  volume    = {586},
  journal   = {Physical review : E, Statistical, nonlinear and soft matter physics},
  publisher = {EDP Sciences},
  address   = {Les Ulis},
  issn      = {1432-0746},
  doi       = {10.1051/0004-6361/201527004},
  pages     = {67 -- 75},
  year      = {2016},
  abstract  = {Aims. In this study we use multi-epoch near-infrared observations from the VISTA survey of the Magellanic Cloud system (VMC) to measure the proper motions of different stellar populations in a tile of 1.5 deg2 in size in the direction of the Galactic globular cluster 47 Tuc. We obtain the proper motion of the cluster itself, of the Small Magellanic Cloud (SMC), and of the field Milky Way stars. Methods. Stars of the three main stellar components are selected according to their spatial distributions and their distributions in colour\&\#8722;magnitude diagrams. Their average coordinate displacement is computed from the difference between multiple Ks-band observations for stars as faint as Ks = 19 mag. Proper motions are derived from the slope of the best-fitting line among ten VMC epochs over a time baseline of ~1 yr. Background galaxies are used to calibrate the absolute astrometric reference frame. Results. The resulting absolute proper motion of 47 Tuc is (\&\#956;\&\#945;cos(\&\#948;), \&\#956;\&\#948;) = (+7.26 ± 0.03, \&\#8722;1.25 ± 0.03) mas yr-1. This measurement refers to about 35 000 sources distributed between 10\&\#8242; and 60\&\#8242; from the cluster centre. For the SMC we obtain (\&\#956;\&\#945;cos(\&\#948;), \&\#956;\&\#948;) = (+1.16 ± 0.07, \&\#8722;0.81 ± 0.07) mas yr-1 from about 5250 red clump and red giant branch stars. The absolute proper motion of the Milky Way population in the line of sight (l = 305.9, b = \&\#8722;44.9) of this VISTA tile is (\&\#956;\&\#945;cos(\&\#948;), \&\#956;\&\#948;) = (+10.22 ± 0.14, \&\#8722;1.27 ± 0.12) mas yr-1 and has been calculated from about 4000 sources. Systematic uncertainties associated with the astrometric reference system are 0.18 mas yr-1. Thanks to the proper motion we detect 47 Tuc stars beyond its tidal radius.},
  language  = {en}
}
@article{IvanovCioniBekkietal.2016,
  author    = {Ivanov, Valentin D. and Cioni, Maria-Rosa L. and Bekki, Kenji and de Grijs, Richard and Emerson, Jim and Gibson, Brad K. and Kamath, Devika and van Loon, Jacco Th. and Piatti, Andres E. and For, Bi-Qing},
  title     = {New quasars behind the Magellanic Clouds. Spectroscopic confirmation of near-infrared selected candidates},
  series = {Current biology},
  volume    = {588},
  journal   = {Current biology},
  publisher = {EDP Sciences},
  address   = {Les Ulis},
  issn      = {1432-0746},
  doi       = {10.1051/0004-6361/201527398},
  pages     = {12},
  year      = {2016},
  abstract  = {Context. Quasi-stellar objects (quasars) located behind nearby galaxies provide an excellent absolute reference system for astrometric studies, but they are difficult to identify because of fore-and background contamination. Deep wide-field, high angular resolution surveys spanning the entire area of nearby galaxies are needed to obtain a complete census of such quasars. Aims. We embarked on a program to expand the quasar reference system behind the Large and the Small Magellanic Clouds, the Magellanic Bridge, and the Magellanic Stream that connects the Clouds with the Milky Way. Methods. Hundreds of quasar candidates were selected based on their near-infrared colors and variability properties from the ongoing public ESO VISTA Magellanic Clouds survey. A subset of 49 objects was followed up with optical spectroscopy. Results. We confirmed the quasar nature of 37 objects (34 new identifications): four are low redshift objects, three are probably stars, and the remaining three lack prominent spectral features for a secure classification. The bona fide quasars, identified from their broad emisison lines, are located as follows: 10 behind the LMC, 13 behind the SMC, and 14 behind the Bridge. The quasars span a redshift range from z similar to 0.5 to z similar to 4.1. Conclusions. Upon completion the VMC survey is expected to yield a total of similar to 1500 quasars with Y < 19.32 mag, J < 19.09 mag, and K-s < 18.04 mag.},
  language  = {en}
}
@article{MorettiClementiniMarconietal.2016,
  author    = {Moretti, M. I. and Clementini, Gisella and Marconi, V. Ripepi M. and Rubele, S. and Cioni, Maria-Rosa L. and Muraveva, T. and Groenewegen, M. A. T. and Cross, N. J. G. and Ivanov, V. D. and Piatti, A. E. and de Grijs, Richard},
  title     = {The VMC survey - XX. Identification of new Cepheids in the Small Magellanic Cloud},
  series = {Monthly notices of the Royal Astronomical Society},
  volume    = {459},
  journal   = {Monthly notices of the Royal Astronomical Society},
  publisher = {Oxford Univ. Press},
  address   = {Oxford},
  issn      = {0035-8711},
  doi       = {10.1093/mnras/stw716},
  pages     = {1687 -- 1697},
  year      = {2016},
  abstract  = {We present K-s-band light curves for 299 Cepheids in the Small Magellanic Cloud (SMC) of which 288 are new discoveries that we have identified using multi-epoch near-infrared photometry obtained by the VISTA survey of the Magellanic Clouds system (VMC). The new Cepheids have periods in the range from 0.34 to 9.1 d and cover the magnitude interval 12.9 <= currency sign < K-s > <= currency sign 17.6 mag. Our method was developed using variable stars previously identified by the optical microlensing survey OGLE. We focus on searching new Cepheids in external regions of the SMC for which complete VMC K-s-band observations are available and no comprehensive identification of different types of variable stars from other surveys exists yet.},
  language  = {en}
}