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We derive the star formation history (SFH) for several regions of the Large Magellanic Cloud (LMC), using deep near-infrared data from the VISTA near-infrared YJKs survey of the Magellanic system (VMC). The regions include three almost-complete 1.4 deg2 tiles located ∼3.5° away from the LMC centre in distinct directions. They are split into 21.0' ×21.5' (0.12 deg2) subregions, and each of these is analysed independently. To this dataset, we add two 11.3' ×11.3' (0.036 deg2) subregions selected based on their small and uniform extinction inside the 30 Doradus tile. The SFH is derived from the simultaneous reconstruction of two different colour-magnitude diagrams (CMDs), using the minimization code StarFISH together with a database of "partial models" representing the CMDs of LMC populations of various ages and metallicities, plus a partial model for the CMD of the Milky Way foreground. The distance modulus (m-M)0 and extinction AV is varied within intervals ∼0.2 and ∼0.5 mag wide, respectively, within which we identify the best-fitting star formation rate SFR(t) as a function of lookback time t, age-metallicity relation (AMR), (m-M)0 and AV. Our results demonstrate that VMC data, due to the combination of depth and little sensitivity to differential reddening, allow the derivation of the space-resolved SFH of the LMC with unprecedented quality compared to previous wide-area surveys. In particular, the data clearly reveal the presence of peaks in the SFR(t) at ages log(t/yr) ≃ 9.3 and 9.7, which appear in most of the subregions. The most recent SFR(t) is found to vary greatly from subregion to subregion, with the general trend of being more intense in the innermost LMC, except for the tile next to the N11 complex. In the bar region, the SFR(t) seems remarkably constant over the time interval from log(t/yr) ≃ 8.4 to 9.7. The AMRs, instead, turn out to be remarkably similar across the LMC. Thanks to the accuracy in determining the distance modulus for every subregion - with typical errors of just ∼0.03 mag - we make a first attempt to derive a spatial model of the LMC disk. The fields studied so far are fit extremely well by a single disk of inclination i = 26.2 ±2.0°, position angle of the line of nodes ϴ0 = 129.1×13.0°, and distance modulus of (m-M)0 = 18.470×0.006 mag (random errors only) up to the LMC centre. We show that once the (m-M)0 values or each subregion are assumed to be identical to those derived from this best-fitting plane, systematic errors in the SFR(t) and AMR are reduced by a factor of about two [ABSTRACT FROM AUTHOR]

We present the first spatially resolved map of stellar proper motions within the central (~3.1 × 2.4 kpc) regions of the Small Magellanic Cloud (SMC). The data used for this study encompasses four tiles from the ongoing near-infrared VISTA survey of the Magellanic Clouds system and covers a total contiguous area on the sky of ~6.81 deg2. Proper motions have been calculated independently in two dimensions from the spatial offsets in the Ks filter over time baselines between 22 and 27 months. The reflex motions of approximately 33 000 background galaxies are used to calibrate the stellar motions to an absolute scale. The resulting catalog is composed of more than 690 000 stars which have been selected based on their position in the (J - Ks; Ks) color-magnitude diagram. For the median absolute proper motion of the SMC, we find (μαcos(δ), μδ) = (1.087 ± 0.192 (sys.) ± 0.003 (stat.), -1.187 ± 0.008 (sys.) ± 0.003 (stat.)) mas yr-1, consistent with previous studies. Mapping the proper motions as a function of position within the SMC reveals a nonuniform velocity pattern indicative of a tidal feature behind the main body of the SMC and a flow of stars in the south-east moving predominantly along the line-of-sight. [ABSTRACT FROM AUTHOR]

Context. The number and spatial distribution of confirmed quasi-stellar objects (QSOs) behind the Magellanic system is limited. This undermines their use as astrometric reference objects for different types of studies. Aims. We have searched for criteria to identify candidate QSOs using observations from the VISTA survey of the Magellanic Clouds system (VMC) that provides photometry in the YJKs bands and 12 epochs in the Ks band. Methods. The (Y - J) versus (J - Ks) diagram has been used to distinguish QSO candidates from Milky Way stars and stars of the Magellanic Clouds. Then, the slope of variation in the Ks band has been used to identify a sample of high confidence candidates. These criteria were developed based on the properties of 117 known QSOs presently observed by the VMC survey. Results. VMC YJKs magnitudes and Ks light-curves of known QSOs behind the Magellanic system are presented. About 75% of them show a slope of variation in Ks > 10-4 mag/day and the shape of the light-curve is in general irregular and without any clear periodicity. The number of QSO candidates found in tiles including the south ecliptic pole and the 30 Doradus regions is 22 and 26, respectively, with a ∼20% contamination by young stellar objects, planetary nebulae, stars and normal galaxies. Conclusions. By extrapolating the number of QSO candidates to the entire VMC survey area we expect to find about 1200 QSOs behind the LMC, 400 behind the SMC, 200 behind the Bridge and 30 behind the Stream areas, but not all will be suitable for astrometry. Further, the Ks band light-curves can help support investigations of the mechanism responsible for the variations. [ABSTRACT FROM AUTHOR]

Galaxy interactions distort the distribution of baryonic matter and can affect star formation. The nearby Magellanic Clouds are a prime example of an ongoing galaxy interaction process. Here, we use the intermediate-age (∼1–10 Gyr) red clump (RC) stars to map the 3D structure of the Small Magellanic Cloud (SMC) and interpret it within the context of its history of interaction with the Large Magellanic Cloud (LMC) and the Milky Way. RC stars are selected from near-infrared colour–magnitude diagrams based on data from the Visible and Infrared Survey Telescope for Astronomy survey of the Magellanic Clouds. Interstellar reddening is measured and removed, and the corrected brightness is converted to a distance, on a star-by-star basis. A flat plane fitted to the spatial distribution of RC stars has an inclination i = 35°–48° and position angle, PA=170°–186°. However, significant deviations from this plane are seen, especially in the periphery and on the eastern side of the SMC. In the latter part, two distinct populations are present, separated in distance by as much as 10 kpc. Distant RC stars are seen in the north of the SMC, and possibly also in the far west; these might be associated with the predicted 'Counter-Bridge'. We also present a dust reddening map, which shows that dust generally traces stellar mass. The structure of the intermediate-age stellar component of the SMC bears the imprints of strong interaction with the LMC a few Gyr ago, which cannot be purely tidal but must have involved ram pressure stripping. [ABSTRACT FROM AUTHOR]

We present results from an analysis of ∼29 000 RR Lyrae stars located in the Large Magellanic Cloud (LMC). For these objects, near-infrared time-series photometry from the VISTA survey of the Magellanic Clouds system (VMC) and optical data from the Optical Gravitational Lensing Experiment (OGLE) IV survey and the Gaia Data Release 2 catalogue of confirmed RR Lyrae stars were exploited. Using VMC and OGLE IV magnitudes we derived period–luminosity (PL), period–luminosity–metallicity (PLZ), period–Wesenheit (PW), and period–Wesenheit–metallicity (PWZ) relations in all available bands. More that  7000 RR Lyrae were discarded from the analysis because they appear to be overluminous with respect to the PL relations. The |$PL_{K_{\mathrm{s}}}$| relation was used to derive individual distance to |${\sim}22\, 000$| RR Lyrae stars, and study the three-dimensional structure of the LMC. The distribution of the LMC RR Lyrae stars is ellipsoidal with the three axis S 1 = 6.5 kpc, S 2 = 4.6 kpc, and S 3 = 3.7 kpc, inclination i  = 22 ± 4° relative to the plane of the sky and position angle of the line of nodes θ = 167 ± 7° (measured from north to east). The north-eastern part of the ellipsoid is closer to us and no particular associated substructures are detected and neither any metallicity gradient. [ABSTRACT FROM AUTHOR]

We present Ks-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 ≤ (Ks) ≤ 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 Ks-band observations are available and no comprehensive identification of different types of variable stars from other surveys exists yet. [ABSTRACT FROM AUTHOR]

Context. Proper motion (PM) studies are fundamental ingredients in the understanding of the orbital history of galaxies. Current measurements do not yet provide a satisfactory answer to the possible scenarios for the formation and evolution of the Magellanic Clouds and of the Bridge and Stream that link them with each other and with our Galaxy. Aims. We use multi-epoch near-infrared observations from the VISTA survey of the Magellanic Cloud system (VMC) to measure the PM of stars of the Large Magellanic Cloud (LMC), in one tile of 1.5 deg² centred at (α, δ) = (05:59:23.136, -66:20:28.68) and including the south ecliptic pole, with respect to their Two Micron All Sky Survey (2MASS) position over a time baseline of about 10 years. Proper motions from VMC observations only, spanning a time range of about 1 year, are also derived. Methods. Stars of different ages are selected from the colour-magnitude diagram, (J - Ks) vs. Ks, and their average coordinate displacement is computed from the difference between Ks band observations from VMC and 2MASS or among VMC data alone for stars as faint as Ks = 19 mag. Proper motions are derived by averaging up to seven 2MASS-VMC combinations in the first case and from the slope of the best-fit line among the seven VMC epochs in the second case. Separate PM values are obtained for Cepheids, RR Lyrae stars, long period variables, and eclipsing binary stars in the field. Results. The PM of ~40 000 LMC stars in the tile, with respect to ~8000 background galaxies, obtained from VMC data alone, is μα cos (δ) = +2.20 ± 0.06 (stat) ±0.29 (sys) and μδ = +1.70 ± 0.06 (stat) ±0.30 (sys) mas yr-1. This value agrees with recent ground-based determinations, but is larger than studies with the Hubble Space Telescope; this discrepancy may be due to additional systematic errors in the data. Our result implies either higher tangential motion or higher internal motion, or a combination of these, although we cannot discuss these possibilities quantitatively based on one field. The PM of the LMC is also clearly distinct from the PM derived for stars in the Milky Way foreground. The relative PM between the foreground stars and the LMC stars is ~5 masyr-1. Furthermore, we measure a decrease in the PM with increasing logarithm of stellar age for LMC stars. Conclusions. This study, based on just one VMC tile, shows the potential of the 2MASS-VMC and VMC-VMC combinations for a comprehensive investigation of PM across the Magellanic system. [ABSTRACT FROM AUTHOR]

Context. The details of how galaxies have evolved over cosmological times are imprinted in their star formation history, chemical enrichment and morpho-kinematic structure. Parameters behind these, such as effective temperature and metallicity, can be measured by combining photometric techniques with modelling. However, there are uncertainties with this indirect approach from the ambiguity of colour and magnitude and the effects of interstellar reddening. Aims. In this paper we present a detailed reddening map of the central 30 Doradus region of the Large Magellanic Cloud; for both community use and as a test of the methods used for future use on a wider area. The reddening, a measurement of dust extinction, acts as a tracer of the interstellar medium (ISM). Methods. Near-infrared (NIR) photometry of the red clump stars is used to measure reddening as their fixed luminosity and intermediate age make extinction the dominant cause of colour and magnitude variance. The star formation history derived previously from these data is used to produce an intrinsic colour to act as a zero point in converting colour to reddening values E(J - Ks) which are subsequently converted to visual extinction AV. Results. Presented is a dust map for the 30 Doradus field in both AV and E(J - Ks). This map samples a region of 1° × 1.°5, containing ∼1.5 × 105 red clump stars which probe reddening up to AV ≃ 6 mag. We compare our map with maps from the literature, including optical extinction maps and radio, mid- and far-infrared maps of atomic hydrogen and dust emission. Through estimation of column density we locate molecular clouds. Conclusions. This new reddening map shows correlation with equivalent maps in the literature, validating the method of red clump star selection. We make our reddening map available for community use. In terms of ISM the red clump stars appear to be more affected by the cooler dust measured by 70 μm emission because there is stronger correlation between increasing emission and extinction due to red clump stars not being located near hot stars that would heat the dust. The transition from atomic hydrogen to molecular hydrogen occurs between densities of NH ≃ 4 × 1021 cm-2 and NH ≃ 6 × 1021 cm-2. [ABSTRACT FROM AUTHOR]

ABSTRACT The VISTA Magellanic Cloud (VMC; PI: M.-R. L. Cioni) survey is collecting deep Ks-band time series photometry of the pulsating variable stars hosted by the system formed by the two Magellanic Clouds (MCs) and the bridge connecting them. In this paper, we present the first results for classical Cepheids, from the VMC observations of two fields in the Large Magellanic Cloud (LMC), centred on the South Ecliptic Pole and the 30 Doradus star-forming regions, respectively. The VMC Ks-band light curves of the Cepheids are well sampled (12 epochs) and of excellent precision (typical errors of ∼0.01 mag). We were able to measure for the first time the Ks magnitude of the faintest classical Cepheids in the LMC ( Ks ∼ 17.5 mag), which are mostly pulsating in the first overtone (FO) mode, and to obtain FO period-luminosity ( PL), period-Wesenheit ( PW) and period-luminosity-colour ( PLC) relations, spanning the full period range from 0.25 to 6 d. Since the longest period Cepheid in our data set has a variability period of 23 d, we have complemented our sample with literature data for brighter F Cepheids. On this basis, we have built a PL relation in the Ks band that, for the first time, includes short-period - hence low-luminosity - pulsators, and spans the full range from 1.6 to 100 d in period.We also provide the first ever empirical PW and PLC relations using the ( V − Ks) colour and time series Ks photometry. The very small dispersion (∼0.07 mag) of these relations makes them very well suited to study the three-dimensional geometry of the Magellanic system. The use of 'direct' (parallax- and Baade-Wesselink-based) distance measurements to both Galactic and LMC Cepheids allowed us to calibrate the zero-points of the PL, PW and PLC relations obtained in this paper, and in turn to estimate an absolute distance modulus of ( m − M)0 = 18.46 ± 0.03 mag for the LMC. This result is in agreement with most of the latest literature determinations based on classical Cepheids. [ABSTRACT FROM AUTHOR]