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We present a map of the total intrinsic reddening across ~90 deg$^{2}$ of the Large Magellanic Cloud (LMC) derived using optical (ugriz) and near-infrared (IR; YJKs) spectral energy distributions (SEDs) of background galaxies. The reddening map is created from a sample of 222,752 early-type galaxies based on the LEPHARE $\chi^{2}$ minimisation SED-fitting routine. We find excellent agreement between the regions of enhanced intrinsic reddening across the central (4x4 deg$^2$) region of the LMC and the morphology of the low-level pervasive dust emission as traced by far-IR emission. In addition, we are able to distinguish smaller, isolated enhancements that are coincident with known star-forming regions and the clustering of young stars observed in morphology maps. The level of reddening associated with the molecular ridge south of 30 Doradus is, however, smaller than in the literature reddening maps. The reduced number of galaxies detected in this region, due to high extinction and crowding, may bias our results towards lower reddening values. Our map is consistent with maps derived from red clump stars and from the analysis of the star formation history across the LMC. This study represents one of the first large-scale categorisations of extragalactic sources behind the LMC and as such we provide the LEPHARE outputs for our full sample of ~2.5 million sources., Comment: 18 pages, 16 figures, accepted for publication in MNRAS

We present a kinematic analysis of the Small Magellanic Cloud using 3700 spectra extracted from the European Southern Observatory archive. We used data from Gaia and near-infrared photometry to select stellar populations and discard Galactic foreground stars. The sample includes main-sequence, red giant branch and red clump stars, observed with the Fibre Large Array Multi Wavelength Spectrograph. The spectra have a resolving power lambda/Delta(lambda) from 6500 to 38000. We derive radial velocities by employing a full spectrum fitting method using a penalised pixel fitting routine. We obtain a mean radial velocity for the galaxy of 159+/-2 km/s, with a velocity dispersion of 33+/-2 km/s. Our velocities agree with literature estimates for similar (young or old) stellar populations. The radial velocity of stars in the Wing and bar-like structure differ as a consequence of the dynamical interaction with the Large Magellanic Cloud. The higher radial velocity of young main-sequence stars in the bar compared to that of supergiants can be attributed to star formation around 40 Myr ago from gas already influenced by tidal stripping. Similarly, young main-sequence stars in the northern part of the bar, resulting from a prominent episode 25 Myr ago, have a higher radial velocity than stars in the southern part. Radial velocity differences between the northern and southern bar over densities are also traced by giant stars. They are corroborated by studies of the cold gas and proper motion indicating stretching/tidal stripping of the galaxy., Comment: 18 pages, 13 figures, accepted for publication in MNRAS

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 deg$^2$. 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., 20 pages, 20 figures, accepted for publication in MNRAS

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 ($\sim1$-$10$ Gyr) red clump stars to map the three-dimensional 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. Red clump stars are selected from near-infrared colour-magnitude diagrams based on data from the VISTA 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 red clump stars has an inclination $i=35\deg$-$48\deg$ and position angle PA$=170\deg$-$186\deg$. 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 red clump 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., Comment: 16 pages, 11 figures; accepted for publication in MNRAS

We perform a statistical clustering analysis of upper main-sequence stars in the Large Magellanic Cloud (LMC) using data from the Visible and Infrared Survey Telescope for Astronomy survey of the Magellanic Clouds. We map over 2500 young stellar structures at 15 significance levels across ~120 square degrees centred on the LMC. The structures have sizes ranging from a few parsecs to over 1 kpc. We find that the young structures follow power-law size and mass distributions. From the perimeter-area relation, we derive a perimeter-area dimension of 1.44+-0.20. From the mass-size relation and the size distribution, we derive two-dimensional fractal dimensions of 1.50+-0.10 and 1.61+-0.20, respectively. We find that the surface density distribution is well-represented by a lognormal distribution. We apply the Larson relation to estimate the velocity dispersions and crossing times of these structures. Our results indicate that the fractal nature of the young stellar structures has been inherited from the gas clouds from which they form and that this architecture is generated by supersonic turbulence. Our results also suggest that star formation in the LMC is scale-free from 10 pc to 700 pc., Comment: 20 pages, 17 figures, accepted for publication in MNRAS

The nearby Magellanic Clouds system covers more than 200 square degrees on the sky. Much of it has been mapped across the electromagnetic spectrum at high angular resolution and sensitivity X-ray (XMM-Newton), UV (UVIT), optical (SMASH), IR (VISTA, WISE, Spitzer, Herschel), radio (ATCA, ASKAP, MeerKAT). This provides us with an excellent dataset to explore the galaxy populations behind the stellar-rich Magellanic Clouds. We seek to identify and characterise AGN via machine learning algorithms on this exquisite data set. Our project focuses not on establishing sequences and distributions of common types of galaxies and active galactic nuclei (AGN), but seeks to identify extreme examples, building on the recent accidental discoveries of unique AGN behind the Magellanic Clouds., Proceedings paper of the IAU symposium "Nuclear Activity in Galaxies Across Cosmic Time" (Ethiopia) accepted to be published under the Cambridge University Press, eds. M. Povic, P. Marziani, J. Masegosa, H. Netzer, S. H. Negu, and S. B. Tessema

For the first time, we report the identification of NUV bright red clump (RC) stars and the extension of RC stars over two magnitudes both in color and magnitude axis in NUV vs (NUV – optical) color magnitude diagram. We find that the extension of RC is not due to photometric uncertainties. We suggest that the extension could be an effect of field star contamination. We also suggest that if it is an intrinsic property of the cluster then age and/or metallicity spread within the cluster could be the possible reasons for extended RC.

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. 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, e.g. with the SMC about 250 Myr ago. {We calculate proper motions using multi-epoch $K_\mathrm{s}$-band images from the VISTA survey of the Magellanic Clouds 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. We investigate the impact of the SMC on the rotational field of the LMC and find hints of stripped SMC debris. The south east 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., Comment: 21 pages, 21 figures, accepted for publication in A&A

Full list of authors: Nidever, David L.; Olsen, Knut; Choi, Yumi; Ruiz-Lara, Tomas; Miller, Amy E.; Johnson, L. Clifton; Bell, Cameron P. M.; Blum, Robert D.; Cioni, Maria-Rosa L.; Gallart, Carme; Majewski, Steven R.; Martin, Nicolas F.; Massana, Pol; Monachesi, Antonela; Noël, Noelia E. D.; Sakowska, Joanna D.; van der Marel, Roeland P.; Walker, Alistair R.; Zaritsky, Dennis; Bell, Eric F. Conn, Blair C.; de Boer, Thomas J. L.; Gruendl, Robert A.; Monelli, Matteo; Muñoz, Ricardo R.; Saha, Abhijit; Vivas, A. Katherina; Bernard, Edouard; Besla, Gurtina; Carballo-Bello, Julio A.; Dorta, Antonio; Martinez-Delgado, David; Goater, Alex; Rusakov, Vadim; Stringfellow, Guy S., We present an analysis of the ionosphere and thermosphere response to Solar Proton Events (SPE) and magnetospheric proton precipitation in January 2005, which was carried out using the model of the entire atmosphere EAGLE. The ionization rates for the considered period were acquired from the AIMOS (Atmospheric Ionization Module Osnabrück) dataset. For numerical experiments, we applied only the proton-induced ionization rates of that period, while all the other model input parameters, including the electron precipitations, corresponded to the quiet conditions. In January 2005, two major solar proton events with different energy spectra and proton fluxes occurred on January 17 and January 20. Since two geomagnetic storms and several sub-storms took place during the considered period, not only solar protons but also less energetic magnetospheric protons contributed to the calculated ionization rates. Despite the relative transparency of the thermosphere for high-energy protons, an ionospheric response to the SPE and proton precipitation from the magnetotail was obtained in numerical experiments. In the ionospheric E layer, the maximum increase in the electron concentration is localized at high latitudes, and at heights of the ionospheric F2 layer, the positive perturbations were formed in the near-equatorial region. An analysis of the model-derived results showed that changes in the ionospheric F2 layer were caused by a change in the neutral composition of the thermosphere. We found that in the recovery phase after both solar proton events and the enhancement of magnetospheric proton precipitations associated with geomagnetic disturbances, the TEC and electron density in the F region and in topside ionosphere/plasmasphere increase at low- and mid-latitudes due to an enhancement of atomic oxygen concentration. Our results demonstrate an important role of magnetospheric protons in the formation of negative F-region ionospheric storms. According to our results, the topside ionosphere/plasmasphere and bottom-side ionosphere can react to solar and magnetospheric protons both with the same sign of disturbances or in different way. The same statement is true for TEC and foF2 disturbances. Different disturbances of foF2 and TEC at high and low latitudes can be explained by topside electron temperature disturbances. © 2021. The American Astronomical Society. All rights reserved, Y.C., E.F.B., and A.M. acknowledge support from NSF grant AST 1655677. A.D., C.G., T.R.L., and M.M. acknowledge support by the Spanish Ministry of Economy and Competitiveness (MINECO) under the grants AYA2014-56795-P and AYA2017-89076-P as well as AYA2016-77237-C3-1-P. T.R.L. has support from a Spinoza grant (NWO) awarded to A. Helmi and acknowledges support by an MCIU Juan de la CiervaFormacion grant (FJCI-2016-30342). C.P.M.B. and M.-R.L.C. acknowledge support from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement No. 682115). A.M. acknowledges support from FONDECYT Regular 1181797. R. R.M. acknowledges partial support from project BASAL AFB170002 as well as FONDECYT project No. 1170364. D.M.D. acknowledges financial support from the State Agency for Research of the Spanish MCIU through the "Center of Excellence Severo Ochoa" award to the Instituto de Astrofisica de Andalucia (SEV-2017-0709). Image processing: Travis Rector (University of Alaska Anchorage), Mahdi Zamani, and Davide de Martin. Based on observations at Cerro Tololo Inter-American Observatory, NSF's National Optical-Infrared Astronomy Research Laboratory (NOAO Prop. ID: 2013A-0411 and 2013B-0440; PI: D. L. Nidever), which is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. IRAF is distributed by the National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. This project used data obtained with the Dark Energy Camera (DECam), which was constructed by the Dark Energy Survey (DES) collaboration. Funding for the DES Projects has been provided by the U.S. Department of Energy, the U.S. National Science Foundation, the Ministry of Science and Education of Spain, the Science and Technology Facilities Council of the United Kingdom, the Higher Education Funding Council for England, the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, the Kavli Institute of Cosmological Physics at the University of Chicago, Center for Cosmology and Astro-Particle Physics at the Ohio State University, the Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University, Financiadora de Estudos e Projetos, Fundacao Carlos Chagas Filho de Amparo, Financiadora de Estudos e Projetos, Fundacao Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Cientifico e Tecnologico and the Ministerio da Ciencia, Tecnologia e Inovacao, the Deutsche Forschungsgemeinschaft, and the Collaborating Institutions in the Dark Energy Survey. The Collaborating Institutions are Argonne National Laboratory, the University of California at Santa Cruz, the University of Cambridge, Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas-Madrid, the University of Chicago, University College London, the DES-Brazil Consortium, the University of Edinburgh, the Eidgenossische Technische Hochschule (ETH) Zurich, Fermi National Accelerator Laboratory, the University of Illinois at Urbana-Champaign, the Institut de Ciencies de l'Espai (IEEC/CSIC), the Institut de Fisica d'Altes Energies, Lawrence Berkeley National Laboratory, the Ludwig-Maximilians Universitat Munchen and the associated Excellence Cluster Universe, the University of Michigan, the National Optical Astronomy Observatory, the University of Nottingham, the Ohio State University, the University of Pennsylvania, the University of Portsmouth, SLAC National Accelerator Laboratory, Stanford University, the University of Sussex, and Texas A&M University. This work has made use of data from the European Space Agency (ESA) mission Gai a (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC,.https://www.cosmos.esa.int/web/gaia/dpac/consortium).Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation.

We have demonstrated the advantage of combining multi-wavelength observations, from the ultraviolet (UV) to near-infrared, to study Kron 3, a massive star cluster in the Small Magellanic Cloud. We have estimated the radius of the cluster Kron 3 to be 2.'0 and for the first time, we report the identification of NUV-bright red clump (RC) stars and the extension of the RCin colour and magnitude in the NUV vs (NUV-optical) colour-magnitude diagram (CMD). We found that extension of the RC is an intrinsic property of the cluster and it is not due to contamination of field stars or differential reddening across the field. We studied the spectral energy distribution of the RC stars and estimated a small range in temperature ~5000 - 5500K, luminosity ~60 - 90 Land radius ~8.0 - 11.0 Supporting their RC nature. The range of UV magnitudes amongst the RC stars (~23.3 to 24.8 mag) is likely caused by the combined effect of variable mass loss, variation in initial helium abundance (Y_ini=0.23 to 0.28), and a small variation in age (6.5-7.5 Gyr) and metallicity ([Fe/H]=-1.5 to -1.3). Spectroscopic follow-up observations of RC stars in Kron 3 are necessary to confirm the cause of the extended RC., Comment: 20 pages, 25 main figures and 2 figures in the appendix

The periphery of the Small Magellanic Cloud (SMC) can unlock important information regarding galaxy formation and evolution in interacting systems. Here, we present a detailed study of the extended stellar structure of the SMC using deep colour-magnitude diagrams, obtained as part of the Survey of the MAgellanic Stellar History (SMASH). Special care was taken in the decontamination of our data from Milky Way (MW) foreground stars, including from foreground globular clusters NGC 362 and 47 Tuc. We derived the SMC surface brightness using a `conservative' approach from which we calculated the general parameters of the SMC, finding a staggered surface brightness profile. We also traced the fainter outskirts by constructing a stellar density profile. This approach, based on stellar counts of the oldest main-sequence turn-off stars, uncovered a tidally disrupted stellar feature that reaches as far out as 12 deg from the SMC centre. We also serendipitously found a faint feature of unknown origin located at similar to 14 deg from the centre of the SMC and that we tentatively associated with a more distant structure. We compared our results to in-house simulations of a 1 x 10(9) M-circle dot SMC, finding that its elliptical shape can be explained by its tidal disruption under the combined presence of the MW and the Large Magellanic Cloud. Finally, we found that the older stellar populations show a smooth profile while the younger component presents a jump in the density followed by a flat profile, confirming the heavily disturbed nature of the SMC. © 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society, SRM acknowledges funding from grant AST-1909497 from the National Science Foundation. AM acknowledges support from Fondo Nacional de Desarrollo Cientifico y Tecnologico (FONDECYT) Regular grant 1181797 and funding from the Max Planck Society through a Partner Group grant. NFM gratefully acknowledge support from the French National Research Agency (ANR) funded project 'Pristine' (ANR-18-CE31-0017) along with funding from INSU,CNRS through the Programme National Galaxies et Cosmologie. M-RC and CPMB acknowledge support from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement no. 682115). RRM acknowledges partial support from project BASAL AFB-170002 as well as FONDECYT project N. 1170364. CG, TRL, and MMacknowledge financial support through the grants (AEI/FEDER, UE) AYA2017-89076-P and AYA2015-63810-P, as well as by the Ministerio de Ciencia, Innovacion y Universidades (MCIU), through the State Budget and by the Consejeria de Economia, Industria, Comercio y Conocimiento of the Canary Islands Autonomous Community, through the Regional Budget (including IAC project, TRACES). TRL is also supported by grant AYA2016-77237-C3-1-P (RAVET project) and a MCIU Juan de la Cierva - Formacion grant (FJCI-2016-30342). DMDacknowledges financial support from the State Agency for Research of the Spanish MCIU through the 'Centre of Excellence Severo Ochoa' award for the Instituto de Astrof ' isica de Andalucia (SEV-2017-0709). Based on observations at Cerro Tololo Inter-American Observatory, NSF's National Optical-Infrared Astronomy Research Laboratory (NOIRLab Prop. ID: 2013A-0411 and 2013B-0440; PI: Nidever), which is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. This project used data obtained with the Dark Energy Camera (DECam), which was constructed by the Dark Energy Survey (DES) collaborating institutions: Argonne National Lab, University of California Santa Cruz, University of Cambridge, Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas-Madrid, University of Chicago, University College London, DES-Brazil consortium, University of Edinburgh, ETH-Zurich, University of Illinois at Urbana-Champaign, Institut de Ci`encies de l'Espai, Institut de F ' isica d'Altes Energies, Lawrence Berkeley National Lab, Ludwig-Maximilians Universitat, University of Michigan, National Optical Astronomy Observatory, University of Nottingham, Ohio State University, University of Pennsylvania, University of Portsmouth, SLAC National Lab, Stanford University, University of Sussex, and Texas A&M University. Funding for DES, including DECam, has been provided by the U.S. Department of Energy, National Science Foundation, Ministry of Education and Science (Spain), Science and Technology Facilities Council (UK), Higher Education Funding Council for England (England), National Center for Supercomputing Applications, Kavli Institute for Cosmological Physics, Financiadora de Estudos e Projetos, Fundacao Carlos Chagas Filho de Amparo a Pesquisa, Conselho Nacional de Desenvolvimento Cientifico e Tecnologico and the Ministerio da Ciencia e Tecnologia (Brazil), the German Research Foundation-sponsored cluster of excellence `Origin and Structure of the Universe' and the DES collaborating institutions. This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.

We present a map of the total intrinsic reddening across similar or equal to 34 deg(2) of the Small Magellanic Cloud (SMC) derived using optical (ugriz) and near-infrared (IR; YJK(s)) spectral energy distributions (SEDs) of background galaxies. The reddening map is created using a subsample of 29 274 galaxies with low levels of intrinsic reddening based on the LEPHARE chi(2) minimization SED-fitting routine. We find statistically significant enhanced levels of reddening associated with the main body of the SMC compared with regions in the outskirts [Delta E(B - V) similar or equal to 0.3 mag]. A comparison with literature reddening maps of the SMC shows that, after correcting for differences in the volume of the SMC sampled, there is good agreement between our results and maps created using young stars. In contrast, we find significant discrepancies between our results and maps created using old stars or based on longer wavelength far-IR dust emission that could stem from biased samples in the former and uncertainties in the far-IR emissivity and the optical properties of the dust grains in the latter. This study represents one of the first large-scale categorizations of extragalactic sources behind the SMC and as such we provide the LEPHARE outputs for our full sample of similar to 500 000 sources. © 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society, This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement no. 682115). SR acknowledges support from the ERC consolidator grant project STARKEY(grant agreement no. 615604). YC acknowledges support from NSF grant AST 1655677. DMDacknowledges financial support from the Spanish Ministry for Science, Innovation and Universities and FEDER funds through grant AYA2016-81065-C2-2, the State Agency for Research of the Spanish MCIU through the 'Centre of Excellence Severo Ochoa' award for the Instituto de Astrofisica de Andalucia (SEV-2017-0709) and from grant PGC2018-095049B-C21. RRM acknowledges partial support from project BASAL AFB-170002 as well as FONDECYT project no. 1170364. SS acknowledges support from the Science and Engineering Research Board, India through a Ramanujan Fellowship. The authors would like to thank the Cambridge Astronomy Survey Unit (CASU) and theWide Field Astronomy Unit (WFAU) in Edinburgh for providing the necessary data products under the support of the Science and Technology Facilities Council (STFC) in theU.K. The authorswould also like to thank K. Gordon and J. Roman-Duval for discussions related to the use of the HERITAGE dust maps. The authors would like to extend their gratitude to the referee, Geoff Clayton, who provided several comments that improved the manuscript. This study was based on observations made with VISTA at the La Silla Paranal Observatory under programme ID 179.B-2003. This project used data obtained with the Dark Energy Camera (DECam), which was constructed by the Dark Energy Survey (DES) collaboration. Funding for the DES Projects has been provided by the U.S. Department of Energy, the U.S. National Science Foundation, the Ministry of Science and Education of Spain, the STFC, the Higher Education Funding Council for England, the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, the Kavli Institute of Cosmological Physics at the University of Chicago, the Center for Cosmology and Astro-Particle Physics at the Ohio State University, the Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University, Financiadora de Estudos e Projetos, Fundacao Carlos Chagas Filho de Amparo 'a Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Cientifico e Tecnologico and the Ministerio da Ciencia, Tecnologia e Inovacao, the Deutsche Forschungsgemeinschaft, and the Collaborating Institutions in the Dark Energy Survey. The Collaborating Institutions are Argonne National Laboratory, the University of California at Santa Cruz, the University of Cambridge, Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas-Madrid, the University of Chicago, University College London, the DES-Brazil Consortium, the University of Edinburgh, the Eidgenossische Technische Hochschule (ETH) Zurich, Fermi NationalAccelerator Laboratory, the University of Illinois atUrbanaChampaign, the Institut de Ciencies de l'Espai (IEEC/CSIC), the Institut de Fisica d'Altes Energies, Lawrence Berkeley National Laboratory, the Ludwig-Maximilians Universitat Munchen and the associated Excellence Cluster Universe, the University of Michigan, the National Optical Astronomy Observatory, the University of Nottingham, the Ohio State University, the University of Pennsylvania, the University of Portsmouth, SLAC National Accelerator Laboratory, Stanford University, the University of Sussex, and Texas A&M University. Based on observations at Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory (NOAO Prop. ID: 2013A-0411 and 2013B-0440; PI: Nidever), which is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. Finally, this project has made extensive use of the Tool for OPerations on Catalogues And Tables (TOPCAT) software package (Taylor 2005) as well as the following open-source PYTHON packages: Astropy (The Astropy Collaboration 2018), MATPLOTLIB (Hunter 2007), NUMPY (Oliphant 2015), PANDAS (McKinney 2010), and SCIPY (Virtanen et al. 2020).

The Magellanic Clouds are nearby dwarf irregular galaxies whose morphologies show different properties when traced by different stellar populations, making them an important laboratory for studying galaxy morphologies. We study the morphology of the Magellanic Clouds using data from the VISTA survey of the Magellanic Clouds system (VMC). We used about $10$ and $2.5$ million sources across an area of $\sim105$ deg$^2$ and $\sim42$ deg$^2$ towards the Large and Small Magellanic Cloud (LMC and SMC), respectively. We estimated median ages of stellar populations occupying different regions of the near-infrared ($J-K_\mathrm{s}, K_\mathrm{s}$) colour-magnitude diagram. Morphological maps were produced and detailed features in the central regions were characterised for the first time with bins corresponding to a spatial resolution of $0.13$ kpc (LMC) and $0.16$ kpc (SMC). In the LMC, we find that main sequence stars show coherent structures that grow with age and trace the multiple spiral arms of the galaxy, star forming regions become dimmer as we progress in age, while supergiant stars are centrally concentrated. Intermediate-age stars, despite tracing a regular and symmetrical morphology, show central clumps and hints of spiral arms. In the SMC, young main sequence stars depict a broken bar. Intermediate-age populations show signatures of elongation towards the Magellanic Bridge that can be attributed to the LMC-SMC interaction $\sim200$ Myr ago. They also show irregular central features suggesting that the inner SMC has also been influenced by tidal interactions., Accepted for publication in MNRAS, 20 pages, 12 figures and 2 tables

We present a self-consistent, absolute isochronal age scale for young (< 200 Myr), nearby (< 100 pc) moving groups, which is consistent with recent lithium depletion boundary ages for both the Beta Pic and Tucana-Horologium moving groups. This age scale was derived using a set of semi-empirical pre-main-sequence model isochrones that incorporate an empirical colour-Teff relation and bolometric corrections based on the observed colours of Pleiades members, with theoretical corrections for the dependence on log g. Absolute ages for young, nearby groups are vital as these regions play a crucial role in our understanding of the early evolution of low- and intermediate-mass stars, as well as providing ideal targets for direct imaging and other measurements of dusty debris discs, substellar objects and, of course, extrasolar planets., 8 pages, Proceedings IAU Symposium No. 314, Young Stars & Planets Near the Sun, 2015, J. H. Kastner, B. Stelzer, & S. A. Metchev, eds

The Magellanic Clouds are nearby dwarf irregular galaxies that represent a unique laboratory for studying galaxy interactions. Their morphology and dynamics have been heavily influenced by their mutual interactions as well as with their interaction(s) with the Milky Way. We use the VISTA near-infrared YJKs survey of the Magellanic Clouds system (VMC) in combination with stellar partial models of the Large Magellanic Cloud (LMC), the Small Magellanic Cloud (SMC) and the Milky Way to investigate the spatial distribution of stellar populations of different ages across the Magellanic Clouds. In this contribution, we present the results of these studies that allow us to trace substructures possibly related to the interaction history of the Magellanic Clouds., Comment: 4 pages, 2 figures, Poster contribution, IAU Symposium 344, Dwarf Galaxies: from the Deep Universe to the Present, (Eds) S. Stierwalt & K. McQuinn

We search for systems hosting eclipsing discs using a complete sample of eclipsing binaries (EBs); those previously identified in the third phase of the Optical Gravitational Lensing Experiment (OGLE-III). Within a subsample of 2,823 high-cadence, high-photometric precision and large eclipsing depth detached EBs previously identified in the Large Magellanic Cloud (LMC), we find that the skewness and kurtosis of the light curves magnitude distribution within the primary eclipse can distinguish EBs hosting a disc from those without. Two systems with previously identified eclipsing discs (OGLE-LMC-ECL-11893 and OGLE-LMC-ECL-17782) are identified with near zero skewness ($|S, 10 pages, 11 figures, 2 tables, accepted for publication in MNRAS

We searched the light curves of over 40000 stars in the 2 Micron All Sky Survey (2MASS) calibration database, spanning approximately 4 years, for objects that have significant day long dimming events. We also searched the multi-color light curves for red dimming events that could be due to transient extinction. In the color independent sigma-limited search, we found 46 previously unknown eclipsing binaries, 6 periodic variable stars likely to be intrinsic pulsators and 21 young stellar objects in the ρ Ophiucus star formation region previously studied by Parks et al. 2013. An additional 11 objects exhibited dimming events and most of these are unclassified. The search for red dimming events primarily reveals a population of low luminosity active galaxies that become bluer when they are brighter, and variable young stellar objects exhibiting high cross-correlation coefficients between color and brightness. The young stellar objects exhibit brightness and color variations in the direction of interstellar extinction whereas the active galaxies can have a bowed distribution in color and magnitude with reduced variation in color when the object is brightest. Among the objects that are usually quiescent (not strongly variable), we failed to find any dimming events deeper than 0.2 magnitude and lasting longer than a day. Two of the least embedded young stellar objects, however, dimmed by 0.2 mag for longer than a day without strong color variation. Having failed to find new exotic objects, we explored ways to eliminate commonly found objects so that a larger number of objects may be searched. We find that all but one eclipsing binary are excluded by requiring moderate color variation during a dimming event and most of the active galaxies are excluded by placing a limit on the standard deviation of the magnitude distribution in the light curve.

We have used medium resolution spectra to search for evidence that proto-stellar objects accrete at high rates during their early 'assembly phase'. Models predict that depleted lithium and reduced luminosity in T-Tauri stars are key signatures of 'cold' high-rate accretion occurring early in a star's evolution. We found no evidence in 168 stars in NGC 2264 and the Orion Nebula Cluster for strong lithium depletion through analysis of veiling corrected 6708 angstrom lithium spectral line strengths. This suggests that 'cold' accretion at high rates (M_dot > 5 x 10-4 M_sol yr-1) occurs in the assembly phase of fewer than 0.5 per cent of 0.3 < M < 1.9 M_sol stars. We also find that the dispersion in the strength of the 6708 angstrom lithium line might imply an age spread that is similar in magnitude to the apparent age spread implied by the luminosity dispersion seen in colour magnitude diagrams. Evidence for weak lithium depletion (< 10 per cent in equivalent width) that is correlated with luminosity is also apparent, but we are unable to determine whether age spreads or accretion at rates less than 5 x 10-4 M_sol yr-1 are responsible., 13 pages, 10 figures; Accepted for publication in Monthly Notices of the Royal Astronomical Society, 2013 June 03

We present a critical assessment of commonly used pre-main-sequence isochrones by comparing their predictions to a set of well-calibrated colour-magnitude diagrams of the Pleiades in the wavelength range 0.4 to 2.5 microns. Our analysis shows that for temperatures less than 4000 K the models systematically overestimate the flux by a factor two at 0.5 microns, though this decreases with wavelength, becoming negligible at 2.2 microns. In optical colours this will result in the ages for stars younger than 10 Myr being underestimated by factors between two and three. We show that using observations of standard stars to transform the data into a standard system can introduce significant errors in the positioning of pre-main-sequences in colour-magnitude diagrams. Therefore we have compared the models to the data in the natural photometric system in which the observations were taken. Thus we have constructed and tested a model of the system responses for the Wide-Field Camera on the Isaac Newton Telescope. As a benchmark test for the development of pre-main-sequence models we provide both our system responses and the Pleiades sequence.

We present three new nearby L dwarf candidates, found in a continued combined color/proper motion search using WISE, 2MASS, and other survey data, where we included extended WISE sources and looked closer to the Galactic plane region. Their spectral types and distances were estimated from photometric comparisons to well-known L dwarfs with trigonometric parallaxes. The first object, 2MASS J07555430-3259589, is an extremely red L7.5p dwarf candidate at a photometric distance of about 16 pc. Its position, proper motion and distance are consistent with membership in the Carina-Near young moving group. The second one, 2MASS J07414279-0506464, is resolved in Gaia DR1 as a close binary (separation 0.3 arcsec), and we classify it as a equal-mass binary candidate consisting of two L5 dwarfs at 19 pc. Our nearest new neighbor, 2MASS J19251275+0700362, is an L7 dwarf candidate at 10 pc.

We present new deep UBVRI images and high-resolution multi-object optical spectroscopy of the young (~ 6 - 10 Myr old), relatively nearby (800 pc) open cluster IC 2395. We identify nearly 300 cluster members and use the photometry to estimate their spectral types, which extend from early B to middle M. We also present an infrared imaging survey of the central region using the IRAC and MIPS instruments on board the Spitzer Space Telescope, covering the wavelength range from 3.6 to 24 microns. Our infrared observations allow us to detect dust in circumstellar disks originating over a typical range of radii ~ 0.1 to ~ 10AU from the central star. We identify 18 Class II, 8 transitional disk, and 23 debris disk candidates, respectively 6.5%, 2.9%, and 8.3% of the cluster members with appropriate data. We apply the same criteria for transitional disk identification to 19 other stellar clusters and associations spanning ages from ~ 1 to ~ 18 Myr. We find that the number of disks in the transitional phase as a fraction of the total with strong 24 micron excesses ([8] - [24] > 1.5) increases from 8.4 +\- 1.3% at ~ 3 Myr to 46 +\- 5% at ~ 10 Myr. Alternative definitions of transitional disks will yield different percentages but should show the same trend., accepted by the Astrophysical Journal

Theory of Star Formation and Dynamical Evolution of Stellar Systems.- Kinematics of Star Clusters and Associations.- From whence the Field.

Using semi-empirical isochrones, we find the age of the Taurus star-forming region to be 3-4 Myr. Comparing the disc fraction in Taurus to young massive clusters suggests discs survive longer in this low density environment. We also present a method of photometrically de-reddening young stars using $iZJH$ data., Comment: 2 pages, 1 figure, To appear in "Young Stars and Planets Near the Sun", Proceedings of IAU Symposium No. 314 (Cambridge University Press), J.H. Kastner, B. Stelzer, S.A. Metchev, eds

We present a deep Cousins RI photometric survey of the open cluster NGC 1960, complete to R_C \simeq 22, I_C \simeq 21, that is used to select a sample of very low-mass cluster candidates. Gemini spectroscopy of a subset of these is used to confirm membership and locate the age-dependent "lithium depletion boundary" (LDB) --the luminosity at which lithium remains unburned in its low-mass stars. The LDB implies a cluster age of 22 +/-4 Myr and is quite insensitive to choice of evolutionary model. NGC 1960 is the youngest cluster for which a LDB age has been estimated and possesses a well populated upper main sequence and a rich low-mass pre-main sequence. The LDB age determined here agrees well with precise age estimates made for the same cluster based on isochrone fits to its high- and low-mass populations. The concordance between these three age estimation techniques, that rely on different facets of stellar astrophysics at very different masses, is an important step towards calibrating the absolute ages of young open clusters and lends confidence to ages determined using any one of them., Comment: Accepted for publication in MNRAS

The Large and Small Magellanic Clouds (LMC and SMC) 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 DECam survey of the Clouds mapping 480 square degrees (distributed over ~2400 square degrees at ~20% filling factor) to ~24th mag in ugriz with the goal of identifying broadly distributed, low surface brightness stellar populations associated with the stellar halos and tidal debris of the Clouds. SMASH will also derive spatially-resolved star formation histories covering all ages out to large radii from the MCs that will further complement our understanding of their formation. 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, PHOTRED, an automated PSF photometry pipeline based mainly on the DAOPHOT suite, and custom calibration software. The attained astrometric precision is ~15 mas and the accuracy is ~2 mas with respect to the Gaia DR1 astrometric reference frame. The photometric precision is ~0.5-0.7% in griz and ~1% in u with a calibration accuracy of ~1.3% in all bands. The median 5 sigma point source depths in ugriz bands are 23.9, 24.8, 24.5, 24.2, 23.5 mag. The SMASH data already have been used to discover the Hydra II Milky Way satellite, the SMASH 1 old globular cluster likely associated with the LMC, and very extended stellar populations around the LMC out to R~18.4 kpc. SMASH DR1 contains measurements of ~100 million objects distributed in 61 fields. A prototype version of the NOAO Data Lab provides data access, including a data discovery tool, SMASH database access, an image cutout service, and a Jupyter notebook server with example notebooks for exploratory analysis., 23 pages, 12 figures. Revised and slightly reorganized based on referee's comments. Accepted for publication in AJ