A survey of extended objects in the Large Magellanic Cloud was carried out on the ESO/SERC R and J Sky Survey Atlases, checking entries in previous catalogs and searching for new objects. The census provided 6659 objects including star clusters, emission-free associations, and objects related to emission nebulae. Each of these classes contains three subclasses with intermediate properties, which are used to infer total populations. The survey includes cross identifications among catalogs, and we present 3246 new objects. We provide accurate positions, classification, and homogeneous measurements of sizes and position angles, as well as information on cluster pairs and hierarchical relation for superimposed objects. This unification and enlargement of catalogs is important for future searches of fainter and smaller new objects. We discuss the angular and size distributions of the objects of the different classes. The angular distributions show two off-centered systems with different inclinations, suggesting that the LMC disk is warped. The present catalog together with its previous counterpart for the SMC and the inter-Cloud region provide a total population of 7847 extended objects in the Magellanic System. The angular distribution of the ensemble reveals important clues on the interaction between the LMC and SMC.
We present 2323 high-amplitude {delta}-Scuti (HADS) candidates discovered in the Large Magellanic Cloud by the SuperMACHO survey (Rest et al., 2005ApJ...634.1103R). Frequency analyses of these candidates reveal that several are multimode pulsators, including 119 whose largest amplitude of pulsation is in the fundamental (F) mode and 19 whose largest amplitude of pulsation is in the first overtone (FO) mode.
We present observational details and first results of a near-infrared (JHK_s_) synoptic survey of the central region of the Large Magellanic Cloud (LMC) using the CPAPIR camera at the CTIO 1.5m telescope. We covered 18 square degrees to a depth of K_s_~16.5mag and obtained an average of 16 epochs in each band at any given location. Our catalog contains more than 3.5x10^6^ sources, including 1417 Cepheid variables previously studied at optical wavelengths by the OGLE survey. Our sample of fundamental-mode pulsators represents a nine-fold increase in the number of these variables with time-resolved, multi-band near-infrared photometry. We combine our large Cepheid sample and a recent precise determination of the distance to the LMC to derive a robust absolute calibration of the near-infrared Leavitt Law for fundamental-mode and first-overtone Cepheids with 10x better constraints on the slopes relative to previous work. We also obtain calibrations for the tip of the red giant branch and the red clump based on our ensemble photometry which are in good agreement with previous determinations.
We present time-series observations of Population II Cepheids in the Large Magellanic Cloud at near-infrared (JHK_s_) wavelengths. Our sample consists of 81 variables with accurate periods and optical (VI) magnitudes from the OGLE survey, covering various subtypes of pulsators (BL Herculis, W Virginis, and RV Tauri). We generate light-curve templates using high-quality I-band data in the LMC from OGLE and K_s_-band data in the Galactic bulge from VISTA Variables in Via Lactea survey (2010NewA...15..433M) and use them to obtain robust mean magnitudes. We derive period-luminosity (P-L) relations in the near-infrared and Period-Wesenheit (P-W) relations by combining optical and near-infrared data. Our P-L and P-W relations are consistent with published work when excluding long-period RV Tauris. We find that Pop II Cepheids and RR Lyraes follow the same P-L relations in the LMC. Therefore, we use trigonometric parallax from the Gaia DR1 (Cat. I/337) for VY Pyx and the Hubble Space Telescope parallaxes for k Pav and 5 RR Lyrae variables to obtain an absolute calibration of the Galactic K_s_-band P-L relation, resulting in a distance modulus to the LMC of {mu}_LMC_=18.54+/-0.08 mag. We update the mean magnitudes of Pop II Cepheids in Galactic globular clusters using our light-curve templates and obtain distance estimates to those systems, anchored to a precise late-type eclipsing binary distance to the LMC. We find that the distances to these globular clusters based on Pop II Cepheids are consistent (within 2{sigma}) with estimates based on the M_V_-[Fe/H] relation for horizontal branch stars.
We present new near-infrared (NIR) Cepheid period-Wesenheit (P-W) relations in the LMC using time-series observations from the Large Magellanic Cloud NIR Synoptic Survey. We also derive optical+NIR P-W relations using V and I magnitudes from the Optical Gravitational Lensing Experiment. We employ our new JHK_s_ data to determine an independent distance to the LMC of {mu}_LMC_=18.47+/-0.07 (statistical) mag, using an absolute calibration of the Galactic relations based on several distance determination methods and accounting for the intrinsic scatter of each technique. We also derive new NIR period-luminosity and Wesenheit relations for Cepheids in M31 using observations from the Panchromatic Hubble Andromeda Treasury survey. We use the absolute calibrations of the Galactic and LMC W_J,H_ relations to determine the distance modulus of M31, {mu}_M31_=24.46+/-0.20 mag. We apply a simultaneous fit to Cepheids in several Local Group galaxies covering a range of metallicities (7.7<12+log[O/H]<8.6 dex) to determine a global slope of -3.244+/-0.016 mag/dex for the W_J,H_ relation and obtain robust distance estimates. Our distances are in good agreement with recent TRGB based distance estimates and we do not find any evidence for a metallicity dependence in the NIR P-W relations.
LMC NIR synoptic survey. V. NIR photometry of Miras
Short Name:
J/AJ/154/149
Date:
21 Oct 2021
Publisher:
CDS
Description:
We study the near-infrared properties of 690 Mira candidates in the central region of the Large Magellanic Cloud, based on time-series observations at JHK_s_. We use densely sampled I-band observations from the OGLE project to generate template light curves in the near-infrared and derive robust mean magnitudes at those wavelengths. We obtain near-infrared Period-Luminosity relations for oxygen-rich Miras with a scatter as low as 0.12 mag at K_s_. We study the Period-Luminosity-Color relations and the color excesses of carbon-rich Miras, which show evidence for a substantially different reddening law.
We describe variable stars found in the data collected during the OGLE-III Shallow Survey covering the I-band magnitude range from 9.7mag to 14.5mag. The main result is the extension of period-luminosity relations for Cepheids up to 134 days. We also detected 82 binary systems and 110 long-period variables not present in the main OGLE catalogs. Additionally 558 objects were selected as candidates for miscellaneous variables.
We present photometric maps based on data from the shallow survey in the Large Magellanic Cloud performed as the supplementary project during the third phase of the Optical Gravitational Lensing Experiment (OGLE) . They cover about 40 square degrees in the LMC and contain mean calibrated VI photometry and astrometry of about 1.7million stars. The magnitudes of the objects range from 9.1 to 18.5.
We present the classification of 197 point sources observed with the Infrared Spectrograph in the SAGE-Spec Legacy programme on the Spitzer Space Telescope. We introduce a decision-tree method of object classification based on infrared spectral features, continuum and spectral energy distribution shape, bolometric luminosity, cluster membership and variability information, which is used to classify the SAGE-Spec sample of point sources. The decision tree has a broad application to mid-infrared spectroscopic surveys, where supporting photometry and variability information are available. We use these classifications to make deductions about the stellar populations of the Large Magellanic Cloud and the success of photometric classification methods. We find 90 asymptotic giant branch (AGB) stars, 29 young stellar objects, 23 post-AGB objects, 19 red supergiants, eight stellar photospheres, seven background galaxies, seven planetary nebulae, two HII regions and 12 other objects, seven of which remain unclassified.
The method developed by Gouliermis et al. (2000AJ....119.1737G), for the detection and classification of stellar systems in the LMC, was used for the identification of stellar associations and open clusters in the central area of the LMC. This method was applied on the stellar catalog produced from a scanned 1.2m UK Schmidt Telescope Plate in U with a field of view almost 6.5degx6.5deg, centered on the Bar of this galaxy. The survey of the identified systems is presented here followed by the results of the investigation on their spatial distribution and their structural parameters, as were estimated according to our proposed methodology. The detected open clusters and stellar associations show to form large filamentary structures, which are often connected with the loci of HI shells. The derived mean size of the stellar associations in this survey was found to agree with the average size found previously by other authors, for stellar associations in different galaxies. This common size of about 80pc might represent a universal scale for the star formation process, whereas the parameter correlations of the detected loose systems support the distinction between open clusters and stellar associations.
