- ID:
- ivo://CDS.VizieR/J/A+A/621/A62
- Title:
- 4 LMC SFRs velocity profile maps
- Short Name:
- J/A+A/621/A62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The aim of our study is to investigate the physical properties of the star-forming interstellar medium (ISM) in the Large Magellanic Cloud (LMC) by separating the origin of the emission lines spatially and spectrally. The LMC provides a unique local template to bridge studies in the Galaxy and high redshift galaxies because of its low metallicity and proximity, enabling us to study the detailed physics of the ISM in spatially resolved individual star-forming regions. Following Okada et al. (2015A&A...580A..54O), we investigate different phases of the ISM traced by carbon-bearing species in four star-forming regions in the LMC, and model the physical properties using the KOSMA-{tau} PDR model. We mapped 3-13 arcmin^2^ areas in 30 Dor, N158, N160, and N159 along the molecular ridge of the LMC in [C II] 158 {mu}m with GREAT on board SOFIA. We also observed the same area with CO(2-1) to (6-5), ^13^CO(2-1) and (3-2), [C I] ^3^P_1_-^3^P_0_ and ^3^P_2_-^3^P_1_ with APEX. For selected positions in N159 and 30 Dor, we observed [O I] 145 {mu}m and [O I] 63 {mu}m with upGREAT. All spectra are velocity resolved. In all four star-forming regions, the line profiles of CO, ^13^CO, and [C I] emission are similar, being reproduced by a combination of Gaussian profiles defined by CO(3-2), whereas [C II] typically shows wider line profiles or an additional velocity component. At several positions in N159 and 30 Dor, we observed the velocity-resolved [O I] 145 and 63 {mu}m lines for the first time. At some positions, the [O I] line profiles match those of CO, at other positions they are more similar to the [C II] profiles. We interpret the different line profiles of CO, [C II] and [O I] as contributions from spatially separated clouds and/or clouds in different physical phases, which give different line ratios depending on their physical properties. We modeled the emission from the CO, [C I], [C II], and [O I] lines and the far-infrared continuum emission using the latest KOSMA-{tau} PDR model, which treats the dust-related physics consistently and computes the dust continuum SED together with the line emission of the chemical species. We find that the line and continuum emissions are not well-reproduced by a single clump ensemble. Toward the CO peak at N159 W, we propose a scenario that the CO, [C II], and [O I] 63 {mu}m emission are weaker than expected because of mutual shielding among clumps.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/811/145
- Title:
- LMC & SMC evolved stars detected with Herschel
- Short Name:
- J/ApJ/811/145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using observations from the Herschel Inventory of The Agents of Galaxy Evolution (HERITAGE) survey of the Magellanic Clouds (MC), we have found 35 evolved stars and stellar end products that are bright in the far-infrared. These 28 (LMC) and 7 (SMC) sources were selected from the 529 evolved star candidates in the HERITAGE far-infrared point source catalogs. Our source identification method is based on spectral confirmation, spectral energy distribution characteristics, careful examination of the multiwavelength images and includes constraints on the luminosity, resulting in a thoroughly vetted list of evolved stars. These sources span a wide range in luminosity and hence initial mass. We found 13 low- to intermediate-mass evolved stars, including asymptotic giant branch (AGB) stars, post-AGB stars, planetary nebulae, and a symbiotic star. We also identify 10 high mass stars, including 4 of the 15 known B[e] stars in the MC, 3 extreme red supergiants that are highly enshrouded by dust, a Luminous Blue Variable, a Wolf-Rayet star, and two supernova remnants. Further, we report the detection of 9 probable evolved objects which were previously undescribed in the literature. These sources are likely to be among the dustiest evolved objects in the MC. The Herschel emission may either be due to dust produced by the evolved star or it may arise from swept-up interstellar medium material.
- ID:
- ivo://CDS.VizieR/J/ApJS/75/407
- Title:
- LMC & SMC PNe optical spectroscopy. I
- Short Name:
- J/ApJS/75/407
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical spectroscopy in the range 3300-7400A for a total of 30 planetary nebulae in the LMC and 11 in the SMC, with measurements of line intensities down to ~1% of H{beta}. Agreement with other authors is on the whole excellent, especially for lines >+10%-20% of H{beta}. Reddening estimates from Balmer line ratios have been determined, and the line intensities dereddened accordingly. Nebular [O III] electron temperature and, where measurable, [N II] temperatures and [S II] densities are given. [O II] electron densities are recalculated using appropriate electron temperatures. A number of spectra exhibit interesting spectral features (including symbiotic-type profiles, unidentified emission lines, and nonsimple Balmer decrements). These objects are discussed in some detail. Zanstra temperatures are derived for a total of 25 objects possessing detectable stellar continua. These temperatures are in agreement with the few published values from various methods, and preliminary photoionization modeling of this sample. The homogeneity and size of the sample make it possible to investigate several interesting correlations between measured parameters.
- ID:
- ivo://CDS.VizieR/J/ApJS/76/1085
- Title:
- LMC & SMC PNe optical spectroscopy. II
- Short Name:
- J/ApJS/76/1085
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical spectroscopy in the range 3300-7400A for a total of 37 planetary nebulae in the LMC and seven in the SMC. Together with the object from the first paper in the series (1991ApJS...75..407M), we now have accurate emission-line intensities down to a few percent of H{beta} for 77 nebulae in the Magellanic Clouds. Agreement with other authors is excellent. Reddening estimates from Balmer line ratios have been determined, and the line intensities have been dereddened accordingly. Nebular [O III] electron temperature and, where measurable, [S II] densities, are derived. [O II] electron densities are recalculated using appropriate electron temperatures. The [S II] and [O II] electron densities correlate well, with n_e_([O II])>n_e_([S II]). Zanstra temperatures are in derived for 22 objects possessing detectable stellar continua. These temperatures are in agreement with photoionization modeling of this sample.
- ID:
- ivo://CDS.VizieR/J/ApJS/83/87
- Title:
- LMC & SMC PNe optical spectroscopy. III
- Short Name:
- J/ApJS/83/87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical spectroscopy in the range 3300-7400A for a total of 52 planetary nebulae in the Large Magellanic Cloud (LMC) and 18 in the Small Magellanic Cloud (SMC). Together with the object from the first (1991ApJS...75..407M) and second (1991ApJS...76.1085M) papers, we now have accurate emission-line intensities for a total of 147 nebulae in the Magellanic Clouds. This sample contains a large selection of objects of low luminosity, with measurements of line intensities down to ~10% of H{beta}. Brighter objects have line intensities measured down to ~2% of H{beta}. Agreement with other authors is generally very good, especially for lines greater than approximately 10% of H{beta}. Reddening estimates from Balmer line ratios have been determined: unreddened and reddened line intensities are tabulated.
- ID:
- ivo://CDS.VizieR/J/AJ/116/723
- Title:
- LMC star clusters ages and metallicity
- Short Name:
- J/AJ/116/723
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Washington system CT_1_ color-magnitude diagrams of 13 star clusters and their surrounding fields that lie in the outer parts of the LMC disk (r>4{deg}), as well as a comparison inner cluster. The total area covered is large (2/3deg^2^), allowing us to study the clusters and their fields individually and in the context of the entire Galaxy. Ages are determined by means of the magnitude difference {delta}T_1_ between the giant branch clump and the turnoff, while metallicities are derived from the location of the giant and subgiant branches as compared with fiducial star clusters. This yields a unique data set in which ages and metallicities for both a significant sample of clusters and their fields are determined homogeneously. We find that in most cases the stellar population of each star cluster is quite similar to that of the field where it is embedded, sharing its mean age and metallicity. The old population (t>=10Gyr) is detected in most fields as a small concentration of stars on the horizontal branch blueward and faintward of the prominent clump.
- ID:
- ivo://CDS.VizieR/J/A+A/586/A41
- Title:
- LMC star clusters catalog
- Short Name:
- J/A+A/586/A41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The main goal of this study is to compile a catalogue of the fundamental parameters of a complete sample of 277 star clusters (SCs) of the Large Magellanic Cloud (LMC) observed in the Washington photometric system. A set of 82 clusters was recently studied by our team. All the clusters' parameters such as radii, deprojected distances, reddenings, ages, and metallicities were obtained by applying essentially the same procedures, which are briefly described here. We used empirical cumulative distribution functions to examine age, metallicity and deprojected distance distributions for different cluster subsamples of the catalogue. Our new sample of 82 additional clusters represents about a 40% increase in the total number of LMC SCs observed to date in the Washington photometric system. In particular, we report here the fundamental parameters obtained for the first time for 42 of these clusters. We found that single LMC SCs are typically older than multiple SCs. Both single and multiple SCs exhibit asymmetrical distributions in log (age). We compared cluster ages derived through isochrone fittings obtained using different models of the Padova group. Although ages obtained using recent isochrones are consistent in general terms, we found that there is some disagreement in the obtained values and their uncertainties.
- ID:
- ivo://CDS.VizieR/J/AJ/142/48
- Title:
- LMC star clusters structural parameters
- Short Name:
- J/AJ/142/48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present and analyze the radial luminosity profiles of a sample of 1066 stellar clusters in the Large Magellanic Cloud (LMC). By design, this study closely follows the compilation by Hill & Zaritsky (2006, Cat. J/AJ/131/414 of the structural parameters of stellar clusters in the Small Magellanic Cloud (SMC). Both King and Elson-Fall-Freeman model profiles are fit to V-band surface brightness profiles measured from the Magellanic Cloud Photometric Survey images. We tabulate the concentration, central surface brightness, tidal radii, 90% enclosed luminosity radii (r_90_), and local background luminosity density. Over two-thirds of the clusters in the sample are adequately fit by one or both of these models. One notable and systematic exception, as in the SMC, is those clusters that lack a central brightness concentration, the "ring" clusters. While the bulk properties of the clusters are similar between the LMC and SMC populations, we find that the LMC lacks clusters that are as large, either in terms of core radii or r90, as the largest in the SMC, perhaps a signature of larger tidal stresses in the LMC.
- ID:
- ivo://CDS.VizieR/J/A+A/405/111
- Title:
- LMC Survey of Young Stellar Systems
- Short Name:
- J/A+A/405/111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 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.
- ID:
- ivo://CDS.VizieR/J/MNRAS/446/3034
- Title:
- LMC Type II Cepheids J and Ks light curves
- Short Name:
- J/MNRAS/446/3034
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The VISTA (Visible and Infrared Survey Telescope for Astronomy) survey of the Magellanic Clouds System (VMC) is collecting deep Ks-band time-series photometry of the pulsating variable stars hosted in the system formed by the two Magellanic Clouds and the Bridge connecting them. In this paper, we have analysed a sample of 130 Large Magellanic Cloud (LMC) Type II Cepheids (T2CEPs) found in tiles with complete or near-complete VMC observations for which identification and optical magnitudes were obtained from the OGLE III (Optical Gravitational Lensing Experiment) survey. We present J and Ks light curves for all 130 pulsators, including 41 BL Her, 62 W Vir (12 pW Vir) and 27 RV Tau variables. We complement our near-infrared photometry with the V magnitudes from the OGLE III survey, allowing us to build a variety of period-luminosity (PL), period-luminosity-colour (PLC) and period-Wesenheit (PW) relationships, including any combination of the V, J, Ks filters and valid for BL Her and W Vir classes. These relationships were calibrated in terms of the LMC distance modulus, while an independent absolute calibration of the PL(Ks) and the PW(Ks, V) was derived on the basis of distances obtained from Hubble Space Telescope parallaxes and Baade-Wesselink technique. When applied to the LMC and to the Galactic globular clusters hosting T2CEPs, these relations seem to show that (1) the two Population II standard candles RR Lyrae and T2CEPs give results in excellent agreement with each other; (2) there is a discrepancy of ~0.1mag between Population II standard candles and classical Cepheids when the distances are gauged in a similar way for all the quoted pulsators. However, given the uncertainties, this discrepancy is within the formal 1{sigma} uncertainties.
