- ID:
- ivo://CDS.VizieR/J/MNRAS/331/609
- Title:
- Catalogue of eclipsing binaries in the SMC
- Short Name:
- J/MNRAS/331/609
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalogue lists 167 eclipsing binary stars in the Small Magellanic Cloud detected in the database of time-series photometry for 400000 SMC stars acquired by the Microlensing Observations in Astrophysics (MOA) project during 1997. Coordinates, ephemerides, magnitudes and light curves are presented. Thirty-five systems are new detections. The limiting magnitude is about 17.5. The majority of periods lie within the range 0.4 to 20 days; 6 systems are possibly eccentric while 14 are probably or certainly so. The majority of the newly-identified systems lie in the outer regions of the SMC.
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- ID:
- ivo://CDS.VizieR/J/MNRAS/389/678
- Title:
- Catalogue of extended objects in Magellanic Clouds
- Short Name:
- J/MNRAS/389/678
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We update the Small Magellanic Cloud (SMC), Bridge and Large Magellanic Cloud (LMC) catalogues of extended objects that were constructed by members of our group from 1995 to 2000. In addition to the rich subsequent literature for the previous classes, we now also include HI shells and supershells. A total of 9305 objects were cross-identified, while our previous catalogues amounted to 7900 entries, an increase of ~12 per cent. We present the results in subcatalogues containing 1445 emission nebulae, 3740 star clusters, 3326 associations and 794 HI shells and supershells. Angular and apparent size distributions of the extended objects are analysed. We conclude that the objects, in general, appear to respond to tidal effects arising from the LMC, SMC and Bridge. Number-density profiles extracted along directions parallel and perpendicular to the LMC bar, can be described by two exponential-discs. A single exponential-disc fits the equivalent SMC profiles. Interestingly, when angular-averaged number-densities of most of the extended objects are considered, the profiles of both Clouds do not follow an exponential-disc. Rather, they are best described by a tidally truncated, core/halo profile, despite the fact that the Clouds are clearly disturbed discs. On the other hand, the older star clusters taken isolately, distribute as an exponential disc. The present catalogue is an important tool for the unambiguous identification of previous objects in current CCD surveys and to establish new findings.
- ID:
- ivo://CDS.VizieR/V/131
- Title:
- Catalogue of LMC stars
- Short Name:
- V/131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalogue is a compilation of the original data related to stars in the Large Magellanic Cloud (LMC); it concerns essentially the stars brighter than m_pg_=13.5. The list includes many comments (in English and French) about errors, identification problems, or membership of 4011 stars.
- ID:
- ivo://CDS.VizieR/J/MNRAS/425/3085
- Title:
- CCD CT1 data of stars in the field of B119
- Short Name:
- J/MNRAS/425/3085
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present for the first time Washington CT_1_ photometry for 11 unstudied or poorly studied candidate star clusters. The selected objects are of small angular size, contain a handful of stars, and are projected towards the innermost regions of the Small Magellanic Cloud (SMC). The respective colour-magnitude diagrams (CMDs) were cleaned of the unavoidable star field contamination by taking advantage of a procedure which makes use of variable size CMD cells. This method has shown to be able to eliminate stochastic effects in the cluster CMDs caused by the presence of isolated bright stars, as well as to make a finer cleaning in the most populous CMD regions. Our results suggest that nearly one-third of the studied candidate star clusters would appear to be genuine physical systems.
- ID:
- ivo://CDS.VizieR/J/A+A/371/L5
- Title:
- CCD {Delta}a-photometry of NGC 1866
- Short Name:
- J/A+A/371/L5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the detection of the first extragalactic, classical chemically peculiar (CP) stars more than 100 years after the discovery of this group. Using the tool of CCD {Delta}a-photometry, eight definite positive detections in the globular-like stellar cluster NGC 1866 and its surrounding in the Large Magellanic Cloud were made. More than 1950 objects within a radius of 9.5' of the cluster center down to 20.5 magnitude were observed in this three filter, narrow band photometric system. Averaging more than 70 individual frames for all three filters yielded a 3{sigma} detection limit of 0.015mag for stars with V=20mag. Furthermore we found three objects with significantly negative {Delta}a-values indicating either an Ae/shell or {lambda} Bootis nature. The overall percentage of chemically peculiar stars for NGC 1866 (1.5%) seems lower than for the majority of open clusters in our Milky Way whereas the incidence within the LMC field is decisively less (0.3%). For a description of the {Delta}a photometric system, see e.g. <GCPD/75>
- ID:
- ivo://CDS.VizieR/J/MNRAS/260/782
- Title:
- CCD photometry of NGC 2004 and 2100
- Short Name:
- J/MNRAS/260/782
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we present results of CCD UBV photometry of stars in two young LMC clusters: NGC 2004 and 2100. A comparison of recent CCD investigations of these clusters shows large zero-point discrepancies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/450/2122
- Title:
- CCD photometry of star clusters in the LMC
- Short Name:
- J/MNRAS/450/2122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Washington system colour-magnitude diagrams (CMDs) for 17 practically unstudied star clusters located in the bar as well as in the inner disc and outer regions of the Large Magellanic Cloud (LMC). Cluster sizes were estimated from star counts distributed throughout the entire observed fields. Based on the best fits of theoretical isochrones to the cleaned (C-T_1_, T_1_) CMDs, as well as on the {delta}T_1_ parameter and the standard giant branch method, we derive ages and metallicities for the cluster sample. Four objects are found to be intermediate-age clusters (1.8-2.5 Gyr), with [Fe/H] ranging from -0.66 to -0.84. With the exception of SL 263, a very young cluster (~16 Myr), the remaining 12 objects are aged between 0.32 and 0.89 Gyr, with their [Fe/H] values ranging from -0.19 to -0.50. We combined our results with those for other 231 clusters studied in a similar way using the Washington system. The resulting age-metallicity relationship shows a significant dispersion in metallicities, whatever age is considered. Although there seems to exist a clear tendency for the younger clusters to be more metal rich than the intermediate ones, we believe that none of the chemical evolution models currently available in the literature reasonably well represents the recent chemical enrichment processes in the LMC clusters. The present sample of 17 clusters is part of our ongoing project of generating a data base of LMC clusters homogeneously studied using the Washington photometric system and applying the same analysis procedure.
- ID:
- ivo://CDS.VizieR/J/AJ/144/100
- Title:
- CCD Washington CT1T2 photometry of stars in LMC
- Short Name:
- J/AJ/144/100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometry for an unprecedented database of some 5.5million stars distributed throughout the Large Magellanic Cloud main body, from 21 fields covering a total area of 7.6deg^2^, obtained from Washington CT_1_T_2_ CTIO 4m MOSAIC data. Extensive artificial star tests over the whole mosaic image data set and the observed behavior of the photometric errors with magnitude demonstrate the accuracy of the morphology and clearly delineate the position of the main features in the color-magnitude diagrams (CMDs). The representative T_1_(MS TO) mags are on average ~0.5mag brighter than the T_1_ mags for the 100% completeness level of the respective field, allowing us to derive an accurate age estimate. We have analyzed the CMD Hess diagrams and used the peaks in star counts at the main sequence turnoff and red clump (RC) locations to age date the most dominant sub-population (or "representative" population) in the stellar population mix. The metallicity of this representative population is estimated from the locus of the most populous red giant branch track. We use these results to derive age and metallicity estimates for all of our fields. The analyzed fields span age and metallicity ranges covering most of the galaxy's lifetime and chemical enrichment, i.e., ages and metallicities between ~1 and 13Gyr and ~-0.2 and -1.2dex, respectively. We show that the dispersions associated with the mean ages and metallicities represent in general a satisfactory estimate of the age/metallicity spread (~1-3 Gyr/0.2-0.3 dex), although a few subfields have a slightly larger age/metallicity spread. Finally, we revisit the study of the vertical structure (VS) phenomenon, a striking feature composed of stars that extend from the bottom, bluest end of the RC to ~0.45mag fainter. We confirm that the VS phenomenon is not clearly seen in most of the studied fields and suggest that its occurrence is linked to some other condition(s) in addition to the appropriate age, metallicity, and the necessary red giant star density.
- ID:
- ivo://CDS.VizieR/J/AJ/119/1214
- Title:
- Census of star clusters in the SMC
- Short Name:
- J/AJ/119/1214
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Surveys using CCD detectors are retrieving bright and faint catalogued clusters and revealing new ones in the Magellanic Clouds. This paper discusses the contribution of the OGLE Survey to the overall census of star clusters in the Small Magellanic Cloud (SMC). A detailed cross-identification indicates that the new objects in the SMC OGLE catalog are 46. The increase in the number of catalogued clusters is {~}7%, the total sample being {~}700. This updated census includes embedded clusters in H II regions and a density range attaining loose systems.
- ID:
- ivo://CDS.VizieR/J/A+A/385/793
- Title:
- Cepheids in Magellanic Clouds. II.
- Short Name:
- J/A+A/385/793
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The analysis of CCD observations of ten new suspected second overtone mode Cepheids in the SMC does not confirm the nature of such stars; most of them appear to be first overtone mode Cepheids. A careful analysis of the OGLE best second overtone mode candidates and of the second overtone component of double mode Cepheids in SMC and LMC has been performed in order to clarify the possible effects of a resonance between pulsation modes. There are some indications that such a resonance is indeed operating in these pulsators. A brief discussion of the effects of blending on the light curve shape is also reported, and the usefulness of the Fourier parameters as mode discriminators is discussed. The observations were performed with the direct CCD camera at the Dutch 0.91m telescope of La Silla (ESO) during three runs in November 1997 (6 nights), July 1998 (12 nights) and October 1998 (15 nights). The CCD detector was the ESO chip No. 33, which is a TEK CCD with 512x512 pixels, pixel size of 27{mu}m and spatial resolution of 0.44", providing a small field of view of 3.77'x3.77'. 8 fields were selected in order to observe the ten second overtone candidates.
