- ID:
- ivo://CDS.VizieR/J/A+A/616/A187
- Title:
- SMC clusters age-dating & classification
- Short Name:
- J/A+A/616/A187
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim to estimate the age and reddening parameters of already identified star clusters within the Small Magellanic Cloud (SMC) in a consistent way using available photometric data, classify them based on their mass and strength, and study their spatio-temporal distribution. We have used a semi-automated quantitative method, developed in the first paper of this series (Paper I), to estimate the cluster parameters using the V and I band photometric data from the Optical Gravitational Lensing Experiment (OGLE) III survey. We estimated parameters of 179 star clusters (17 are newly parameterised) and classified them into four groups. We present an online catalogue of parameters as well as cleaned and isochrone-fitted colour magnitude diagrams of 179 clusters. We compiled age information of 468 clusters by combining previous studies with our catalogue, to study their spatio-temporal distribution. Most of the clusters located in the southern part of the SMC are in the age range 600Myr-1.25Gyr, whereas, the clusters younger than 100Myr are mostly found in the northern SMC, with the central SMC showing continuous cluster formation. The peak of the cluster age distribution is identified at 130+/-35Myr, very similar to the Large Magellanic Cloud (LMC) in Paper I. We suggest that the burst of cluster formation at 130Myr is due to the most recent LMC-SMC interaction. 90% of the studied sample is found to have mass <1700M_{sun}_, suggesting that the SMC is dominated by low mass clusters. There is tentative evidence for compact clusters in the LMC when compared to those in the Galaxy and the SMC. A progressive shifting of cluster location from the south to north of the SMC is identified in last ~600Myr. The details of spatio-temporal distribution of clusters presented in two videos as part of this study can be used as a tool to constrain details of the recent LMC-SMC interactions.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/438/521
- Title:
- SMC C stars B and R light curves
- Short Name:
- J/A+A/438/521
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A sample of carbon-rich stars (C-stars) in the Small Magellanic Cloud (SMC) was selected from the combined 2MASS and DENIS catalogues on the basis of their J-Ks colour. This sample was extended to include confirmed C-stars from the Rebeirot et al. (1993, Cat. <J/A+AS/97/603>) spectroscopic atlas. In this combined sample (N=1149), a smaller number (N=1079) were found to have MACHO observations. For this sub-sample, light curves were determined and 919 stars were found to have high quality light-curves with amplitudes of at least 0.05mag.
- ID:
- ivo://CDS.VizieR/J/ApJ/771/111
- Title:
- SMC dusty OB stars. I. Optical spectroscopy
- Short Name:
- J/ApJ/771/111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of optical spectroscopic follow-up of 125 candidate main sequence OB stars in the Small Magellanic Cloud (SMC) that were originally identified in the S^3^MC infrared imaging survey as showing an excess of emission at 24{mu}m indicative of warm dust, such as that associated with a transitional or debris disks. We use these long-slit spectra to investigate the origin of the 24{mu}m emission and the nature of these stars. A possible explanation for the observed 24{mu}m excess, that these are emission line stars with dusty excretion disks, is disproven for the majority of our sources. We find that 88 of these objects are normal stars without line emission, with spectral types mostly ranging from late-O to early-B; luminosity classes from the literature for a sub-set of our sample indicate that most are main-sequence stars. We further identify 17 emission-line stars, 7 possible emission-line stars, and 5 other objects with forbidden-line emission in our sample. We discover a new O6 Iaf star; it exhibits strong HeII4686{AA} emission but relatively weak NIII4640{AA} emission which we attribute to the lower nitrogen abundance in the SMC. Two other objects are identified with planetary nebulae, one with a young stellar object, and two with X-ray binaries. To shed additional light on the nature of the observed 24{mu}m excess we use optical and infrared photometry to estimate the dust properties of the objects with normal O and B star spectra and compare these properties to those of a sample of hot spots in the Galactic interstellar medium (ISM).
- ID:
- ivo://CDS.VizieR/J/MNRAS/311/741
- Title:
- SMC emission-line objects
- Short Name:
- J/MNRAS/311/741
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- H{alpha} and [OIII] narrow-band, wide-field (7x7deg^2^), CCD images of the Small Magellanic Cloud were compared, and a catalogue of candidate planetary nebulae and H{alpha} emission-line stars was compiled. The catalogue contains 131 planetary nebulae candidates, 23 of which are already known to be or are probable planetary nebulae or very low excitation objects. Also, 218 emission-line candidates have been identified, with 113 already known. Our catalogue therefore provides a useful supplement to those of Meyssonnier & Azzopardi (1993, Cat. <J/A+AS/102/451>) and Sanduleak, MacConnell & Davis Phillip (1978PASP...90..621S). Further observations are required to confirm the identity of the unknown objects.
- ID:
- ivo://CDS.VizieR/J/MNRAS/289/225
- Title:
- SMC HI shells velocities
- Short Name:
- J/MNRAS/289/225
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a survey of neutral hydrogen emission in the Small Magellanic Cloud (SMC) with the Australia Telescope Compact Array (ATCA). The survey consists of a mosaic of 320 separate pointings of the 375-m array, resulting in a resolution of 1.6arcmin (28pc, for a distance of 60kpc) over a field of 20deg^2^. The rms brightness temperature sensitivity is 1.4K, corresponding to an H I column density sensitivity of 4x^18^cm^-2^ for each velocity channel of width 1.6km/s. The HI distribution is complex and, on scales <=1kpc, appears to be dominated by the effects of expanding H I shells, which are probably driven by the combined effects of supernovae and stellar winds from massive stars. The picture of the SMC that arises from the current data seems to challenge the earlier belief that the SMC consists of two or more spatially separate structures with different systemic velocities. We find that the observed multiple components are, in many cases, caused by the combined effects of the numerous shells and supershells. Altogether, we identify six supershells (defined here as those with radii greater than 300pc) and 495 giant shells. For each of these, we measure positions. radii, velocities and expansion rates, and derive ages and kinetic energy requirements. The apparent age distribution of shells is remarkably narrow, with a mean age of 5.4Myr and an intrinsic dispersion of 2Myr. Southern shells appear to be older, on average, by 2.5Myr. The kinetic energy of the shells is a large fraction of the gravitational binding energy of the SMC, implying that further disintegration of the SMC will occur with time, and especially at the next close passage with the Large Magellanic Cloud (LMC) or the Galaxy, unless the SMC possesses a massive halo. Because of their interferometric nature, the images presented here are insensitive to structures of size >=0.6{deg}, and should not be used for deriving total H I column densities
- ID:
- ivo://CDS.VizieR/J/ApJ/655/212
- Title:
- S3MC IRAC and MIPS photometry
- Short Name:
- J/ApJ/655/212
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the initial results from the Spitzer Survey of the Small Magellanic Cloud (S^3^MC), which imaged the star-forming body of the SMC in all seven MIPS and IRAC wave bands. We find that the F8/F24 ratio (an estimate of PAH abundance) has large spatial variations and takes a wide range of values that are unrelated to metallicity but anticorrelated with 24um brightness and F24/F70 ratio. This suggests that photodestruction is primarily responsible for the low abundance of PAHs observed in star-forming low-metallicity galaxies. We use the S^3^MC images to compile a photometric catalog of 400000 mid- and far-infrared point sources in the SMC.
- ID:
- ivo://CDS.VizieR/J/A+A/436/687
- Title:
- SMC NGC 346-11 and AV 304 spectra
- Short Name:
- J/A+A/436/687
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An analysis of high-resolution VLT/UVES spectra of two B-type main sequence stars, NGC 346-11 and AV 304, in the Small Magellanic Cloud (SMC), has been undertaken, using the non-LTE TLUSTY model atmospheres to derive the stellar parameters and chemical compositions of each star. The chemical compositions of the two stars are in reasonable agreement. Moreover, our stellar analysis agrees well with earlier analyses of HII regions. The results derived here should be representative of the current base-line chemical composition of the SMC interstellar medium as derived from B-type stars.
- ID:
- ivo://CDS.VizieR/J/other/Ser/183.103
- Title:
- SMC observations at 13, 20 and 36cm
- Short Name:
- J/other/Ser/183.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new catalogue of radio-continuum sources in the field of the Small Magellanic Cloud (SMC). This catalogue contains sources previously not found in 2370MHz (λ=13cm) with sources found at 1400MHz (λ=20cm) and 843MHz (λ=36cm). 45 sources have been detected at 13cm, with 1560 sources at 20cm created from new high sensitivity and resolution radio-continuum images of the SMC at 20cm from paper I (Wong et al., <A HREF="http://simbad.cds.unistra.fr/simbad/sim-ref?bibcode=2011SerAJ.182...43W%202011SerAJ.182...43W">2011SerAJ.182...43W 2011SerAJ.182...43W</A>). We also created a 36cm catalogue to which we listed 1689 radio-continuum sources.
- ID:
- ivo://CDS.VizieR/J/ApJ/744/20
- Title:
- S^4^MC project: 6 star forming regions PAHs
- Short Name:
- J/ApJ/744/20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of mid-infrared spectroscopic mapping observations of six star-forming regions in the Small Magellanic Cloud (SMC) from the Spitzer Spectroscopic Survey of the SMC (S^4^MC). We detect the mid-IR emission from polycyclic aromatic hydrocarbons (PAHs) in all of the mapped regions, greatly increasing the range of environments where PAHs have been spectroscopically detected in the SMC. We investigate the variations of the mid-IR bands in each region and compare our results to studies of the PAH bands in the SINGS sample and in a sample of low-metallicity starburst galaxies. PAH emission in the SMC is characterized by low ratios of the 6-9um features relative to the 11.3um feature and weak 8.6 and 17.0um features. Interpreting these band ratios in the light of laboratory and theoretical studies, we find that PAHs in the SMC tend to be smaller and less ionized than those in higher metallicity galaxies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/426/2063
- Title:
- SMC RR Lyrae Fourier decomposition
- Short Name:
- J/MNRAS/426/2063
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have performed the Fourier decomposition analysis of 8- and 13-yr V-band light curves of a carefully selected sample of 454 fundamental-mode RR Lyrae variables (RRab type), detected in an ~=14 square degree area of the Small Magellanic Cloud (SMC) and listed in the Optical Gravitational Lensing Experiment, phase III, Catalogue of Variable Stars. The Fourier decomposition parameters were used to derive metal abundances and distance moduli, following the methodology described by Kapakos, Hatzidimitriou & Soszynski, Paper I (2011, Cat. J/MNRAS/415/1366).
