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Start Over Subject magellanic clouds Validation Level 2
501. SMC blob N26 multiband photometry
ID:
ivo://CDS.VizieR/J/A+A/564/A31
Title:
SMC blob N26 multiband photometry
Short Name:
J/A+A/564/A31
Date:
21 Oct 2021
Publisher:
CDS
Description:
High-excitation compact HII regions of the Magellanic Clouds are sites of recent massive star formation in low metallicity environments. Detailed study of these regions and their environments using high-spatial resolution observations is necessary to better understand massive star formation, which is still an unsolved problem. We aim at a detailed study of the Small Magellanic Cloud compact HII region N26, which is only ~4" in diameter. This study is based on high spatial resolution imaging (~0.1"-0.3") in JHKs and L' bands, using the VLT equipped with the NAOS adaptive optics system. A larger region (~50pcx76pc) was also imaged at medium spatial resolution, using the ESO 2.2m telescope in optical wavelengths. We also used the JHKs archival data from the IRSF survey and the Spitzer Space Telescope SAGE-SMC survey.
502. SMC BV photometry of 9 star cluster fields
ID:
ivo://CDS.VizieR/J/A+A/591/A11
Title:
SMC BV photometry of 9 star cluster fields
Short Name:
J/A+A/591/A11
Date:
21 Oct 2021
Publisher:
CDS
Description:
The evolution and structure of the Magellanic Clouds is currently under debate. The classical scenario in which both the Large and Small Magellanic Clouds (LMC, SMC) are orbiting the Milky Way has been challenged by an alternative in which the LMC and SMC are in their first close passage to our Galaxy. The clouds are close enough to us to allow spatially resolved observation of their stars, and detailed studies of stellar populations in the galaxies are expected to be able to constrain the proposed scenarios. In particular, the west halo (WH) of the SMC was recently characterized with radial trends in age and metallicity that indicate tidal disruption. We intend to increase the sample of star clusters in the west halo of the SMC with homogeneous age, metallicity, and distance derivations to allow a better determination of age and metallicity gradients in this region. Distances and positions are compared with the orbital plane of the SMC depending on the scenario adopted. Comparisons of observed and synthetic V(B-V) colour-magnitude diagrams were used to derive age, metallicity, distance, and reddening for star clusters in the SMC west halo. Observations were carried out using the 4.1m SOAR telescope. Photometric completeness was determined through artificial star tests, and the members were selected by statistical comparison with a control field. We derived an age of 1.23+/-0.07Gyr and [Fe/H]=-0.87+/-0.07 for the reference cluster NGC 152, compatible with literature parameters. Age and metallicity gradients are confirmed in the WH: 2.6+/-0.6Gyr/{deg} and -0.19+/-0.09dex/{deg}, respectively. The age-metallicity relation for the WH has a low dispersion in metallicity and is compatible with a burst model of chemical enrichment. All WH clusters seem to follow the same stellar distribution predicted by dynamical models, with the exception of AM-3, which should belong to the counter-bridge. Bruck 6 is the youngest cluster in our sample. It is only 130+/-40Myr old and may have been formed during the tidal interaction of SMC-LMC that created the WH and the Magellanic bridge. We suggest that it is crucial to split the SMC cluster population into groups: main body, wing and bridge, counter-bridge, and WH. This is the way to analyse the complex star formation and dynamical history of our neighbour. In particular, we show that the WH has clear age and metallicity gradients and an age-metallicity relation that is also compatible with the dynamical model that claims a tidal influence of the LMC on the SMC.
503. SMC catalogue of radiosources
ID:
ivo://CDS.VizieR/J/A+AS/121/321
Title:
SMC catalogue of radiosources
Short Name:
J/A+AS/121/321
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present catalogues of radio sources in the Small Magellanic Cloud from observations with the Parkes radio telescope at 1.42, 2.45, 4.75 and 8.55GHz, and an additional catalogue from the Parkes-MIT-NRAO survey at 4.85GHz. A total of 224 sources were detected at at least one of these frequencies, 60 of which are reported here for the first time as radio sources. We compare positions and flux densities of these sources with previously published results and find no significant positional displacement or flux discrepancies.
504. SMC Cepheids K-band and RV curves
ID:
ivo://CDS.VizieR/J/A+A/620/A99
Title:
SMC Cepheids K-band and RV curves
Short Name:
J/A+A/620/A99
Date:
21 Oct 2021
Publisher:
CDS
Description:
The extragalactic distance scale builds on the Cepheid period-luminosity (PL) relation. Decades of work have not yet convincingly established the sensitivity of the PL relation to metallicity. This currently prevents a determination of the Hubble constant accurate to 1% from the classical Cepheid-SN Ia method. In this paper we carry out a strictly differential comparison of the absolute PL relations obeyed by classical Cepheids in the Milky Way (MW), LMC, and SMC galaxies. Taking advantage of the substantial metallicity difference among the Cepheid populations in these three galaxies, we want to establish a possible systematic trend of the PL relation absolute zero point as a function of metallicity, and to determine the size of such an effect in the optical and near-infrared photometric bands. We used a IRSB Baade-Wesselink-type method to determine individual distances to the Cepheids in our samples in the MW, LMC, and SMC. For our analysis, we used a greatly enhanced sample of Cepheids in the SMC (31 stars) compared to the small sample (5 stars) available in our previous work. We used the distances to determine absolute Cepheid PL relations in the optical and near-infrared bands in each of the three galaxies. Our distance analysis of 31 SMC Cepheids with periods of 4-69 days yields tight PL relations in all studied bands, with slopes consistent with the corresponding LMC and MW relations. Adopting the very accurately determined LMC slopes for the optical and near-infrared bands, we determine the zero point offsets between the corresponding absolute PL relations in the three galaxies. We find that in all bands the metal-poor SMC Cepheids are intrinsically fainter than their more metal-rich counterparts in the LMC and MW. In the K band the metallicity effect is -0.23+/-0.06mag/dex, while in the V,(V-I) Wesenheit index it is slightly stronger, -0.34+/-0.06mag/dex. We find suggestive evidence that the metallicity sensitivity of the PL relation might be nonlinear, being small in the range between solar and LMC Cepheid metallicity, and becoming steeper towards the lower-metallicity regime.
505. SMC clusters age-dating & classification
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.
506. SMC C stars B and R light curves
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.
507. SMC dusty OB stars. I. Optical spectroscopy
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).
508. SMC emission-line objects
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.
509. SMC HI shells velocities
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
510. S3MC IRAC and MIPS photometry
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.