- ID:
- ivo://CDS.VizieR/J/A+A/600/A16
- Title:
- Six LMC star forming region spectra
- Short Name:
- J/A+A/600/A16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The kinetic temperature of molecular clouds is a fundamental physical parameter affecting star formation and the initial mass function. The Large Magellanic Cloud (LMC), the closest star forming galaxy with low metallicity, provides an ideal laboratory to study star formation in such an environment. The classical dense molecular gas thermometer NH_3_ is rarely available in a low metallicity environment because of photoionization and a lack of nitrogen atoms. Our goal is to directly measure the gas kinetic temperature with formaldehyde toward six star-forming regions in the LMC. Three rotational transitions (J_KAKC_ = 3_03_-2_02_, 3_22_-2_21_, and 3_21_-2_20_) of para-H_2_CO near 218GHz were observed with the Atacama Pathfinder EXperiment (APEX) 12m telescope toward six star forming regions in the LMC. Those data are complemented by C^18^O 2-1 spectra.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/161/74
- Title:
- SMASH DR2. 197 SMASH fields
- Short Name:
- J/AJ/161/74
- Date:
- 19 Jan 2022 09:37:25
- Publisher:
- CDS
- Description:
- The Large and Small Magellanic Clouds (LMC and SMC) are the largest satellite galaxies of the Milky Way and close enough to allow for a detailed exploration of their structure and formation history. The Survey of the MAgellanic Stellar History (SMASH) is a community Dark Energy Camera (DECam) survey of the Magellanic Clouds using ~50 nights to sample over ~2400deg^2^ centered on the Clouds at ~20% filling factor (but with contiguous coverage in the central regions) and to depths of ~24th mag in ugriz. The primary goals of SMASH are to map out the extended stellar peripheries of the Clouds and uncover their complicated interaction and accretion history as well as to derive spatially resolved star formation histories of the central regions and create a "movie" of their past star formation. Here we announce the second SMASH public data release (DR2), which contains all 197 fully calibrated DECam fields including the main body fields in the central regions. The DR2 data are available through the Astro Data Lab hosted by the NSF's National Optical-Infrared Astronomy Research Laboratory. We highlight three science cases that make use of the SMASH DR2 data and will be published in the future: (1) preliminary star formation histories of the LMC, (2) the search for Magellanic star clusters using citizen scientists, and, (3) photometric metallicities of Magellanic Cloud stars using the DECam u-band.
- ID:
- ivo://CDS.VizieR/J/AJ/154/199
- Title:
- SMASH: Survey of the MAgellanic Stellar History
- Short Name:
- J/AJ/154/199
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Large and Small Magellanic Clouds are unique local laboratories for studying the formation and evolution of small galaxies in exquisite detail. The Survey of the MAgellanic Stellar History (SMASH) is an NOAO community Dark Energy Camera (DECam) survey of the Clouds mapping 480 deg^2^ (distributed over ~2400 square degrees at ~20% filling factor) to ~24th mag in ugriz. The primary goals of SMASH are to identify low surface brightness stellar populations associated with the stellar halos and tidal debris of the Clouds, and to derive spatially resolved star formation histories. Here, we present a summary of the survey, its data reduction, and a description of the first public Data Release (DR1). The SMASH DECam data have been reduced with a combination of the NOAO Community Pipeline, the PHOTRED automated point-spread-function photometry pipeline, and custom calibration software. The astrometric precision is ~15 mas and the accuracy is ~2 mas with respect to the Gaia reference frame. The photometric precision is ~0.5%-0.7% in griz and ~1% in u with a calibration accuracy of ~1.3% in all bands. The median 5{sigma} point source depths in ugriz are 23.9, 24.8, 24.5, 24.2, and 23.5 mag. The SMASH data have already been used to discover the Hydra II Milky Way satellite, the SMASH 1 old globular cluster likely associated with the LMC, and extended stellar populations around the LMC out to R~18.4 kpc. SMASH DR1 contains measurements of ~100 million objects distributed in 61 fields. A prototype version of the NOAO Data Lab provides data access and exploration tools.
- ID:
- ivo://CDS.VizieR/J/A+A/622/A29
- Title:
- SMC AGN in XMM-Newton
- Short Name:
- J/A+A/622/A29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Finding active galactic nuclei (AGN) behind the Magellanic Clouds (MCs) is difficult because of the high stellar density in these fields. Although the first AGN behind the Small Magellanic Cloud (SMC) were reported in the 1980s, it is only recently that the number of AGN known behind the SMC has increased by several orders of magnitude. The mid-infrared colour selection technique has proven to be an efficient means of identifying AGN, especially obscured sources. The X-ray regime is complementary in this regard and we use XMM-Newton observations to support the identification of AGN behind the SMC. We present a catalogue of AGN behind the SMC by correlating an updated X-ray point-source catalogue from our XMM-Newton survey of the SMC with previously identified AGN from the literature as well as a list of candidates obtained from the ALLWISE mid-infrared colour-selection criterion. We studied the properties of the sample with respect to their redshifts, luminosities, and X-ray spectral characteristics. We also identified the near-infrared counterpart of the sources from the VISTA observations. The redshift and luminosity distributions of the sample (where known) indicate that we detect sources ranging from nearby Seyfert galaxies to distant and obscured quasars. The X-ray hardness ratios are compatible with those typically expected for AGN, and the VISTA colours and variability are also consistent with AGN. A positive correlation was observed between the integrated X-ray flux (0.2-12keV) and the ALLWISE and VISTA magnitudes. We further present a sample of new candidate AGN and candidates for obscured AGN. Together these make an interesting subset for further follow-up studies. An initial spectroscopic follow-up of 6 out of the 81 new candidates showed that all six sources are active galaxies, although two have narrow emission lines.
- ID:
- ivo://CDS.VizieR/J/ApJS/101/41
- Title:
- SMC and Bridge extended catalog
- Short Name:
- J/ApJS/101/41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A survey of extended objects in the Magellanic System was carried out on the ESO/SERC R and J Sky Survey Atlases. The present work is dedicated to the Small Magellanic Cloud and to the inter-Magellanic Cloud region ("Bridge") totaling 1188 objects, of which 554 are classified as star clusters, 343 are emissionless associations, and 291 are related to emission nebulae. The survey includes cross-identifications among catalogs, and we present 284 new objects. We provide accurate positions, classification, homogeneous sizes, and position angles, as well as information on cluster pairs and hierarchical relation for superimposed objects. Two clumps of extended objects in the Bridge and one at the Small Magellanic Cloud wing tip might be currently forming dwarf spheroidal galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/393/887
- Title:
- SMC Be stars candidates
- Short Name:
- J/A+A/393/887
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recently the OGLE experiment has provided accurate light curves and colours for about 2 millions stars in the Small Magellanic Cloud. We have examined this database for its content of Be stars, applying some selection criteria, and we have found a sample of ~1000 candidates. Some of these stars show beautiful light curves with amazing variations never observed in any Galactic variable. We find outbursts in 13% of the sample (type-1 stars), high and low states in 15%, periodic variations in 7%, and the usual variations seen in Galactic Be stars in 65% of the cases. The Galactic counterparts of type-1 objects could be the outbursting Be stars found by Hubert & Floquet (1998, Cat. J/A+A/335/565) after the analysis of Hipparcos photometry. We discuss the possibility that type-1 stars could correspond to Be stars with accreting white dwarf companions or alternatively, blue pre-main sequence stars surrounded by thermally unstable accretion disks. We provide coordinates and basic photometric information for these stars and some examples of light curves.
- 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.
- 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.
- 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.
- 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.
