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Start Over Subject magellanic clouds Validation Level 2
471. RGB stars in LMC outer disk
ID:
ivo://CDS.VizieR/J/AJ/142/61
Title:
RGB stars in LMC outer disk
Short Name:
J/AJ/142/61
Date:
21 Oct 2021
Publisher:
CDS
Description:
The outer disk of the Large Magellanic Cloud (LMC) is studied in order to unveil clues about its formation and evolution. Complementing our previous studies in innermost fields (3kpc<~R<~7kpc), we obtained deep color-magnitude diagrams in six fields with galactocentric distances from 5.2kpc to 9.2kpc and different azimuths. The comparison with isochrones shows that while the oldest population is approximately coeval in all fields, the age of the youngest populations increases with increasing radius. This agrees with the results obtained in the innermost fields. Low-resolution spectroscopy in the infrared CaII triplet region has been obtained for about 150 stars near the tip of the red giant branch in the same fields. Radial velocities and stellar metallicities have been obtained from these spectra. The metallicity distribution of each field has been analyzed together with those previously studied.
472. Ridgelines of six intermediate-age SMC clusters
ID:
ivo://CDS.VizieR/J/AJ/136/1703
Title:
Ridgelines of six intermediate-age SMC clusters
Short Name:
J/AJ/136/1703
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a photometric analysis of the star clusters Lindsay 1, Kron 3, NGC 339, NGC 416, Lindsay 38, and NGC 419 in the Small Magellanic Cloud (SMC), observed with the Hubble Space Telescope Advanced Camera for Surveys (ACS) in the F555W and F814W filters. Our color-magnitude diagrams (CMDs) extend ~3.5mag deeper than the main-sequence turnoff points, deeper than any previous data. Cluster ages were derived using three different isochrone models: Padova, Teramo, and Dartmouth, which are all available in the ACS photometric system. Fitting observed ridgelines for each cluster, we provide a homogeneous and unique set of low-metallicity, single-age fiducial isochrones.
473. RI photometry of LMC carbon stars
ID:
ivo://CDS.VizieR/J/A+A/369/932
Title:
RI photometry of LMC carbon stars
Short Name:
J/A+A/369/932
Date:
21 Oct 2021
Publisher:
CDS
Description:
A catalogue of 7760 carbon stars in the Large Magellenic Cloud is presented. The stars were identified during a systematic survey of objective-prism plates taken with the UK 1.2m Schmidt Telescope. The catalogue is compared with other lists of carbon stars and the distribution of the carbon stars is discussed.
474. ROSAT HRI catalogue of LMC X-ray sources
ID:
ivo://CDS.VizieR/J/A+AS/143/391
Title:
ROSAT HRI catalogue of LMC X-ray sources
Short Name:
J/A+AS/143/391
Date:
21 Oct 2021
Publisher:
CDS
Description:
The ROSAT HRI LMC source catalogue is based on all 543 pointed observations of the ROSAT HRI between 1990 and 1998 with exposure times higher than 50 sec. The observations covered a 10 deg x 10 deg field including the LMC. The catalogue contains 397 X-ray sources. Sources showing flux variability in ROSAT HRI and PSPC are listed in Table 1. Table 2 contains HRI sources which were identified with known objects in other catalogues and literature. Table 3 is a list of new classifications. The whole source catalogue from HRI observations is given in Table 4.
475. ROSAT HRI catalogue of SMC X-ray sources
ID:
ivo://CDS.VizieR/J/A+AS/147/75
Title:
ROSAT HRI catalogue of SMC X-ray sources
Short Name:
J/A+AS/147/75
Date:
21 Oct 2021
Publisher:
CDS
Description:
The ROSAT HRI SMC source catalogue is based on all 71 pointed observations of the Small Magellanic Cloud by the ROSAT HRI between 1990 and 1998. The data was selected in a 5{deg}x5{deg} field covering the SMC. The catalogue which contains 121 X-ray sources, was cross-correlated with data bases and catalogues like SIMBAD, TYCHO, or USNO as well as other publications in order to classify the X-ray sources and find new candidates for various source classes.
476. ROSAT X-ray sources in LMC. II.
ID:
ivo://CDS.VizieR/J/A+A/388/100
Title:
ROSAT X-ray sources in LMC. II.
Short Name:
J/A+A/388/100
Date:
21 Oct 2021
Publisher:
CDS
Description:
About 200 X-ray sources from a sample of spectrally hard ROSAT PSPC sources, given in the catalog of Haberl & Pietsch (1999, Cat. <J/A+AS/139/277>), and observed in a ~60 square degree field of the LMC during several archival pointed observations with a wide range of exposure times have been reanalyzed. For these sources accurate count rates and hardness ratios have been recalculated. In comparison to Haberl & Pietsch (1999, Cat. <J/A+AS/139/277>) we used merged data from all available observations and we derived average source parameters by investigating each source individually. From a simulation power-law spectral tracks have been derived in the HR1-HR2 plane and ~170 sources have been classified as background X-ray sources or as LMC X-ray binaries. 80% of the spectrally hard X-ray sources with more than 50 observed counts have been found to be consistent with background X-ray sources and 20% with LMC X-ray binaries (53 sources with AGN and 15 with X-ray binaries).
477. Rotation measures at 1.4GHz toward the LMC
ID:
ivo://CDS.VizieR/J/ApJ/759/25
Title:
Rotation measures at 1.4GHz toward the LMC
Short Name:
J/ApJ/759/25
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a study of the magnetic field of the Large Magellanic Cloud (LMC), carried out using diffuse polarized synchrotron emission data at 1.4GHz acquired at the Parkes Radio Telescope and the Australia Telescope Compact Array. The observed diffuse polarized emission is likely to originate above the LMC disk on the near side of the galaxy. Consistent negative rotation measures (RMs) derived from the diffuse emission indicate that the line-of-sight magnetic field in the LMC's near-side halo is directed coherently away from us. In combination with RMs of extragalactic sources that lie behind the galaxy, we show that the LMC's large-scale magnetic field is likely to be of quadrupolar geometry, consistent with the prediction of dynamo theory. On smaller scales, we identify two brightly polarized filaments southeast of the LMC, associated with neutral hydrogen arms. The filaments' magnetic field potentially aligns with the direction toward the Small Magellanic Cloud (SMC). We suggest that tidal interactions between the SMC and the LMC in the past 10^9^ years are likely to have shaped the magnetic field in these filaments.
478. Rotation rates of very massive stars
ID:
ivo://CDS.VizieR/J/ApJ/700/844
Title:
Rotation rates of very massive stars
Short Name:
J/ApJ/700/844
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present projected rotational velocity values for 96 Galactic, 55 SMC, and 106 LMC O-B type stars from archival FUSE observations. The evolved and unevolved samples from each environment are compared through the Kolmogorov-Smirnov test to determine if the distribution of equatorial rotational velocities is metallicity dependent for these massive objects. Stellar interior models predict that massive stars with SMC metallicity will have significantly reduced angular momentum loss on the main sequence compared to their Galactic counterparts. Our results find some support for this prediction but also show that even at Galactic metallicity, evolved and unevolved massive stars have fairly similar fractions of stars with large Vsin i values. Macroturbulent broadening that is present in the spectral features of Galactic evolved massive stars is lower in the LMC and SMC samples. This suggests the processes that lead to macroturbulence are dependent upon metallicity.
479. RSGs in the LMC & sp. follow-up for LMC & SMC
ID:
ivo://CDS.VizieR/J/ApJ/900/118
Title:
RSGs in the LMC & sp. follow-up for LMC & SMC
Short Name:
J/ApJ/900/118
Date:
20 Jan 2022 11:32:23
Publisher:
CDS
Description:
The binary fraction of unevolved massive stars is thought to be 70%-100% but there are few observational constraints on the binary fraction of the evolved version of a subset of these stars, the red supergiants (RSGs). Here we identify a complete sample of RSGs in the Large Magellanic Cloud (LMC) using new spectroscopic observations and archival UV, IR, and broadband optical photometry. We find 4090 RSGs with logL/L_{sun}_>3.5, with 1820 of them having logL/L_{sun}_>4, which we believe is our completeness limit. We additionally spectroscopically confirmed 38 new RSG + B-star binaries in the LMC, bringing the total known up to 55. We then estimated the binary fraction using a k-nearest neighbors algorithm that classifies stars as single or binary based on photometry with a spectroscopic sample as a training set. We take into account observational biases such as line-of-sight stars and binaries in eclipse while also calculating model- dependent corrections for RSGs with companions that our observations were not designed to detect. Based on our data, we find an initial result of 13.5_-6.67_^+7.56^% for RSGs with O- or B-type companions. Using the Binary Population and Spectral Synthesis models to correct for unobserved systems, this corresponds to a total RSG binary fraction of 19.5_-6.7_^+7.6^% . This number is in broad agreement with what we would expect given an initial OB binary distribution of 70%, a predicted merger fraction of 20%-30%, and a binary interaction fraction of 40%-50%.
480. RSGs in the SMC
ID:
ivo://CDS.VizieR/J/A+A/639/A116
Title:
RSGs in the SMC
Short Name:
J/A+A/639/A116
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the most comprehensive red supergiant (RSG) sample for the Small Magellanic Cloud (SMC) to date, including 1239 RSG candidates. The initial sample was derived based on a source catalog for the SMC with conservative ranking. Additional spectroscopic RSGs were retrieved from the literature, and RSG candidates were selected based on the inspection of Gaia and 2MASS color-magnitude diagrams (CMDs). We estimate that there are in total ~1800 or more RSGs in the SMC. We purify the sample by studying the infrared CMDs and the variability of the objects, though there is still an ambiguity between asymptotic giant branch stars (AGBs) and RSGs at the red end of our sample. One heavily obscured target was identified based on multiple near-IR (NIR) and mid-IR (MIR) CMDs. The investigation of color-color diagrams (CCDs) shows that there are fewer RSGs candidates (~4%) showing PAH emission features compared to the Milky Way and LMC (~15%). The MIR variability of RSG sample increases with luminosity. We separate the RSG sample into two subsamples (risky and safe), and identify one M5e AGB star in the risky subsample based on simultaneous inspection of variabilities, luminosities, and colors. The degeneracy of mass loss rate (MLR), variability, and luminosity of the RSG sample is discussed, indicating that most of the targets with high variability are also the bright ones with high MLR. Some targets show excessive dust emission, which may be related to previous episodic mass loss events. We also roughly estimate the total gas and dust budget produced by entire RSG population as ~1.9^+2.4^_-1.1_x10^-6^M_{sun}_/yr in the most conservative case, according to the derived MLR from IRAC1-IRAC4 color. Based on the MIST models, we derive a linear relation between T_eff_ and observed J-Ks color with reddening correction for the RSG sample. By using a constant bolometric correction and this relation, the Geneva evolutionary model is compared with our RSG sample, showing a good agreement and a lower initial mass limit of ~7M_{sun}_ for the RSG population. Finally, we compare the RSG sample in the SMC and the LMC. Despite the incompleteness of LMC sample in the faint end, the result indicates that the LMC sample always shows redder color (except for the IRAC1-IRAC2 and WISE1-WISE2 colors due to CO absorption) and higher variability than the SMC sample, which is likely due to a positive relation between MLR, variability and the metallicity.