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Start Over Subject magellanic clouds Validation Level 2
101. Chemical properties of 89 stars in the LMC disk
ID:
ivo://CDS.VizieR/J/ApJ/761/33
Title:
Chemical properties of 89 stars in the LMC disk
Short Name:
J/ApJ/761/33
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have used high-resolution spectra obtained with the multifiber facility FLAMES at the Very Large Telescope of the European Southern Observatory to derive kinematic properties and chemical abundances of Fe, O, Mg, and Si for 89 stars in the disk of the Large Magellanic Cloud (LMC). The derived metallicity and [{alpha}/Fe], obtained as the average of O, Mg, and Si abundances, allow us to draw a preliminary scheme of the star formation history of this region of the LMC. The derived metallicity distribution shows two main components: one component (comprising ~84% of the sample) peaks at [Fe/H]=-0.48dex and it shows an [{alpha}/Fe] ratio slightly under solar ([{alpha}/Fe]~-0.1dex). This population probably originated in the main star formation event that occurred 3-4Gyr ago (possibly triggered by tidal capture of the Small Magellanic Cloud). The other component (comprising ~16% of the sample) peaks at [Fe/H]~-0dex and it shows an [{alpha}/Fe]~0.2dex. This population was probably generated during the long quiescent epoch of star formation between the first episode and the most recent bursts. Indeed, in our sample we do not find stars with chemical properties similar to the old LMC globular clusters nor to the iron-rich and {alpha}-poor stars recently found in the LMC globular cluster NGC 1718 and also predicted to be in the LMC field, thus suggesting that both of these components are small (<1%) in the LMC disk population.
102. CII emission-line stars in LMC with MagE spectra
ID:
ivo://CDS.VizieR/J/ApJ/898/85
Title:
CII emission-line stars in LMC with MagE spectra
Short Name:
J/ApJ/898/85
Date:
21 Mar 2022 08:48:14
Publisher:
CDS
Description:
We present a narrowband imaging survey of the Large Magellanic Cloud (LMC), designed to isolate the CII{lambda}{lambda}7231,7236 emission lines in objects as faint as m_{lambda}7400_~18. The work is motivated by the recent serendipitous discovery in the LMC of the first confirmed extragalactic [WC11] star, whose spectrum is dominated by CII emission, and the realization that the number of such objects is currently largely unconstrained. The survey, which imaged ~50deg^2^ using on-band and off-band filters, will significantly increase the total census of these rare stars. In addition, each new LMC [WC] star has a known luminosity, a quantity quite uncertain in the Galactic sample. Multiple known CII emitters were easily recovered, validating the survey design. We find 38 new CII emission candidates; spectroscopy of the complete sample will be needed to ascertain their nature. In a preliminary spectroscopic reconnaissance, we observed three candidates, finding CII emission in each. One is a new [WC11]. Another shows both the narrow CII emission lines characteristic of a [WC11], but also broad emission of CIV, OV, and HeII characteristic of a much hotter [WC4] star; we speculate that this is a binary [WC]. The third object shows weak CII emission, but the spectrum is dominated by a dense thicket of strong absorption lines, including numerous OII transitions. We conclude it is likely an unusual hot, hydrogen-poor post-AGB star, possibly in transition from [WC] to white dwarf. Even lacking a complete spectroscopic program, we can infer that late [WC] stars do not dominate the central stars of LMC planetary nebulae, and that the detected CII emitters are largely of an old population.
103. Classical Cepheids in MCs. I. LMC disk
ID:
ivo://CDS.VizieR/J/ApJ/832/176
Title:
Classical Cepheids in MCs. I. LMC disk
Short Name:
J/ApJ/832/176
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a detailed investigation of the Large Magellanic Cloud (LMC) disk using classical Cepheids. Our analysis is based on optical (I, V; OGLE-IV), near-infrared (NIR: J, H, K_S_) and mid-infrared (MIR: w1; WISE) mean magnitudes. By adopting new templates to estimate the NIR mean magnitudes from single-epoch measurements, we build the currently most accurate, largest, and homogeneous multi-band data set of LMC Cepheids. We determine Cepheid individual distances using optical and NIR Period-Wesenheit relations (PWRs), to measure the geometry of the LMC disk and its viewing angles. Cepheid distances based on optical PWRs are precise at 3%, but accurate to 7%, while the ones based on NIR PWRs are more accurate (to 3%), but less precise (2%-15%), given the higher photometric error on the observed magnitudes. We found an inclination of i=25.05+/-0.02(stat.)+/-0.55(syst.){deg}, and a position angle of the lines of nodes P.A.=150.76+/-0.02(stat.)+/-0.07(syst.){deg}. These values agree well with estimates based either on young (Red Supergiants) or on intermediate-age (Asymptotic Giant Branch, Red Clump) stellar tracers, but they significantly differ from evaluations based on old (RR Lyrae) stellar tracers. This indicates that young/intermediate and old stellar populations have different spatial distributions. Finally, by using the reddening-law fitting approach, we provide a reddening map of the LMC disk, which is 10 times more accurate and 2 times larger than similar maps in the literature. We also found an LMC true distance modulus of {mu}_0,LMC_=18.48+/-0.10(stat. and syst.)mag, in excellent agreement with the currently most accurate measurement.
104. Classification of IRS sources in the SMC
ID:
ivo://CDS.VizieR/J/MNRAS/451/3504
Title:
Classification of IRS sources in the SMC
Short Name:
J/MNRAS/451/3504
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Magellanic clouds are uniquely placed to study the stellar contribution to dust emission. Individual stars can be resolved in these systems even in the mid-infrared, and they are close enough to allow detection of infrared excess caused by dust. We have searched the Spitzer Space Telescope data archive for all Infrared Spectrograph (IRS) staring-mode observations of the Small Magellanic Cloud (SMC) and found that 209 Infrared Array Camera (IRAC) point sources within the footprint of the Surveying the Agents of Galaxy Evolution in the Small Magellanic Cloud (SAGE-SMC) Spitzer Legacy programme were targeted, within a total of 311 staring mode observations. We classify these point sources using a decision tree method of object classification, based on infrared spectral features, continuum and spectral energy distribution shape, bolometric luminosity, cluster membership and variability information. We find 58 asymptotic giant branch (AGB) stars, 51 young stellar objects (YSOs), 4 post-AGB objects, 22 Red Supergiants (RSGs), 27 stars (of which 23 are dusty OB stars), 24 planetary nebulae (PNe), 10 Wolf-Rayet (WR) stars, 3 HII regions, 3 R Coronae Borealis (R CrB) stars, 1 Blue Supergiant and 6 other objects, including 2 foreground AGB stars. We use these classifications to evaluate the success of photometric classification methods reported in the literature.
105. Cloud decomposition & SFR measurements
ID:
ivo://CDS.VizieR/J/ApJ/841/109
Title:
Cloud decomposition & SFR measurements
Short Name:
J/ApJ/841/109
Date:
21 Oct 2021
Publisher:
CDS
Description:
Galactic star formation scaling relations show increased scatter from kpc to sub-kpc scales. Investigating this scatter may hold important clues to how the star formation process evolves in time and space. Here, we combine different molecular gas tracers, different star formation indicators probing distinct populations of massive stars, and knowledge of the evolutionary state of each star-forming region to derive the star formation properties of ~150 star-forming complexes over the face of the Large Magellanic Cloud (LMC). We find that the rate of massive star formation ramps up when stellar clusters emerge and boost the formation of subsequent generations of massive stars. In addition, we reveal that the star formation efficiency of individual giant molecular clouds (GMCs) declines with increasing cloud gas mass (M_cloud_). This trend persists in Galactic star-forming regions and implies higher molecular gas depletion times for larger GMCs. We compare the star formation efficiency per freefall time ({epsilon}_ff_) with predictions from various widely used analytical star formation models. While these models can produce large dispersions in {epsilon}_ff_ similar to those in observations, the origin of the model-predicted scatter is inconsistent with observations. Moreover, all models fail to reproduce the observed decline of {epsilon}_ff_ with increasing M_cloud_ in the LMC and the Milky Way. We conclude that analytical star formation models idealizing global turbulence levels and cloud densities and assuming a stationary star formation rate (SFR) are inconsistent with observations from modern data sets tracing massive star formation on individual cloud scales. Instead, we reiterate the importance of local stellar feedback in shaping the properties of GMCs and setting their massive SFR.
106. Clump properties in the LMC 30 Dor region
ID:
ivo://CDS.VizieR/J/ApJ/703/736
Title:
Clump properties in the LMC 30 Dor region
Short Name:
J/ApJ/703/736
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a complete ^12^CO(J=1-0) map of the prominent molecular ridge in the Large Magellanic Cloud (LMC) obtained with the 22m ATNF Mopra Telescope. The region stretches southward by ~2{deg} (or 1.7kpc) from 30 Doradus, the most vigorous star-forming region in the Local Group. The location of this molecular ridge is unique insofar as it allows us to study the properties of molecular gas as a function of the ambient radiation field in a low-metallicity environment. The mass spectrum and the scaling relations between the properties of the CO clumps in the molecular ridge are similar, but not identical, to those that have been established for Galactic molecular clouds.
107. Clusters and associations in SMC and LMC
ID:
ivo://CDS.VizieR/J/MNRAS/403/996
Title:
Clusters and associations in SMC and LMC
Short Name:
J/MNRAS/403/996
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate the degree of spatial correlation among extended structures in the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC). To this purpose, we work with subsamples characterized by different properties such as age and size, taken from the updated catalogue of Bica et al. (2008, Cat. J/MNRAS/389/678), or gathered in the present work. The structures are classified as star clusters or non-clusters (basically, nebular complexes and their stellar associations).
108. Clusters and field stars in LMC. I.
ID:
ivo://CDS.VizieR/J/A+AS/110/533
Title:
Clusters and field stars in LMC. I.
Short Name:
J/A+AS/110/533
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present CCD photometry in the Johnson BV system to about V=23^m^ for the stars in six clusters and the surrounding fields in two regions of different nature in the Large Magellanic Cloud. The analysis includes estimations of loss of measured stars due to crowding effects.
109. 6cm and 3cm sources in SMC
ID:
ivo://CDS.VizieR/J/other/Ser/184.93
Title:
6cm and 3cm sources in SMC
Short Name:
J/other/Ser/184.
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present two new catalogues of radio-continuum sources in the field of the Small Magellanic Cloud (SMC). These catalogues contain sources found at 4800MHz (&#955;=6cm) and 8640MHz (&#955;=3cm). Some 457 sources have been detected at 3cm with 601 sources at 6cm created from new high-sensitivity and resolution radio-continuum images of the SMC from Crawford et al. (<A HREF="http://simbad.cds.unistra.fr/simbad/sim-ref?bibcode=2011SerAJ.183...95C%202011SerAJ.183...95C">2011SerAJ.183...95C 2011SerAJ.183...95C</A>).
110. CO catalog of LMC molecular clouds
ID:
ivo://CDS.VizieR/J/PASJ/53/971
Title:
CO catalog of LMC molecular clouds
Short Name:
J/PASJ/53/971
Date:
21 Oct 2021
Publisher:
CDS
Description:
From a ^12^CO (J=1-0) survey with the NANTEN telescope, we present a complete catalog of giant molecular clouds (GMCs) in the Large Magellanic Cloud. In total, 107 CO clouds have been identified, 55 of which were detected at more than 3 observed positions. For the 55 clouds, the physical properties, such as size, line-width, virial mass, and CO luminosity, are cataloged.