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181. LAMOST K giants in Galactic halo substructures
ID:
ivo://CDS.VizieR/J/ApJ/880/65
Title:
LAMOST K giants in Galactic halo substructures
Short Name:
J/ApJ/880/65
Date:
21 Oct 2021
Publisher:
CDS
Description:
We construct a large halo K-giant sample by combining the positions, distances, radial velocities, and metallicities of over 13000 LAMOST DR5 halo K giants with the Gaia DR2 proper motions, which covers a Galactocentric distance range of 5-120kpc. Using a position-velocity clustering estimator (the 6Distance), we statistically quantify the presence of position-velocity substructure at high significance: K giants have more close pairs in position-velocity space than a smooth stellar halo. We find that the amount of substructure in the halo increases with increasing distance and metallicity. With a percolation algorithm named friends-of-friends to identify groups, we identify members belonging to Sagittarius (Sgr) Streams, Monoceros Ring, Virgo Overdensity, Hercules-Aquila Cloud, Orphan Streams, and other unknown substructures and find that the Sgr streams account for a large part of grouped stars beyond 20kpc and enhance the increase of substructure with distance and metallicity. For the first time, we identify spectroscopic members of Monoceros Ring in the southern and northern Galactic hemispheres, which presents a rotation of about 185km/s and a mean metallicity of -0.66dex.
182. LAMOST survey of star clusters in M31. II.
ID:
ivo://CDS.VizieR/J/AJ/152/45
Title:
LAMOST survey of star clusters in M31. II.
Short Name:
J/AJ/152/45
Date:
21 Oct 2021
Publisher:
CDS
Description:
We select from Paper I a sample of 306 massive star clusters observed with the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) in the vicinity fields of M31 and M33, and determine their metallicities, ages, and masses. Metallicities and ages are estimated by fitting the observed integrated spectra with stellar synthesis population (SSP) models with a pixel-to-pixel spectral fitting technique. Ages for most young clusters are also derived by fitting the multi-band photometric measurements with model spectral energy distributions (SEDs). The estimated cluster ages span a wide range, from several million years to the age of the universe. The numbers of clusters younger and older than 1Gyr are, respectively, 46 and 260. With ages and metallicities determined, cluster masses are then estimated by comparing the multi-band photometric measurements with SSP model SEDs. The derived masses range from ~10^3^ to ~10^7^M_{Sun}_, peaking at ~10^4.3^ and ~10^5.7^M_{Sun}_ for young (<1Gyr) and old (>1Gyr) clusters, respectively. Our estimated metallicities, ages, and masses are in good agreement with available literature values. Old clusters richer than [Fe/H]~-0.7dex have a wide range of ages. Those poorer than [Fe/H]~-0.7dex seem to be composed of two groups, as previously found for Galactic globular clusters-one of the oldest ages with all values of metallicity down to ~-2dex and another with metallicity increasing with decreasing age. The old clusters in the inner disk of M31 (0-30kpc) show a clear metallicity gradient measured at -0.038+/-0.023dex/kpc.
183. Larson relations in massive clumps
ID:
ivo://CDS.VizieR/J/MNRAS/477/2220
Title:
Larson relations in massive clumps
Short Name:
J/MNRAS/477/2220
Date:
21 Oct 2021
Publisher:
CDS
Description:
We tested the validity of the three Larson relations in a sample of 213 massive clumps selected from the Herschel infrared Galactic Plane (Hi-GAL) survey, also using data from the Millimetre Astronomy Legacy Team 90 GHz (MALT90) survey of 3-mm emission lines. The clumps are divided into five evolutionary stages so that we can also discuss the Larson relations as a function of evolution. We show that this ensemble does not follow the three Larson relations, regardless of the clump's evolutionary phase. A consequence of this breakdown is that the dependence of the virial parameter {alpha}_vir_ on mass (and radius) is only a function of the gravitational energy, independent of the kinetic energy of the system; thus, {alpha}_vir_ is not a good descriptor of clump dynamics. Our results suggest that clumps with clear signatures of infall motions are statistically indistinguishable from clumps with no such signatures. The observed non-thermal motions are not necessarily ascribed to turbulence acting to sustain the gravity, but they might be a result of the gravitational collapse at the clump scales. This seems to be particularly true for the most massive (M>=1000M_{sun}_) clumps in the sample, where exceptionally high magnetic fields might not be enough to stabilize the collapse.
184. LH 47 UVBRI photometry
ID:
ivo://CDS.VizieR/J/A+AS/123/455
Title:
LH 47 UVBRI photometry
Short Name:
J/A+AS/123/455
Date:
21 Oct 2021
Publisher:
CDS
Description:
Table 3 lists the final photometric data of our observations. The UBVRI observations were done with the 1.54m Danish telescope at ESO on October 3rd and 4th, 1992. The CCD was ESO#28, a TEK 1024x1024 with a pixel size of 24mue corresponding to 0.377" per pixel. The total field of view is 6.4'x6.4'. A standard reduction was done with MIDAS and IRAF, the photometry was performed with DAOPHOT within IRAF. The images of Oct 4th have been calibrated using the calibration field around PG 0231+051 (Landolt 1992, Cat. <II/183>). The images of Oct 3rd have then been adopted to the system of Oct 4th. The final Table 3 lists 4613 stars with V and B-V information. In addition U-B is available for 1159 of these stars, V-R for 3519 and V-I for 2854 stars. Table 4 gives those stars from our field of view which are present in the MACS (Magellanic Catalogue of Stars; Tucholke et al. 1996, Cat. <I/221>). The table contains the MACS Id., our x and y position and our UBV photometry, and right ascension and declination from the MACS. These stars may serve to calculate an exact position for every star from Table 3 or to define a coordinate grid for comparison with other observations, such as radio or X-ray data.
185. Lindsay 1 spectroscopy for 34 targets
ID:
ivo://CDS.VizieR/J/MNRAS/465/L39
Title:
Lindsay 1 spectroscopy for 34 targets
Short Name:
J/MNRAS/465/L39
Date:
21 Oct 2021
Publisher:
CDS
Description:
Lindsay 1 is an intermediate-age (~=8Gyr) massive cluster in the Small Magellanic Cloud. Using VLT FORS2 spectra of 16 probable cluster members on the lower red giant branch of the cluster, we measure CN and CH band strengths (at ~=3883 and 4300{AA}, respectively), along with carbon and nitrogen abundances and find that a sub-population of stars has significant nitrogen enrichment. A lack of spread in carbon abundances excludes evolutionary mixing as the source of this enrichment, so we conclude that this is evidence of multiple populations. Therefore, Lindsay 1 is the youngest cluster to show such variations, implying that the process triggering the onset of multiple populations must operate until at least redshift ~1.
186. LMC bar star clusters
ID:
ivo://CDS.VizieR/J/A+A/606/A21
Title:
LMC bar star clusters
Short Name:
J/A+A/606/A21
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report results on star clusters located in the South-Eastern half of the Large Magellanic (LMC) bar fromWashington CT1 photometry. Using appropriate kernel density estimators we detected 73 star cluster candidates, three of which do not show any detectable trace of star cluster sequences in their colour-magnitude diagrams (CMDs).We did not detect other 38 previously catalogued clusters, which could not be recognized when visually inspecting the C and T1 images either; the distribution of stars in their respective fields do not resemble that of an stellar aggregate. They represent ~33 per cent of all catalogued objects located within the analysed LMC bar field. From matching theoretical isochrones to the cluster CMDs cleaned from field star contamination, we derived ages in the range 7.2<log(t[yr^-1^])<10.1. As far as we are aware, this is the first time homogeneous age estimates based on resolved stellar photometry are obtained for most of the studied clusters. We built the cluster frequency (CF) for the surveyed area, and found that the major star cluster formation activity has taken place during the period log(t[yr^-1^])~8.0-9.0. Since ~100Myr ago, clusters have been formed during few bursting formation episodes. When comparing the observed CF to that recovered from the star formation rate we found noticeable differences, which suggests that field star and star cluster formation histories could have been significantly different.
187. LMC extended catalog
ID:
ivo://CDS.VizieR/J/AJ/117/238
Title:
LMC extended catalog
Short Name:
J/AJ/117/238
Date:
21 Oct 2021
Publisher:
CDS
Description:
A survey of extended objects in the Large Magellanic Cloud was carried out on the ESO/SERC R and J Sky Survey Atlases, checking entries in previous catalogs and searching for new objects. The census provided 6659 objects including star clusters, emission-free associations, and objects related to emission nebulae. Each of these classes contains three subclasses with intermediate properties, which are used to infer total populations. The survey includes cross identifications among catalogs, and we present 3246 new objects. We provide accurate positions, classification, and homogeneous measurements of sizes and position angles, as well as information on cluster pairs and hierarchical relation for superimposed objects. This unification and enlargement of catalogs is important for future searches of fainter and smaller new objects. We discuss the angular and size distributions of the objects of the different classes. The angular distributions show two off-centered systems with different inclinations, suggesting that the LMC disk is warped. The present catalog together with its previous counterpart for the SMC and the inter-Cloud region provide a total population of 7847 extended objects in the Magellanic System. The angular distribution of the ensemble reveals important clues on the interaction between the LMC and SMC.
188. LMC star clusters catalog
ID:
ivo://CDS.VizieR/J/A+A/586/A41
Title:
LMC star clusters catalog
Short Name:
J/A+A/586/A41
Date:
21 Oct 2021
Publisher:
CDS
Description:
The main goal of this study is to compile a catalogue of the fundamental parameters of a complete sample of 277 star clusters (SCs) of the Large Magellanic Cloud (LMC) observed in the Washington photometric system. A set of 82 clusters was recently studied by our team. All the clusters' parameters such as radii, deprojected distances, reddenings, ages, and metallicities were obtained by applying essentially the same procedures, which are briefly described here. We used empirical cumulative distribution functions to examine age, metallicity and deprojected distance distributions for different cluster subsamples of the catalogue. Our new sample of 82 additional clusters represents about a 40% increase in the total number of LMC SCs observed to date in the Washington photometric system. In particular, we report here the fundamental parameters obtained for the first time for 42 of these clusters. We found that single LMC SCs are typically older than multiple SCs. Both single and multiple SCs exhibit asymmetrical distributions in log (age). We compared cluster ages derived through isochrone fittings obtained using different models of the Padova group. Although ages obtained using recent isochrones are consistent in general terms, we found that there is some disagreement in the obtained values and their uncertainties.
189. LMC Survey of Young Stellar Systems
ID:
ivo://CDS.VizieR/J/A+A/405/111
Title:
LMC Survey of Young Stellar Systems
Short Name:
J/A+A/405/111
Date:
21 Oct 2021
Publisher:
CDS
Description:
The method developed by Gouliermis et al. (2000AJ....119.1737G), for the detection and classification of stellar systems in the LMC, was used for the identification of stellar associations and open clusters in the central area of the LMC. This method was applied on the stellar catalog produced from a scanned 1.2m UK Schmidt Telescope Plate in U with a field of view almost 6.5degx6.5deg, centered on the Bar of this galaxy. The survey of the identified systems is presented here followed by the results of the investigation on their spatial distribution and their structural parameters, as were estimated according to our proposed methodology. The detected open clusters and stellar associations show to form large filamentary structures, which are often connected with the loci of HI shells. The derived mean size of the stellar associations in this survey was found to agree with the average size found previously by other authors, for stellar associations in different galaxies. This common size of about 80pc might represent a universal scale for the star formation process, whereas the parameter correlations of the detected loose systems support the distinction between open clusters and stellar associations.
190. LMC Washington CMT1 photometry of star clusters
ID:
ivo://CDS.VizieR/J/MNRAS/473/105
Title:
LMC Washington CMT1 photometry of star clusters
Short Name:
J/MNRAS/473/105
Date:
21 Oct 2021
Publisher:
CDS
Description:
We analysed Washington CMT1 photometry of star clusters located along the minor axis of the Large Magellanic Cloud (LMC), from the LMC optical centre up to ~39{deg} outwards to the North-West. The data base was exploited in order to search for new star cluster candidates, to produce cluster CMDs cleaned from field star contamination and to derive age estimates for a statistically complete cluster sample. We confirmed that 146 star cluster candidates are genuine physical systems, and concluded that an overall ~30 per cent of catalogued clusters in the surveyed regions are unlikely to be true physical systems. We did not find any new cluster candidates in the outskirts of the LMC (deprojected distance >~8{deg}). The derived ages of the studied clusters are in the range 7.2<log(t[yr^-1^])<=9.4, with the sole exception of the globular cluster NGC 1786 (log(t[yr^-1^])=10.10). We also calculated the cluster frequency for each region, from which we confirmed previously proposed outside-in formation scenarios. In addition, we found that the outer LMC fields show a sudden episode of cluster formation (log(t[yr^-1^])~7.8-7.9) which continued until log(t[yr^-1^])~7.3 only in the outermost LMC region. We link these features to the first pericentre passage of the LMC to the Milky Way (MW), which could have triggered cluster formation due to ram pressure interaction between the LMC and MW halo.

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