CCD SDSS gr Photometry of Poorly Studied Star Clusters in the Large Magellanic Cloud

We present for the first time CCD SDSS gr photometry, obtained at the Gemini South telescope with the GMOS attached, of stars in the field of the poorly studied star clusters NGC1768, HS 85, SL 676, NGC2107, NGC2190, and SL 866, which are distributed in the main body of the Large Magellanic Cloud. We applied a subtraction procedure to statistically clean the cluster CMDs from field star contamination. In order to disentangle cluster features from those belonging to their surrounding fields, we applied a subtraction procedure which makes use of variable cells to reproduce the field star color-magnitude diagrams (CMDs) as closely as possible. We then traced their stellar density radial profiles from star counts performed over the cleaned field stars dataset and derived their radii. Using the cleaned cluster CMDs, we estimated ages and metallicities from matching theoretical isochrones computed for the SDSS system. The studied star clusters have ages from 0.1 up to 2.0 Gyr and are of slightly metal-poor metal content ([Fe/H]≈−0.4 dex).

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The VISCACHA survey – II. Structure of star clusters in the Magellanic Clouds periphery

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2425 ◽

2020 ◽

Vol 498 (1) ◽

pp. 205-222

Author(s):

João F C Santos ◽

Francisco F S Maia ◽

Bruno Dias ◽

Leandro de O Kerber ◽

Andrés E Piatti ◽

...

Keyword(s):

Surface Brightness ◽

Structural Parameters ◽

Star Clusters ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

The Core ◽

Optical Images ◽

Low Surface Brightness ◽

Homogeneous Set ◽

Stellar Density

ABSTRACT We provide a homogeneous set of structural parameters of 83 star clusters located at the periphery of the Small Magellanic Cloud (SMC) and the Large Magellanic Cloud (LMC). The clusters’ stellar density and surface brightness profiles were built from deep, AO assisted optical images, and uniform analysis techniques. The structural parameters were obtained from King and Elson et al. model fittings. Integrated magnitudes and masses (for a subsample) are also provided. The sample contains mostly low surface brightness clusters with distances between 4.5 and 6.5 kpc and between 1 and 6.5 kpc from the LMC and SMC centres, respectively. We analysed their spatial distribution and structural properties, comparing them with those of inner clusters. Half-light and Jacobi radii were estimated, allowing an evaluation of the Roche volume tidal filling. We found that: (i) for our sample of LMC clusters, the tidal radii are, on average, larger than those of inner clusters from previous studies; (ii) the core radii dispersion tends to be greater for LMC clusters located towards the southwest, with position angles of ∼200° and about ∼5° from the LMC centre, i.e. those LMC clusters nearer to the SMC; (iii) the core radius evolution for clusters with known age is similar to that of inner clusters; (iv) SMC clusters with galactocentric distances closer than 4 kpc are overfilling; (v) the recent Clouds collision did not leave marks on the LMC clusters’ structure that our analysis could reveal.

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Dwarf galaxies: evidence of differential tidal effects in the Large Magellanic Cloud

Proceedings of the International Astronomical Union ◽

10.1017/s1743921318005197 ◽

2018 ◽

Vol 14 (S344) ◽

pp. 114-117

Author(s):

Andrés E. Piatti ◽

Dougal Mackey

Keyword(s):

Gravitational Field ◽

Radial Velocity ◽

Globular Clusters ◽

Surface Brightness ◽

Dwarf Galaxies ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Tidal Effects ◽

Radial Profiles ◽

Stellar Density

AbstractWe built the most extended stellar density and/or surface brightness radial profiles for 13 old Large Magellanic Cloud (LMC) globular clusters (GCs). The studied GCs located farther than ~ 5 kpc from the LMC center would not seem to present any hint of extended stellar structures, while those closer than ~ 5 kpc do show extended structures. Such an excess of stars tightly depends on the position of the GCs, so that the closer the GC to the LMC center, the larger the excess of stars. Furthermore, the GC radii also show a remarkable trend with the position of the GC in the LMC disc. These outcomes can be fully interpreted in the light of the known GC radial velocity disc-like kinematics, from which GCs have been somehow mostly experiencing the influence of the LMC gravitational field at their respective mean distances from the LMC center.

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Washington photometry of five star clusters in the Large Magellanic Cloud

Proceedings of the International Astronomical Union ◽

10.1017/s1743921309991827 ◽

2009 ◽

Vol 5 (S266) ◽

pp. 500-503

Author(s):

Andrés E. Piatti ◽

Doug Geisler ◽

Ata Sarajedini ◽

Carme Gallart

Keyword(s):

Detailed Analysis ◽

Cluster Formation ◽

Star Clusters ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Ccd Photometry ◽

Outer Disk ◽

Field Star ◽

Show Evidence

AbstractWe present CCD photometry in the Washington-system C and T1 passbands down to T1 ~ 22.5 mag in the fields of NGC 1697, SL 133, NGC 1997, SL 663, and OHSC 28, five mostly unstudied star clusters in the LMC. Cluster radii were estimated from star counts in appropriately sized boxes distributed throughout the entire observed fields. We perform a detailed analysis of field-star contamination and derive cluster colour–magnitude diagrams (CMDs). Based on the best fits of isochrones computed by the Padova group to the (C − T1, T1) CMDs, the δ(T1) index and the ‘standard giant-branch’ procedure, we derive metallicities and ages for the five clusters. With the exception of NGC 1697 (age = 0.7 Gyr, [Fe/H] = 0.0 dex), the remaining four clusters are of intermediate age (from 2.2 to 3.0 Gyr) and relatively metal poor ([Fe/H] = −0.7 dex). We combine our sample with clusters with ages and metallicities on a similar scale and examine relationships between position in the LMC, age and metallicity. We confirm previous results that clusters younger than ~ 1 Gyr were formed during an outside-in process; this occurred after a burst of cluster formation that took place mainly in the outer disk and peaked ~ 2 Gyr ago. Finally, the cluster and field age–metallicity relations (AMRs) show evidence for a metallicity offset but do overlap, particularly on the upper-envelope side of the cluster AMR.

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Detailed chemical composition of classical Cepheids in the LMC cluster NGC 1866 and in the field of the SMC

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731370 ◽

2017 ◽

Vol 608 ◽

pp. A85 ◽

Cited By ~ 9

Author(s):

B. Lemasle ◽

M. A. T. Groenewegen ◽

E. K. Grebel ◽

G. Bono ◽

G. Fiorentino ◽

...

Keyword(s):

Chemical Composition ◽

Theoretical Models ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Main Body ◽

Depth Direction ◽

Classical Cepheids ◽

Age Relations ◽

First Time ◽

Detailed Chemical

Context. Cepheids are excellent tracers of young stellar populations. They play a crucial role in astrophysics as standard candles. The chemistry of classical Cepheids in the Milky Way is now quite well-known, however despite a much larger sample, the chemical composition of Magellanic Cepheids has been only scarcely investigated. Aims. For the first time, we study the chemical composition of several Cepheids located in the same populous cluster: NGC 1866, in the Large Magellanic Cloud (LMC). To also investigate the chemical composition of Cepheids at lower metallicity, we look at four targets located in the Small Magellanic Cloud (SMC). Our sample allows us to increase the number of Cepheids with known metallicities in the LMC/SMC by 20%/25% and the number of Cepheids with detailed chemical composition in the LMC/SMC by 46%/50%. Methods. We use canonical spectroscopic analysis to determine the chemical composition of Cepheids and provide abundances for a good number of α, iron-peak, and neutron-capture elements. Results. We find that six Cepheids in the LMC cluster NGC 1866 have a very homogeneous chemical composition, also consistent with red giant branch (RGB) stars in the cluster. Period–age relations that include no or average rotation indicate that all the Cepheids in NGC 1866 have a similar age and therefore belong to the same stellar population. Our results are in good agreement with theoretical models accounting for luminosity and radial velocity variations. Using distances based on period-luminosity relations in the near- or mid-infrared, we investigate for the first time the metallicity distribution of the young population in the SMC in the depth direction. Preliminary results show no metallicity gradient along the SMC main body, but our sample is small and does not contain Cepheids in the inner few degrees of the SMC.

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Molecules in the Magellanic Clouds

Symposium - International Astronomical Union ◽

10.1017/s0074180900201046 ◽

1991 ◽

Vol 148 ◽

pp. 415-420 ◽

Cited By ~ 1

Author(s):

R. S. Booth ◽

Th. De Graauw

Keyword(s):

High Resolution ◽

Molecular Clouds ◽

Short Review ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Magellanic Clouds ◽

Giant Molecular Clouds ◽

Interstellar Molecules ◽

First Time ◽

Excitation Conditions

In this short review we describe recent new observations of millimetre transitions of molecules in selected regions of the Magellanic Clouds. The observations were made using the Swedish-ESO Submillimetre Telescope, SEST, (Booth et al. 1989), the relatively high resolution of which facilitates, for the first time, observations of individual giant molecular clouds in the Magellanic Clouds. We have mapped the distribution of the emission from the two lowest rotational transitions of 12CO and 13CO and hence have derived excitation conditions for the molecule. In addition, we have observed several well-known interstellar molecules in the same regions, thus doubling the number of known molecules in the Large Magellanic Cloud (LMC). The fact that all the observations have been made under controlled conditions with the same telescope enables a reasonable intercomparison of the molecular column densities. In particular, we are able to observe the relative abundances among the different isotopically substituted species of CO.

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Line observations of the 30-Dor complex and N159A5 with the MPE imaging NIR spectrometer FAST

Symposium - International Astronomical Union ◽

10.1017/s0074180900200375 ◽

1991 ◽

Vol 148 ◽

pp. 205-206 ◽

Cited By ~ 1

Author(s):

A. Krabbe ◽

J. Storey ◽

V. Rotaciuc ◽

S. Drapatz ◽

R. Genzel

Keyword(s):

Spatial Resolution ◽

Molecular Hydrogen ◽

Near Infrared ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Emission Lines ◽

Resolving Power ◽

Max Planck ◽

First Time ◽

Infrared Array

Images with subarcsec spatial resolution in the light of near-infrared atomic (Bry) and molecular hydrogen H2 (S(1) v=1-0) emission lines were obtained for some extended, pointlike objects in the Large Magellanic Cloud (LMC) for the first time. We used the Max-Planck-Institut für extraterrestrische Physik (MPE) near-infrared array spectrometer FAST (image scale 0.8”/pix, spectral resolving power 950) at the ESO/MPI 2.2m telescope, La Silla. We present some results on the 30-Dor complex and N159A5.

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New optically identified supernova remnants in the Large Magellanic Cloud

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3382 ◽

2020 ◽

Vol 500 (2) ◽

pp. 2336-2358

Author(s):

Miranda Yew ◽

Miroslav D Filipović ◽

Milorad Stupar ◽

Sean D Points ◽

Manami Sasaki ◽

...

Keyword(s):

Supernova Remnants ◽

Supernova Remnant ◽

Narrow Band Imaging ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Main Body ◽

Found Objects ◽

Type Ia ◽

Optical Sample

ABSTRACT We present a new optical sample of three Supernova Remnants (SNRs) and 16 Supernova Remnant (SNR) candidates in the Large Magellanic Cloud (LMC). These objects were originally selected using deep H α, [S ii], and [O iii] narrow-band imaging. Most of the newly found objects are located in less dense regions, near or around the edges of the LMC’s main body. Together with previously suggested MCSNR J0541–6659, we confirm the SNR nature for two additional new objects: MCSNR J0522–6740 and MCSNR J0542–7104. Spectroscopic follow-up observations for 12 of the LMC objects confirm high [S ii]/H α emission-line ratios ranging from 0.5 to 1.1. We consider the candidate J0509–6402 to be a special example of the remnant of a possible type Ia Supernova (SN) which is situated some 2° (∼1.75 kpc) north from the main body of the LMC. We also find that the SNR candidates in our sample are significantly larger in size than the currently known LMC SNRs by a factor of ∼2. This could potentially imply that we are discovering a previously unknown but predicted, older class of large LMC SNRs that are only visible optically. Finally, we suggest that most of these LMC SNRs are residing in a very rarefied environment towards the end of their evolutionary span where they become less visible to radio and X-ray telescopes.

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