scholarly journals An estimate of the structural parameters of the Large Magellanic Cloud using red clump stars

2010 ◽  
Vol 520 ◽  
pp. A24 ◽  
Author(s):  
S. Subramanian ◽  
A. Subramaniam
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 ◽  
...  

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.


2007 ◽  
Vol 134 (2) ◽  
pp. 680-693 ◽  
Author(s):  
Aaron J. Grocholski ◽  
Ata Sarajedini ◽  
Knut A. G. Olsen ◽  
Glenn P. Tiede ◽  
Conor L. Mancone

2009 ◽  
Vol 5 (S266) ◽  
pp. 320-325 ◽  
Author(s):  
Léo Girardi ◽  
Stefano Rubele ◽  
Leandro Kerber

AbstractA few star clusters in the Magellanic Clouds exhibit composite structures in the red-clump region of their colour–magnitude diagrams. The most striking case is NGC 419 in the Small Magellanic Cloud (SMC), where the red clump is composed of a main blob as well as a distinct secondary feature. This structure is demonstrated to be real and corresponds to the simultaneous presence of stars which passed through electron degeneracy after central-hydrogen exhaustion and those that did not. This rare occurrence in a single cluster allows us to set stringent constraints on its age and on the efficiency of convective-core overshooting during main-sequence evolution. We present a more detailed analysis of NGC 419, together with a first look at other populous Large Magellanic Cloud clusters which are apparently in the same phase: NGC 1751, NGC 1783, NGC 1806, NGC 1846, NGC 1852 and NGC 1917. We also compare these Magellanic Cloud cases with their Galactic counterparts, NGC 752 and NGC 7789. We emphasise the extraordinary potential of these clusters as absolute calibration marks on the age scale of stellar populations.


2002 ◽  
Vol 573 (1) ◽  
pp. L51-L54 ◽  
Author(s):  
David R. Alves ◽  
Marina Rejkuba ◽  
Dante Minniti ◽  
Kem H. Cook

2019 ◽  
Vol 490 (1) ◽  
pp. 385-407
Author(s):  
Ying-Yi Song ◽  
Mario Mateo ◽  
A D Mackey ◽  
Edward W Olszewski ◽  
Ian U Roederer ◽  
...  

ABSTRACT As an introduction of a kinematic survey of Magellanic Cloud (MC) star clusters, we report on the dynamical masses and mass-to-light ratios (M/L) of NGC 419 (Small Magellanic Cloud) and NGC 1846 (Large Magellanic Cloud). We have obtained more than one hundred high-resolution stellar spectra in and around each cluster using the multi-object spectrograph M2FS on the Magellan/Clay Telescope. Line-of-sight velocities and positions of the stars observed in each cluster were used as input to an expectation-maximization algorithm used to estimate cluster membership probabilities, resulting in samples of 46 and 52 likely members (PM ≥ 50 per cent) in NGC 419 and NGC 1846, respectively. This process employed single-mass King models constrained by the structural parameters of the clusters and provided self-consistent dynamical mass estimates for both clusters. Our best-fitting results show that NGC 419 has a projected central velocity dispersion of $2.44^{+0.37}_{-0.21}$ km s−1, corresponding to a total mass of $7.6^{+2.5}_{-1.3}\times 10^4\ {\rm M}_{\odot }$ and V-band M/L ratio of $0.22^{+0.08}_{-0.05}$ in solar units. For NGC 1846, the corresponding results are $2.04^{+0.28}_{-0.24}$ km s−1, $5.4^{+1.5}_{-1.4}\times 10^4\ {\rm M}_{\odot }$, and $0.32^{+0.11}_{-0.11}$. The mean metallicities of NGC 419 and NGC 1846 are found to be $\rm [Fe/H]=-0.84\pm 0.19$ and −0.70 ± 0.08, respectively, based on the spectra of likely cluster members. We find marginal statistical evidence of rotation in both clusters, though in neither cluster does rotation alter our mass estimates significantly. We critically compare our findings with those of previous kinematic studies of these two clusters in order to evaluate the consistency of our observational results and analytic tools.


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