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Red Giant stars in the Large Magellanic Cloud clusters

A. Mucciarelli·L. Origlia·F. R. Ferraro·C. Maraston·V. Testa
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Abstract

We present deep J,H,Ks photometry and accurate Color Magnitude Diagrams down to K ~18.5, for a sample of 13 globular clusters in the Large Magellanic Cloud. This data set combined with the previous sample of 6 clusters published by our group gives the opportunity to study the properties of giant stars in clusters with different ages (ranging from ~80 Myr up to ~3.5 Gyr). Quantitative estimates of star population ratios (by number and luminosity) in the Asymptotic Giant Branch, the Red Giant Branch and the He-clump, have been obtained and compared with theoretical models in the framework of probing the so-called phase transitions. The AGB contribution to the total luminosity starts to be significant at ~200 Myr and reaches its maximum at ~5-600 Myr, when the RGB Phase Transition is starting. At ~900 Myr the full developing of an extended and well populated RGB has been completed. Both the occurrence of the AGB and RGB Phase Transitions are sharp events, lasting a few hundreds Myr only. These empirical results agree very well with the theoretical predictions of simple stellar population models based on canonical tracks and the fuel-consumption approach.

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A. Mucciarelli, L. Origlia, F. R. Ferraro, C. Maraston, V. Testa. 2006-04-06. Red Giant stars in the Large Magellanic Cloud clusters. https://doi.org/10.1086/504969

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