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Wide-field HST/ACS images of M81: The Population of Compact Star Clusters
MAYRA SANTIAGO CORTES
YALIA DIVAKARA MAYYA
DANIEL ROSA GONZALEZ
Acceso Abierto
Atribución-NoComercial-SinDerivadas
Catalogs
Galaxies: individual (M81)
Galaxies: spiral
Galaxies: star clusters
We study the population of compact stellar clusters (CSCs) in M81, using the HST/ACS images in the filters F435W, F606W and F814W covering, for the first time, the entire optical extent of the galaxy. Our sample contains 435 clusters of FWHM less than 10 ACS pixels (9 pc). The sample shows the presence of two cluster populations, a blue group of 263 objects brighter than B = 22 mag, and a red group of 172 objects, brighter than B = 24 mag. Based on the analysis of colour magnitude diagrams and making use of simple stellar population models, we find the blue clusters are younger than 300 Myr with some clusters as young as few Myr, and the red clusters are as old as globular clusters. The luminosity function of the blue group follows a power-law distribution with an index of 2.0, typical value for young CSCs in other galaxies. The power-law shows unmistakable signs of truncation at I = 18.0 mag (M🇮 = −9.8 mag), which would correspond to a mass-limit of 4 × 10⁴M⊙ if the brightest clusters are younger than 10 Myr. The red clusters have photometric masses between 10⁵ to 2×10⁷M⊙ for the adopted age of 5 Gyr and their luminosity function resembles very much the globular cluster luminosity function in the Milky Way. The brightest GC in M81 has M⁰🇧 = −10.3 mag, which is ∼ 0.9 mag brighter than ω Cen, the most massive GC in the Milky Way.
Monthly Notices of the Royal Astronomical Society
2010
Artículo
Inglés
Estudiantes
Investigadores
Público en general
Santiago Cortés, M., Mayya, Y. D. and Rosa González, D., (2010), Wide-field HST/ACS images of M81: The Population of Compact Star Clusters, Monthly Notices of the Royal Astronomical Society, Vol. 405(2):1293-1302
ASTRONOMÍA Y ASTROFÍSICA
Versión aceptada
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Aparece en las colecciones: Artículos de Astrofísica

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