Statistical fractal analysis of 25 young star clusters

Autor(es)

Gregorio-Hetem, J. ^[1] ; Hetem, A. ^[2] ; Santos-Silva, T. ^[1] ; Fernandes, B. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, IAG, BR-05508900 Sao Paulo - Brazil

^[2] Univ Fed ABC, CECS, BR-09210580 Santo Andre, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Monthly Notices of the Royal Astronomical Society; v. 448, n. 3, p. 2504-2513, APR 11 2015.
• Citações Web of Science: 13

Resumo

A large sample of young stellar groups is analysed to investigate their clustering properties and dynamical evolution. A comparison of the Q statistical parameter, measured for the clusters, with the fractal dimension estimated for the projected clouds, shows that 52 per cent of the sample has substructures and tends to follow the theoretically expected relation between clusters and clouds, according to calculations for the artificial distribution of points. The fractal statistics was also compared to structural parameters, revealing that clusters having a radial density profile show a trend of parameter (s) over bar increasing with mean surface stellar density. The core radius of the sample, as a function of age, follows a similar distribution to that observed in stellar groups of the Milky Way and other galaxies. They also have dynamical age, indicated by their crossing time, which is similar to unbound associations. The statistical analysis allowed us to separate the sample into two groups showing different clustering characteristics. However, they have the same dynamical evolution, since the whole sample has been revealed as expanding objects, for which the substructures seem to have not been erased. These results are in agreement with simulations that adopt low surface densities and models under supervirial conditions. (AU)

• Processo FAPESP: 10/50930-6 - Evolução química e populações estelares galácticas e extragalácticas, por espectroscopia e imageamento
• Beneficiário: Beatriz Leonor Silveira Barbuy
• Linha de fomento: Auxílio à Pesquisa - Temático