The embedded cluster DBSB 48 in the nebula Hoffleit 18: Comparison with Trumpler 14

Autor: Eduardo Luiz Damiani Bica, Sergio Ortolani, Beatriz Barbuy, Yazan Momany, C. Bonatto
Rok vydání: 2008
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Zdroj: New Astronomy. 13:508-518
ISSN: 1384-1076
Popis: We derive fundamental parameters of the embedded cluster DBSB48 in the southern nebula Hoffleit18 and the very young open cluster Trumpler14, by means of deep JHKs infrared photometry. We build colour-magnitude and colour-colour diagrams to derive reddening and age, based on main sequence and pre-main sequence distributions. Radial stellar density profiles are used to study cluster structure and guide photometric diagram extractions. Field-star decontamination is applied to uncover the intrinsic cluster sequences in the diagrams. Ages are inferred from K-excess fractions. A prominent pre-main-sequence population is present in DBSB48, and the K-excess fraction f_K=55+/-6% gives an age of 1.1+/-0.5Myr. A mean reddening of A_K_s=0.9+/-0.03 was found, corresponding to $A_V=8.2\pm0.3$. The cluster CMD is consistent with the far kinematic distance of 5 kpc for Hoffleit 18. For Trumpler 14 we derived similar parameters as in previous studies in the optical, in particular an age of $1.7\pm0.7$ Myr. The fraction of stars with infrared excess in Trumpler 14 is $f_K=28\pm4%$. Despite the young ages, both clusters are described by a King profile with core radii $\rc=0.46\pm0.05$ pc and $\rc=0.35\pm0.04$ pc, respectively for DBSB 48 and Trumpler 14. Such cores are smaller than those of typical open clusters. Small cores are probably related to the cluster formation and/or parent molecular cloud fragmentation. In DBSB 48, the magnitude extent of the upper main sequence is $\Delta \ks\approx2$ mag, while in Trumpler 14 it is $\Delta \ks\approx5$ mag, consistent with the estimated ages.
Comment: 25 pages, 11 figures. Accepted by New Astronomy
Databáze: OpenAIRE
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