Analysis of the stellar population in the central area of the HII region Sh 2-284 - Astrophysics > Astrophysics of GalaxiesReportar como inadecuado




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Abstract: There is a lack of state-of-the-art information on very young open clusters,with implications for determining the structure of the Galaxy. Our mainobjective is to study the timing and location of the star formation processeswhich yielded the generation of the giant HII region Sh 2-284. The analysis isbased on UBVRcIc CCD measurements and JHKs photometry in the central part ofthe HII region, where the cluster Dolidze 25 is located.The determination ofcluster distance, reddening and age is carried out through comparison withZAMS, post-MS and PMS isochrones. Reference lines for metallicity Z=0.004 areused, in agreement with spectroscopic metallicity determination published forseveral cluster members. The results are: EB-V=0.78+-0.02, M=12.8+-0.2,LogAgeyr=6.51+-0.07. A PMS member sequence is proposed, coeval within theerrors with the post-MS cluster age LogAgeyr=6.7+-0.2. The mass functionfor this PMS population in the mass range above 1.3-3.5 Msun is well fitted bya Salpeter mass function.The presence of a different star generation in thecluster with a distinctly older age, around 40 Myr, is suggested. The NIRresults indicate a large number of sources with H-Ks excess, practicallydistinct from the optical PMS candidate members.The distance determined for the cluster is distinctly lower than previouslypublished values. This result originates in the consistent use of lowmetallicity models for ZAMS fitting, applying published metallicity values forthe cluster.



Autor: Antonio J. Delgado, Anlaug A. Djupvik, Emilio J. Alfaro

Fuente: https://arxiv.org/







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