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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 742894.0, MPI für Astronomie / Publikationen_mpia
Very low-mass stellar content of the young supermassive Galactic star cluster Westerlund 1
Authors:Andersen, M.; Gennaro, M.; Brandner, W.; Stolte, A.; de Marchi, G.; Meyer, M. R.; Zinnecker, H.
Date of Publication (YYYY-MM-DD):2017
Title of Journal:Astronomy and Astrophysics
Start Page:id. A22 (16 pp)
Audience:Not Specified
Abstract / Description:We present deep near-infrared HST/WFC3 observations of the young supermassive Galactic star cluster Westerlund 1 and an adjacent control field. The depth of the data is sufficient to derive the mass function for the cluster as a function of radius down to 0.15 M in the outer parts of the cluster. We identify for the first time a flattening in the mass function (in logarithmic units) at a mass range that is consistent with that of the field and nearby embedded clusters. Through log-normal functional fits to the mass functions we find the nominal peak mass to be comparable to that of the field and nearby embedded star clusters. The width of a log-normal fit appears slightly narrow compared to the width of the field initial mass function, closer to the values found for globular clusters. The subsolar content within the cluster does not appear to be mass segregated in contrast to the findings for the supersolar content. The total mass of Westerlund 1 is estimated to be 44-57 × 103M where the main uncertainty is the choice of the isochrone age and the higher mass slope. Comparing the photometric mass with the dynamically determined mass, Westerlund 1 is sufficiently massive to remain bound and could potentially evolve into a lowmass globular cluster. Full Table 1 is only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A> (<A href=""></A>) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/602/A22">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/602/A22</A>
Free Keywords:stars: formation; open clusters and associations: individual: Westerlund 1; stars: low-mass; stars: luminosity function; mass function; stars: pre-main sequence
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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