Please note that eDoc will be permanently shut down in the first quarter of 2021!      Home News About Us Contact Contributors Disclaimer Privacy Policy Help FAQ

Home
Search
Quick Search
Advanced
Fulltext
Browse
Collections
Persons
My eDoc
Session History
Login
Name:
Password:
Documentation
Help
Support Wiki
Direct access to
document ID:


          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents



  history
ID: 448057.0, MPI für Astronomie / Publikationen_mpia
The low-mass initial mass function in the 30 Doradus starburst cluster
Authors:Andersen, M.; Zinnecker, H.; Moneti, A.; McCaughrean, M. J.; Brandl, B.; Brandner, W.; Meylan, G.; Hunter, D.
Language:English
Date of Publication (YYYY-MM-DD):2009
Title of Journal:The Astrophysical Journal
Journal Abbrev.:ApJ
Volume:707
Issue / Number:2
Start Page:1347
End Page:1360
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:We present deep Hubble Space Telescope NICMOS 2 F160W band observations of the central 56'' × 57'' (14 pc × 14.25 pc) region around R136 in the starburst cluster 30 Dor (NGC 2070) located in the Large Magellanic Cloud. Our aim is to derive the stellar initial mass function (IMF) down to ~1 M sun in order to test whether the IMF in a massive metal-poor cluster is similar to that observed in nearby young clusters and the field in our Galaxy. We estimate the mean age of the cluster to be 3 Myr by combining our F160W photometry with previously obtained HST WFPC2 optical F555W and F814W band photometry and comparing the stellar locus in the color-magnitude diagram with main sequence and pre-main sequence isochrones. The color-magnitude diagrams show the presence of differential extinction and possibly an age spread of a few megayear. We convert the magnitudes into masses adopting both a single mean age of 3 Myr isochrone and a constant star formation history from 2 to 4 Myr. We derive the IMF after correcting for incompleteness due to crowding. The faintest stars detected have a mass of 0.5 M sun and the data are more than 50% complete outside a radius of 5 pc down to a mass limit of 1.1 M sun for 3 Myr old objects. We find an IMF of \frac{dN}{d\log M }\propto M^{-1.20\pm 0.2} over the mass range 1.1-20 M sun only slightly shallower than a Salpeter IMF. In particular, we find no strong evidence for a flattening of the IMF down to 1.1 M sun at a distance of 5 pc from the center, in contrast to a flattening at 2 M sun at a radius of 2 pc, reported in a previous optical HST study. We examine several possible reasons for the different results including the possible presence of mass segregation and the effects of differential extinction, particularly for the pre-main sequence sources. If the IMF determined here applies to the whole cluster, the cluster would be massive enough to remain bound and evolve into a relatively low-mass globular cluster.
Free Keywords:globular clusters: individual: 30 Doradus; stars: formation; stars: luminosity function; mass function; stars: pre-main sequence
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:URL:http://adsabs.harvard.edu/abs/2009ApJ...707.1347A [ID No:1]
The scope and number of records on eDoc is subject to the collection policies defined by each institute - see "info" button in the collection browse view.