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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 731677.0, MPI für Astronomie / Publikationen_mpia
The bimodal initial mass function in the Orion nebula cloud
Authors:Drass, H.; Haas, M.; Chini, R.; Bayo, A.; Hackstein, M.; Hoffmeister, V.; Godoy, N.; Vogt, N.
Date of Publication (YYYY-MM-DD):2016
Title of Journal:Monthly Notices of the Royal Astronomical Society
Issue / Number:2
Start Page:1734
End Page:1744
Audience:Not Specified
Abstract / Description:Due to its youth, proximity and richness, the Orion nebula cloud (ONC) is an ideal testbed to obtain a comprehensive view on the initial mass function (IMF) down to the planetary mass regime. Using the HAWK-I camera at the VLT, we have obtained an unprecedented deep and wide near-infrared JHK mosaic of the ONC (90 per cent completeness at K ˜ 19.0 mag, 22 × 28 arcmin2). Applying the most recent isochrones and accounting for the contamination of background stars and galaxies, we find that ONC's IMF is bimodal with distinct peaks at about 0.25 and 0.025 M separated by a pronounced dip at the hydrogen burning limit (0.08 M), with a depth of about a factor of 2-3 below the log-normal distribution. Apart from ˜920 low-mass stars (M < 1.4 M) the IMF contains ˜760 brown dwarf candidates and ˜160 isolated planetary mass object candidates with M > 0.005 M, hence about 10 times more substellar candidates than known before. The substellar IMF peak at 0.025 M could be caused by brown dwarfs and isolated planetary mass objects which have been ejected from multiple systems during the early star formation process or from circumstellar discs.
Free Keywords:brown dwarfs; stars: formation; dust; extinction; infrared: stars
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:ISSN:0035-8711 %R 10.1093/mnras/stw1094
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