The bimodal initial mass function in the Orion Nebula Cloud

Abstract

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% completeness at K~19.0mag, 22'x28). 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_sun separated by a pronounced dip at the hydrogen burning limit (0.08 M_sun), with a depth of about a factor 2-3 below the log-normal distribution. Apart from ~920 low-mass stars (M < 1.4 M_sun) the IMF contains ~760 brown dwarf (BD) candidates and ~160 isolated planetary mass object (IPMO) candidates with M > 0.005 M_sun, hence about ten times more substellar candidates than known before. The substellar IMF peak at 0.025 M_sun could be caused by BDs and IPMOs which have been ejected from multiple systems during the early star-formation process or from circumstellar disks.

Accepted at MNRAS, 12 pages, 13 figures, 3 tables

References in corpus (10)

• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• New evolutionary models for pre-main sequence and main sequence low-mass stars down to the hydrogen-burning limit
• The distance to the Orion Nebula
• The Importance of Radiative Feedback for the Stellar Initial Mass Function
• A SCUBA survey of Orion, the low-mass end of the core mass function
• Tidally induced brown dwarf and planet formation in circumstellar discs
• Infrared Spectroscopy and Analysis of Brown Dwarf and Planetary Mass Objects in the Orion Nebula Cluster
• Characterizing the Brown Dwarf Formation Channels from the Initial Mass Function and Binary-star Dynamics
• A discontinuity in the low-mass IMF - the case of high multiplicity
• An optical spectroscopic H-R diagram for low-mass stars and brown dwarfs in Orion

Cited by in corpus (24)

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• The Origin of the Stellar Mass Distribution and Multiplicity
• Multiple Star Systems in the Orion Nebula
• Looking deep into the Rosette Nebula's heart: the (sub)stellar content of the massive young cluster NGC 2244
• System IMF of the 25 Ori Group from Planetary-Mass Objects to Intermediate/High-Mass Stars
• Youth analysis of near infrared spectra of young low-mass stars and brown dwarfs
• HST survey of the Orion Nebula Cluster in the H${}_2$O 1.4 $\mu$m absorption band: I. A census of substellar and planetary mass objects
• HST survey of the Orion Nebula Cluster in the H${}_2$O 1.4 $\mu$m absorption band: II. The substellar IMF down to planetary masses
• VISION - Vienna Survey in Orion II. Infrared extinction in Orion A
• The TEMPO Survey I: Predicting Yields of the Transiting Exosatellites, Moons, and Planets from a 30-day Survey of Orion with the Nancy Grace Roman Space Telescope
• A candidate planetary-mass object with a photoevaporating disk in Orion
• The Energy and Dynamics of Trapped Radiative Feedback with Stellar Winds
• A Dual Power Law Distribution for the Stellar Initial Mass Function
• Orbital Migration of Protoplanets in a Marginally Gravitationally Unstable Disk. II. Migration, Merging, and Ejection
• Search for Brown Dwarfs in IC 1396 with Subaru HSC: Interpreting the Impact of Environmental Factors on Sub-stellar Population
• An APEX search for carbon emission from NGC 1977 proplyds
• Early phases in the stellar and substellar formation and evolution: Infrared and submillimeter data in the Barnard 30 dark cloud
• A Multiple Power Law Distribution for Initial Mass Functions
• Forming short period sub-stellar companions in 47 Tuc: I. Dynamical model and brown dwarf tidal capture rates
• History of Globulettes in the Milky Way
• Hidden power of near-infrared data for the study of young clusters: Illustrative case of RCW 38
• The Future of IMF studies with the ELT and MICADO I: The local Universe as a resolved IMF laboratory
• On the coupled origin of the stellar IMF and multiplicity