The bimodal initial mass function in the Orion nebula cloud

Drass, H.; Haas, Martín; Chini, R.; Bayo, A.; Hackstein, M.; Hoffmeister, V. H.; Godoy, N.; Vogt, N.

doi:10.1093/mnras/stw1094

Cited by 33 publications

(29 citation statements)

References 57 publications

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“…The discovery of Proplyd133-353 may provide a clue to understanding the significant peak at 10-20M J of the ONC initial mass function (Muench et al 2002;Drass et al 2016). The second-generation star formation in the very low-mass globulettes or in the EGGs could overpopulate the objects of the ONC within such a mass range.…”

Section: Resultsmentioning

confidence: 99%

A Candidate Planetary-Mass Object With a Photoevaporating Disk in Orion

Fang

Kim

Pascucci

et al. 2016

ApJL

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In this work, we report the discovery of a candidate planetary-mass object with a photoevaporating protoplanetary disk, Proplyd133-353, which is near the massive star θ 1 Ori C at the center of the Orion Nebula Cluster (ONC). The object was known to have extended emission pointing away from θ 1 OriC, indicating ongoing external photoevaporation. Our near-infrared spectroscopic data and the location on the H-R diagram suggest that the central source of Proplyd133-353 is substellar (∼M9.5) and has a mass probably less than 13 Jupiter mass and an age younger than 0.5 Myr. Proplyd133-353 shows a similar ratio of X-ray luminosity to stellar luminosity to other young stars in the ONC with a similar stellar luminosity and has a similar proper motion to the mean one of confirmed ONC members. We propose that Proplyd133-353 formed in a very low-mass dusty cloud or an evaporating gas globule near θ 1 Ori C as a second generation of star formation, which can explain both its young age and the presence of its disk.

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Section: Resultsmentioning

confidence: 99%

A Candidate Planetary-Mass Object With a Photoevaporating Disk in Orion

Fang

Kim

Pascucci

et al. 2016

ApJL

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“…For example, a study of the large massive star forming cluster RCW 38 by Mužić et al (2017) using adaptive optics imaging on the Very Large Telescope (VLT) reveals a large number of spectroscopically confirmed substellar objects, with the ratio of substellar to stellar objects estimated to be about 1:2. A new survey of the Orion Nebula Cluster by Drass et al (2016), also using the VLT, finds a ratio of substellar to stellar objects of about 1:1, although the putative substellar objects are not yet spectroscopically confirmed.…”

Section: Introductionmentioning

confidence: 99%

A dual power-law distribution for the stellar initial mass function

Hoffmann

Essex

Basu

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We introduce a new dual power law (DPL) probability distribution function for the mass distribution of stellar and substellar objects at birth, otherwise known as the initial mass function (IMF). The model contains both deterministic and stochastic elements, and provides a unified framework within which to view the formation of brown dwarfs and stars resulting from an accretion process that starts from extremely low mass seeds. It does not depend upon a top down scenario of collapsing (Jeans) masses or an initial lognormal or otherwise IMF-like distribution of seed masses. Like the modified lognormal power law (MLP) distribution, the DPL distribution has a power law at the high mass end, as a result of exponential growth of mass coupled with equally likely stopping of accretion at any time interval. Unlike the MLP, a power law decay also appears at the low mass end of the IMF. This feature is closely connected to the accretion stopping probability rising from an initially low value up to a high value. This might be associated with physical effects of ejections sometimes (i.e., rarely) stopping accretion at early times followed by outflow driven accretion stopping at later times, with the transition happening at a critical time (therefore mass). Comparing the DPL to empirical data, the critical mass is close to the substellar mass limit, suggesting that the onset of nuclear fusion plays an important role in the subsequent accretion history of a young stellar object.

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“…In this sense, the environments we aim to cover are significantly different from those in nearby star forming regions, with the exception of the Orion Nebula Cluster (ONC), the only site of massive star formation within 500 pc from the Sun. The latest results from the ONC show a bimodal form of an IMF, with a secondary peak in the substellar regime (Drass et al 2016). The authors interpret the substellar peak as possibly formed by BDs ejected from multiple systems or circumstellar disks at an early stage of star formation.…”

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confidence: 97%

Looking Deep into the Rosette Nebula’s Heart: The (Sub)stellar Content of the Massive Young Cluster NGC 2244

Mužić

Scholz

Ramírez

et al. 2019

ApJ

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As part of the ongoing effort to characterize the low-mass (sub)stellar population in a sample of massive young clusters, we have targeted the ∼2 Myr old cluster NGC 2244. The distance to NGC 2244 from Gaia DR2 parallaxes is 1.59 kpc, with errors of 1% (statistical) and 11% (systematic). We used the Flamingos-2 near-infrared camera at the Gemini-South telescope for deep multi-band imaging of the central portion of the cluster (∼ 2.4 pc 2 ). We determined membership in a statistical manner, through a comparison of the cluster's color-magnitude diagram to that of a control field. Masses and extinctions of the candidate members are then calculated with the help of evolutionary models, leading to the first initial mass function (IMF) of the cluster extending into the substellar regime, with the 90% completeness limit around 0.02 M . The IMF is well represented by a broken power law (dN/dM ∝ M −α ), with a break at ∼0.4 M . The slope on the high-mass side (0.4 − 7 M ) is α = 2.12 ± 0.08, close to the standard Salpeter's slope. In the low-mass range (0.02 − 0.4 M ), we find a slope α = 1.03 ± 0.02, which is on the high end of the typical values obtained in nearby star-forming regions (α = 0.5 − 1.0), but still in agreement within the uncertainties. Our results reveal no clear evidence for variations in the formation efficiency of brown dwarfs and very low-mass stars due to the presence of OB stars, or for a change in stellar densities. Our finding rules out photoevaporation and fragmentation of infalling filaments as substantial pathways for BD formation.

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The bimodal initial mass function in the Orion nebula cloud

Cited by 33 publications

References 57 publications

A Candidate Planetary-Mass Object With a Photoevaporating Disk in Orion

A Candidate Planetary-Mass Object With a Photoevaporating Disk in Orion

A dual power-law distribution for the stellar initial mass function

Looking Deep into the Rosette Nebula’s Heart: The (Sub)stellar Content of the Massive Young Cluster NGC 2244

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