Brown dwarf formation by gravitational fragmentation of massive, extended protostellar discs

Stamatellos, Dimitris; Hubber, D. A.; Whitworth, Anthony Peter

doi:10.1111/j.1745-3933.2007.00383.x

Cited by 159 publications

(155 citation statements)

References 25 publications

Supporting

Mentioning

143

Contrasting

Order By: Relevance

“…Our scenario only requires a single extended disk. This scenario can produce very low mass companions at large distances from the primary star and may help explain recent direct detections of massive planets orbiting at >100 AU, far beyond where core accretion could have formed them 5 , as well as intermediate (Liu et al 2002) and distant (Stamatellos et al 2007a;Stamatellos & Whitworth 2009a) BD companions to stars. Like Stamatellos & Whitworth (2009a), we are also able to form BD binaries through three-body encounters within the disk and, in addition, through dissipative encounters.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Tidally Induced Brown Dwarf and Planet Formation in Circumstellar Disks

Thies

Kroupa

Goodwin

et al. 2010

ApJ

View full text Add to dashboard Cite

Most stars are born in clusters and the resulting gravitational interactions between cluster members may significantly affect the evolution of circumstellar disks and therefore the formation of planets and brown dwarfs (BDs). Recent findings suggest that tidal perturbations of typical circumstellar disks due to close encounters may inhibit rather than trigger disk fragmentation and so would seem to rule out planet formation by external tidal stimuli. However, the disk models in these calculations were restricted to disk radii of 40 AU and disk masses below 0.1 M . Here, we show that even modest encounters can trigger fragmentation around 100 AU in the sorts of massive (∼0.5 M ), extended ( 100 AU) disks that are observed around young stars. Tidal perturbation alone can do this; no disk-disk collision is required. We also show that very low mass binary systems can form through the interaction of objects in the disk. In our computations, otherwise non-fragmenting massive disks, once perturbed, fragment into several objects between about 0.01 and 0.1 M , i.e., over the whole BD mass range. Typically, these orbit on highly eccentric orbits or are even ejected. While probably not suitable for the formation of Jupiter-or Neptune-type planets, our scenario provides a possible formation mechanism for BDs and very massive planets which, interestingly, leads to a mass distribution consistent with the canonical substellar initial mass function. As a minor outcome, a possible explanation for the origin of misaligned extrasolar planetary systems is discussed.

show abstract

Section: Discussionmentioning

confidence: 99%

“…Most of the numerical parameter settings have been adopted from Stamatellos et al (2007a) and Stamatellos & Whitworth (2009a). Gravitationally collapsing clumps are treated by sink particles which form if the volume density exceeds 10 −9 g cm −3 , and the clump is bound.…”

Section: Smoothed Particle Hydrodynamics (Sph)mentioning

confidence: 99%

Tidally Induced Brown Dwarf and Planet Formation in Circumstellar Disks

Thies

Kroupa

Goodwin

et al. 2010

ApJ

View full text Add to dashboard Cite

show abstract

“…This method explains very well the formation of planets on close-in orbit (<10 au, Mordasini et al 2012), but struggles to explain the formation of planets on wide orbits. The second process suggests that planets form from the fragmentation of a gravitationally unstable disk (Boss 2011), which forms clumps that then can accrete gas and dust to become planets (Stamatellos et al 2007;Bate 2012). However, this mechanism also has difficulties forming planets on wide orbits, as shown by Nayakshin (2017) and Vigan et al (2017), for example.…”

Section: Introductionmentioning

confidence: 99%

WEIRD: Wide-orbit Exoplanet Search with InfraRed Direct Imaging

Baron

Artigau

Rameau

et al. 2018

View full text Add to dashboard Cite

We report results from the Wide-orbit Exoplanet search with InfraRed Direct imaging, or WEIRD, a survey designed to search for Jupiter-like companions on very wide orbits (1000-5000 au) around young stars (<120 Myr) that are known members of moving groups in the solar neighborhood (<70 pc). Companions that share the same age, distance, and metallicity as their host while being on large enough orbits to be studied as "isolated" objects make prime targets for spectroscopic observations, and they are valuable benchmark objects for exoplanet atmosphere models. The search strategy is based on deep imaging in multiple bands across the near-infrared domain. For all 177 objects of our sample, ¢ z ab , J, [3.6], and [4.5] images were obtained with CFHT/MegaCam, GEMINI/GMOS, CFHT/WIRCam, GEMINI/Flamingos-2, and Spitzer/IRAC. Using this set of four images per target, we searched for sources with red ¢ z ab and [3.6]-[4.5] colors, typically reaching good completeness down to 2 M Jup companions, while going down to 1 M Jup for some targets, at separations of 1000-5000 au. The search yielded four candidate companions with the expected colors, but they were all rejected through follow-up proper motion observations. Our results constrain the occurrence of 1-13 M Jup planetary-mass companions on orbits with a semimajor axis between 1000 and 5000 au at less than 0.03, with a 95% confidence level.

show abstract

“…Whitworth & Stamatellos 2006) or a more specific channel of early ejection of gaseous clumps (Reipurth & Clarke 2001;Basu & Vorobyov 2012). Other plausible mechanisms suggest massive disc fragmentation (Stamatellos et al 2007) or gravitational instabilities induced in discs as a result of encounters in embedded clusters (Thies et al 2010).…”

Section: Treating Brown Dwarfs As a Separate Population (Model D)mentioning

confidence: 99%

Reverse dynamical evolution ofηChamaeleontis

Becker

Moraux

Duchêne

et al. 2013

A&A

View full text Add to dashboard Cite

Context. In the scope of the star formation process, it is unclear how the environment shapes the initial mass function (IMF). While observations of open clusters propose a universal picture for the IMF from the substellar domain up to a few solar masses, the young association η Chamaeleontis presents an apparent lack of low mass objects (m < 0.1 M ). Another unusual feature of this cluster is the absence of wide binaries with a separation >50 AU. Aims. We aim to test whether dynamical evolution alone can reproduce the peculiar properties of the association under the assumption of a universal IMF. Methods. We use a pure N-body code to simulate the dynamical evolution of the cluster for 10 Myr, and compare the results with observations. A wide range of values for the initial parameters are tested (number of systems, typical radius of the density distribution and virial ratio) in order to identify the initial state that would most likely lead to observations. In this context we also investigate the influence of the initial binary population on the dynamics and the possibility of having a discontinuous single IMF near the transition to the brown dwarf regime. We consider as an extreme case an IMF with no low mass systems (m < 0.1 M ). Results. The initial configurations cover a wide range of initial density, from 10 2 to 10 8 stars/pc 3 , in virialized, hot and cold dynamical state. We do not find any initial state that would evolve from a universal single IMF to fit the observations. Only when starting with a truncated IMF without any very low mass systems and no wide binaries, can we reproduce the cluster core properties with a success rate of 10% at best. Conclusions. Pure dynamical evolution alone cannot explain the observed properties of η Chamaeleontis from universal initial conditions. The lack of brown dwarfs and very low mass stars, and the peculiar binary properties (low binary fraction and lack of wide binaries), are probably the result of the star formation process in this association.

show abstract

Brown dwarf formation by gravitational fragmentation of massive, extended protostellar discs

Cited by 159 publications

References 25 publications

Tidally Induced Brown Dwarf and Planet Formation in Circumstellar Disks

Tidally Induced Brown Dwarf and Planet Formation in Circumstellar Disks

WEIRD: Wide-orbit Exoplanet Search with InfraRed Direct Imaging

Reverse dynamical evolution ofηChamaeleontis

Contact Info

Product

Resources

About