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We model the coagulation and fragmentation of dust grains during the protostellar collapse with our newly developed shark code. It solves the gas-dust hydrodynamics in a spherical geometry and the coagulation/fragmentation equation. It also…

Astrophysics of Galaxies · Physics 2022-11-16 Ugo Lebreuilly , Valentin Vallucci-Goy , Vincent Guillet , Maxime Lombart , Pierre Marchand

It is likely that young protostellar disks undergo a self-gravitating phase. Such systems are characterized by the presence of a spiral pattern that can be either in a quasi-steady state or in a nonlinear unstable condition. This spiral…

Earth and Planetary Astrophysics · Physics 2022-01-12 Cristiano Longarini , Giuseppe Lodato , Claudia Toci , Benedetta Veronesi , Cassandra Hall , Ruobing Dong , Jason Patrick Terry

Angular momentum transport within young massive protoplanetary discs may be dominated by self-gravity at radii where the disk is too weakly ionized to allow the development of the magneto-rotational instability. We use time-dependent…

Solar and Stellar Astrophysics · Physics 2011-11-15 W. K. M. Rice , P. J. Armitage

Due to the gas rich environments of early circumstellar disks, the gravitational collapse of cool, dense regions of the disk form fragments largely composed of gas. During formation, disk fragments may attain increased metallicities as they…

Earth and Planetary Astrophysics · Physics 2019-08-26 Hans Baehr , Hubert Klahr

Observations with the Atacama Large Millimeter/Submillimeter array (ALMA) have dramatically improved our understanding of the site of exoplanet formation: protoplanetary discs. However, many basic properties of these discs are not…

Solar and Stellar Astrophysics · Physics 2020-12-09 C. Hall , R. Dong , R. Teague , J. Terry , C. Pinte , T. Paneque-Carreño , B. Veronesi , R. D. Alexander , G. Lodato

Determining the initial stellar multiplicity is a challenging problem since protostars are faint and deeply embedded at early times; once formed, multiple protostellar systems may significantly dynamically evolve before they are optically…

Solar and Stellar Astrophysics · Physics 2015-06-03 Stella S. R. Offner , John Capodilupo , Scott Schnee , Alyssa A. Goodman

In the disk-mediated accretion scenario for the formation of the most massive stars, gravitational instabilities in the disk can force it to fragment. We investigate the effects of inclination and spatial resolution on observable kinematics…

Astrophysics of Galaxies · Physics 2019-11-27 Aida Ahmadi , Rolf Kuiper , Henrik Beuther

The observation of massive exoplanets at large separation from their host star, like in the HR 8799 system, challenges theories of planet formation. A possible formation mechanism involves the fragmentation of massive self-gravitating discs…

Earth and Planetary Astrophysics · Physics 2015-05-28 Clément Baruteau , Farzana Meru , Sijme-Jan Paardekooper

We numerically model fragmentation of a gravitationally unstable gaseous disc under conditions that may be appropriate for the formation of the young massive stars observed in the central parsec of our Galaxy. In this study, we adopt a…

Astrophysics · Physics 2008-11-26 Sergei Nayakshin , Jorge Cuadra , Volker Springel

We present the analysis of the properties of large samples of protostellar discs formed in four radiation hydrodynamical simulations of star cluster formation. The four calculations have metallicities of 0.01, 0.1, 1 and 3 times solar…

Astrophysics of Galaxies · Physics 2021-10-13 Daniel Elsender , Matthew R. Bate

Observations of systems hosting close in ($<1$ AU) giant planets and brown dwarfs ($M\gtrsim7$ M$_{\rm Jup}$) find an excess of binary star companions, indicating that stellar multiplicity may play an important role in their formation.…

Earth and Planetary Astrophysics · Physics 2022-01-19 James Cadman , Cassandra Hall , Clémence Fontanive , Ken Rice

Supermassive stars (SMSs) with mass $\sim10^{5}~\rm{M}_{\odot}$ are promising candidates for the origin of supermassive black holes observed at redshift $\gtrsim6$. They are supposed to form as a result of rapid accretion of primordial gas,…

Astrophysics of Galaxies · Physics 2019-01-09 Ryoki Matsukoba , Sanemichi Z. Takahashi , Kazuyuki Sugimura , Kazuyuki Omukai

We construct an analytical model of Population III star formation that connects the cosmological radiation background to sub-AU protostellar disk fragmentation, a dynamic range inaccessible to any single simulation. Our approach is based on…

Astrophysics of Galaxies · Physics 2026-04-30 James Gurian , Boyuan Liu , Donghui Jeong , Takashi Hosokawa , Shingo Hirano , Volker Bromm , Naoki Yoshida

We analyze the first cosmological simulations that recover the fragmentation of high-redshift galactic discs driven by cold streams. The fragmentation is recovered owing to an AMR resolution better than 70 pc with cooling below 10^4 K. We…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Daniel Ceverino , Avishai Dekel , Frederic Bournaud

We carry out three dimensional SPH simulations to show that a migrating giant planet strongly suppresses the spiral structure in self-gravitating discs. We present mock ALMA continuum observations which show that in the absence of a planet,…

Earth and Planetary Astrophysics · Physics 2020-11-30 Sahl Rowther , Farzana Meru , Grant M. Kennedy , Rebecca Nealon , Christophe Pinte

Gravitationally unstable disks can fragment and form bound objects provided that their cooling time is short. In protoplanetary disks radiative cooling is likely to be too slow to permit formation of planets by fragmentation within several…

Astrophysics · Physics 2011-02-11 Roman R. Rafikov

We investigate the gravitational fragmentation of expanding shells driven by HII regions using the three-dimensional Lagrangian simulation codes based on the Riemann solver, called Godunov smoothed particle hydrodynamics. The ambient gas is…

Astrophysics of Galaxies · Physics 2015-05-27 Kazunari Iwasaki , Shu-ichiro Inutsuka , Toru Tsuribe

The mechanisms which could lead to chemo-thermal instabilities and fragmentation during the formation of primordial protostars are investigated analytically. We introduce approximations for H2 cooling rates bridging the optically thin and…

Astrophysics · Physics 2009-11-10 Emanuele Ripamonti , Tom Abel

Studying star formation in spiral arms tells us not only about the evolution of star formation, and molecular clouds, but can also tell us about the nature of spiral structure in galaxies. I will address both these topics using the results…

Astrophysics of Galaxies · Physics 2015-06-16 Clare Dobbs

We investigate how the detectability of signatures of self-gravity in a protoplanetary disc depends on its temporal evolution. We run a one-dimensional model for secular timescales to follow the disc mass as a function of time. We then…

Earth and Planetary Astrophysics · Physics 2019-06-11 Cassandra Hall , Ruobing Dong , Ken Rice , Tim J. Harries , Joan Najita , Richard Alexander , Sean Brittain