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We present the first results of the \textsc{Dragon-II} simulations, a suite of 19 $N$-body simulations of star clusters with up to $10^6$ stars, with up to $33\%$ of them initially paired in binaries. In this work, we describe the main…

Most subdwarf B (sdB) + Helium white dwarf (He WD) binaries are believed to be formed from a particular channel. In this channel, the He WDs are produced first from red giants (RGs) with degenerate cores via stable mass transfer and sdB…

Solar and Stellar Astrophysics · Physics 2021-07-07 Yangyang Zhang , Hai-Liang Chen , Heran Xiong , Xuefei Chen , Zhanwen Han

Fast radio bursts (FRBs) are transient intense radio pulses with duration of milliseconds. Although the first FRB was detected more than a decade ago, the progenitors of these energetic events are not yet known. The currently preferred…

High Energy Astrophysical Phenomena · Physics 2020-01-08 Esha Kundu , Lilia Ferrario

The formation of protoplanetary discs during the collapse of molecular dense cores is significantly influenced by angular momentum transport, notably by the magnetic torque. In turn, the evolution of the magnetic field is determined by…

Astrophysics of Galaxies · Physics 2017-02-01 Patrick Hennebelle , Benoit Commercon , Gilles Chabrier , Pierre Marchand

We present a comprehensive Bayesian statistical analysis of brown dwarf companions to investigate the physical mechanisms responsible for the observed ``brown dwarf desert'' -- the notable paucity of brown dwarf companions at orbital…

Earth and Planetary Astrophysics · Physics 2026-03-25 Behrooz Karamiqucham

Stars form as an end product of the gravitational collapse of cold, dense gas in magnetized molecular clouds. This multi-scale scenario occurs via the formation of two quasi-hydrostatic cores and involves complex physical processes, which…

Solar and Stellar Astrophysics · Physics 2020-07-01 Asmita Bhandare , Rolf Kuiper , Thomas Henning , Christian Fendt , Mario Flock , Gabriel-Dominique Marleau

Hot subdwarf stars of spectral type B (sdBs) are evolved, core helium-burning objects. The formation of those objects is puzzling, because the progenitor star has to lose almost its entire hydrogen envelope in the red-giant phase. Binary…

Solar and Stellar Astrophysics · Physics 2014-10-22 V. Schaffenroth , L. Classen , K. Nagel , S. Geier , C. Koen , U. Heber , H. Edelmann

With the help of 3D MHD simulations we investigate the collapse and fragmentation of rotating turbulent prestellar core embedded into turbulent medium. The numerical code is based on a high resolution Godunov-type finite-difference scheme.…

Solar and Stellar Astrophysics · Physics 2015-03-17 Alexander E. Dudorov , Sergey N. Zamozdra

We propose that there is an evolutionary link between ultra-compact blue dwarf galaxies (UCBDs) with active star formation and nucleated dwarfs based on the results of numerical simulations of dwarf-dwarf merging. We consider the…

Astrophysics of Galaxies · Physics 2015-10-21 Kenji Bekki

Star formation in our Galaxy occurs in molecular clouds that are self-gravitating, highly turbulent, and magnetized. We study the conditions under which cloud cores inherit large-scale magnetic field morphologies and how the field is…

Astrophysics of Galaxies · Physics 2017-03-29 Philip Mocz , Blakesley Burkhart , Lars Hernquist , Chris McKee , Volker Springel

The origin of very low-mass hydrogen-burning stars, brown dwarfs, and planetary-mass objects at the low-mass end of the initial mass function is not yet fully understood. Gravitational fragmentation of circumstellar discs provides a…

Solar and Stellar Astrophysics · Physics 2017-07-12 Yun Li , M. B. N. Kouwenhoven , D. Stamatellos , S. P. Goodwin

One of the most debated subjects in Astronomy since the discovery of exoplanets is how can we distinguish the most massive of such objects from very-low mass stars like Brown Dwarfs (BDs)? We have been looking for evidences of a difference…

Earth and Planetary Astrophysics · Physics 2016-07-28 Lauren Melissa Flor Torres , Roger Coziol , Klauss-Peter Schröeder , César A. Caretta , Dennis Jack

For a rotating galaxy, the inner circular-velocity gradient d_{R}V(0) provides a direct estimate of the central dynamical mass density, including gas, stars, and dark matter. We consider 60 low-mass galaxies with high-quality HI and/or…

Astrophysics of Galaxies · Physics 2014-03-05 Federico Lelli , Filippo Fraternali , Marc Verheijen

Abridged: We use three-dimensional SPH simulations to investigate the collapse of low-mass prestellar cores and the formation and early evolution of protostellar discs. The initial conditions are slightly supercritical Bonnor-Ebert spheres…

Astrophysics of Galaxies · Physics 2015-05-13 S. Walch , A. Burkert , A. Whitworth , T. Naab , M. Gritschneder

Context. Most observational studies so far point towards brown dwarfs sharing a similar formation mechanism as the one accepted for low mass stars. However, larger databases and more systematic studies are needed before strong conclusions…

Solar and Stellar Astrophysics · Physics 2017-08-30 A. Bayo , D. Barrado , N. Huélamo , M. Morales-Calderón , C. Melo , J. Stauer , B. Stelzer

We show that the dearth of brown dwarfs in short-period orbits around Solar-mass stars - the brown dwarf desert - can be understood as a consequence of inward migration within an evolving protoplanetary disc. Brown dwarf secondaries forming…

Astrophysics · Physics 2009-11-07 Philip J. Armitage , Ian A. Bonnell

We examine the evolution of low-mass star and brown dwarf eclipsing binaries. These objects are rapid rotators and are believed to shelter large magnetic fields. We suggest that reduced convective efficiency, due to fast rotation and large…

Astrophysics · Physics 2008-12-18 Gilles Chabrier , Jose Gallardo , Isabelle Baraffe

It has been argued that the low-mass primordial stars ($m_{\rm Pop III}\,\leq 0.8\,M_\odot$) are likely to enter the main sequence and hence possibly be found in the present-day Galaxy. However, due to limitations in existing numerical…

Astrophysics of Galaxies · Physics 2023-02-22 Shubham Raghuvanshi , Jayanta Dutta

Recent studies have shown that close-in brown dwarfs in the mass range 35-55 M$_{\rm Jup}$ are almost depleted as companions to stars, suggesting that objects with masses above and below this gap might have different formation mechanisms.…

Solar and Stellar Astrophysics · Physics 2017-06-07 J. Maldonado , E. Villaver

We present 2.5D radiation-hydrodynamics simulations of the accretion-induced collapse (AIC) of white dwarfs, starting from 2D rotational equilibrium configurations of a 1.46-Msun and a 1.92-Msun model. Electron capture leads to the collapse…

Astrophysics · Physics 2009-11-11 Luc Dessart , Adam Burrows , Christian Ott , Eli Livne , Sung-Chul Yoon , Norbert Langer