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DOI | 10.1017/S174392130999113X |
The formation of brown dwarfs | |
Whitworth, Ant1; Stamatellos, Dimitri1; Walch, Steffi1; Kaplan, Murat1; Goodwin, Simon2; Hubber, David2; Parker, Richard2 | |
通讯作者 | Whitworth, Ant |
会议名称 | 266th Symposium of the International-Astronomical-Union |
会议日期 | AUG 10-14, 2009 |
会议地点 | Rio de Janeiro, BRAZIL |
英文摘要 | We argue that brown dwarfs (BDs) and planemos form by the same mechanisms as low-mass hydrogen-burning stars, but that as one moves to lower and lower masses, an increasing fraction of these objects is formed by fragmentation of the outer parts (R greater than or similar to 100 AU) of protostellar accretion discs around more massive primary protostars, which in turn formed in their own very-low-mass prestellar cores. Numerical simulations of disc fragmentation with realistic thermodynamics show that low-mass objects are readily formed by fragmentation of short-lived massive, extended protostellar accretion discs. Such objects tend subsequently to be liberated into the field at low speed, due to mutual interactions with the primary protostar. Many (similar to 20%) are in low-mass (M-1 + M-2 < 0.2 M-circle dot) binary systems with semi-major axes a similar to 1 to 2 AU or similar to 200 AU and mass ratios q equivalent to M-2/M-1 greater than or similar to 0.7. Most of the brown dwarfs have sufficiently large attendant discs to sustain accretion and outflows. Most of the BDs that remain bound to the primary protostar have wide orbits (i.e., there is a BD desert), and these BDs also have a significantly higher probability of being in a BD/BD binary system than do the brown dwarfs that are liberated into the field (just as observed). In this picture, the multiplicity statistics and velocity dispersion of brown dwarfs are largely determined by the eigen evolution of a small-N system, born from a single prestellar core, rather than the larger-scale dynamics of the parent cluster. Consequently, many of the statistical properties of brown dwarfs should not differ very much from one star-formation region to another. |
英文关键词 | accretion accretion disks gravitation hydrodynamics radiative transfer stellar dynamics binaries: general stars: formation stars: low-mass brown dwarfs |
来源出版物 | STAR CLUSTERS: BASIC GALACTIC BUILDING BLOCKS THROUGHOUT TIME AND SPACE |
ISSN | 1743-9213 |
EISSN | 1743-9221 |
出版年 | 2010 |
期号 | 266 |
页码 | 264-+ |
ISBN | 978-0-521-76499-5 |
出版者 | CAMBRIDGE UNIV PRESS |
类型 | Proceedings Paper |
语种 | 英语 |
国家 | Wales;England |
收录类别 | CPCI-S |
WOS记录号 | WOS:000282782600034 |
WOS关键词 | INITIAL MASS FUNCTION ; STAR-FORMATION ; PRESTELLAR CORES ; FRAGMENTATION ; STELLAR ; MULTIPLICITY ; OBJECTS ; CLOUD |
WOS类目 | Astronomy & Astrophysics |
WOS研究方向 | Astronomy & Astrophysics |
资源类型 | 会议论文 |
条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/298153 |
作者单位 | 1.Cardiff Univ, Sch Phys & Astron, Cardiff CF24 3AA, S Glam, Wales; 2.Univ Sheffield, Dept Phys & Astron, Sheffield S3 7RH, S Yorkshire, England |
推荐引用方式 GB/T 7714 | Whitworth, Ant,Stamatellos, Dimitri,Walch, Steffi,et al. The formation of brown dwarfs[C]:CAMBRIDGE UNIV PRESS,2010:264-+. |
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