Scale-free equilibria of isopedic polytropic clouds

被引:22
作者
Galli, D
Lizano, S
Li, ZY
Adams, FC
Shu, FH
机构
[1] Osservatorio Astrofis Arcetri, I-50125 Florence, Italy
[2] Univ Nacl Autonoma Mexico, Inst Astron, Mexico City 04510, DF, Mexico
[3] Univ Virginia, Dept Astron, Charlottesville, VA 22903 USA
[4] Univ Michigan, Dept Phys, Ann Arbor, MI 48109 USA
[5] Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA
关键词
ISM : clouds; ISM : magnetic fields; MHD; stars : formation;
D O I
10.1086/307579
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We investigate the equilibrium properties of self-gravitating magnetized clouds with polytropic equations of state with negative index n. In particular, we consider scale-free isopedic configurations that have constant dimensionless spherical mass-to-flux ratio lambda(r) and that may constitute "pivotal" states for subsequent dynamical collapse to form groups or clusters of stars. For given Gamma = 1 + 1/n, equilibria with smaller values of lambda(r) are more flattened, ranging from spherical configurations with lambda(r) = infinity to completely flattened states for lambda(r) = 1. For a given amount of support provided by the magnetic field as measured by the dimensionless parameter H-0, equilibria with smaller values of Gamma are more flattened. However, logatropic (defined by Gamma = 0) disks do not exist. The only possible scale-free isopedic equilibria with logatropic equation of state are spherical uniformly magnetized clouds.
引用
收藏
页码:630 / 639
页数:10
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