The solar motion relative to the local group

被引:154
作者
Courteau, S [1 ]
van den Bergh, S [1 ]
机构
[1] Natl Res Council Canada, Herzberg Inst Astrophys, Dominion Astrophys Observ, Victoria, BC V8X 4M6, Canada
关键词
galaxies : clusters : general; galaxies : kinematics and dynamics; galaxies : spiral; Local Group;
D O I
10.1086/300942
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
New data on the membership of the Local Group (LG) are used, in conjunction with new and improved radial velocity data, to refine the derivation of the motion of the Sun relative to the LG. The Sun is found to be moving with a velocity of V = 306 +/- 18 km s(-1) toward an apex at l = 99 degrees +/- 5 degrees and b = -4 degrees +/- 4 degrees. This finding agrees very well with previous analyses, but we discuss the possibility of a bias if the phase-space distribution of LG galaxies is bimodal. The LG radial velocity dispersion is 61 +/- 8 km s(-1). We use various mass estimators to compute the mass of the LG and the Andromeda subgroup. We find M-LG = (2.3 +/- 0.6) x 10(12) M-., from which M/L-V = 44 +/- 12 (in solar units). For an assumed LG age of 14 +/- 2 Gyr, the radius of an idealized LG zero-velocity surface is r(0) = 1.18 +/- 0.15 Mpc. The LG is found to have 35 likely members. Only three of these have (uncertain) distances greater than or similar to 1.0 Mpc from the LG barycenter. Barring new discoveries of low surface brightness dwarfs, this suggests that the LG is more compact and more isolated from its surroundings than previously believed.
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页码:337 / 345
页数:9
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