COSPATIAL COUNTERROTATING STELLAR DISKS IN THE VIRGO E7/S0 GALAXY NGC-4550

被引:179
作者
RUBIN, VC [1 ]
GRAHAM, JA [1 ]
KENNEY, JDP [1 ]
机构
[1] YALE UNIV,DEPT ASTRON,NEW HAVEN,CT 06511
关键词
GALAXIES; CLUSTERING; ELLIPTIC AND LENTICULAR; CD; KINEMATICS AND DYNAMICS;
D O I
10.1086/186460
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We have discovered two cospatial stellar disks, one orbiting prograde, one orbiting retrograde, in NGC 4550, an E7/S0 galaxy in the core of the Virgo Cluster. One of the stellar disks is coincident with a gas disk. Absorption and emission-line velocities for the two counterrotating components have been measured over about one-third of the optical diameter (30"). We propose that after the initial stellar disk of NGC 4550 was formed, a substantial amount of counterrotating gas was acquired greater-than-or-equal-to 10(9) yr ago. It then settled to the plane via dissipation; the bulk of the counterrotating stars most likely for-med after the gas settled to the plane.
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页码:L9 / &
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