THE DYNAMICS AND STRUCTURE OF THE S0 GALAXY NGC-7332

被引:48
作者
FISHER, D
ILLINGWORTH, G
FRANX, M
机构
[1] CTR ASTROPHYS,CAMBRIDGE,MA 02138
[2] UNIV GRONINGEN,KAPTEYN ASTRON INST,9700 AV GRONINGEN,NETHERLANDS
关键词
D O I
10.1086/116841
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Spectroscopic and photometric observations of the edge-on SO galaxy NGC 7332 are presented. The spectra show the galaxy to possess a rapidly counter-rotating extended gas disk as detected from both [O III] 5007 angstrom and Halpha emission. Multiple slit orientations at a variety of position angles clearly show the decoupling of the angular momenta between the stellar and gaseous components. The gas is distributed asymmetrically and displays noncircular motions indicating that it has not reached equilibrium. These observations are strong evidence in support of an accretion process having occurred in NGC 7332. Broad R and B band CCD images show the boxy isophotes that NGC 7332 has long been known to possess while offset spectra taken parallel to the major and minor axes display the cylindrical rotation common to galaxies with box-shaped bulges. The bulge of NGC 7332 is well described by an r1/4-law on both the major and minor axes while the outer disk is exponential. The B-R color of the disk is uniform; the only indication of a trend to blue colors is a DELTA(B-R(c))/DELTA log r = -0.04 +/- 0.01 gradient seen perpendicular to the bulge and disk. There exists a 10'' long region of nearly constant surface brightness along the major axis between the bulge and disk components. Not likely due to absorbing material, the relation of this feature to the already complicated structure of the galaxy is considered.
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页码:160 / 172
页数:13
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