Morphological dependence of the orientation of the spin vectors of disk galaxies in the Virgo cluster.
Based on our database, the catalogue of 310 disk galaxies in the Virgo area, three sets of representative samples have been used to study the spatial distribution of the spin vectors of disk galaxies of the Virgo cluster. The main results are as follows: 1. The orientation of spin vectors of disk galaxies of the Virgo cluster is found to be anisotropic, which is shown well in both the histogram and the χ^2^ test of the θ distribution, but also in the histogram of the φ distribution (θ and φ are the polar angle and the azimuthal angle of the supergalactic coordinate system, respectively). Two humps at low and high θ in the histograms indicate excesses of the orientation of galaxies in the directions perpendicular and parallel to the Local supercluster (LSC) plane with respect to the expected random distribution. The discernible anisotropy, indicated by the dip near φ=+/-90deg in the histogram of φ distribution, means that the projections on the LSC plane of the spin vectors of the disk galaxies in the Virgo cluster tend to point towards the Virgo center. 2. We have probably detected a morphological dependence of the orientation of the spin vectors of disk galaxies which may deserve special attention. The evidences are: (a) Both distinct humps at low and high θ are found to be strong for the spirals, however no high θ hump, i.e. an excess in the perpendicular direction, is found for the lenticulars; (b) The dip near φ=+/-90deg may be deeper for the lenticulars than that for the spirals; (c) The results of the χ^2^ test of the area distribution with a bin size 30 x 30 square degrees shows significant anisotropy for spirals, but not for lenticulars. 3. The anisotropic feature of both the θ and the φ distributions for the early-type spirals is found to be something in-between that for the lenticulars and the late-type spirals, which means the orientation of disk galaxies might constitute a continuous sequence from lenticulars to late spirals and irregulars alongside the Hubble sequence.
Astronomy and Astrophysics
- Pub Date:
- October 1995
- GALAXIES: CLUSTERS: VIRGO CLUSTER;
- GALAXIES: GENERAL;
- GALAXIES: FORMATION