TY - JOUR
T1 - A dynamical study of three-dimensional spiral galaxies
AU - Xin-Lian, Luo
AU - Min, Long
AU - Qiu-He, Peng
AU - Chi-Kang, Chou
PY - 2001/4
Y1 - 2001/4
N2 - On the basis of a rigorous solution of the three-dimensional (3D) gravitational Poisson equation for density disturbance of logarithmic spiral type, a dispersion relation of 3D mixed disk density wave in the plane of symmetry (z = 0) has been derived. With this result the local stability for disturbed disks of various types is investigated and the group velocity of density waves on the disk surface is calculated. As shown by numerical computations, the logarithmic spiral density disturbance can well satisfy the antiphase relation between the disturbed density and potential. An increase in the thickness or in the number of spiral arms is favourable to the stability of the disk, while a gaseous content may lead to instability. When the effect of thickness is considered, the dynamic time scale of the propagation of density waves in the Galaxy will be very much longer than Toomre's estimate and it may be at least 4.17 × 109 yr, or about one third of the cosmic age. So the problem of too large a group velocity in the previous theories of density waves may be alleviated.
AB - On the basis of a rigorous solution of the three-dimensional (3D) gravitational Poisson equation for density disturbance of logarithmic spiral type, a dispersion relation of 3D mixed disk density wave in the plane of symmetry (z = 0) has been derived. With this result the local stability for disturbed disks of various types is investigated and the group velocity of density waves on the disk surface is calculated. As shown by numerical computations, the logarithmic spiral density disturbance can well satisfy the antiphase relation between the disturbed density and potential. An increase in the thickness or in the number of spiral arms is favourable to the stability of the disk, while a gaseous content may lead to instability. When the effect of thickness is considered, the dynamic time scale of the propagation of density waves in the Galaxy will be very much longer than Toomre's estimate and it may be at least 4.17 × 109 yr, or about one third of the cosmic age. So the problem of too large a group velocity in the previous theories of density waves may be alleviated.
KW - Spiral galaxy - galactic dynamics-density waves
UR - http://www.scopus.com/inward/record.url?scp=0346941254&partnerID=8YFLogxK
U2 - 10.1016/S0275-1062(01)00057-1
DO - 10.1016/S0275-1062(01)00057-1
M3 - Article
AN - SCOPUS:0346941254
SN - 0275-1062
VL - 25
SP - 159
EP - 169
JO - Chinese Astronomy and Astrophysics
JF - Chinese Astronomy and Astrophysics
IS - 2
ER -