| Project/Area Number |
61540181
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
Astronomy
|
|---|
| Research Institution | Aichi University of Education |
|---|
Principal Investigator |
TAKEYASU Sawa Associate Professor, Faculty of Education, 教育学部, 助教授 (90111864)
|
|---|
| Project Period (FY) |
1986 – 1988
|
| Project Status |
Completed (Fiscal Year 1988)
|
| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1988: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1987: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1986: ¥1,300,000 (Direct Cost: ¥1,300,000)
|
|---|
| Keywords | galactic magnetic fields (BSS magnetic fields) / dynamo action / Lorentz force / spiral galaxies / spiral arm / density wave / 吸収帯 / 磁場(BSS磁場) / 誘導・発電方程式 / 銀河磁場 / 磁場の散逸 / 微分回転 |
|---|
| Research Abstract |
The configuration of magnetic fields and its maintenance in spiral galaxies are investigated by solving an induction equation in which the effects of the turbulent diffusion and the dynamo action are taken into account in the differentially rotating gaseous disk. It is shown that the bisymmetric spiral (BSS) magnetic fields observed in many spiral galaxies are maintained by the galactic dynamo action in the wide area of the galactic disk without being further twisted by differential rotation.
An attempt is made to derive the physical conditions favorable for the excitation of BSS magnetic fields by a galactic dynamo action. The theoretical results agree very well with the observations.
Three-dimensional configuration of magnetic fields shows the arch-like structure spanning interarm regions. The magnetic lines of forces are nearly perpendicular to the galactic plane at the boundary layer between the disk and halo. It seems to be related to dark filaments observed as emerging vertically from the galactic plane of edge-on galaxies.
Linearized equations of motion are studied for the self-gravitating gaseous disk disturbed by the Lorentz force due to the BSS magnetic fields. Since the angular velocity of the BSS magnetic fields is very close to that of the spiral density wave, a nearly-resonant interaction is caused between these two waves to produce large-amplitude condensation of gas in a duble-spiral way. The BSS magnetic fields are considered as a possible agency to trigger and maintain the spiral density wave.
|
