Местоположение издательства:Noordwijk, The Netherlands [etc.], Netherlands
Первая страница:551
Последняя страница:556
Аннотация:The galactic disk is modeled by an oblate spheroid with cofocal isodensity surfaces. An explicit analytical expression is found for the angular velocity of the gas outside the disk. Parameters of a three-component mass model of a spiral galaxy are adjusted to give a double-peaked rotation curve (as in the M31 and M81 Galaxies) in a disk. It is shown that the halo gas corotates with the disk at moderate heights, z less than or = 2 kpc. However, farther above the disk the doublepeaked form is washed out. Gas pressure gradient in the halo only weakly changes the rotation curve just above the disk (r less than r disk) and causes the decrease of the rotational velocity beyond the disk edge (r greater than r disk).