galactic rotation

galactic rotation

The rotation of the Galaxy about its center, all its components sharing in this rotation to varying degrees. The predominant motion in the galactic disk is circular and parallel to the galactic plane. The orbital speed is determined by the mass within a star's orbit, not by the Galaxy's total mass, so the stars' rotation speeds do not follow Kepler's laws. The rotation speed increases from near zero to 150 km s–1 in the first kiloparsec of the Galaxy's radius, then increases more gradually to a peak near the Sun's orbit (at a radius of about 10 kpc). Farther away it may fall off gradually or remain roughly constant. The rotation velocity of the local standard of rest in the galactic plane was formerly taken to be 250 km s–1, but the accepted value is now 220 km s–1 as a result of the Galaxy's massive dark halo. Objects in the galactic halo display much more random motions than those in the disk and the system as a whole has only a small residual rotation with respect to the galactic center. See also rotation curve.

galactic rotation

[gə′lak·tik rō′tā·shən]
(astronomy)
The rotation of the Milky Way about an axis through the center and perpendicular to the plane of the Galaxy; the rotation is apparent from the highly flattened shape and from relative stellar motion.
References in periodicals archive ?
In addition to the regular Galactic rotation the scientists found the Milky Way moving perpendicular to the Galactic plane.
Richard Miles said he too had his doubts on the subject of galactic rotation speeds.
for his model of galactic rotation in the fifth dimension.
Three interesting possible explanations for galactic rotation curves have been proposed: (1) the dark matter hypothesis (DM) introduces non-baryonic matter that is insensitive to all interactions except gravitation, but there has been no detection of any possible form of dark matter; (2) a modified Newtonian dynamics (MOND) effective at all distance scales when the accelerations are less than 1.
the elliptical shape of the cluster is a consequence of a rotation considerably greater than galactic rotation.
Washington, October 6 ( ANI ): The distance from the solar system to the galactic center is approximately 26,100 light-years, and the galactic rotation velocity in the solar system (V0) is approximately 240 km/s.
So in terms of galactic rotation, when you look north from Elnath along the winter Milky Way, you're looking forward as well as out of our galaxy.
To explain the apparent pattern, scientists have invoked cyclic meteor showers, galactic rotation and other periodic events.
Because we're near the inner edge of our Orion-Cygnus Spiral Arm, we see no nearby young clusters and only one nearby stellar association (Scorpius-Centaurus) until we sweep upward to the Cygnus-Cepheus Milky Way, which in terms of galactic rotation is ahead of us in our orbit around the galactic center.
Differential galactic rotation and encounters with interstellar clouds do rip clusters apart, though some, like Messier 67 in Cancer, have survived for billions of years.
It arises from internal sources, such as heat and shock waves, as well as from outside forces, such as galactic rotation and supernova explosions.
Such arms are probably created by ephemeral star-forming regions that are stretched into spiral-like shreds by galactic rotation.