rotation curve

Typical rotation curveclick for a larger image
Typical rotation curve

rotation curve

A plot of the rotational velocity, V , as a function of radius, R , in a spiral galaxy (see illustration). Rotation curves are an important tool in mapping the distribution of mass in a galaxy. The velocity increases rapidly with distance from the center of the galaxy, and then remains approximately constant, even in the outermost parts of the visible galaxy. This implies that the mass is not centrally concentrated, as might be expected, but is distributed into a dark halo extending up to five times the radius of the optical disk. The rotation velocities are measured from the Doppler shift in stellar absorption lines or the emission line spectra of H II regions in the plane of the galaxy. Neutral hydrogen extends farther than the luminous matter of a galactic disk and radio observations can trace out the rotation curve to radii of tens of kiloparsecs.

References in periodicals archive ?
Upon finishing her observations, Rubin's galactic rotation curve extended about five times farther than it had in the early 1960s--and it was still flat.
Modeling the Newtonian dynamics for rotation curve analysis of thin-disk galaxies.
Difference in the external rotation curve was induced by the swing of ipsilateral leg in walking posture.
In describing a one-parameter motion, a rotation curve r(v) = ([r.
The new observations with KAT-7 allow the measurement of the rotation curve of NGC 3109 out to 32, doubling the angular extent of existing measurements.
The Milky Way's Rotation Curve to 60 kpc and an Estimate of the Dark Matter Halo Mass from Kinematics of 2500 SDSS Blue Horizontal Branch Stars.
We are sensitive enough that we made a rotation plot of the hydrogen in the Andromeda Galaxy at different angular offsets from its center," says frequent observer Paul Boven, "and in the rotation curve you can see which side of Andromeda is coming toward us and which is going away.
He was able to fit lensing data from CLASS/JVAS with a [mu](x) that is consistent with one that was constrained from galactic rotation curve data (Sanders 2007).
Context only carries you so far, and at some point you may find your mind spinning as someone asks, "So, what's with the galaxy's rotation curve lately?
The agreement with the observed rotation curve is striking: the calculations even reproduce a hitherto unexplained "kink" in the curve 35,000 light-years from the center.
Another motivation for the new dust-penetrated classification scheme is that it is related to the kinematics or dynamics of a galaxy, factors that are best understood by analyzing a galaxy's rotation curve.
They then used the resulting rotation curve to "weigh" the material within about 40,000 light-years of the Milky Way's core.