Rotating Disk of M33

A false color representation of the velocity field for the Scd galaxy Messier 33, also known as the "Triangulum Galaxy". The velocities are inferred from observations of the atomic hydrogen gas in the disk of this galaxy. This gas emits light at a very well defined rest frequency, but this frequency becomes "Doppler shifted", depending on whether the gas is moving towards or away from us. In this image, gas which is moving towards us is shown in blue, and gas that is moving away from us is shown in red, with other colors depicting gas at intermediate velocities. The brightness of each pixel reflects how much gas is at each location. The motion of the gas indicates that it is in a thin disk rotating around the center of the galaxy. Astronomers can analyze the rotation of a galaxy to measure its total mass.

The data were obtained from VLA observations taken both in its B-array and CS-array configurations, with a spatial resolution of 10" and velocity resolution of 1.3 km/s. The VLA data have been supplemented by total power observations obtained at the Westerbork Synthesis Radio Telescope.

Legacy Astronomical Images

NRAO/AUI/NSF does not hold full copyright for this image. Contact the archivist for details.

Legacy Astronomical Image

M33

David Thilker, Robert Braun, Rene Walterbos

Very Large Array (VLA)

WSRT

1998-08-15

spectral line

21 cm

1420.4 MHz

HI

RA 1:33:51.020, Dec: 30:39:36.700 (J2000)

1.000000 x 1.250000 degrees

Galaxies Series

Spiral Unit