The Rotating Disk of M33

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About this Image

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.

Investigator(s):  David Thilker, Robert Braun, and Rene Walterbos

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Technical Data

    Telescope VLA 
    Date of Observation 1998-08-15 
    Type of Observation Spectral Line Observations 
    Wavelength 21 cm 
    Frequency 1420.4 MHz 
    Species HI 
    Center of Image RA: 01:33:51.02, Dec: 30:39:36.70 (J2000)  
    Field of View 1.0000 x 1.2500 degrees  
    Technical Caption 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.  

  • Astronomical database entries for M33
    • Query NED for images of M33
    • Query SIMBAD for more M33 data


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