A survey of bright variable stars in M33.

Thirty-eight new variable stars have been discovered in M33. These bright variables were found on plates obtained with the Palomar 48-inch (1.2 m) Schmidt telescope during the period 1966 - 1974. Twelve of these objects are red semiregular or irregular variables. These stars typically have light cycles of 1-2 years. The brightest red variable has V(max) = 17.0, corresponding to M (max) = -7.6. Red supergiant variables appear to favor the outer regions of M33. The Cepheids in M33 do not seem to be concentrated in the major associations which outline the spiral arms. At present the brightest nonstable star in M33 is the yellow variable No. 83 with V(max) = 15.8, corresponding to M(max) = - 8.8. Subject headings: Cepheids and W Virginis stars -galaxies, individual - luminosities - semiregular variables