Photometric variability of stars belonging to the Trapezium-type systems

We report the variability of 21 stars belonging to 17 systems considered to be Trapezium-type systems by Allenet al. (1977a). In order to avoid serious problems due to possible light contamination by neighbouring stars, we have only considered systems with angular separations between components equal or greater than five seconds of arc. Among the new variables here reported there are five having V variations greater than 0 ^m .3. For six systems we have spectrograms of the individual components. Three of the six systems are probably optical configurations and only two of the variables in the remaining three systems may be physical companions.