5 Comments

The Hipparcos photometry indicates that the Am stars as a class are a slightly better candidate for internal constancy than the HgMn stars. To resolve the constancy questions requires careful study of the indicated stars as well as those whose positions in the standard error vs. mean magnitude diagrams are close to them. It is critical to be certain that any photometric variability is not due to eclipses or to variable companions. If for either class, the indicated stars or others are found to be intrinsically variable and true class members, then the question is resolved. If they can be excluded, then stars which are less variable via Hipparcos photometry will have to be studied until one reaches the point where constancy can be assured by comparison with other classes of stars whose members are intrinsically constant.

Acknowledgements

I thank Dr. Robert J. Dukes Jr., for some useful discussions of stellar variability and Dr. Diane Pyper Smith for recommending some MCP stars to be examined.