Soderblom: I have a question for the solar people. If I want to observe changes in stars like this, I can get signal-to-noise a lot faster at H alpha than I can at Ca H&K. What is the constrast of the solar cycle in the core of H alpha? Do I have a chance of seeing it?
White: Yes. Bill Livingston and I have plots of that. We have about half a solar cycle of measurements in H alpha.
Giampapa: The amplitude is about a factor of two less than that in H and K.
Soderblom: So if it's only a factor of two, it seems like it might be more productive to go to H alpha than to stay with the calcium lines.
Giampapa: For an initial survey, I chose H and K because of the large body of data that exists for the Sun for these lines. For a monitoring program, H alpha might indeed be a good choice for very faint stars.
Friel: In regard to the possible contamination of your sample by binaries, have you looked at the positions of the stars on a color-magnitude diagram and checked them for any correlations with activity level?
Giampapa: I have not looked at their CMD positions, but I did show the one viewgraph that showed four known binaries lying near the top of the observed activity envelope. And Montgomery et al. claim that there does appear to be a photometric binary sequence in M67.
Lockwood: Well, Mark, good luck on the next 10 years [laughter].
Giampapa: Yes, the real challenge there is getting 3.5 or four-meter telescope time on a regular basis!