A Survey of Chromospheric Activity in the Solar-Type Stars in M67
Mark S. Giampapa (National Solar Observatory)


4. Summary

The Ca II H and K survey of solar analogs in M67 is expected to be completed by the conclusion of the Spring 1998 semester. Following reduction and calibration, as outlined above, we will measure the total H and K line emission strengths in 1 A bandpasses intended to be centered at the respective line cores. In fact, we will fix the bandpasses at the cluster radial velocity, thus ensuring that the results can be examined and reproduced by other investigators. The total H+K flux, and the H+K flux normalized to the stellar bolometric flux, will be computed and compared to the corresponding values for the Sun ranging from solar minimum to solar maximum. We will also compute the K-index utilized at NSO/Kitt Peak for observing the Sun as a star as well as the Mt. Wilson S-index. Multiple frames that have been obtained since the implementation of this project in 1996 will be compared to search for possible binary systems. Binaries may exhibit a somewhat greater level of chromospheric emission and thereby give an inaccurate impression of the potential excursion in solar activity at the high-activity end.

While the survey is expected to yield insights on the range of amplitudes of the solar cycle, a monitoring program of solar analogs in M67 must be implemented in order to fully understand the possible modes of the solar cycle. This survey is a necessary prelude to such a long-term program.

Acknowledgments

We wish to thank the NOAO/KPNO Galactic TAC for its continuing support of this program. The author also acknowledges many useful discussions with Dr. Jeff Hall concerning reduction and calibration issues.

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