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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