Stars in the central region of the old open cluster M67 were monitored for stability using CCD, time-resolved photometry. Five sites with 1 m class telescopes participated in an intensive monitoring effort, yielding contiguous 14 night coverage with 1 min temporal resolution. Noise levels to 0.0008 mag variation relative to an ensemble mean were attained at 13th mag over 9 hr time series. Limits to detection of coherent oscillations with periods of 3-20 min, assuming a solarlike spectrum of frequencies, are ∼100 μmag (30 times solar amplitude) for the best cases. Evidence suggestive of p-mode oscillations is shown for a few stars, but an unambiguous detection is not claimed. Serendipitous detection was made of: two new W UMa stars in M67, two oscillating blue stragglers (with multiple modes), a likely AM Her cataclysmic variable with a 2.091 hr period, and several stars with low-amplitude intensity changes over timescales of 1-10 days, that presumably results from rotation or orbital motion.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science