TIME-RESOLVED CCD PHOTOMETRY OF AN ENSEMBLE OF STARS IN THE OPEN CLUSTER M67

被引:136
作者
GILLILAND, RL
BROWN, TM
DUNCAN, DK
SUNTZEFF, NB
LOCKWOOD, GW
THOMPSON, DT
SCHILD, RE
JEFFREY, WA
PENPRASE, BE
机构
[1] SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218
[2] NATL CTR ATMOSPHER RES,HIGH ALTITUDE OBSERV,BOULDER,CO 80307
[3] CERRO TOLOLO INTERAMER OBSERV,LA SERENA,CHILE
[4] LOWELL OBSERV,FLAGSTAFF,AZ 86001
[5] CTR ASTROPHYS,CAMBRIDGE,MA 02138
[6] INST DEF ANAL,DIV SCI & TECHNOL,ALEXANDRIA,VA 22311
[7] SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218
关键词
D O I
10.1086/115703
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
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 ensembel 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 approximately 100-mu-mag (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. Serendipituous 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.
引用
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页码:541 / 561
页数:21
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