WOCS Variability:Monitoring NGC6939S. Kafka (IUB)D. Gibbs II (Univ. of Wyoming) A. Henden (US Naval Obs.) R.K.Honeycutt (IUB)BGSU, April 3, 2004
WIYN Open Cluster StudyAgeReddeningMetallicity AbundancesAstrometric infoVariability
http://www.astro.ufl.edu/~ata/wocs/Establish a standard database of open clusters
Our motivation:Cataclysmic VariablesInteracting binariesWD accretes H-rich material from its low-mass, Roche-lobe filling companionUnique natural laboratories for studyingAccretion PhysicsClassical NovaeSNe Ia progenitors ?
Why Open Clusters?Bonus: age, distance, metallicity Not many CVs known in globular/open clustersOnly 3 CVs known in all open clusters!
NGC 6939 Age = 1.6 0.3 Gyr
0.29 < E(B-V) < 0.41
12.21 < m-M < 12.39 (Rosvick & Balam 2002)
[Fe/H] = -0.140.13(Friel et al 2002)
Variability study : 6 vars(Robb & Cardinal 1998)
Credit: J. Burkle, D. Gibbs, D. Hoffmann, S. Kafka,WIYN 0.9m, IU REU 2003
Data
NGC 6939USNOFS 1.3mR- filterNGC 6939WIYN 0.9mEN
Data Reduction
CMD
Results
ResultsP=0.5668d P=1.143d P>95d
Oddities
NGC 6939USNOFS 1.3mR- filter
OdditiesGlushkova & Rastorguev 1991Monet et al. 2003 (USNO-B)
Conclusions:
Conclusions: No CVs found in the cluster Cluster depleted of faint variables???Future work: X-rays? More data! More Clusters!
Kafka et al, 2004, AJ, 127, 1622