NGC 6811: AN INTERMEDIATE-AGE CLUSTER IN THE KEPLER FIELD

Journal Article · Tue Jan 01 04:00:00 EST 2013 · Astronomical Journal (New York, N.Y. Online)

DOI:https://doi.org/10.1088/0004-6256/145/1/7· OSTI ID:22089737

Janes, Kenneth; Hoq, Sadia ^[1]; Barnes, Sydney A. ^[2]; Meibom, Soren ^[3]

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1. Astronomy Department, Boston University, Boston, MA 02215 (United States)
2. Space Science Institute, Boulder, CO 80301 (United States)
3. Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States)

NGC 6811 is one of the four open clusters located in the Kepler spacecraft field of view. We obtained UBVRI photometry of the cluster on six nights (four of them photometric) with the 1.08 m Hall and 1.83 m Perkins telescopes at Lowell Observatory. The mean photometric precision ranges from better than 0.01 mag in the V, B - V, V - R, and V - I indices among stars brighter than magnitude 15 to about 0.05 mag for U - B at magnitude 18. We followed a Bayesian statistical approach using the Markov Chain Monte Carlo algorithm to determine the cluster reddening, distance, age, and iron content from a maximum-likelihood fit to stellar isochrones. Using the Yale-Yonsei isochrones, we derived E(B - V) 0.066 {+-} 0.025, (m - M){sub V} = 10.13 {+-} 0.19, age = 1.06 {+-} 0.19 Gyr, and Z = 0.012 {+-} 0.004 ([Fe/H] = -0.18); with the Padova isochrones, we found E(B - V) = 0.081 {+-} 0.015, (m - M){sub V} = 10.31 {+-} 0.11, age = 0.94 {+-} 0.08 Gyr, and Z = 0.012 {+-} 0.002 ([Fe/H] = -0.20). The uncertainties include possible errors in the photometric zero points of {+-}0.01 mag, but do not include uncertainties in the models. Taking into account the differences between the two sets of models, we find the best estimate for the cluster parameters to be E(B - V) = 0.074 {+-} 0.024, (m - M){sub V} = 10.22 {+-} 0.18, age = 1.00 {+-} 0.17 Gyr, and Z = 0.012 {+-} 0.004 ([Fe/H] = -0.19).

• OSTI ID: 22089737
• Journal Information: Astronomical Journal (New York, N.Y. Online), Journal Name: Astronomical Journal (New York, N.Y. Online) Journal Issue: 1 Vol. 145; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ALGORITHMS
ASTRONOMY
ASTROPHYSICS
COSMOLOGY
DATA ANALYSIS
DIAGRAMS
DISTANCE
HYDROGEN
IRON
MARKOV PROCESS
MAXIMUM-LIKELIHOOD FIT
MONTE CARLO METHOD
PHOTOMETRY
STAR CLUSTERS
STARS
TELESCOPES