SCYON Abstract

Received on December 22 2011

Strengthening the Open Cluster Distance Scale via VVV Photometry

Authors	D. Majaess (¹), D.G. Turner (¹), C. Moni Bidin (²), D. Geisler (²), J. Borissova (⁷), D. Minniti (^3,4,5), C. Bonatto (⁸), W. Gieren (²), G. Carraro (⁹), R. Kurtev (⁷), F. Mauro (²), A-N. Chene (^2,7), D.W. Forbes (¹⁰), P. Lucas (⁶), I. Dekany (³), R.K. Saito (³), and M. Soto (¹¹)
Affiliation	(¹) Saint Mary's University, Halifax, Nova Scotia, Canada (²) Universidad de Concepcion, Concepcion, Chile (³) Pontificia Universidad Catolica de Chile, Santiago, Chile (⁴) Vatican Observatory, Vatican City, Italy (⁵) Princeton University, Princeton, New Jersey, USA (⁶) University of Hertfordshire, Hatfield, United Kingdom (⁷) Departamento de Fisica y Astronomia, Facultad de Ciencias, Universidad de Valparaiso, Valparaiso, Chile (⁸) Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil (⁹) ESO, Santiago de Chile, Chile (¹⁰) Sir Wilfred Grenfell College, Memorial University, Corner Brook, Newfoundland, Canada (¹¹) Universidad de la Serena, la Serena, Chile
Accepted by	Astronomy & Astrophysics
Contact	dmajaess@ap.smu.ca
URL	http://adsabs.harvard.edu/abs/2011arXiv1112.3957M
Links	Pismis 19 / NGC 4349

Abstract

Approximately 14% of known Galactic open clusters possess absolute errors <20% as evaluated from n>3 independent distance estimates, and the statistics for age estimates are markedly worse. That impedes such diverse efforts as calibrating standard candles and constraining masses for substellar companions. New data from the VVV survey may be employed to establish precise cluster distances with comparatively reduced uncertainties (<10%). This is illustrated by deriving parameters for Pismis 19 and NGC 4349, two pertinent open clusters which hitherto feature sizable uncertainties (60%). Fundamental parameters determined for Pismis 19 from new VVV JHKs photometry are d=2.40+-0.15 kpc, <E(J-H)>=0.34+-0.04, and log(t)=9.05+-0.10, whereas for NGC 4349 the analysis yielded d=1.63+-0.13 kpc, E(J-H)=0.09+-0.02, log(t)=8.55+-0.10. The results exhibit a significant (>5x) reduction in uncertainties, and indicate that: i) existing parameters for the substellar object NGC 4349 127b require revision, in part because the new cluster parameters imply that the host is 20% less-massive (M*/Ms~3.1); ii) R Cru is not a member of NGC 4349 and should be excluded from period-Wesenheit calibrations that anchor the distance scale; iii) and results for Pismis 19 underscore the advantages gleaned from employing deep VVV JHKs data to examine obscured (Av~4) and differentially reddened intermediate-age clusters.