C. A. Guerrero,1 J. H. Peña,1 and J. P. Sareyan2
1 Instituto de Astronomía, Universidad Nacional Autónoma de México, Apdo. Postal 70–264, 04510, México, D. F., México (cguerrero@astro.unam.mx, jhpena@astro.unam.mx)
2 Lesia, Observatoire de Paris–Meudon and Observatoire de la Cote d'Azur, France (jean–pierre.sareyan@obspm.fr).
Received 2010 October 21
Accepted 2011 February 15
]]> RESUMEN
Se presenta fotometría uvby — β de 35 estrellas en la dirección del cúmulo abierto NGC 1647 y de 16 estrellas del cúmulo NGC 1778. Del análisis de los datos obtenidos para NGC 1647 se ha determinado un enrojecimiento E(b — y) = 0.32±0.02 mag y un módulo de distancia de V0 — MV = 8.75±0.09 correspondiente a una distancia d = 564 ± 106 pc; asimismo, se han encontrado las estrellas miembros y se ha determinado un valor numérico para la edad del cúmulo de log edad (en años) = 7.98 ± 0.23. A partir del análisis de los datos obtenidos para NGC 1778, se concluye que no es posible determinar si hay un cúmulo en esa dirección, pues las distancias encontradas para las estrellas observadas son muy diferentes.
ABSTRACT
We present photometry uvby — β for 35 stars in the direction of the open cluster NGC 1647 and for 16 stars in the direction of the cluster NGC 1778. From the analysis of the data obtained for NGC 1647 we determine a mean reddening of E(b –y) = 0.32 ± 0.02 mag and a distance modulus of V0 — MV = 8.75 ± 0.09 corresponding to a distance d = 564 ±106 pc; also, we find the cluster member stars and a numerical value of log age (in years) = 7.89 ±0.23. From the analysis of data obtained for NGC 1778, we conclude that it is not possible to determine whether there is a cluster in that direction, because the distances found for the observed stars are very different.
Key Words: open clusters and associations: individual (NGC 1647, NGC 1778) — techniques: photometric.
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ACKNOWLEDGMENTS
]]> We would like to thank the staff of the OANSPM for their assistance in securing the observations. Proofreading was done by J. Miller. One of us, Guerrero, C. A., would like to thank S. S. Gil for fruitful discussions. This work was partially supported by PAPIITIN 108106 and PAPIITIN 114309. This research has made use of the Simbad databases operated at CDS, Strasbourg, France; NASA ADS Astronomy Query Form and the WEBDA database, operated at the Institute for Astronomy of the University of Vienna.
REFERENCES
Andrievsky, S. M., Bersier, D., Kovtyukh, V. V., Luck, R. E., Maciel, W. J., Lépine, J. R. D., Beletsky, Yu. V. 2002, A & A, 384, 140 [ Links ]
Arellano Ferro, A., & Parrao, L. 1988, Reporte Técnico, 57 (México: IA–UNAM) [ Links ]
Barbon, R., & Hassan, S. M. 1973, A & AS, 10, 1 [ Links ]
Crawford, D. L. 1975, AJ, 80, 955 [ Links ]
––––––––––. 1979, AJ, 84, 1858 [ Links ]
Crawford, D. L., & Barnes, J. V. 1970, AJ, 75, 978 [ Links ]
Crawford, D. L., & Mander, J. 1966, AJ, 71, 114 [ Links ]
Hebb, L., Wyse, F. G. R., & Gilmore, G. 2004, AJ, 128, 2881 [ Links ]
ESA 1997, Hipparcos and Tycho Catalogues, ESA SP–1200 (Noordwijk: ESA) [ Links ]
Hoag, A., & Applequist, N. L. 1965, ApJS, 12, 215 [ Links ]
Johnson, H. L. 1968, in Nebulae and Interstellar Matter, ed. B. M. Middlehurst & L. H. Aller (Chicago: University of Chicago), 167 [ Links ]
Joshi, U. C., Sagar, R., & Pandey, P. 1975, Pramana, 4, 160 [ Links ]
Lester, J. B., Gray, R. O., & Kurucz, R. I. 1986, ApJ, 61, 509 (LGK86) [ Links ]
Lindroos, K. P. 1980, Stockholms Obs. Rep., 17, 68 [ Links ]
Meynet, G., Mermilliod, J. C., & Maeder, A. 1993, A & AS, 98, 477 [ Links ]
Nissen, P. 1988, A & A, 199, 146 [ Links ]
Olsen, E. H. 1983, A & AS, 54, 55 [ Links ]
Pandey, A. K. 1998, Bull. Astron. Soc. India, 26, 539 [ Links ]
Paunzen, E., & Mermilliod, J. C. 2007, WEBDA, A Site Devoted to Stellar Clusters in the Galaxy and the Magellanic Clouds (Vienna: Institute of Astronomy of the University of Vienna), http://www.univie.ac.at/webda/ [ Links ]
Shobbrook, R. R. 1984, MNRAS, 211, 659 [ Links ]
Turner, D. G. 1992, AJ, 104, 1865 [ Links ]
Xin, Y., Deng, L., & Han, Z. W. 2007, ApJ, 660, 319 [ Links ]
Zdanavicius, J., et al. 2005, Baltic Astron., 14, 179 [ Links ] ]]>