A. Ruelas–Mayorga,2 L. J. Sánchez,2 G. Herrera,3 and A. Nigoche–Netro4
2 Instituto de Astronomía, Universidad Nacional Autónoma de México, Apdo. Postal 70–264, 04510, México, D. F., Mexico. (rarm@astroscu.unam.mx, leonardo@astroscu.unam.mx).
3 Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Apdo. Postal 70–543, 04510, México, D. F., Mexico. (guillermo.herrera@nucleares.unam.mx).
4 Instituto de Astrofísica de Canarias (IAC), Vía Láctea s/n, 38200 La Laguna, Tenerife, Spain. (anigoche@iac.es).
Received 2009 January 9
Accepted 2009 September 1
RESUMEN
Presentamos observaciones CCD del cúmulo galáctico M15 en los filtros B y V. El cúmulo fue cubierto razonablemente bien excepto en su parte norte, en donde nuestras observaciones presentan falta de datos. Se obtuvo el diagrama Hertzsprung–Russell (HR) para cada una de las regiones observadas y posteriormente se produjo un diagrama HR combinado que contiene más de 3000 estrellas. Generamos un Diagrama Color Magnitud (CMD) limpio y una Línea Súper Fiduciaria (SFL). La aplicación de varios métodos y el ajuste de isócronas nos lleva a obtener los siguientes valores para la metalicidad [Fe/H]M15 ~ –2.16 ± 0.10, el enrojecimiento E(B – V)M15~ 0.11 ± 0.03, y un módulo de distancia de [(m–M)0]M15 ~ 15.03.
ABSTRACT
We present CCD observations of the galactic globular cluster M15, in the B and V filters. The cluster was reasonably covered, except in its northern region where our observations present a gap. We obtained a Hertzsprung–Russell (HR) diagram for each region observed, and later we produced a combined HR diagram containing more than 3000 stars. We generate a clean Colour Magnitude Diagram (CMD) and a Super Fiducial Line (SFL). Application of several methods and isochrone fitting leads us to obtain values for the metallicity [Fe/H]M15~ –2.16 ± 0.10, the reddening E(B – V)M15~ 0.11 ± 0.03, and a distance modulus of [(m–M)0]M15 ~ 15.03.
Key Words: Galaxy: halo — globular clusters: general — globular clusters: individual (NGC 7078) — techniques: photometric.
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]]> APPENDIX A
1 Based on observations obtained at the Observatorio Astronómico Nacional at San Pedro Mártir, Baja California, Mexico.
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