J. García,1,2 N. Sánchez,3 and R. Velásquez4
1 NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA. (javier@milkyway.gsfc.nasa.gov).
2 IACS/Department of Physics, The Catholic University of America, Washington, USA.
3 Instituto de Astrofísica de Andalucía, CSIC, Apdo. Postal 3004, E–18080, Granada, Spain. (nestor@iaa.es).
4 Centro de Modelado Científíco, Universidad del Zulia, Maracaibo, 4004, Venezuela. (raulv@cida.ve).
Received 2008 July 30 ]]> Accepted 2008 September 18
RESUMEN
En este trabajo realizamos la primera prueba de un método de clasificación espectral estelar (Stock & Stock 1999), aplicándolo a estrellas tempranas. La muestra contiene estrellas miembros del cúmulo abierto IC 2391, para las cuales se dispone de espectros de alta resolución del Projecto UVES del Observatorio Paranal. Mostramos que, en general, las magnitudes absolutas Mv y los colores intrínsecos (B — V)0 pueden ser recuperados dentro de los errores predichos por la calibración original (~ 0.4 para las magnitudes y ~ 0.03 para los colores). Este tipo de precisión nos permite estimar las distancias de estrellas individuales e inferir su membresía, para así obtener una distancia promedio al cúmulo de 156 ± 24 pc, en muy buena concordancia con valores reportados previamente. Finalmente discutimos las ventajas y dificultades de usar este método y cómo puede ser mejorado para su implementación en estudios futuros.
ABSTRACT
In this work we perform the first test of a stellar spectral classification method (Stock & Stock 1999) by applying it to early type stars. The sample of stars are the members of the open cluster IC 2391 that have high–resolution spectra available in the UVES Project of Paranal Observatory. We show that, in general, absolute magnitudes Mv and intrinsic colors (B — V)0can be recovered within the uncertainties stated in the original calibration (~ 0.4 for the magnitudes and ~ 0.03 for the colors). This accuracy allows us to estimate distances and to infer membership of individual stars to obtain an average distance to the cluster of 156 ± 24 pc, which is in good agreement with previously reported determinations. Finally, we identify and discuss the real strengths and limitations of this method and we suggest how it can be improved for future studies.
Key Words: methods: data analysis — open clusters and associations: individual (IC 2391) — stars: fundamental parameters, classification.
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