Detección de estrellas variables en cúmulos abiertos

PETRUCCI, R.; JOFRÉ, E.; GONZALEZ, J. F.; MUÑOZ, M. R.

Malargüe, Mendoza, Argentina

Congreso; 50 Reunión de la Asociación Argentina de Astronomía; 2007

Asociación Argentina de Astronomía

We present partial results of the photometric following of stars in the open clusters IC 4651, NGC 6281 and NGC 3532. This work belong to a project for the search of variable stars in open clusters of the south hemisphere to carry out with the Helen Sawyer Hogg (HSH) telescope of the CASLEO. We analyze photometric observations CCD in the V band, taken during 2006 may-august and 2007 april-june. The magnitudes were measured using PSF photometry and aperture photometry. It was carried out differential photometry and was evaluated the variability using the dispersion of the relative magnitudes. We find photometric variations from some centesimal of magnitudes in the stars NGC6281-6 and IC4651-44, two spectroscopic binaries candidates to blue stragglers with orbital periods of 8.04 and 1.11 days respectively. On the other hand, we confirm to the star NGC 3532-363 like eclipsing binary with variations of 4 decimal of magnitude. Finally, we develop a comparative analysis between the aperture photometry results and PSF, and we found that in weak stars(V=12.5-13.5) the typical error with aperture photometry are of 15 mmag, while with profile fitting are roughly 8 mmag. In bright stars (V<11) both photometries gave precisions smaller than 8 mmag. These results reveal that for works of precision with weak components using the HSH telescope is convenient obtain instrumentals magnitudes with PSF photometry.