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Fundamental parameters and new variables of the galactic open cluster NGC 7128 |
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| Authors: | Z Balog † A J Delgado ‡ A Moitinho G F&#;rész † G Kaszás † J Vinkó E J Alfaro |
| Institution: | Department of Optics &Quantum Electronics, University of Szeged, Dóm tér 9, Szeged, H-6720 Hungary;Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA, USA;Instituto de Astrofísica de Andalucia, CSIC, Granada, Spain;Instituto de Astronomía, UNAM, Apdo. Postal 877, 22800 Ensenada BC, Mexico;Department of Experimental Physics, University of Szeged, Dóm tér 9, Szeged, H-6720 Hungary |
| Abstract: | CCD photometry in Johnson UBV and Strömgren uvby systems and medium-resolution spectroscopy of the galactic open cluster NGC 7128 are presented. Spectral types of the brightest 12 stars in the cluster field were determined based on equivalent widths of the H α and the He i 6678-Å line. The spectroscopic observations also revealed two obvious and one probable Be-type stars showing H α emission. The analysis of the photometric diagrams gave a colour excess of E ( B ? V )=1.03±0.06 mag, a distance modulus DM =13.0±0.2 mag and an age above 10 Myr. Time-resolved photometric observations obtained on one night resulted in the detection of short time-scale light variations of seven new and three already known variable stars in the cluster field. |
| Keywords: | techniques: photometric techniques: spectroscopic stars: variables: other open clusters and associations: individual: NGC 7128 |