Open AccessFundamental parameters and new variables of the galactic open cluster NGC 7128
Author(s) -
Balog Z.,
Delgado A. J.,
Moitinho A.,
Fűrész G.,
Kaszás G.,
Vinkó J.,
Alfaro E. J.
Publication year - 2001
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2001.04280.x
Subject(s) - physics , astrophysics , distance modulus , open cluster , photometry (optics) , stars , astronomy , blue straggler , variable star , star cluster
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.