We present UBV photometry of the highly reddened and poorly studied open cluster Berkeley 55 (= C 2115+515), revealing an important population of B-type stars and several evolved stars of high luminosity. Intermediate-resolution far-red spectra of several candidate members confirm the presence of one F-type supergiant and six late supergiants or bright giants. The brightest blue stars are mid-B giants. Spectroscopic and photometric analyses indicate an age 50+/-10Myr. The cluster is located at a distance d~4kpc, consistent with other tracers of the Perseus Arm in this direction. Berkeley 55 is thus a moderately young open cluster with a sizable population of candidate red (super)giant members, which can provide valuable information about the evolution of intermediate-mass stars.
UBV photometry is presented for stars from AGK3R, NPZT, the Yale Bright Star Catalog (HR), and the FK5 faint extension. Stars with previously published UBV data were not selected. Observations were taken at the Kvistaberg Observatory and La Palma.
We report on Planetary Camera observations of the central region of 30 Doradus in the Large Magellanic Cloud. These images of 30 Doradus are the first "deep" HST exposures that have appropriate photometric calibration. The B band (F439W) image, which shows R136a at the center of the PC6 CCD chip, reveals over 200 stars within 3" of the center of R136a, and over 800 stars in a 35"x35" area. We used Malumuth et al.'s [The First Year of HST Observations, edited by A. L. Kinney and J. C. Blades (ST ScI, Baltimore) (1991)] PSF-fitting method to measure the magnitudes of all stars on the PC6 chip. These new B magnitudes, along with U and V magnitudes from archival PC images, yield a luminosity function, mass density profile, and initial mass function of the 30 Doradus ionizing cluster. The mass distribution is well fit by a King model with a core radius, Rc=0.96" (0.24pc), a tidal radius, Rt=110" (28pc), and a total mass, M=16800M_{sun}_. Both the luminosity function and initial mass function show evidence for mass segregation, in the sense that the central region has a higher fraction of massive stars than the outer regions. This is the first observational evidence for mass segregation in a very young cluster (age ~3 million years). The observations admit the hypothesis that the mass segregation occurred in the process of star formation and/or that the mass segregation is the result of dynamical evolution.
Several binaries with masses anomalously small for their observed spectral types have been discussed in the astronomical literature and interpreted as the result of envelope ejection. V379 Cep is one of these objects. We obtained new series of electronic spectra and UBV photometry of V379 Cep and analysed them in an effort to check whether the conclusion about its anomalous masses may not be premature.
The data file (v899her.dat) includes photometric observations of the eclipsing binary system V899 Herculis. The observations were carried out at the Ankara University Observatory in Johnson UBV filters by using an SSP-5 photometer head attached to the 30-cm Maksutov telescope of the Observatory. Observational standard errors are 0.020m, 0.016m, and 0.021m in U, B, and V filters, respectively. A total of 301, 305, and 298 data points are included for each UBV filters, respectively, in the Table.
An analysis of an extensive collection of photometric and spectroscopic observations of the little studied bright Be star V360 Lac lead to the following main conclusions: (1) V360 Lac is a binary system consisting of a B3e primary and a F9IV secondary which probably fills the Roche lobe and losses mass towards the primary. Radial-velocity curves of both components were obtained. (2) The light variations arise from superposition of variations on at least three time scales: phase-locked orbital brightness and colour changes with two minima; sinusoidal variation with a 322.24^d^ period and low-amplitude rapid changes with a possible period of 1.6738^d^. (3) A tentative solution of the B and V light curves which assumes the semi-detached configuration and presence of a disk around the primary, combined with the orbital solution, leads to preliminary basic physical elements of the system which are consistent with the radiative properties of the binary components.
