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Photometric Study (photometric + study)
Selected AbstractsPhotometric study of the OB star clusters NGC 1502 and NGC 2169 and mass estimation of their members at the University Observatory Jena,ASTRONOMISCHE NACHRICHTEN, Issue 5 2009M.M. Hohle Abstract In this work we present detailed photometric results of the trapezium like galactic nearby OB clusters NGC 1502 and NGC 2169 carried out at the University Observatory Jena. We determined absolute BVRI magnitudes of the mostly resolved components using Landolt standard stars. This multi colour photometry enables us to estimate spectral type and absorption as well as the masses of the components, which were not available for most of the cluster members in the literature so far, using models of stellar evolution. Furthermore, we investigated the optical spectrum of the components ADS 2984A and SZ Cam of the sextuple system in NGC 1502. Our spectra clearly confirm the multiplicity of these components, which is the first investigation of this kind at the University Observatory Jena (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Non-radial pulsation of the , Scuti star UV TrianguliMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2002Ai-Ying Zhou Abstract We present the results of a three-year photometric study of the , Scuti star UV Trianguli. Our data sets consist of 9378 differential measurements in Johnson V together with a few data collected into the Strömgren uvby, system. UV Tri is at least a biperiodic variable. The two best-fitting frequencies, f1= 9.3298 d,1 and f2= 10.8513 d,1, are still not the complete set of pulsation frequencies representing the light variations of the star. A suspected third frequency might present in the star. Several ,anomalous cycles' are observed in the light curves. They seem real, but are aperiodic. We derive the colour indices and physical parameters for the variable and conclude that it is a Population I , Sct star with normal metal abundance ([Me/H]= 0.0 ± 0.1 dex) evolving on its main-sequence stage at an early evolutionary phase before the turn-off point. Finally, we compare the observed oscillation frequencies with theoretical models. The two pulsation modes of UV Tri are likely to be non-radial gravity modes. [source] The open cluster Berkeley 53,ASTRONOMISCHE NACHRICHTEN, Issue 8 2009G. Maciejewski Abstract We present a photometric study of the neglected open cluster Berkeley 53. We derived its fundamental parameters, such as the age, the interstellar reddening, and the distance from the Sun, based on BV photometry combined with near-infrared JHKS data. The structure and the mass function of the cluster were also studied and the total number of members and the total mass were estimated. The cluster was found to be a rich and massive stellar system, located in the Perseus Arm of the Milky Way, 3.1 ± 0.1 kpc from the Sun. Its age exceeds 1 Gy but it seems tobe very young in the context of its dynamical evolution. The analysis of the two-color diagrams and color-magnitude diagrams indicates that the cluster is significantly reddened. However, both methods resulted in different values of E (B , V), i.e. 1.21 ± 0.04 and 1.52 ± 0.01, respectively. This discrepancy suggests the presence of an abnormal interstellar extinction law toward the cluster (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Spot modelling of the flare M4.5 dwarf YZ CMiASTRONOMISCHE NACHRICHTEN, Issue 6 2003M. Zboril Abstract We report on a photometric study of the flareM4.5 dwarf YZ CMi as based on photoelectric observations from the seasons 1972/73, 1979/80 and 1996/97. We suggest spot activity to explain the light and colour curves. Spots are generally 500K cooler than the surrounding photosphere and there are basically two solutions available for the observations: high latitude spot changing slightly basic properties such as radius and latitude or active near-equatorial (belt-like) centers represented by three spots. However, the activity centers changed in longitudes (,180°). The typical spot coverage (inclination i = 60°) is 10-15% and 5% for the season 1996/97 or ,25% for the stellar inclination i = 75°. As a by-product, V curve and (V-I) and (V-K) indexes turn out to be most promising in modelling of M-type stars as far as present calibrations are concerned. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||