Systematic errors in the WRF model planetary boundary layer schemes for two contrasting monsoon seasons over the state of Odisha and its neighborhood region

Theoretical and Applied Climatology - This study evaluates the characteristics of systematic errors (up to day 4) in the planetary boundary layer (PBL) parameterization schemes over the state of...     

Photometric Study Of W Uma Type Binary In The Old Cluster Ngc 6791

Study of eclipsing binaries in an open cluster offer information regarding the age of the cluster in addition to the component stars. In this paper we present the analysis of a W UMa system discovered in the open cluster NGC 6791 using the Wilson–Devinney (W–D) method.     

The distortion wave on the light curve of the RS CVn binary UV piscium

The eclipsing binary UV Piscium was observed with the standardUBV filters during 1976-77, 1977-78 and 1978-79 observing seasons with the 1.22-m reflecting telescope of the Japal-Rangapur Observatory. A wave-like distortion on the light curve noticed by Carr (1969), Oliver (1974), Sadik (1979) and Zeiliket al. (1982a) is confirmed by the present observations. Combining our observations with those of Carr, Oliver and Sadik, it is found that the distortion wave is moving towards decreasing orbital phase with a period of about 1200 days. The source of the observed distortion wave is found to be the hotter component.     

Evolutionary status of UV Piscium and its comparison with other short period RS CVn binaries

From the derived elements of UV Piscium, the evolutionary status of both of its components are compared with the Schaller et al. models and also with other main sequence systems having spectral types of late F to K range. From these models the ages of the components of UV Psc are determined. The Rossby number, which is a measure of chromospheric activity, has been derived from the convective turnover time scales and also from the age estimates.     

Orbital elements and evolutionary nature of the long period RS CVn type eclipsing binary RZ eridani

Light curves of the long period RS CVn type eclipsing binary RZ Eri, obtained during the period 1976–1979 with the 1.2 m telescope of the Japal-Rangapur Observatory are analysed, using Wilson-Devinney method, by fixing the two parametersT _h (7400°K) andq(0.963), resulting in the following absolute elements:A = 72.5 ± 1.4R _⊙,R _h = 2.84 ± 0.12R _⊙,R _c = 6.94 ± 0.20R _⊙,M _bol,_h = 1.35 ± 0.28,M _bol ,_c= 1.41 ± 0.28,m _h = 1.69 ± 0.6m _⊙ andmc= 1.63 ± 0.13m _⊙. The presence of humps and dips of varying amplitudes at a few phases in the normal UBV light curves is explained as due to residual distortion wave. The derived (B-V) and (U-B) colours of both the components appear to have been reddened to an extent of 0 ^m .20 in (B-V) and 0 ^m .16 in (U-B) colours. This reddening is attributed to the presence of an envelope around the system, the material of which might have come from the loss of mass experienced by the evolving cooler component. Taking into consideration the dereddened colours and temperatures of the components, spectral types ofF0 IV for the primary and G 5–8 III–IV for the secondary component were derived. The fractional radii of 0.039 and 0.096 of the two components, when compared with the radii of their critical Roche lobes of 0.378 and 0.372 suggest that these components are well within their critical sizes. From the position of the components on the. isochrones and the evolutionary tracks of stars of Pop I composition computed by Maeder & Meynet, it is concluded that the evolution of the components of RZ Eri is abnormal. This system is found to be situated at a distance of 185 pc, with an age of about 2.5 × 10⁹ yrs.     

Photometry of the RS CVn type eclipsing binary UV piscium

The analysis of the UBV photoelectric study of the short period RS CVn eclipsing binary, UV Psc, has suggested that the primary is a transit with _e=27°,i=88 _. ^o 5, andk=0.75. The spectral type and luminosity of the hotter component is estimated to be G4-6V and that of the cooler component to be K0-2V. Absolute dimensions for the components of UV Psc were derived by combining the present analysis with that of the spectroscopic analysis given by Popper.The out-of-eclipse observations have showed large amount of scatter and an investigation of this showed that hotter component could be an intrinscic variable. No periodicity for this variation has been fixed due to lack of sufficient data.Paper presented at the Lembang-Bamberg IAU Colloquium No.80 on Double Stars: Physical Properties and Generic Relations, held at Bandung, Indonesia, 3–7 June, 1983.     

VV Orionis – improved elements

TheUBV light curves obtained by Duerbeck (1975) andHa (wide) and Ha (narrow) light curves obtained by Chambliss & Davan (1987) of the detached eclipsing binary VV Orionis (VV Ori) were analysed using the Wilson-Devinney method fixing the two parametersT _h (25,000 K) and q(0.4172), resulting in the following absolute elements:A = 13.605 ± 0.03 LR_⊙,R _h = 5.03 ±0.03R _⊙, R_c = 2.43 ±0.02R _⊙,M _bol,h = -5.18 ± 0.11,M _bol,c = -1.54 ± 0.06,m _h =10.81 + 0.42m _⊙ andm _c = 4.51 ± 0.41m _⊙. The de-reddened colours obtained from applying the reddening corrections ofE(B-V) = 0^m.05 andE(U-B) = O ^m .04, and the derived temperatures of the components, gave spectral types ofB 1.5V for the primary and 54-5V with anUV excess of 0 ^m ·3 for the secondary component. A comparison of the logL and logT _e of the components with the observed ZAMS shows the primary component to be a little above and the secondary component to be a little below/or on the ZAMS. A comparison of the properties of the components of VV Ori and a few other detached systems with the normal stars in the logL, logR and logT _e versus logm planes, indicated a need for either a readjustment of the scales of the above parameters or modifications in the theoretical models. From the position of the components on the evolutionary tracks of Pop I composition computed by Schaller et al. (1992) it is noticed that while the primary component of W Ori had slightly evolved along the main-sequence, its secondary is still unevolved. The age of VV Ori is found to be 10 ± 1 million years and it is at a distance of 368 ± 10 pc.     

UV Piscium and the Radiative Flux Scale

Studies of eclipsing binaries with Hipparcos parallaxes are found to define a radiative flux relation for main sequence stars in the spectral range from B6 – F0which is about as well as to the stars derived from angular diameters. At lower temperatures the fluxes of the components fall below this curve which is caused due to the large intrinsic variations and starspots. From the present analysis it is found that the secondary component of UV Piscium, a late type eclipsing binary, is a normal K3V star and it fits the radiative flux-colour relation quite satisfactorily. This is explained due to the reliable values of the fluxes and colours derived from the clean light curves (light curves obtained after removing the effect of the distortion wave). However, the primary component which is also responsible for the intrinsic variations and starspots continue to deviate from this curve. This revised version was published online in July 2006 with corrections to the Cover Date.     

Photometric study of eclipsing binaries in the Large Magellanic Cloud——I.W UMa type binaries in the Large Magellanic Cloud

Eclipsing binaries are among the most important sources of information on stellar parameters like radii,masses,luminosities,etc.We present the analysis of six W UMa systems discovered in the Large Magellanic Cloud using the Wilson-Devinney method.