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We present the photometric solutions of the variable star V30 that is in the foreground of intermediate open cluster NGC 7789.The observations were done in the V passband using the 2 m telescope at the IUCAA-Girawali Observatory in India.The analysis is done using the Wilson-Devinney Code (2003) and the fitted light curve is presented.The photometric solutions reveal a W-subtype contact configuration.The photometric mass ratio is found to be 0.395 and the absolute masses and radii for the components are ded... 相似文献
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We present the combined BVI multicolor photometric solutions of seven EW variables in the old open cluster Berkeley 39.The observations were carried out in the B and V passbands from the 2 m telescope at the IUCAA-Girawali Observatory in India.The analysis is done using the 2003 version of the Wilson-Devinney code and the fitted light curves are presented.The light curves appear to be symmetric in all the passbands.The photometric solutions suggest that the variables are W-type systems.The new ephemeris ind... 相似文献
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J.?Rukmini P.?Vivekananda?RaoEmail author K.?Sriram 《Astrophysics and Space Science》2005,299(2):109-116
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. 相似文献
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S. N. Tandon J. B. Hutchings S. K. Ghosh A. Subramaniam G. Koshy V. Girish P. U. Kamath S. Kathiravan A. Kumar J. P. Lancelot P. K. Mahesh R. Mohan J. Murthy S. Nagabhushana A. K. Pati J. Postma N. Kameswara Rao K. Sankarasubramanian P. Sreekumar S. Sriram C. S. Stalin F. Sutaria Y. H. Sreedhar I. V. Barve C. Mondal S. Sahu 《Journal of Astrophysics and Astronomy》2017,38(2):28
The performance of the ultraviolet telescope (UVIT) on-board AstroSat is reported. The performance in orbit is also compared with estimates made from the calibrations done on the ground. The sensitivity is found to be within \(\sim \)15% of the estimates, and the spatial resolution in the NUV is found to exceed significantly the design value of \(1.8^{\prime \prime }\) and it is marginally better in the FUV. Images obtained from UVIT are presented to illustrate the details revealed by the high spatial resolution. The potential of multi-band observations in the ultraviolet with high spatial resolution is illustrated by some results. 相似文献
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Ultraviolet Imaging Telescope (UVIT) is one of the payloads onboard AstroSat, India’s first multi-wavelength Astronomy mission. UVIT is primarily designed to make high resolution images in wide field, in three wavelength channels simultaneously: FUV (130–180 nm), NUV (200–300 nm) and VIS (320–550 nm). The intensified imagers used in UVIT suffer from distortions, and a correction is necessary for these to achieve good astrometry. In this article we describe the methodology and calculations used to estimate the distortions in ground calibrations. 相似文献
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Mehmet Baran Ulak Ayberk Kocatepe Lalitha Madhavi Konila Sriram Eren Erman Ozguven Reza Arghandeh 《Natural Hazards》2018,92(3):1489-1508
Natural disasters have devastating effects on the infrastructure and disrupt every aspect of daily life in the regions they hit. To alleviate problems caused by these disasters, first an impact assessment is needed. As such, this paper focuses on a two-step methodology to identify the impact of Hurricane Hermine on the City of Tallahassee, the capital of Florida. The regional and socioeconomic variations in the Hermine’s impact were studied via spatially and statistically analyzing power outages. First step includes a spatial analysis to illustrate the magnitude of customers affected by power outages together with a clustering analysis. This step aims to determine whether the customers affected from outages are clustered or not. Second step involves a Bayesian spatial autoregressive model in order to identify the effects of several demographic-, socioeconomic-, and transportation-related variables on the magnitude of customers affected by power outages. Results showed that customers affected by outages are spatially clustered at particular regions rather than being dispersed. This indicates the need to pinpoint such vulnerable locations and develop strategies to reduce hurricane-induced disruptions. Furthermore, the increase in the magnitude of affected customers was found to be associated with several variables such as the power network and total generated trips as well as the demographic factors. The information gained from the findings of this study can assist emergency officials in identifying critical and/or less resilient regions, and determining those demographic and socioeconomic groups which were relatively more affected by the consequences of hurricanes than others. 相似文献
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The Paleocene-recent post-rift subsidence history recorded in the Mumbai Offshore Basin off western continental margin of India is examined. Results obtained through 2-D flexural backstripping modelling of new seismic data reveal considerable thermo-tectonic subsidence over last ca. 56 Myr. Reverse postrift subsidence modelling with variable β stretching factor predicts residual topography of ca. 2000 m to the west of Shelf Margin Basin and fails to restore late Paleocene horizon and the underlying igneous basement to the sea level. This potentially implies that:(1) either the igneous basement formed during the late Cretaceous was emplaced under open marine environs; or(2) a laterally varying cumulative subsidence occurred within Mumbai Offshore Basin(MOB) during ca. 68 to ca. 56 Ma. Pre-depositional topographic variations at ca. 56 Ma across the basin could be attributed to the extensional processes such as varied lower crustal underplating along Western Continental Margin of India(WCMI). Investigations about basement tectonics after unroofing of sediments since late Paleocene from this region support a transitional and heavily stretched nature of crust with high to very high β factors. Computations of past sediment accumulation rates show that the basin sedimentation peaked during late Miocene concurrently with uplift of Himalayan-Tibetan Plateau and intensification of Indian monsoon system. Results from basin subsidence modelling presented here may have significant implications for further studies attempting to explore tectono-climatic interactions in Asia. 相似文献
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T. Ramprasad P. Dewangan M.V. Ramana A. Mazumdar S.M. Karisiddaiah E.R. Ramya G. Sriram 《Marine and Petroleum Geology》2011,28(10):1806-1816
The Krishna–Godavari (KG) offshore basin is one of the promising petroliferous basins of the eastern continental margin of India. Drilling in this basin proved the presence of gas hydrate deposits in the shallow marine sediments beyond 750 m water depths, and provided lithologic and stratigraphic information. We obtained multibeam swath bathymetry covering an area of about 4500 km2 in water depths of 280–1800 m and about 1260 line km of high resolution seismic (HRS) records. The general lithology of midslope deposits is comprised of nannofossil-rich clay, nannofossil-bearing clay and foraminifera-bearing clay. The HRS records and bathymetry reveal evidence of slumping and sliding of the upper and midslope sediments, which result in mass transport deposits (MTD) in the northwestern part of the study area. These deposits exhibit 3–9.5 km widths and extend 10–13 km offshore. The boundaries of the MTDs are often demarcated by sharp truncation of finely layered sediments (FLS) and the MTDs are characterized by acoustically transparent zones in the HRS data. Average thickness of recent MTDs varies with depth, i.e., in the upper slope, the thickness is about 45 m, while in the lower slope it is about 60 m, and in deeper offshore locations they attain a maximum thickness of about 90 m. A direct indication for slumping and mass transportation of deposits is provided by the age reversal in 14C AMS dates observed in a sediment core located in the midslope region. Seismic profiling signatures provide indications of fluid/gas movement. We propose that the presence of steep topographic gradients, high sedimentation rates, a regional fault system, diapirism, fluid/gas movement, and neotectonic activity may have facilitated the slumping/sliding of the upper slope sediments in the KG offshore basin. 相似文献