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Browsing by Author "Raju, K. P"

Browsing by Author "Raju, K. P"

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  • The Chromospheric Network - (A) Network Evolution Viewed as a Diffusion Process 
    Srikanth, R; Singh, J; Raju, K. P (Kluwer Academic Publishers, 1999-03)
    Autocorrelation and cross-correlation techniques have been applied to obtain quantitative information about the dynamics of magnetic flux on the solar surface. The speed of network magnetic elements and the diffusion ...
  • The chromospheric network: Dependence of cell lifetime on length-scale 
    Srikanth, R; Raju, K. P; Singh, J (Kluwer Academic Publishers, 1999-02)
    A time series of CaiiK filtergrams of the chromosphere was used to study the relationship between correlation lifetimes and autocorrelation length scales. The form of the lifetime-scale relation is inferred by comparing ...
  • Correlation between Supergranular Lane Widths and Sunspot Number; A Simple Way to Predict the Amplitude of Sunspot Cycle 
    Raju, K. P; Singh, Jagdev; Ravindra, B; Priyal, M (American Astronomical Society, 2023-12-20)
    The network structure seen in the solar images is the outline of supergranulation, which is the large-scale convection in the Sun with a size of about 30 Mm and a lifetime of 24 hr. We have obtained the supergranulation lane ...
  • The Correlation Lifetimes of Chromospheric CA II K Network Cells 
    Raju, K. P; Srikanth, R; Singh, J (Springer, 1998-03)
    The lifetimes and spatial scales of emission network cells in the solar chromosphere were studied from a nearly continuous sequence of Caii K filtergrams, obtained from Antarctica. The temporal autocorrelation function ...
  • The Dependence of Chromospheric CA II K Network Cell Sizes on Solar Latitude 
    Raju, K. P; Srikanth, R; Singh, J (Springer, 1998-06)
    Calcium K line spectroheliograms obtained during the solar minimum phases at Kodaikanal between 1913–1974 have been used to study the network cell sizes. The autocorrelation is calculated for two-dimensional strips at 5° ...
  • Dependence of Supergranular Length-Scales on Network Magnetic Fields 
    Raju, K. P; Singh, J (Springer, 2002-05)
    In an earlier paper by Raju, Srikanth, and Singh (1998), the average size of chromospheric network cells has been shown to have a dependence on the solar latitude. This was presumed to be due to the reduction of supergranular ...
  • Distribution of Supergranular Sizes 
    Srikanth, R; Singh, J; Raju, K. P (The American Astronomical Society, 2000-05)
    A gradient-based method of tessellation was applied to SOHO Dopplergrams and to Ca II K filtergrams in order to study the cellular pattern of the solar surface, in specific the geometric relationship between the tessellation ...
  • The Effect of Mass Motions Inside the Coronal Loops on Emission Line Profiles 
    Raju, K. P (Kluwer Academic Publishers, 1999-04)
    The observed green coronal emission line profiles have been often found to have multi-components. Further examinations reveal that the occurrence of multi-components in line profiles is related to the solar cycle variations ...
  • EUV line intensity distribution in the solar atmosphere: differences between a polar coronal hole and its equatorial extension 
    Raju, K. P; Bromage, B. J. I (EDP Sciences, 2006-01)
    Intensity histograms of 14 EUV emission lines in a polar coronal hole, its equatorial extension, the "Elephant's Trunk", and the adjacent quiet Sun regions have been obtained from SOHO/CDS observations made in August and ...
  • Fabry-Perot Interferometric Observations of the Solar Corona in the Green Line 
    Raju, K. P; Singh, J; Muralishankar, S (Indian Institute of Astrophysics, Bangalore, 1997)
    An imaging Fabry-Perot interferometer was designed and used for coronal observations in the green line (FeXIV) 5303 Armstrong. The observations were carried our at Nim Ka Thana, Rajasthan, India during the total solar ...
  • High resolution interferometry of astrophysical objects 
    Raju, K. P (Astronomical Society of India, 1993)
    The thesis comprises studies on two distinctly diverse astrophysical situations; one on the outer envelope of a late-type star at its main sequence stage (solar corona), the other on the ionized cloud surrounding an ...
  • Intensity distribution and contrast of the solar EUV network 
    Raju, K. P (Springer, 2010-03)
    Intensity distributions of the EUV network and the cell interior in the solar atmosphere have been obtained in fourteen emission lines from Solar and Heliospheric Observatory (SOHO)/Coronal Diagnostic Spectrometer (CDS) ...
  • Intensity oscillation in the corona as observed during the Total Solar Eclipse of 29 March 2006 
    Singh, J; Hasan, S. S; Gupta, G. R; Banerjee, D; Muneer, S; Raju, K. P; Bagare, S. P; Srinivasan, R (Springer, 2009-11)
    We obtained the images of the eastern part of the solar corona in the Fe xiv 530.3 nm (green) and Fe x 637.4 nm (red) coronal emission lines during the total solar eclipse of 29 March 2006 at Manavgat, Antalya, Turkey. ...
  • Lifetimes and sizes of supergranular cells 
    Raju, K. P; Srikanth, R; Singh, J (Astronomical Society of India, 1999)
    Supergranulation is the surface manifestation of large scale solar convection. Since there is a strong correspondence between supergranulation pattern and Ca K chromospheric network, lifetimes and sizes may be obtained ...
  • Line Profile Studies of Coronal Active Regions in Fe XII λ195.12 Using Hinode/EIS 
    Prabhakar, Maya; Raju, K. P (American Astronomical Society, 2022-05-20)
    Coronal active regions are studied using Hinode/EIS observations in the EUV line Fe xii λ195.12 by analyzing their line profiles from 2006 December to 2019 December. The period covers the last 2 yr of solar cycle 23 and ...
  • Narrow Band Photometry in Emission Lines during the Total Solar Eclipse of October 24, 1995 
    Singh, J; Cowsik, R; Venkatakrishnan, P; Srinivasan, R; Chinnappan, V; Raju, K. P; Srikanth, R (Indian Institute of Astrophysics, Bangalore, 1997)
    To investigate the spatial variation of tempereture and density within coronal strucures, narrow band photometry in three coronal emission lines was done during this eclipse. The emission lines 6374 (FeX), 7892 (Fe XI) and ...
  • Network and plage indices from Kodaikanal Ca-K data 
    Raju, K. P; Singh, J (IOP Publishing, 2014-02)
    The Ca II K filtergrams from Kodaikanal Solar Observatory have been used to study solar activity. The images are dominated by the chromospheric network and plages. Programs have been developed to obtain the network and ...
  • The Physical Conditions in a Polar Coronal Hole and Nearby Regions from Norikura and SOHO Observations 
    Raju, K. P; Sakurai, T; Ichimoto, K; Singh, J (The American Astronomical Society, 2000-11)
    The distribution of emission-line intensities, Doppler velocities, and line widths in a polar coronal hole and nearby regions are obtained from the spectroscopic observations carried out on 1998 November 3 at the Norikura ...
  • Possible Evidence of Long-Term Oscillations in the Solar Atmosphere 
    Raju, K. P; Singh, J; Srikanth, R; Chou, Dean-Yi; CA, TON team (Springer, 2001-03)
    We have obtained the temporal correlation function, Q(t), from time sequences of Caii K filtergrams and Dopplergrams from Antarctica, Taiwan Oscillation Network (TON) and Solar and Heliospheric Observatory (SOHO). Q(t) ...
  • Relative velocities and linewidths in a coronal hole and outside 
    Raju, K. P (Springer Netherlands, 2009-03)
    Relative Doppler velocities and spectral linewidths in a coronal hole and in the quiet Sun region outside have been obtained from Solar and Heliospheric Observatory (SOHO)/Coronal Diagnostic Spectrometer (CDS) observations. ...

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