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Browsing by Author "Narasimha, D"

Browsing by Author "Narasimha, D"

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  • Lenses of small angular scales from Jodrell Bank survey 
    Patnaik, A; Narasimha, D (Astronomical Society of India, 1993)
    The Jodrell Bank 5 GHz sky survey provides a complete flux-limited sample of radio sources at latitude greater than 2.5 deg which are brighter than 200 mJy and have a spectrum flatter than 0.5. From the analysis of nearly ...
  • PKS1830-211: The strongest lensed radio source 
    Narasimha, D (Astronomical Society of India, 2004-09)
    The Ooty lens PKS1830-211 is a bright, variable radio source at a redshift of 2.507 consisting of a compact flat spectrum core, associated knot and jet, which are lensed by an intervening spiral galaxy at a redshift of ...
  • Possible Microlensing Event in the direction of M31 
    Joshi, Y. C; Pandey, A. K; Narasimha, D; Sagar, R (Astronomical Society of India, 2003)
    The Cousin R and I band photometric observations of ~ 13 x 13 field in the direction of M31 galaxy have been carried out during 1999-2001 to search for microlensing events using pixel technique. Here we report a microlensing-like ...
  • Probes of superclusters at moderate redshifts 
    Narasimha, D; Singh, K. P (Astronomical Society of India, 2000)
    Detection of superclusters at z = 0.2 - 1.0 and determination of their mass provide constraints on the theories of structure formation in the Universe. A combination of the study of hot gas observed in X-rays, and the ...
  • Search for Microlensing Events Towards M31 Galaxy 
    Joshi, Y. C; Pandey, A. K; Narasimha, D; Sagar, R (Astronomical Society of India, 2001)
    M31, the prominent galaxy of the Local Group, is located at a distance of about 700 kpc. Due to its convenient orientation, it is an alluring target for gravitational microlensing to search for massive astrophysical compact ...
  • Solar and Stellar Convection 
    Narasimha, D (Indian Institute of Astrophysics, Bangalore, 1988)
    The flow field in stellar convection zones, characterised by high Rayleigh number, low Prandtl number and large Reynolds number, is time dependent and turbulent, consisting of eddies having a range of scale-lengths upto ...
  • Straight arcs in gravitational lens systems 
    Narasimha, D; Chitre, S. M (Astronomical Society of India, 1993)
    Faint straight arcs extending over ten to twenty arcseconds have been observed behind rich clusters of galaxies elongated by the lensing action of the foreground cluster. When a cluster of galaxies has its projected surface ...
  • Study of quasar broad emission region from spectroscopy of multiple images 
    Narasimha, D; Srianand, R (Astronomical Society of India, 2000)
    Using the high resolution radio observations and analysis of the broad emission lines as well as continum in the optical spectra of the multiple images of quasars, we provide a method to probe the structure and dynamics ...
  • Surface effects on the solar oscillation frequencies 
    Narasimha, D (Astronomical Society of India, 1996)
    The solar p-mode frequencies and eigenfunctions are modified by four processes operative in the atmosphere and the subphotospheric layers which can be, to a good approximation, treated as surface phenomena; they are the ...
  • Time delay in gravitational lens systems and cosmological parameters 
    Narasimha, D (Astronomical Society of India, 2002-09)
    The time delay between the multiple images in gravitational lens systems is affected by large scale mass distribution in the lens, even though it might not have observable effects on the macro images. Inhomogeneity at ...

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