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Browsing IIAP Publications by Title

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  • Raman scattering of the synchrotron self-absorbed radiation in accretion discs 
    Krishan, V (Royal Astronomical Society, 1988-01)
    The quasar non-thermal continuum in the radio region can undergo Raman scattering in the accretion disc plasma around the central black hole provided that the frequency and the wave vector matching and the threshold ...
  • Random phase approximation for allowed and parity non-conserving electric dipole transition amplitudes and its connection with many-body perturbation theory and coupled-cluster theory 
    Gopakumar, G; Sur, C; Das, B. P; Chaudhuri, R. K; Mukherjee, D; Hirao, K (World Scientific Publishing Co, 2006)
    The connections between the Random Phase Approximation (RPA) and Many-Body Perturbation Theory (MBPT) and its all order generalization, the Coupled-Cluster Theory (CCT), have been explored. Explicit expressions have been ...
  • Range and frequency spread-F at Kodaikanal 
    Sastri, J. H; Sasidharan, K; Subramanyam, V; Srirama Rao, M (European Geophysical Society, 1979-09)
    Using ionogram data at Kodaikanal (geomagnetic lat. 06 deg N, Dip 3.5 deg N) over a seven year period, Jan. 1957-Dec. 1963, a study is made of the seasonal and sunspot cycle variations in the nocturnal occurrence of amplitude ...
  • The Rann of Kuchchh earthquake, 26 January 2001 
    Gaur, V. K (Indian Academy of Sciences, 2001-02)
  • Rapid continuum level variability in Be stars earlier than B2 
    Ghosh, K. K (American Astronomical Society, 1990-05)
    H-alpha profiles for 12 Be stars and four standard stars were obtained on six nights in January and February, 1988, in order to search for rapid spectral variability in these stars. The results show that the Be stars earlier ...
  • Rapid disappearance of penumbra-like features near a flaring polarity inversion line: the hinode observations 
    Ravindra, B; Gosain, S (Hindawi Publishing Corporation, 2012-03)
    We present the observations of penumbra like features (PLFs) near a polarity inversion line (PIL) of flaring region. The PIL is located at the moat boundary of active region (NOAA 10960). The PLFs appear similar to sunspot ...
  • Rapid H-alpha variability in Phi Persei 
    Ghosh, K. K; Sanjeevkumar, T; Jaykumar, K; Kuppuswamy, K; Rosario, M. J (Astronomical Society of the Pacific, 1988-06)
    A search for rapid variability of H-alpha with a time resolution from 30 to 45 seconds is performed for Phi Per. In total, 42 spectra in H-alpha were obtained during three nights. Results show the presence of rapid irregular ...
  • Rapid optical variability of TeV blazars 
    Gopal-Krishna; Goyal, A; Joshi, S; Karthick, C; Sagar, R; Wiita, P. J; Anupama, G. C; Sahu, D. K (Wiley-Blackwell, 2011-09)
    In this first systematic attempt to characterize the intranight optical variability (INOV) of TeV-detected blazars, we have monitored a well-defined set of nine TeV blazars on total 26 nights during 2004–10. In this R- or ...
  • Rapid polarization variability in intense sources 
    Gangadhara, R. T; Krishan, V (The American Astronomical Society, 1995-02)
    We have recently reported the polarization changes of the intense electromagnetic radiation, in active galactic nuclei and pulsars, due to stimulated Raman scattering. In this paper, we show that the incident and the ...
  • Rapid searches for counterparts of GRB 930131 
    Schaefer, Bradley. E; Barthelmy, Scott. D; Palmer, David. M; Cline, Thomas. L; Hurley, Kevin. C; Sommer, Michael; Boer, Michel; Niel, Michel; Fishman, Gerald. J; Kouveliotou, Chryssa; Meegan, Charles. A; Coe, M. J; Elmegreen, Bruce. G; McNamara, Bernard. J; Harrison, Thomas; Owens, Alan; Sollee, Neyle; Stull, John; Palermiti, Michael; Schwartz, Richard; Brooks, Jack; Vanderspek, Roland; Ricker, George. R; Krimm, Hans. A; Wenzel, Wolfgang; Greiner, Jochen; Hudec, Rene; Novak, Miroslav; Borovicka, Jiri; Predota, Miroslav; Bailyn, Charles. D; Hanlon, Lorraine. O; Bennett, K; Spoelstra, Titus. A. Th; Smette, Alain; Pedersen, Holger; Florentin, Ralph; Pollas, Christian; Steinle, Helmut; Schramm, K. J; Iyengar, K. V. K; Prabhu, T. P (American Astronomical Society, 1994-02)
    A fading counterpart to a gamma-ray burst (GRB) would appear as a point source inside a GRB error region soon after the burst which dims on a timescale from minutes to days. The favorable circumstances of the burst GRB ...
  • Rapid simultaneous observations of Fe II and Balmer emission lines of X OPH 
    Ghosh, K. K; Jayakumar, K (D. Reidel Publishing Co., 1988-02)
    Sudden brightening of Fe II and Balmer (Hβ and Hα) lines of X Oph was observed on 28 - 29 May, 1986. Equivalent width of Fe II and Hβ lines increased by a factor of two and that for Hα line by a factor of four, during the ...
  • Rapid variations of H-alpha emission strength of eight Be stars 
    Ghosh, K. K (Kluwer Academic Publishers, 1988-08)
    Rapid observations of H profiles of eight Be stars have been obtained and it is found that rapid (in a time-scale of 4 to 6 minutes) and irregular variations of total emission strength of H line are present in these stars. ...
  • The Rapidly Flaring Afterglow of the Very Bright and Energetic GRB 070125 
    Updike, A. C; Haislip, J. B; Nysewander, M. C; Fruchter, A. S; Kann, D. A; Klose, S; Milne, P. A; Williams, G. G; Zheng, W; Hergenrother, C. W; Prochaska, J. X; Prochaska, J. X; Mirabal, N; Thorstensen, J. R; van der Horst, A. J; Starling, R. L. C; Racusin, J. L; Burrows, D. N; Kuin, N. P. M; Roming, P. W. A; Bellm, E; Hurley, K; Li, W; Filippenko, A. V; Blake, C; Starr, D; Falco, E. E; Brown, W. R; Dai, X; Deng, J; Xin, L; Qiu, Y; Wei, J; Urata, Y; Nanni, D; Palazzi, E; Greco, G; Bartolini, C; Guarnieri, A; Piccioni, A; Pizzichini, G; Terra, F; Misra, K; Bhatt, B. C; Anupama, G. C; Fan, X; Jiang, L; Wijers, R. A. M. J; Reichart, D. E; Eid, H. A; Bryngelson, G; Puls, J; Goldthwaite, R. C; Hartmann, D. H (The American Astronomical Society, 2008-09)
    We report on multiwavelength observations, ranging from X-ray to radio wave bands, of the IPN-localized gamma-ray burst GRB 070125. Spectroscopic observations reveal the presence of absorption lines due to O I, Si II, and ...
  • Rapidly Rotating Strange Stars for a New Equation of State of Strange Quark Matter 
    Bombaci, I; Thampan, A. V; Datta, B (The American Astronomical Society, 2000-10)
    For a new equation of state of strange quark matter, we construct equilibrium sequences of rapidly rotating strange stars in general relativity. The sequences are the normal and supramassive evolutionary sequences of ...
  • Rare Finding of a 100 Kpc Large, Double-lobed Radio Galaxy Hosted in the Narrow-line Seyfert 1 Galaxy SDSS J103024.95+551622.7 
    Rakshit, S; Stalin, C. S; Hota, A; Konar, C (IOP Publishing, 2018-12)
    Among the many varieties of active galactic nuclei (AGNs) known, narrow-line Seyfert 1 (NLSy1) galaxies are a puzzling class, particularly after the discovery of γ-ray emission in a handful of them using observations from ...
  • A Raspberry Pi-based attitude sensor 
    Sreejith, A. G; Mathew, J; Mayuresh, Sarpotdar; Mohan, Rekhesh; Akshata Nayak; Safonova, M; Murthy, J (World Scientific Publishing Co., 2014-11)
    We have developed a lightweight low-cost attitude sensor, based on a Raspberry Pi, built with readily available commercial components. It can be used in experiments where weight and power are constrained, such as in ...
  • [Rb/Zr] ratio in Ba stars as a diagnostic of the companion AGB stellar mass 
    Shejeelammal, J; Goswami, A (Indian Academy of Sciences, 2020-12)
    Understanding nucleosynthesis in and evolution of asymptotic giant branch (AGB) stars is of primary importance as these stars are the main producers of some of the key elements in the Universe. They are the predominant ...
  • Re-analysis of close binary systems 
    Indulekha, K; Kundt, W; Shylaja, B. S (Kluwer Academic Publishers, 1990-10)
    The facts indicating that large line-forming regions occur among the best-studied close binaries are outlined. It is pointed out that emission lines are often redshifted while absorption lines are blueshifted, emission ...
  • Re-Analysis of QPO in 3C 273 Light Curve 
    Mohan, Prashanth; Mangalam, A; Chand, H; Gupta, A. C (Indian Academy of Sciences, 2011-06)
    We have developed analysis tools to search for quasi periodic oscillations in light curves from active galactic nuclei, using the following time series techniques: Wavelets, periodogram, Lomb–Scargle periodogram, structure ...
  • Re-appraisal of the P,T-odd interaction constant Wd in YbF: relativistic configuration interaction approach 
    Nayak, M. K; Chaudhuri, R. K (Indian Academy of Sciences, 2009-09)
    Restricted active space (RAS) configuration interaction (CI) approach is employed to compute the P,T-odd interaction constant W-d for the ground ((2)Sigma(1/2)) state of YbF molecule. The present estimate of W-d = -1.164 ...

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