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Browsing IIAP Publications by Title

Browsing IIAP Publications by Title

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  • Orbital solutions derived from radial velocities and time delays for four Kepler systems with A/F-type (candidate) hybrid pulsators⋆ 
    Lampens, P; Vermeylen, L; Fremat, Y; Sodor, A; Skarka, M; Samadi-Ghadim, A; Bognar, Zs; Lehmann, H; De Cat, P; Goswami, A; Dumortier, L (EDP Sciences, 2021-03)
    Context. The presence of A/F-type Kepler hybrid stars extending across the entirety of the δ Scuti – γ Doradus instability strips and beyond remains largely unexplained. In order to better understand these particular stars, ...
  • Origin and propagation of extremely high-energy cosmic rays 
    Bhattacharjee, P; Sigl, G. G (Elsevier, 2000-04)
    Cosmic ray particles with energies in excess of 10**20 eV have been detected. The sources as well as the physical mechanism(s) responsible for endowing cosmic ray particles with such enormous energies are unknown. This ...
  • The Origin of Dust Polarization in the Orion Bar 
    Gouellec, Valentin J. M. Le; Andersson, B-G; Archana Soam; Schirmer, Thiébaut; Michail, Joseph M.; Lopez-Rodriguez, Enrique; Flores, Sophia; Chuss, David T.; Vaillancourt, John E.; Hoang, Thiem; Lazarian, Alex (American Astronomical Society, 2023-07-10)
    The linear polarization of thermal dust emission provides a powerful tool to probe interstellar and circumstellar magnetic fields, because aspherical grains tend to align themselves with magnetic field lines. While the ...
  • Origin of Lithium Enrichment in K Giants 
    Bharat Kumar, Y; Reddy, B. E; Lambert, D. L (Institute of Physics Publishing, 2011-03-20)
    In this Letter, we report on a low-resolution spectroscopic survey for Li-rich K giants among 2000 low-mass (M ≤ 3 M sun) giants spanning the luminosity range from below to above the luminosity of the clump. Fifteen new ...
  • Origin of MeV gamma-ray emissions from blazars 
    Ghosh, K. K; Ramsey, B. D; Sivaram, C (Elsevier Science B. V, 1999-06)
    We have developed a model for MeV emission from blazars that involves the production of MeV gamma-rays through Inverse Compton (IC) scattering of electrons in the blob of a jet, with the UV photons of the accretion disk. ...
  • Origin of quantum-mechanical complementarity without momentum back action in atom-interferometry experiments 
    Unnikrishnan, C. S (The American Physical Society, 2000-07)
    We identify the physical origin of the loss of interference pattern in the which-path atom-interferometery experiments that have been discussed widely. The origin of complementarity between the which-path information and ...
  • Origin of Quasi-periodic Pulsation at the Base of a Kink-unstable Jet 
    Mishra, S. K; Sangal, Kartika; Kayshap, Pradeep; Jelinek, Petr; Srivastava, A. K; Rajaguru, S. P (American Astronomical Society, 2023-03-10)
    We studied a blowout jet that occurred at the west limb of the Sun on 2014 August 29 using high-resolution imaging/spectroscopic observations provided by the Solar Dynamics Observatory/Atmospheric Imaging Assembly and ...
  • Origin of short-period (30-300 s) Doppler frequency fluctuations of lower F region reflections in the equatorial electrojet region 
    Sastri, J. H; Ramesh, K. B; Rao, J. V. S. V; Somayajulu, V. V (American Geophysical Union, 1991-12)
    Measurements of phase path P of lower F-region reflections at normal incidence at Kodaikanal revealed the ubiquitous presence of 30-300-s quasi-sinusoidal variations in the time rate of change of phase path, P (Doppler ...
  • Origin of spatial variations of scattering polarization in the wings of the Ca I 4227 Å line 
    Sampoorna, M; Stenflo, J. O; Nagendra, K. N; Bianda, M; Ramelli, R; Anusha, L. S (The American Astronomical Society, 2009-07-10)
    Polarization that is produced by coherent scattering can be modified by magnetic fields via the Hanle effect. This has opened a window to explorations of solar magnetism in parameter domains not accessible to the Zeeman ...
  • Origin of the broadband emission from the transition blazar B2 1308+326 
    Pandey, Ashwani; Kushwaha, Pankaj; Wiita, Paul J; Prince, Raj; Czerny, Bożena; Stalin, C. S (EDP Sciences, 2024-01)
    Context. Transition blazars exhibit a shift from one subclass to the next during different flux states. It is therefore crucial to study them to understand the underlying physics of blazars. Aims. We probe the origin of ...
  • Origin of the highest energy cosmic rays 
    Bhattacharjee, P (Indian Academy of Sciences, 1996-10)
    After briefly recalling the history of discovery of cosmic rays, the present statns of the subject is discussed. Cosmic-ray particles with energy exceeding 1020 eV have been detected. The origin of cosmic rays remains ...
  • Origin of the proper motion and spin of pulsars 
    Cowsik, R (The European Southern Observatory, 1998-12)
    It is suggested that the proper motion and the spin of pulsars at birth are causally connected. Accordingly, the observed mean values of these parameters can be attributed to the recoil momentum and torque impulse imparted ...
  • Origin of the Solar Rotation Harmonics Seen in the EUV and UV Irradiance 
    Giono, G; Zender, J. J; Kariyappa, R; Dame, L (Springer, 2021-11)
    Long-term periodicities in the solar irradiance are often observed with periods proportional to the solar rotational period of 27 days. These periods are linked either to some internal mechanism in the Sun or said to be ...
  • Oscillations and heating in chromospheric fine scale structures 
    Kariyappa, R (Astronomical Society of the Pacific, 1999)
    We have analyzed a 35-min-long time sequence of spectra obtained simultaneously in CaII H-line, NaI D1 and D2 lines, and in strong and weak FeI lines in a quiet region at; the center of the solar disc under high spatial, ...
  • Oscillations in active region fan loops: observations from EIS/Hinode and AIA/SDO 
    Krishna Prasad, S; Banerjee, D; Singh, J (Springer, 2012-11)
    Active region fan loops in AR 11076 were studied, in search of oscillations, using high cadence spectroscopic observations from Extreme-ultraviolet Imaging Spectrometer (EIS) on board Hinode combined with imaging sequences ...
  • Oscillations in F-region doppler velocity in the dip equatorial region associated with ULF geomagnetic pulsations 
    Sastri, J. H; Ramesh, K. B; Rao, D. R. K; Rao, J. V. S. V (Elsevier Science, 1993-07)
    Measurements are presented, made on March 24, 1991 over the Kodaikanal, showing that, around sunset, the Doppler velocity of F-region reflections at vertical incidence is influenced by MHD waves, the magnetic effects of ...
  • Oscillations In Galaxies 
    Namboodiri, P. M. S (Springer, 2000-02)
    Oscillations in galaxies have been investigated by numerical simulations. The various models used have density distributions corresponding to that of polytrope of index n in the range 0 ≤ n ≤ 4 and their evolution has been ...
  • Oscillations In Galaxies 
    Namboodiri, P. M. S (Kluwer Academic Publishers, 2000-01)
    Oscillations in galaxies have been investigated by numerical simulations. The various models used have density distributions corresponding to that of polytrope of index n in the range 0 ≤ n ≤ 4 and their evolution has been ...
  • Oscillatory motions in intense flux tubes 
    Hasan, S. S (Royal Astronomical Society, 1986-03)
    The intricate nature of oscillatory motions in intene flux tubes is examined and states in which the ratio of gas to magnetic pressure (Beta) is constant are considered. Results are presented for both polytropic and real ...
  • Our Present Understanding of Solar Flares 
    Dwivedi, B. N (Indian Institute of Astrophysics, Bangalore, 1986)
    A general discussion of solar flares with emphasis on two-ribbon flares is given. The basic differences between compact (simple-loop) and two-ribbon flares have also been pointed. Skylab observations have been presented ...

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