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  • Optimum design and development of segmented mirror telescope optics and phasing system 
    Jacob, A (Indian Institute of Astrophysics, 2020-10)
    Astronomy today is in the path of constructing large telescopes. Due to several manufacturing and maintenance difficulties, large telescopes of more than 8 m are predominantly segmented. To fulfill the need for its growing ...
  • Optimum image parameter ranges for TACTIC imaging elements : guidance from simulations 
    Koul, M. K; Charagi, S. K; Rannot, R. C; Sapru, M. L; Bhat, C. L (Astronomical Society of India, 2002)
    In this paper, we present some results on the performance characteristics of the TACTIC Imaging Element (IE) as predicted by extensive simulation studies. The main features studied are the optimum image parameter ranges ...
  • Opto-mechanical assembly and ground calibration of LUCI 
    Mathew, J; Nair, B. G; Sriram, S; Kamath, P. U; Prakash, A; Mayuresh, Sarpotdar; Ambily, S; Nirmal, K; Sreejith, A. G; Safonova, M; Murthy, J; Brosch, N (SPIE--The International Society for Optical Engineering, 2018-08-20)
    The Lunar Ultraviolet Cosmic Imager (LUCI) is an innovative all-spherical mirrors telescope, proposed to fly as a scientific UV imaging payload on a lunar mission in collaboration with Indian Aerospace Company-TeamIndus, ...
  • Opto-thermal analysis of a lightweighted mirror for solar telescope 
    Banyal, R. K; Ravindra, B; Chatterjee, S (Optical Society of America, 2013-03-25)
    In this paper, an opto-thermal analysis of a moderately heated lightweighted solar telescope mirror is carried out using 3D finite element analysis (FEA). A physically realistic heat transfer model is developed to account ...
  • Orbit of Eros, its next opposition on april 19th, 1917 
    Ridsdale, A. C (Astronomical Society of India, 1917)
  • Orbit of the spectroscopic binary B Persei 
    Rajamohan, R; Parthasarathy, M (Indian Academy of Sciences, 1975-04)
    Spectroscopic orbital elements are derived for the close binary system b Persei on the basis of forty spectrograms. The period is redetermined as 1.527360 days, and variations in the orbital elements are confirmed by ...
  • Orbital decay of protostellar binaries in molecular clouds 
    Gorti, U; Bhatt, H. C (Royal Astronomical Society, 1996-11)
    The evolution of protostellar binary system is investigated while it is embedded in its parent molecular cloud core and is acted upon by gas drag as a result of dynamical friction. Approximate analytical results are obtained ...
  • Orbital Evolution of the Binary X-ray Pulsar Her X-1 
    Bhatt, N; Paul, B; Koul, C. L (Astronomical Society of India, 2003)
    We report the discovery of a break in the orbital period evolution of Her X-1, coincident with a recent anomalous low state.
  • Orbital period modulation and spot activity in the RS CVn binary V711 Tauri 
    Muneer, S; Jayakumar, K; Rosario, M. J; Raveendran, A. V; Mekkaden, M. V (EDP Sciences, 2010-10)
    We attempt to establish the real nature of the orbital period variation and its relation to the spot activity of V711 Tau, and determine why the (B–V) colour of the star appears to be nearly independent of its V magnitude. ...
  • Orbital signatures from observed light curves of blazars 
    Mangalam, A; Mohan, Prashanth (Indian Academy of Sciences, 2014-04)
    Variability in active galactic nuclei is observed in ultraviolet to X-ray emission based light curves. This could be attributed to orbital signatures of the plasma that constitutes the accretion flow on the putative disk ...
  • 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, ...
  • Orbits of double stars 
    Jacob, W. S (Royal Astronomical Society, 1847-01)
  • 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 dark matter and its estimate in the metagalaxy 
    Srivastava, D. N (Astronomical Society of India, 1993)
    On dark matter, whereas current research is in the field of weakly interacting particles, this work puts forward a different line of approach. It interprets dark matter as a transformation of matter by a generalized ...
  • 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 electric and magnetic fields in the early universe 
    Davies, J. B (Astronomical Society of India, 1997)
    A fundamental unanswered question of cosmology is the origin of the magnetic fields observed in the various types of astrophysical bodies. It is still argued whether these magnetic fields are primordial or whether they ...
  • 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 ...

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