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Browsing IIAP Publications by Title

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  • Dynamics of Photospheric Magnetic Flux Distribution and Variations in Solar RVs: A Study Using HARPS-N Solar and SDO Observations 
    Sen, Anisha; Rajaguru, S. P (American Astronomical Society, 2023-10-20)
    The distribution and evolution of photospheric magnetic fields in sunspots, plages, and network, and variations in their relative flux content, play key roles in radial velocity (RV) fluctuations observed in Sun-as-a-star ...
  • Dynamics of Subarcsecond Bright Dots in the Transition Region above Sunspots and Their Relation to Penumbral Micro-jets 
    Samanta, T; Tian, H; Banerjee, D; Schanche, N (IOP Publishing, 2017-02-01)
    Plages are the magnetically active chromospheric structures prominently visible in the Ca ii K line (3933.67 Å). A plage may or may not be associated with a sunspot, which is a magnetic structure visible in the solar ...
  • The dynamics of the quiet solar chromosphere 
    Kalkofen, W; Hasan, S. S; Ulmschneider, P (Cambridge University Press, 2003)
    Wave propagation in the nonmagnetic chromosphere is described for plane and spherical waves, and excitation by means of impulses in small source regions in the photosphere; excitation for flux tube waves in the magnetic ...
  • Dynamics of the Solar Magnetic Bright Points Derived from Their Horizontal Motions 
    Pradeep Chitta, L; van Ballegooijen, A. A; Rouppe van der Voort, L; DeLuca, E. E; Kariyappa, R (IOP Publishing, 2012-06-10)
    The subarcsecond bright points (BPs) associated with the small-scale magnetic fields in the lower solar atmosphere are advected by the evolution of the photospheric granules. We measure various quantities related to the ...
  • Dynamics of the Solar Magnetic Network. II. Heating the Magnetized Chromosphere 
    Hasan, S. S; van Ballegooijen, A. A (The American Astronomical Society, 2008-06-20)
    We consider recent observations of the chromospheric network and argue that the bright network grains observed in the Ca ii H and K lines are heated by an as-yet-unidentified quasi-steady process. We propose that the heating ...
  • Dynamics of the Solar Magnetic Network: Two-dimensional MHD Simulations 
    Hasan, S. S; van Ballegooijen, A. A; Kalkofen, W; Steiner, O (The American Astronomical Society, 2005-10)
    The aim of this work is to identify the physical processes that occur in the network and contribute to its dynamics and heating. We model the network as consisting of individual flux tubes, each with a nonpotential field ...
  • E2-transition probabilities for NiXVIII 
    Ray, H (Kluwer Academic Publishers, 2003-02)
    Accurate theoretical data for the transition probabilities are highly demanding in astrophysics and in the study of plasma in astrophysical objects and fusion devices. Na-like highly stripped ions of iron group, specially ...
  • Early Holocene climate recorded in geomorphological features in Western Tibet 
    Brown, E. T; Bendick, R; Bourles, D. L; Gaur, V. K; Molnar, P; Raisbeck, G. M (Elsevier Science BV, 2003-10)
    Cosmic ray exposure ages for formation of perched alluvial terraces and for abundant of an alluvial/debrisflow fan on opposite slides of the Tangtse Valley (The out flow at the northwest end of lake panggong, which is in ...
  • Early mass-varying neutrino dark energy: nugget formation and Hubble anomaly 
    Gogoi, Antareep; Sharma, Ravi Kumar; Chanda, Prolay; Das, Subinoy (IOP Publishing, 2021-07-10)
    We present a novel scenario in which light (~few eV) dark fermions (sterile neutrinos) interact with a scalar field as in mass-varying neutrino dark energy theories. As the eV sterile states naturally become nonrelativistic ...
  • Early Nebular Stage of Nova Cygni, 1975 
    Prabhu, T. P (Indian Institue of Astrophysics, Bangalore, 1977)
    The emission line profiles of the spectrum of the spectrum of the envelope of Nova V 1500 Cyg, 1975 are studied. The spectral region covers LamdaLamda 3700-8800. The velocity structure of the profiles and the time variation ...
  • Early Observations of the Afterglow of GRB 000301c 
    Bhargavi, S. G; Cowsik, R (The American Astronomical Society, 2000-12)
    We report multiband observations of the optical transient associated with GRB 000301c carried out 2000 March 2-4 using the 2.34 m Vainu Bappu Telescope at Kavalur, India. When combined with other reported data, the initial ...
  • Early optical and millimeter observations of GRB 030226 afterglow 
    Pandey, S. B; Sagar, R; Anupama, G. C; Bhattacharya, D; Sahu, D. K; Castro-Tirado, A. J; Bremer, M (EDP Sciences, 2004-04)
    The CCD magnitudes in Johnson UBV and Cousins RI photometric passbands for the afterglow of the long duration GRB 030226 are presented. Upper limits of a few mJy to millimeter wave emission at the location of optical are ...
  • Early pioneers of telescopic astronomy in India: G.V.Juggarow and his Observatory 
    Kameswara Rao, N; Vagiswari, A; Birdie, C (Indian Academy of Sciences, 2011-05-25)
    G.V.Juggarow was one of the early pioneers of observational astronomy in India who built his own observatory in 1840 at Vizagapatam (Vizagapatnam). His legacy was continued by his son-in-law A.V.Nursing Row till 1892, his ...
  • Early time optical spectroscopy of supernova SN 1998S 
    Anupama, G. C; Sivarani, T; Pandey, G (EDP Sciences, 2001-02)
    We present medium-resolution optical spectra of the type II supernova SN 1998S obtained during the pre-maximum, maximum and early decline phases. The early decline spectra show complex Balmer line profiles: a narrow P-Cygni ...
  • Earth's equatorial ionosphere and the heliospheric current sheet 
    Sastri, J. H (D. Reidel Publishing Company, 1986-05)
    Evidence is presented to show that during epochs of high sunspot activity, the duration of manifestation of equatorial spread-F (ESF) irregularities in the Earth's equatorial ionosphere undergoes a systematic modulation ...
  • Earthquakes:Himalayan Seismic Hazard 
    Bilham, R; Gaur, V. K; Molnar, P (American Association for the Advancement of Science, 2001-08)
    The devastating earthquake in Bhuj on 26 January 2001 highlighted the high earthquake risk in the Indian region of Gujarat. In their Perspective, Bilham et al. warn that major earthquakes may be expected in another part ...
  • The eccentric double-lined binary BD - 1 deg 1004 
    Kameswara Rao, N; Ashoka, B. N; Lloyd, C; Pike, C. D; Stickland, D. J (Indian Academy of Sciences, 1990-12)
    A new radial velocity study has been made of the highly eccentric, early-type binary BD - 1 deg 1004 using spectra from the Kavalur Observatory. All available archival material has also been reexamined. An attempt has been ...
  • Eccentric equatorial trajectories around a Kerr black hole asa QPO model for M82X-1 
    Prerna Rana; Mangalam, A (World Scientific Publishing, 2022)
    We study the bound orbit conditions for equatorial and eccentric orbits around a Kerrblack hole both in the parameter space (E,L,a) representing the energy, angular mo-mentum of the test particle, and spin of the black ...
  • Eclipse Observations of Compact Sources in the Outer Solar Corona 
    Ramesh, R; Subramanian, K. R; Sastry, Ch. V (Kluwer Academic Publishers, 1999-03)
    We report here on high angular resolution observations of solar noise storm sources at a frequency of 75MHz. The data for the study were obtained at the Gauribidanur Radio Observatory (long.: 77 deg26'12''E, lat.: 13 ...
  • Eclipse observations of coronal emission lines. I.[FeX]6374 A profiles at the eclipse of 16 February 1980 
    Singh, J; Bappu, M. K. V; Saxena, A. K (Indian Academy of Sciences, 1982-09)
    Coronal spectra during the total solar eclipse of February 16, 1980, obtained in the 6374 A (forbidden Fe X) line using a multislit spectrograph are discussed. The dispersion of these spectra is 2.5 A/mm. The observed line ...

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