IIA Institutional Repository: Recent submissions

  • On the triggering of a spotless double-ribbon flare 
    Rausaria, R. R; Aleem, S. M; Sundararaman, K (Springer Netherlands, 1992-11)
    We have studied the evolution of the double-ribbon, spotless flare of 21 February, 1992, using Kodaikanal Hagr and Kf1 observations. The analysis of the data shows that the Hagr filament underwent a large change in shear ...
  • First X-ray spectrum of the most luminous quasar PKS 2126 - 158 
    Ghosh, K. K; Soundararajaperumal, S (EDP Sciences, 1992-11)
    For the first time the detailed results of the spectral analysis of the X-ray (0.1 - 10 keV) spectrum of the luminous radio-loud quasar PKS 2126 - 158 are presented. Power law and fixed absorption model fits well with the ...
  • Wind induced instabilities in accretion flow around black holes 
    Acharya, K; Chakrabarti, S. K; Molteni, D (Astronomical Society of India, 2002)
    We identify a new type of instability of the accrelation flow which is formed due to interaction of the outgoing winds with the incoming flow. Mainly due to shear instability, the flow oscillates around the equatorial ...
  • Shocks in winds from accretion discs and the formation of high energy particles 
    Chattopadhyay, I; Chakrabarti, S. K (Astronomical Society of India, 2002)
    We study effects of radiation momentum deposition on jets and outflows from the disks and show that if disks are perturbed, jets could have propagating shock waves which may accelerate particles to observed slopes.
  • Possible young stellar objects in the region of the Cygnus OB2 (VI Cygni) association from IRAS observations 
    Parthasarathy, M; Jain, S. K; Bhatt, H. C (EDP Sciences, 1992-12)
    Several massive young stellar objects are found from an analysis of the 12- to 100-micron flux data of IRAS sources in the region of the Cyg OB2 association. Sixty-four sources with positive spectral indices and steeply ...
  • Pressure structure of solar coronal loops. III 
    Sreedharan, T. D; Sasidharan, K; Satya Narayanan, A; Krishan, V (Springer Netherlands, 1992-12)
    The theory of ideal magnetohydrodynamic turbulence in cylindrical geometry is used to study the steady-state structure of a coronal loop. The pressure profile is derived from MHD equations by representing the velocity and ...
  • High Resolution Spectroscopy of the Semi-Regular Variable LR Sco 
    Giridhar, S; Kameswara Rao, N; Lambert, D. L (Indian Academy of Sciences, 1992)
    A detailed spectroscopic investigation of LR Sco which was earlier misclassified as R CrB star is made. Atmospheric parameters and elemental abundances are determined using detailed depth-dependent model atmospheres and ...
  • VRI Photometry of M67 for CCD Standardization at 2.3m VBT 
    Bhat, P. N; Singh, K. P; Prabhu, T. P; Kembhavi, A. K (Indian Academy of Sciences, 1992)
    We present the results from CCD photometry in the V, R and I bands, of the ‘Dipper Asterism’ region of the open cluster Μ67 based on observations carried out at the prime focus of the 2.3 m Vainu Bappu Telescope of the ...
  • Astronomical gamma-ray lines predicting probable gamma-emitter nucleosynthesis sites as explosive events 
    Bardoloi, I; Barua, M. M (Astronomical Society of India, 2002)
    Astronomical gamma-ray (?) lines with energy 0.5 - 15 MeV have been interpreted as due to e+ - e- annihilation and decay and de-excitation of the excited nucleosynthesis yields produced in some explosive sites and then ...
  • Variability study of Mrk-421 in near IR bands from Mt. Abu observatory 
    Joshi, U. C; Baliyan, K. S; Ganesh, S (Astronomical Society of India, 2002)
    Mrk421 is the nearest, and brightest blazar detected in almost all the spectral windows, including high energy gamma-rays. It exhibits short and long timescale variations at all frequency bands. Though it has been observed ...
  • X-ray Spectroscopy of the HMXB Pulsar GX 301-2 with Chandra 
    Mukherjee, U; Paul, B (Astronomical Society of India, 2003)
    We present analysis of X-ray spectra of the accreting pulsar GX 301-2, from two observations with the Chandra X-ray observatory made during different phases of its orbital period. Analysis of the zeroth order ACIS spectra ...
  • Observations of Mkn 421 with TACTIC 
    Kaul, R. K; Bhat, C. L (Astronomical Society of India, 2002)
    The TACTIC imaging element has observed the extragalactic BL Lac object Mkn 421 for ~ 78h during Jan. - April 2001. Analysis of the overall data set, using the dynamic supercuts methodology, has revealed the presence of a ...
  • 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.
  • Of Neutrinos and Magnetars 
    Konar, S (Astronomical Society of India, 2003)
  • Observations of Markarian 421 by the CAT imaging telescope 
    Fleury, P (Astronomical Society of India, 2002)
    The CAT imaging telescope has been exploited since 1997 for the observation of Mrk-421 among other sources. After a brief review of the characteristics of the CAT telescope, the event reconstruction method will be described. ...
  • TeV Gamma-ray flares from Mkn 421 detected by the pachmarhi array of Cverenkov Telescopes 
    Bhat, P. N; Acharya, B. S; Chitnis, V. R; Majumdar, P; Rahman, M. A; Singh, B. B; Vishwanath, P. R (Astronomical Society of India, 2002)
    Pachmarhi Array of Cverenkov Telescopes (PACT), based on wavefront sampling technique, has been used for detecting TeV gamma rays from galactic and extra-galactic ?-ray sources. The Blaar, Mkn 421 was one such extra-galactic ...
  • Observations of Mrk 421 with the CELESTE Heliostat array 
    Le Gallou, R; Smith, D. A (Astronomical Society of India, 2002)
    Since CELESTE first began routine observations in November 1999 in the 50 GeV range Mrk 421 has been a prime target. Here we report the preliminary average integral flux measurement obtained with 31.5 hours of ON-source ...
  • The Magnetar Fields 
    Konar, S (Astronomical Society of India, 2003)
    We discuss the nature of evolution of the magnetic field in magnetars
  • Introduction to Markarian 421 special session 
    Fleury, P (Astronomical Society of India, 2002)
  • Radio Emission by Particles Accelerated in Pulsar Magnetosphere 
    Thomas, R. M. C; Gangadhara, R. T (Astronomical Society of India, 2003)
    We present a relativistic model of pulsar radio emission by plasma accelerated along the rotating magnetic field lines projected on to a 2D plane perpendicular to the rotation axis. We have derived the expression for the ...

Search DSpace

Browse

My Account