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Browsing IIAP Publications by Subject "Accretion Disks"

Browsing IIAP Publications by Subject "Accretion Disks"

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  • Correlated X-ray timing and spectral behavior in GX 349+2 
    Agrawal, V. K; Bhattacharyya, S (The European Southern Observatory, 2003-01)
    We present a detailed and systematic investigation of correlated spectral and timing properties of the Z source GX 349+2, using extensive data ( ~ 221 ks) obtained from the Proportional-Counter-Array on-board RXTE satellite, ...
  • Discovery of a flare star near Sirius 
    Sharma, D. P; Marar, T. M. K; Seetha, S; Shyla, K. S; Kasturirangan, K; Rao, U. R; Bhattacharyya, J. C; Rozario, M. J (D. Reidel Publishing Co., 1983-04)
    The discovery of a flare star (R.A. (1950)=6/Suph43/Supm6/Sups.07, Decl.(1950)=–16°45'24") located about 6 arc min south of Sirius is reported. During photometric observations on the night of 13 January, 1982, using the ...
  • Formation of a proto-quasar from accretion flows in a halo 
    Mangalam, A (E D P Sciences, 2001-12)
    We present a detailed model for the formation of massive objects at the centers of galaxies. The effects of supernovae heating and the conditions of gas loss are revisited. The escape time of the gas is compared with the ...
  • High speed photometry of PG 1012-029 
    Ashoka, B. N; Seetha, S; Marar, T. M. K; Kasturirangan, K; Rao, U. R; Bhattacharyya, J. C (European Southern Observatory, 1994-03)
    High speed optical photometric observations of PG 1012 - 029, conducted during 1990-1991, confirm the nova-like classification of the object. Several eclipses observed by us have been used to refine the orbital period of ...
  • Hybrid viscosity and magnetoviscous instability in hot, collisionless accretion disks 
    Subramanian, P; Becker, P. A; Kafatos, M. (Springer Netherlands, 2008)
    We aim to illustrate the role of hot protons in enhancing the magnetorotational instability (MRI) via the “hybrid” viscosity, which is due to the redirection of protons interacting with static magnetic field perturbations, ...
  • Limits to the Mass and the Radius of the Compact Star in SAX J1808.4-3658 and Their Implications 
    Bhattacharyya, S (American Astronomical Society, 2001-06)
    We show that a survey of equations of state and observations of X-ray pulsations from SAX J1808.4-3658 give 2.27 Msolar as the upper limit of the compact star mass. The corresponding upper limit of the radius comes out to ...
  • Magnetorotational instability in accretion disks 
    Krishan, V; Mahajan, S. M (Springer Netherlands, 2008)
    Accretion disks are a basic and an ubiquitous construct of nature. We describe their formation, briefly and qualitatively, in diverse astrophysical situations. These systems, though controlled by the gravitational forces, ...
  • Microflares in accretion disks 
    Krishan, V; Ramadurai, S; Wiita, P. J (The European Southern Observatory, 2003-02)
    We have investigated the phenomenon of explosive chromospheric evaporation from an accretion disk as a mechanism for fast variability in accreting sources such as low mass X-ray binaries and active galactic nuclei. This ...
  • On the hypothesis of ejection of supermassive black holes from centers of galaxies and its application to quasar-galaxy associations 
    Kapoor, R. C (D. Reidel Publishing Co., 1983-06)
    It is argued that accreting supermassive black holes ejected from centers of galaxies are the likely models for the quasars observed in association with galaxies. Also pointed out are the implications of a recent suggestion ...
  • On the slow-down of the millisecond pulsar PSR 1937 + 214 
    Sivaram, C; Kochhar, R. K (Springer, 1984-01)
    There are indications that less than 10/sup-3 of the spin-down energy of the millisecond pulsar PSR 1937+214 emerges as electromagnetic radiation. The implications of this result are discussed. The surface magnetic field ...
  • Possible signatures for strange stars in stellar X-ray binaries 
    Datta, B; Thampan, A. V; Bombaci, I (European Southern Observatory, 2000-03)
    Kilohertz quasi-periodic brightness oscillations (kHz QPOs) observed in certain X-ray burst sources may represent Keplerian frequencies in the inner regions of the accretion disk in such systems. If this assumption is ...
  • Some implications of escape of supermassive black holes from galactic nuclei due to plasmoid ejection 
    Kapoor, R. C (D. Reidel Publishing Co., 1983-09)
    Shklovsky (1982) has hypothesized escape of accreting supermassive black holes from galactic nuclei as a consequence of asymmetric ejection of plasma clouds from their accretion disks and their subsequent defunction for ...
  • Temperature Profiles of Accretion Disks around Rapidly Rotating Neutron Stars in General Relativity and the Implications for Cygnus X-2 
    Bhattacharyya, S; Thampan, A. V; Misra, R; Datta, B (The American Astronomical Society, 2000-10)
    We calculate the temperature profiles of (thin) accretion disks around rapidly rotating neutron stars (with low surface magnetic fields), taking into account the full effects of general relativity. We then consider a model ...

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