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Browsing by Subject "Accretion discs"

Browsing by Subject "Accretion discs"

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  • The 1995-96 decline of R Coronae Borealis: high-resolution optical spectroscopy 
    Kameswara Rao, N; Lambert, D. L; Adams, M. T; Doss, D. R; Gonzalez, G; Hatzes, A. P; James, C. R; Johns-Krull, C. M; Luck, R. E; Pandey, G; Reinsch, K; Tomkin, J; Woolf, V. M (The Royal Astronomical Society, 1999-12)
    A set of high-resolution optical spectra of R CrB acquired before, during and after its 1995-96 decline is discussed. All of the components reported from earlier declines are seen. This novel data set provides new information ...
  • Anomalous nature of outbursts of black hole candidate 4U 1630-472 
    Chatterjee, Kaushik; Debnath, Dipak; Bhowmick, Riya; Nath, Sujoy Kumar; Chatterjee, Debjit (Oxford University Press on behalf of Royal Astronomical Society, 2022-02)
    The Galactic black hole candidate (BHC) 4U 1630−472 has gone through several outbursts (13 to be particular) in the last two and a half decades starting from the RXTE era till date. Like the outbursts of other transient ...
  • AstroSat view of GRS 1915+105 during the soft state: detection of HFQPOs and estimation of mass and spin 
    Sreehari, H; Nandi, Anuj; Das, Santabrata; Agrawal, V. K; Mandal, Samir; Ramadevi, M. C; Katoch, Tilak (Oxford University Press on behalf of the Royal Astronomical Society, 2020-12)
    We report the results of AstroSat observations of GRS 1915+105 obtained using 100 ks Guaranteed Time during the soft state. The colour–colour diagram indicates a variability class of δ with the detection of high-frequency ...
  • Discovery of soft and hard X-ray time lags in low-mass AGNs 
    Mallick, L; Wilkins, D. R; Alston, W. N; Markowitz, A; Marco, B. De; Parker, M. L; Lohfink, A. M; Stalin, C. S (Oxford University Press on behalf of the Royal Astronomical Society, 2021-05)
    The scaling relations between the black hole (BH) mass and soft lag properties for both active galactic nuclei (AGNs) and BH X-ray binaries (BHXRBs) suggest the same underlying physical mechanism at work in accreting BH ...
  • The intermediate polar cataclysmic variable GK Persei 120 years after the nova explosion: a first dynamical mass study 
    Alvarez-Hernandez, A; Torre, M. A. P; Rodriguez-Gil, P; Shahbaz, T; Anupama, G. C; Gazeas, K. D; Pavana, M; Raj, A; Hakala, P; Stone, G; Gomez, S; Jonker, P. G; Ren, J.- J; Cannizzaro, G; Pastor-Marazuela, I; Goff, W; Corral-Santana, J. M; Sabo, R (Oxford University Press on behalf of Royal Astronomical Society, 2021-11)
    We present a dynamical study of the intermediate polar and dwarf nova cataclysmic variable GK Persei (Nova Persei 1901) based on a multisite optical spectroscopy and R-band photometry campaign. The radial velocity curve ...
  • Low-frequency quasi-periodic oscillations and shocks in accretion on to black hole 
    Singh, Chandra B; Mondal, Santanu; Garofalo, David (Oxford University Press on behalf of Royal Astronomical Society, 2022-02)
    Low-frequency quasi-periodic oscillations (LFQPOs) have been routinely observed in black hole X-ray binaries (BHXRBs). These LFQPOs can be explained by axisymmetric shock oscillation in accretion flow around a rotating ...
  • A machine learning approach for classification of accretion states of black hole binaries 
    Sreehari, H; Nandi, Anuj (Oxford University Press on behalf of the Royal Astronomical Society, 2021-03)
    In this paper, we employ Machine Learning algorithms on multimission observations for the classification of accretion states of outbursting black hole X-ray binaries for the first time. Archival data from RXTE, Swift, MAXI, ...
  • The Nebular Remnant and Quiescent Spectrum of Nova Gk-Persei 
    Anupama, G. C; Prabhu, T. P (Royal Astronomical Society, 1993-07-15)
    CCD images of the nebular shell of the old nova GK Per in [N II] and [O III] emission lines, and also the quiescent spectrum in the optical region, are presented. Proper motion measurements of the knots in [N II]over the ...
  • SWIFT J0503.7-2819: a nearly synchronous intermediate polar below the period gap? 
    Rawat, Nikita; Pandey, J. C; Joshi, Arti; Scaringi, Simone; Yadava, Umesh (Oxford University Press on behalf of Royal Astronomical Society, 2022-12)
    Based on the X-ray observations from XMM–Newton and Swift, and optical observations from Transiting Exoplanet Survey Satellite (TESS) and AAVSO, we present temporal and spectral properties of probable intermediate polar ...

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