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Browsing IIAP Publications by Title

Browsing IIAP Publications by Title

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  • Stellar contents of two young open clusters: NGC 663 and 654 
    Pandey, A. K; Upadhyay, K; Ogura, K; Sagar, R; Mohan, V; Mito, H; Bhatt, H. C; Bhatt, B. C (Royal Astronomical Society, 2005-04)
    UBVRI CCD photometry in a wide field around two young open clusters, NGC 663 and 654, has been carried out. Hα and polarimetric observations for the cluster NGC 654 have also been obtained. We use the photometric data to ...
  • Stellar Disruption by Supermassive Black Holes and the Quasar Radio Loudness Dichotomy 
    Gopal-Krishna; Mangalam, A; Wiita, P. J (The American Astronomical Society, 2008-06-10)
    The origin of the dichotomy of radio loudness among quasars can be explained using recent findings that the mass of the central supermassive black hole (SMBH) in extended radio-loud quasars is systematically a few times ...
  • A stellar endgame - the born-again Sakurai's object 
    Asplund, M; Gustafsson, B; Lambert, D. L; Kameswara Rao, N (European Southern Observatory, 1997-05)
    The surface chemical composition of this remarkable star shows that it is hydrogen-deficient, carbon-rich and enriched in the light s-process elements. Spectra taken in May and October 1996 indicate a decrease in the surface ...
  • Stellar libraries as used in ISM modelling 
    Murthy, J (Astronomical Society of India, 2012)
    I present the use of stellar libraries in interstellar medium work. Stars are used as background sources against which interstellar absorption lines are observed and their modeling is necessary in order to set the baseline ...
  • The stellar parametrization using Artificial Neural Network 
    Giridhar, S; Goswami, A; Kunder, A; Muneer, S; Selvakumar, G (Astronomical Society of India, 2012)
    An update on recent methods for automated stellar parametrization is given. We present preliminary results of the ongoing program for rapid parametrization of field stars using medium resolution spectra obtained using Vainu ...
  • Stellar populations in the magellanic clouds 
    Subramanian, S; Subramaniam, A (Astronomical Society of India, 2013)
    The structural parameters of the Large Magellanic Cloud and the Small Magellanic Cloud are derived from the study of di erent stellar populations, such as, Cepheids (age 100 Myr), Red Clump stars (age 2-9 Gyr) and RR ...
  • Stellar Relics from the Early Galaxy 
    Sivarani, T (Indian Academy of Sciences, 2013-03)
    We reviewed the recent progress in the field of stellar/galactic archeology, which is a study of the relics from the early galaxy. The oldest and most pristine objects that can be observed in the galaxy are the low mass ...
  • Stellar rotation on the zero age main sequence 
    Rajamohan, R (Royal Astronomical Society, 1978-09)
    Analysis of rotational velocities of unevolved members in clusters indicates that for a given mass the dispersion in the true rotational velocities is small for normal, single main-sequence stars. The envelope of highest ...
  • Stellar streams in the Galactic thick disk: preliminary results 
    Ramya, P; Reddy, B. E (Astronomical Society of India, 2012)
    Here we report preliminary results of our study of chemical tagging of member stars of two Galactic stellar streams. Both the streams, kinematically belong to the thick disk component of the Galaxy. We analysed high ...
  • Stellar substructures in the periphery of the Magellanic Clouds with the VISTA hemisphere survey from the red clump and other tracers 
    El Youssouf, Dalal; Cioni, Maria-Rosa L; Bell, C. P. M; de Grijs, Richard; Groenewegen, M. A. T; Ivanov, Valentin D; Matijevic, Gal; Niederhofer, Florian; Oliveira, Joana M; Ripepi, Vincenzo; Schmidt, Thomas; Subramanian, S; Sun, Ning-Chen; van Loon, Jacco Th (Oxford University Press on behalf of the Royal Astronomical Society, 2021-08)
    We study the morphology of the stellar periphery of the Magellanic Clouds in search of substructure using near-infrared imaging data from the Visible and Infrared Survey Telescope for Astronomy Hemisphere Survey. Based on ...
  • Stellar Winds in O and B Type Stars: Hydrogen Atmosphere 
    Peraiah, A; Varghese, B. A (Indian Institute of Astrophysics, Bangalore, 1993)
    We present the results of calculations of radiation driven stellar winds O-B stars. The equations of conservation of mass and momentum are solved self consistently with the equation of line transfer. The influence of ...
  • Stellar yields and Galactic chemical evolution 
    Goswami, A (Astronomical Society of India, 2011)
    The chemical composition of stars belonging to the halo and the disk of our Galaxy as well as a few nearby galaxies are the primary sources of our understanding of the Galactic Chemical Evolution (GCE). The abundance trends ...
  • Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. 6: Variability of NGC 3783 from ground-based data 
    Stirpe, G. M; Winge, C; Altieri, B; Alloin, D; Aguero, E. L; Anupama, G. C; Ashley, R; Bertram, R; Calderon, J. H; Catchpole, R. M; Corradi, R. L. M; Covino, E; Dottori, H. A; Feast, M. W; Ghosh, K. K; Hutton, R. Gil; Glass, I. S; Grebel, E. K; Jorda, L; Koen, C; Laney, C. D; Maia, M; Marang, F; Mayya, Y. D; Morrell, N; Nakada, Y; Pastoriza, M. G; Pati, A. K; Pelat, D; Peterson, B. M; Prabhu, T. P; Roberts, G; Sagar, R; Salamanca, I; Sekiguchi, K; Storchi-Bergmann, T; Subramaniam, A; Van Winckel, H; Van Wyk, F; Villada, M; Wagner, R. M; Whitelock, P. A; Winkler, H; Clavel, J; Dietrich, M; Kollatschny, W; O'Brien, P. T; Perola, G. C; Recondo-Gonzalez, M. C; Rodriguez-Pascual, P; Santos-Lleo, M (The American Astronomical Society, 1994-04)
    The Seyfert 1 galaxy NGC 3783 was intensely monitored in several bands between 1991 December and 1992 August. This paper presents the results from the ground-based observations in the optical and near-IR bands, which ...
  • Steps toward Determination of the Size and Structure of the Broad-Line Region in Active Galactic Nuclei. X. Variability of Fairall 9 from Optical Data 
    Santos-Lleo, M; Chatzichristou, E; de Oliveira, C. M; Winge, C; Alloin, D; Peterson, B. M; Rodriguez-Pascual, P. M; Stirpe, G. M; Beers, T; Bragaglia, A; Claeskens, J. F; Federspiel, M; Giannuzzo, E; Gregorio-Hetem, J; Mathys, G; Salamanca, I; Stein, P; Stenholm, B; Wilhelm, R; Zanin, C; Albrecht, P; Calderon, J; Caretta, C. A; Carranza, G; da Costa, R. D. D; Diaz, R; Dietrich, M; Dottori, H; Elizalde, F; Goldes, G; Ghosh, K. K; Maia, M. A. G; Paolantonio, S; de Oliveira Filho, R. I; Rodriguez-Ardila, A; Schmitt, H. R; Soundararajaperumal, S; de Souza, R. E; Willmer, C. N. A; Zheng, W (American Astronomical Society, 1997-10)
    The results of an optical monitoring campaign on the active nucleus in the luminous Seyfert 1 galaxy Fairall 9 are presented. This campaign was undertaken in parallel with ultraviolet spectroscopic monitoring with the IUE ...
  • Steps toward Determination of the Size and Structure of the Broad-Line Region in Active Galactic Nuclei. XII. Ground-based Monitoring of 3C 390.3 
    Dietrich, M; Peterson, B. M; Albrecht, P; Altmann, M; Barth, A. J; Bennie, P. J; Bertram, R.; Bochkarev, N. G; Bock, H; Braun, J. M; Burenkov, A; Collier, S; Fang, L. Z; Francis, O. P; Filippenko, A. V; Foltz, C. B; Gaessler, W; Gaskell, C. M; Geffert, M; Ghosh, K. K; Hilditch, R. W; Honeycutt, R. K; Horne, K; Huchra, J. P; Kaspi, S; Kuemmel, M; Leighly, K. M; Leonard, D. C; Malkov, Yu. F; Mikhailov, V; Miller, H. R; Morrill, A. C; Noble, J; O'Brien, P. T; Oswalt, T. D; Pebley, S. P; Pfeiffer, M; Pronik, V. I; Qian, B. C; Robertson, J. W; Robinson, A.; Rumstay, K. S; Schmoll, J; Sergeev, S. G; Sergeeva, E. A; Shapovalova, A. I; Skillman, D. R; Snedden, S. A; Soundararajaperumal, S; Stirpe, G. M; Tao, J; Turner, G. W; Wagner, R. M; Wagner, S. J; Wei, J. Y; Wu, H.; Zheng, W; Zou, Z. L (The American Astronomical Society, 1998-04)
    Results of a ground-based optical monitoring campaign on 3C 390.3 in 1994-1995 are presented. The broadband fluxes (B, V, R, and I), the spectrophotometric optical continuum flux F lambda (5177 A), and the integrated ...
  • Stigmatic mounting of holographic plane grating 
    Singh, M (Tipografia Baccini and Chiappi, 1977-10)
    A Stigmatic mounting of holographic plane has been proposed and its properties have been studied theoretically. In this mounting the observation is to be made about a normal direction and different regions of the spectrum ...
  • Stimulated raman scattering in active galactic nuclei 
    Krishan, V; Wiita, P. J (International Astronomical Union, 1986)
    Stimulated Raman Scattering (SRS) processes offer an attractive and efficient method for producing both essentially the entire non-thermal continuum as well as fast electrons in active galactic nuclei (AGN). In this picture, ...
  • Stimulated Raman scattering of water maser lines in astrophysical plasmas 
    Gangadhara, R. T; Deguchi, S; Lesch, H (American Institute of Physics, 1999-10)
    Radiative transfer equations are derived and solved for the stimulated Raman scattering of water maser lines in the astrophysical plasmas with electrons density of about 106 - 107cm-3. In stimulated Raman scattering, the ...
  • Stochastic modeling of multiwavelength variability of the classical BL Lac Object OJ 287 on timescales ranging from decades to hours 
    Goyal, A; Stawarz, L; Zola, S; Marchenko, V; Soida, M; Nilsson, K; Ciprini, S; Baran, A; Ostrowski, M; Wiita, P. J; Gopal-Krishna; iemiginowska, A; Sobolewska, M; Jorstad, S; Marscher, A; Aller, M. F; Aller, H. D; Hovatta, T; Caton, D. B; Reichart, D; Matsumoto, K; Sadakane, K; Gazeas, K; Kidger, M; Piirola, V; Jermak, H; Alicavus, F; Baliyan, K. S; Baransky, A; Berdyugin, A; Blay, P; Boumis, P; Boyd, D; Bufan, Y; Campas Torrent, M; Campos, F; Carrillo Gomez, J; Dalessio, J; Debski, B; Dimitrov, D; Drozdz, M; Er, H; Erdem, A; Escartin Perez, A; Fallah Ramazani, V; Filippenko, A. V; Gafton, E; Garcia, F; Godunova, V; Gomez Pinilla, F; Maheswar, G; Haislip, J. B; Haque, S; Harmanen, J; Hudec, R; Hurst, G; Ivarsen, K. M; Joshi, A; Kagitani, M; Karaman, N; Karjalainen, R; Kaur, N; Koziel-Wierzbowska, D; Kuligowska, E; Kundera, T; Kurowski, S; Kvammen, A; LaCluyze, A. P; Lee, B. C; Liakos, A; Lozano de Haro, J; Moore, J. P; Mugrauer, M; Naves Nogues, R; Neely, A. W; Ogloza, W; Okano, S; Pajdosz, U; Pandey, J. C; Perri, M; Poyner, G; Provencal, J; Pursimo, T; Raj, A; and 29 co-authors (IOP Publishing, 2018-08-20)
    We present the results of our power spectral density analysis for the BL Lac object OJ 287, utilizing the Fermi-LAT survey at high-energy γ-rays, Swift-XRT in X-rays, several ground-based telescopes and the Kepler satellite ...
  • Stochastic polarized line formation. I. Zeeman propagation matrix in a random magnetic field 
    Frisch, H; Sampoorna, M; Nagendra, K. N (The European Southern Observatory, 2005-10)
    This paper considers the effect of a random magnetic field on Zeeman line transfer, assuming that the scales of fluctuations of the random field are much smaller than photon mean free paths associated to the line formation ...

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