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Browsing IIAP Publications by Title

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  • The X-ray spectrum of the superluminal quasar 1928 + 73 
    Ghosh, K. K; Soundararajaperumal, S (Blackwell Publishing, 1992-02)
    Exosat observations (0.1-10 keV) of the radio-loud quasar 1928 + 73, which displays superluminal motion, were made at four epochs between 1983/283 and 1984/009, and spectra of this source are obtained from the Exosat ...
  • X-ray variability and the inner region in active galactic nuclei 
    Mohan, Prashanth; Mangalam, A (IOP Publishing, 2014-08-20)
    We present theoretical models of X-ray variability attributable to orbital signatures from an accretion disk including emission region size, quasi-periodic oscillations (QPOs), and its quality factor Q, and the emergence ...
  • X-Ray variability of active galactic nuclei in the soft and hard X-Ray bands 
    Chitnis, V. R; Pendharkar, J. K; Bose, D; Agrawal, V. K; Rao, A. R; Misra, R (Institute of Physics, 2009-06)
    We investigate the X-ray variability characteristics of hard X-ray-selected active galactic nuclei (AGNs)—based on Swift/Burst Alert Telescope—in the soft X-ray band using the Rossi X-ray Timing Explorer/All-Sky Monitor ...
  • X-shaped Radio Galaxies: Optical Properties, Large-scale Environment, and Relationship to Radio Structure 
    Joshi, Ravi; Gopal Krishna; Yang, Xiaolong; Shi, Jingjing; Yu, Si-Yue; Wiita; Paul J.; Ho, Luis C.; Wu, Xue-Bing; An, Tao; Wang, Ran; Subramanian, S; Yesuf, Hassen (IOP Publishing, 2019-12)
    In pursuit of clues to the origin of “ winged ” or X-shaped radio galaxies ( XRGs ) we investigate the parent galaxies of a large sample of 106 XRGs for optical – radio axes alignment, interstellar medium, black ...
  • The X-shaped Radio Galaxy J0725+5835 is Associated with an AGN Pair 
    Yang, Xiaolong; Ji, Jialu; Joshi, Ravi; Yang, Jun; An, Tao; Wang, Ran; Ho, Luis C; Roberts, David H; Saripalli, Lakshmi (IOP Publishing, 2022-07-01)
    X-shaped radio galaxies (XRGs) are those that exhibit two pairs of unaligned radio lobes (main radio lobes and wings). One of the promising models for the peculiar morphology is jet reorientation. To clarify this, we ...
  • The XMM-SERVS Survey: XMM-Newton point-source catalogs for the W-CDF-S and ELAIS-S1 fields 
    Ni, Qingling; Brand, W. N; Chen, Chien-Ting; Luo, Bin; Nyland, Kristina; Yang, Guang; Zou, Fan; Aird, James; Alexander, David M; Bauer, Franz Erik; Lacy, Mark; Lehmer, Bret D; Mallick, Labani; Salvato, Mara; Schneider, Donald P; Tozzi, Paolo; Traulsen, Iris; Vaccari, Mattia; Vignali, Cristian; Vito, Fabio; Xue, Yongquan; Banerji, Manda; Chow, Kate; Comastri, Andrea; Del Moro, Agnese; Gilli, Roberto; Mullaney, James; Paolillo, Maurizio; Schwope, Axel; Shemmer, Ohad; Sun, Mouyuan; Timlin III, John D; Trump, Jonathan R (IOP Publishing, 2021-09)
    We present the X-ray point-source catalogs in two of the XMM-Spitzer Extragalactic Representative Volume Survey (XMM-SERVS) fields, W-CDF-S (4.6 deg2) and ELAIS-S1 (3.2 deg2), aiming to fill the gap between deep pencil-beam ...
  • XX Cam -The Inactive R CrB Star 
    Kameswara Rao, N; Ashok, N. M; Kulkarni, P. V (Indian Academy of Sciences, 1980-09)
    Infrared observations obtained six years apart of the R CrB type star XX Cam do not show any infrared excess, unlike all other members of the class. The observed colours match a 7000 K black body energy distribution quite ...
  • Yields of nucleosynthesis from massive and intermediate mass stars and constraints on their final evolution 
    Mallik, D. C. V; Mallik, S. G. V (Indian Academy of Sciences, 1985-09)
    Nucleosynthetic yields and production rates of He and heavy elements are derived using recent revisions in O star counts and the stellar models of Maeder (1981). The current production rates and yields are significantly ...
  • Young LMC star clusters as a test for stellar evolutionary models. 
    Subramaniam, A; Sagar, R (The European Southern Observatory, 1995-05)
    We compare the observed colour-magnitude diagrams (CMD) and the main sequence luminosity functions (LFs) of four Large Magellanic Cloud (LMC) star clusters namely, NGC 1711, NGC 2004, NGC 2164 and NGC 2214 with the synthetic ...
  • The Young Open Star Clusters: Stability and Structure 
    Pandey, A. K; Mahra, H. S; Sagar, R (American Astronomical Society, 1990-02)
    It is found to the differential extinction ΔE (B-V) in open clusters which may be due to the presence of gas and dust, decreases systematically with age of the cluster. Consequently we can infer that the average gas removal ...
  • Young star clusters of our galaxy and the large magellanic cloud as test for stellar evolutionary models 
    Sagar, R; Subramaniam, A (Universidad Nacional Autonoma de Mexico, 1999)
    A comparison of the colour-magnitude diagrams (CMDs) and the main sequence luminosity function (LF) of five young Galactic star clusters and four young Large Magellanic Cloud star clusters derived from precise CCD observations ...
  • Young Stars and Nonstellar Emission in the Aligned Radio Galaxy 3C 256 
    Simpson, C; Eisenhardt, P; Armus, L; Chokshi, A; Dickinson, M; Djorgovski, S. G; Elston, R; Jannuzi, B. T; McCarthy, P. J; Pahre, M. A; Soifer, B. T (The American Astronomical Society, 1999-11)
    We present ground-based images of the z=1.824 radio galaxy 3C 256 in the standard BVRIJHK filters and an interference filter centered at 8800 Å, a Hubble Space Telescope image in a filter dominated by Lyα emission (F336W), ...
  • Young stellar objects and their environment 
    Choudhury, R (Astronomical Society of India, 2012)
    This paper presents the results of a Ph.D thesis emphasizing the studies of various characteristics of Young Stellar Objects (YSOs) and their environment. The main objective of the thesis is to study the effects of mechanical ...
  • Young stellar population and ongoing star formation in the H ii complex Sh2-252 
    Jose, J; Pandey, A. K; Samal, M. R; Ojha, D. K; Ogura, K; Kim, J. S; Kobayashi, N; Goyal, A; Chauhan, N; Eswaraiah, C (Oxford University Press on behalf of the Royal Astronomical Society, 2013-07-11)
    In this paper, an extensive survey of the star-forming complex Sh2-252 has been undertaken with an aim to explore its hidden young stellar population as well as to understand the structure and star formation history for ...
  • Young stellar population in the star-forming complex Sh2-252 
    Jose, J; Pandey, A. K; Ogura, K; Bhatt, B. C (Astronomical Society of India, 2012)
    We present the preliminary results of our multi-wavelength analyses of the young stellar population associated with the star forming complex Sh2-252. The NIR and MIR data sets from 2MASS and Spitzer-IRAC, MIPS identified ...
  • Young stellar population of bright-rimmed clouds BRC 5, BRC 7 and BRC 39 
    Panwar, N; Chen, W. P; Pandey, A. K; Samal, M. R; Ogura, K; Ojha, D. K; Jose, J; Bhatt, B. C (Oxford University Press on behalf of the Royal Astronomical Society, 2014-09-11)
    Bright-rimmed clouds (BRCs), illuminated and shaped by nearby OB stars, are potential sites of recent/ongoing star formation. Here we present an optical and infrared photometric study of three BRCs: BRC 5, BRC 7 and BRC ...
  • Zeeman line formation in solar magnetic fields. Studies with empirical probability distribution functions 
    Sampoorna, M; Nagendra, K. N; Frisch, H; Stenflo, J. O (EDP Sciences, 2008-07)
    Context. Numerical simulations of magneto-convection and analysis of solar magnetograms provide probability distribution functions (PDFs) for the magnetic field strength. Aims. In the paper, we explore the effects of these ...
  • The zenithal 4-m International Liquid Mirror Telescope: a unique facility for supernova studies 
    Brajesh Kumar; Pandey, Kanhaiya L; Pandey, S. B; Hickson, P; Borra, E. F; Anupama, G. C; Surdej, J (Oxford University Press on behalf of the Royal Astronomical Society, 2018-05)
    The 4-m International Liquid Mirror Telescope (ILMT) will soon become operational at the newly developed Devasthal observatory near Nainital (Uttarakhand, India). Coupled with a 4k × 4k pixels CCD detector and TDI optical ...
  • Zonal velocity bands and the solar activity cycle 
    Sivaraman, K. R; Antia, H. M; Chitre, S. M; Makarova, V. V (Springer Netherlands, 2008-09)
    We compare the zonal-flow pattern in subsurface layers of the Sun with the distribution of surface magnetic features such as sunspots and polar faculae. We demonstrate that, in the activity belt, the butterfly pattern of ...
  • ɛ Aur in eclipse: Post-AGB primary and disk-shaped secondary 
    Muthumariappan, C; Parthasarathy, M; Jayakumar, K; Appakutty, M (Cambridge University Press, 2012-08)
    We present physical and chemcal properties of the disk in the eclipsing binary system ɛ Aur by solving 2D radiative transfer problem. We also present preliminary results of our high resolution spectroscopic monitoring of ...

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