IIA Institutional Repository: Recent submissions

  • Compton Scattering, Pair Annihilation, and Pair Production in a Plasma 
    Krishan, V (International Astronomical Union, 2000)
    The square of the four-momentum of a photon in vacuum is zero. However, in an unmagnetized plasma, it is equal to the square of the plasma frequency. Further, the electron-photon coupling vertex is modified in a plasma to ...
  • Magnetic helicity in galactic dynamos 
    Subramanian, K (Astronomical Society of India, 2002-09)
    Magnetic fields correlated on kiloparsec scales are seen in spiral galaxies. Their origin ~ould be due to amplification of a small seed field by a turbulent galactic dynamo. We review the current status of the galactic dynamo, ...
  • HD 105262: a high latitude metal-poor post-AGB. A supergiant with large proper motion 
    Reddy, B. E; Parthasarathy, M; Sivarani, T (European Southern Observatory, 1996-09)
    The large proper motion post-AGB supergiant stars are very rare. HD 105262 is a high galactic latitude (+72deg) A-type star with large proper motion (0.057arcsec/year) and high c1-index. Earlier, it was classified as a ...
  • Search for Lithium-Rich Stars Among G-K Giants with IR-excess 
    Jasniewicz, G; Parthasarathy, M; de Laverny, P; Thevenin, F; Mauron, N; Chadid, M (International Astronomical Union, 2000)
    We report here new results about a search for Li- rich stars among 52 G-K giant stars which are known to have near IR excess. Eleven giants have been found to have loge (Li)≥ 1.0. Five are new Li-rich stars. We suspect ...
  • Evolution of Lithium Abundance in Pop I Giants 
    Mallik, S. G. V (International Astronomical Union, 2000)
    Recent observations of cool giants have shown that there exists a large range in their lithium abundances even for apparently similar stars. In order to explore whether this large spread could be interpreted in terms of ...
  • Dependence of Supergranular Length-Scales on Network Magnetic Fields 
    Raju, K. P; Singh, J (Springer, 2002-05)
    In an earlier paper by Raju, Srikanth, and Singh (1998), the average size of chromospheric network cells has been shown to have a dependence on the solar latitude. This was presumed to be due to the reduction of supergranular ...
  • Ohmic decay of magnetic flux expelled from neutron star interiors 
    Bhattacharya, D; Datta, B (Royal Astronomical Society, 1996-10)
    We study Ohmic diffusion of magnetic flux expelled from the superconducting core of a neutron star to its crust owing to spindown-induced field evolution. We find that Ohmic decay time-scales in the range 10^7.5-10^9 yr ...
  • Evolutionary connection between C-rich AGB stars and C-rich central stars of PNe 
    Parthasarathy, M (International Astronomical Union, 1999)
    On the basis of C/O ratios the evolutionary connection between C-rich AGB/post-AGB stars and C-rich central stars of PNe is discussed. The proportion of carbon-rich post-AGB stars is comparable to that of carbon-rich PNe. ...
  • The emission-line spectrum of the hot R Coronae Borealis star MV SGR 
    Pandey, G; Kameswara Rao, N; Lambert, D. L (Royal Astronomical Society, 1996-10)
    Spectra of MV Sgr obtained at CTIO in 1992 May show many emission lines in the red. Most of the emission lines show two components with a minimum centred at the stellar velocity. Species represented include H, HeI, TiII ...
  • Integrated photometric characteristics of galactic open star clusters 
    Lata, S; Pandey, A. K; Sagar, R; Mohan, V (E D P Sciences, 2002-06)
    Integrated UBVRI photometric parameters of 140 galactic open clusters have been computed. Integrated I(V-R)0 and I(V-I)0 colours as well as integrated parameters for 71 star clusters have been obtained for the first time. ...
  • Circumstellar disks around Herbig Ae/Be stars: Polarization, outflows and binary orbits 
    Maheswar, G; Manoj, P; Bhatt, H. C (EDP Sciences, 2002-06)
    The geometrical relationship between the distribution of circumstellar matter, observed optical linear polarization, outflows and binary orbital plane in Herbig Ae/Be stars is investigated. Optical linear polarization ...
  • Atmospheres of components of the close binary stars 
    Srinivasa Rao, M (Astronomical Society of India, 2002-09)
    For theoretical modeling of binary systems, one has to consider realistic models which takes into account the radiative transfer, hydrodynamics, and the effect of irradiation from the secondary component on the atmosphere of ...
  • H(alpha) Imaging of the Hickson Compact Group 62 
    Valluri, M; Anupama, G. C (American Astronomical Society, 1996-10)
    We report results of a search for optical emission line gas in the Hickson compact group 62. From narrow band (Hα) imaging observations we estimate 10^4^ M_sun_ of ionized hydrogen gas within the central regions of three ...
  • The electron temperatures of HII regions S 201, S 206 and S 209 : Multi-frequency GMRT observations 
    Omar, A; Chengalur, J. N; Roshi, D. A (Astronomical Society of India, 2002-09)
    Three Galactic HII regions, viz., S 201, S 206, and S 209 have been imaged at three frequencies, viz., 232, 327, and 610 MHz using the GMRT. The resolutions of these images are typically 15" at 232, 10" at 327, and 6" ...
  • Vertical scaleheights of stars and gas in the galaxy 
    Narayan, C. A; Jog, C. J (Astronomical Society of India, 2002-09)
    The vertical scaleheight of atomic hydrogen gas is observed to be nearly constant with radius in the inner Galaxy « 8.5 kpc). This has been a long-standing puzzle (Oort 1962) because the gas scaleheight should ...
  • The parsec-scale central components of FR I radio galaxies 
    Kharb, P; Shastri, P (International Astronomical Union, 2001)
    A majority of a complete sample of 3CR FR I radio galaxies show unresolved optical nuclear sources on the scales of 0.1 arcsec. These Compact Central Cores (CCC) have been interpreted as the optical counterparts of the ...
  • A Spectroscopic Study of the Solar Corona from Norikura and SOHO data 
    Raju, K. P; Sakurai, T; Ichimoto, K (International Astronomical Union, 2001)
    We report the results from a spectroscopic study of the solar corona, wherein, we examine some of the current problems in the corona, such as the plume-interplume differences in coronal holes, coronal loops in active regions ...
  • CCD Photometry and Spectroscopy of IRAS Sources Having Far-IR Colors Similar to Planetary Nebulae 
    Reddy, B. E; Parthasarathy, M (American Astronomical society, 1996-11)
    CCD imaging and BVRI photometry of 14 IRAS sources with far-IR colors similar to planetary nebulae and post-AGB stars are presented. Also results of optical and near -IR spectroscopy of 10 of these candidates are given. ...
  • The Influence of Magnetic Flux Tubes on Their Environment 
    Hasan, S. S; Kalkofen, W (Astronomical Society of the Pacific, 1998)
    We present new calculations for model atmospheres in magnetic flux tubes extending vertically through the photosphere and convection zone of the Sun. This study is a continuation of earlier work by Hasan & Kalkofen (1994) ...
  • Astrometry from CCD photometry of mutual events of Jovian satellites from VBO during 1997 
    Vasundhara, R (EDP Sciences, 2002-07)
    Astrometric results of CCD observations of the mutual events of the Galilean satellites of Jupiter from the Vainu Bappu Observatory are presented. The shifts in the photo-centers on the disks of Io and Europa due to albedo ...

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