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Browsing by Author "Mallik, S. G. V"

Browsing by Author "Mallik, S. G. V"

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  • Effect of Lyman radiation transfer on the formation of the H-alpha line in supergiant chromospheres 
    Mallik, S. G. V; Mallik, D. C. V; Mohan Rao, D (European Southern Observatory, 1991-03)
    The paper pesents radiative transfer calculations of the H-alpha line in spherically expanding chromospheres of late-type supergiants where the assumption of radiative detailed balance in Lyman transitions has been relaxed. ...
  • Equivalent width of OI λ7774 and absolute magnitude relation for F and G supergiants 
    Kameswara Rao, N; Mallik, S. G. V (Royal Astronomical Society, 1978-04)
    Luminosity calibration is established for F5-G2 supergiants using the equivalent width measures of OI λ7774 and FeI λ7748
  • 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 ...
  • Expanding chromospheres of late G and K supergiants 
    Mallik, S. G. V (Royal Astronomical Society, 1986-09)
    The radiative transfer problem in non-LTE moving atmospheres has been explicitly solved for Hα line profiles. These computations have been done for a schematic model of the line-forming region over a wide range of optical ...
  • The H Alpha Line in Late G and K Supergaints 
    Mallik, S. G. V (Indian Institute of Astrophysics, Bangalore, 1979-10)
  • Lithium abundance and mass 
    Mallik, S. G. V (The European Southern Observatory, 1999-12)
    Observations of cool giants have shown that there exists a large range in their lithium abundances even for apparently similar stars. The depletions are large in a majority of them, far in excess of the predictions of the ...
  • Lithium abundances in the α Per cluster 
    Balachandran, S. C; Mallik, S. G. V; Lambert, D. L (Wiley Blackwell, 2011-02)
    Lithium (Li) abundances are presented and discussed for 70 members of the 50-Myr-old open cluster α Per. More than half of the abundances are from new high-resolution spectra. The Li abundance in the F-type stars is equal ...
  • Lithium abundances in the α Per cluster 
    Mallik, S. G. V; Balachandran, S. C; Lambert, D. L (Cambridge University Press, 2010-04)
    As a sequel to the Li observations by Balachandran, Lambert & Stauffer (1988, 1996) in 35 stars of the 50 Myr old cluster α Persei, we have obtained and analyzed high resolution spectra of another 51 stars. Following a ...
  • Lithium and rotation in F and G dwarfs and subgiants 
    Mallik, S. G. V; Parthasarathy, M; Pati, A. K (The European Southern Observatory, 2003-10)
    Lithium abundances have been determined in 127 F and G Pop I stars based on new measurements of the equivalent width of the 6707 Å Li I line from their high resolution CCD spectra. Distances and absolute magnitudes of these ...
  • Lithium and Rotation in Pop I stars 
    Mallik, S. G. V (Cambridge University Press, 2004)
    Lithium abundances have been determined for 130 stars sampled on the basis that they have just about completed depletion of Li on the main sequence and have not yet begun their ascent on the red giant branch. The ...
  • Lithium in Stars on the Main Sequence and Beyond 
    Mallik, S. G. V (Astronomical Society of India, 2003)
    7Li provides a rare constraint on the baryonic density of the Universe and because of its fragile nature, it is also an excellent diagnostic of the physical processes occurring inside stars. The study of Li in Pop.I stars ...
  • A method to determine distances to molecular clouds using near-IR photometry 
    Maheswar, G; Lee, C. W; Bhatt, H. C; Mallik, S. G. V; Dib, S (EDP Sciences, 2010-01)
    We aim to develop a method to determine distances to molecular clouds using JHK near-infrared photometry. Methods: The method is based on a technique that aids spectral classification of stars lying towards the fields ...
  • Role of nonthermal velocity fields in determining the H-alpha widths in supergiant chromospheres 
    Mallik, S. G. V (The Astronomical Society of the Pacific., 1990-10)
    Radiative transfer calculations of the H-alpha line in spherically symmetric, expanding chromospheres explain the large widths of the line observed in late G and K supergiants. The role of various dynamical processes as ...
  • Simultaneous X-ray and Optical Observations of the T Tauri star TW Hya 
    Mallik, S. G. V; Brickhouse, N. S; Dupree, A. K (Springer, 2010)
    We report preliminary results obtained from a spectroscopy and photometry campaign of the T Tauri star TW Hya in February- March, 2007. A long HETG observation with CHANDRA and simultaneous optical observations around the ...
  • A study of the H-alpha line in late G and K supergiants 
    Mallik, S. G. V (Indian Academy of Sciences, 1982-03)
    H-alpha is investigated spectroscopically in order to gain information on the properties of expanding chromospheres of late G and K supergiants. Spectra of 23 stars brighter than V equals 6.0 are obtained at dispersions ...
  • 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 ...

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