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Browsing by Subject "Stars: Low-Mass"

Browsing by Subject "Stars: Low-Mass"

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  • Explaining the Observed Polarization from Brown Dwarfs by Single Dust Scattering 
    Sengupta, S (The American Astronomical Society, 2003-03)
    Recent observation of linear optical polarization from brown dwarfs confirms the dust hypothesis in the atmospheres of brown dwarfs with effective temperature higher than 1400 K. The observed polarization could arise because ...
  • Line formation in the Atmosphere of brown dwarf Gliese 229B : CH_4 at 2.3 mu m 
    Sengupta, S; Krishan, V (European Southern Observatory, 2000-06)
    We investigate the formation of methane line at 2.3 μm in Brown Dwarf Gliese 229B. Two sets of model parameters with (a) T_eff=940 K and log (g) =5.0, (b) T_eff=1030 K and log (g)=5.5 are adopted both of which provide ...
  • Optical linear polarization in ultra cool dwarfs: A tool to probe dust in the ultra cool dwarf atmospheres 
    Tata, R; Martin, E. L; Sengupta, S; Phan-Bao, N; Zapatero Osorio, M. R; Bouy, H (European Space Agency, 2009-12)
    Aims.Recent studies have detected linear polarization in L dwarfs in the optical I band. Theoretical models have been developed to explain this polarization. These models predict higher polarization at shorter wavelengths. ...
  • Origin of Lithium Enrichment in K Giants 
    Bharat Kumar, Y; Reddy, B. E; Lambert, D. L (Institute of Physics Publishing, 2011-03-20)
    In this Letter, we report on a low-resolution spectroscopic survey for Li-rich K giants among 2000 low-mass (M ≤ 3 M sun) giants spanning the luminosity range from below to above the luminosity of the clump. Fifteen new ...
  • Polarization of L Dwarfs by Dust Scattering 
    Sengupta, S; Kwok, S (The American Astronomical Society, 2005-06)
    The degree of polarization in L dwarfs of spectral types L0-L6 resulting from dust scattering in a rotation-induced oblate photosphere is calculated. Assuming that forsterite is the main condensate, we derive the atmospheric ...
  • Probing Dust in the Atmosphere of Brown Dwarfs through Polarization 
    Sengupta, S; Krishan, V (The American Astronomical Society, 2001-11)
    The theoretical analysis and observational evidence indicate that a brown dwarf with an effective temperature greater than 1300 K would have a dust cloud in its atmosphere. In this Letter, we show that dust scattering ...

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