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Browsing by Author "Lambert, D. L"

Browsing by Author "Lambert, D. L"

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  • R Coronae Borealis at the 2003 light minimum 
    Kameswara Rao, N; Lambert, D. L; Shetrone, M. D (Blackwell Publishing, 2006-08)
    A set of five high-resolution optical spectra of R CrB obtained in 2003 March is discussed. At the time of the first spectrum (March 8), the star was at V = 12.6, a decline of more than six magnitudes. By March 31, the ...
  • The R Coronae Borealis stars - A few mere facts 
    Lambert, D. L; Kameswara Rao, N (Indian Academy of Sciences, 1994-03)
    This review presents a selection of recent highlights of observations of R Coronae Borealis (RCB) variables. Emphasis is placed on an abundance analysis of a complete sample (18 stars) of the warm galactic RCBs. It is shown ...
  • The R Coronae Borealis stars - atmospheres and abundances 
    Asplund, M; Gustafsson, B; Lambert, D. L; Kameswara Rao, N (European Southern Observatory, 2000-01)
    An abundance analysis of the H-deficient and He- and C-rich R Coronae Borealis (R CrB) stars has been undertaken to examine the ancestry of the stars. The investigation is based on high-resolution spectra and line-blanketed ...
  • R Coronae Borealis stars at minimum light - UW Cen 
    Kameswara Rao, N; Reddy, B. E; Lambert, D. L (Blackwell Publishing, 2004-12)
    Two high-resolution optical spectra of the R Coronae Borealis (R CrB) star UW Cen in decline are discussed. A spectrum from mid-1992 when the star had faded by 3 mag shows just a few differences with the spectrum at maximum ...
  • The R Coronae Borealis stars: carbon abundances from forbidden carbon lines 
    Pandey, G; Lambert, D. L; Kameswara Rao, N; Gustafsson, B; Ryde, N; Yong, D (Royal Astronomical Society, 2004-09)
    Spectra of several R Coronae Borealis (RCB) stars at maximum light have been examined for the [CI] 9850- and 8727-Åabsorption lines. The 9850-Åline is variously blended with an FeII and CN lines, but positive identifications ...
  • SALT revisits DY Cen: a rapidly evolving strontium-rich single helium star 
    Jeffery, C. S; Kameswara Rao, N; Lambert, D. L (Oxford University Press on behalf of the Royal Astronomical Society, 2020-04)
    The hydrogen-deficient star DY Cen has been reported as an R CrB-type variable, an extreme helium star (with some hydrogen), and as a single-lined spectroscopic binary. It has been associated with a dramatic change in ...
  • Searching for the metal-weak thick disc in the solar neighbourhood 
    Reddy, B. E; Lambert, D. L (Royal Astronomical Society, 2008-11)
    An abundance analysis is presented of 60 metal-poor stars drawn from catalogues of nearby stars provided by Arifyanto et al. and Schuster et al. In an attempt to isolate a sample of metal-weak thick disc stars, we applied ...
  • A Spectral Analysis of HD 165553 
    Goswami, A; Kameswara Rao, N; Lambert, D. L (Astronomical Society of India, 2003)
    High resolution spectra of HD 165553, a star reported to be a spectroscopic binary of spectral type F8 Ib are analysed. The stellar parameters - effective temperature, surface gravity and microturbulence are determined ...
  • Spectral Variations of DY Cen 
    Giridhar, S; Kameswara Rao, N; Lambert, D. L (Indaian Academy of Sciences, 1996-06)
    Two high resolution spectra of the hot RCrB star DY Cen in the red region are compared. The photospheric absorption lines show a radial velocity variation of 12 km s(sup -1) between 1989 July and 1992 May. Emission components ...
  • Spectrum of S Aps at deep minimum 
    Kameswara Rao, N; Goswami, A; Smith, V. V; Lambert, D. L (Astronomical Society of the Pacific, 1996)
  • The Spectrum of the Cool R Coronae Borealis Variable S Apodis in a Deep Decline 
    Goswami, A; Kameswara Rao, N; Lambert, D. L; Smith, V. V (Astronomical Society of the Pacific, 1997-03)
    A high resolution spectrum (5575 - 8875\AA) of the cool R Coronae Borealis variable S Apodis in its 1993 deep decline is discussed. Narrow or chromospheric emission lines of Na I, K I, Ca II, and Ba II and broad emission ...
  • The spectrum of the cool R Coronae Borealis variable Z Ursae Minoris at minimum 
    Goswami, A; Kameswara Rao, N; Lambert, D. L (The Observatory, 1999-02)
  • 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 ...
  • Three Li-rich K Giants: IRAS 12327-6523, 13539-4153, and 17596-3952 
    Reddy, B. E; Lambert, D. L (University of Chicago Press, 2005-06)
    We report on spectroscopic analyses of three K giants previously suggested to be Li-rich: IRAS 12327-6523, 13539-4153, and 17596-3952. High-resolution optical spectra and the LTE model atmospheres are used to derive the ...
  • Unveiling Vela – time variability of Na I D lines in the direction of the Vela supernova remnant 
    Kameswara Rao, N; Muneer, S; Lambert, D. L; Varghese, B. A (Oxford University Press on behalf of the Royal Astronomical Society, 2016-01-21)
    High-resolution spectral profiles of Na I D lines from the interstellar medium towards 64 stars in the direction of the Vela supernova remnant are presented. This survey conducted mostly between 2011 and 12 complements an ...
  • Unveiling Vela – variability of interstellar lines in the direction of the Vela supernova remnant – III. Na D and Ca II K 
    Kameswara Rao, N; Lambert, D. L; Reddy, A. B. S; Gupta, R; Muneer, S; Singh, H. P (Oxford University Press on behalf of the Royal Astronomical Society, 2020-03)
    High-resolution optical spectra were obtained in 2017–2019 with The Southern African Large Telescope of 15 stars in the direction of the Vela supernova remnant. Interstellar Ca II H & K and Na I D lines are discussed in ...
  • Unveiling Vela: time variability of interstellar lines in the direction of the Vela supernova remnant – II. Na D and Ca II 
    Kameswara Rao, N; Lambert, D. L; Reddy, A. B. S; Gupta, R; Muneer, S; Singh, H. P (IOP Publishing, 2017-05)
    In a survey conducted between 2011 and 2012 of interstellar Na I D line profiles in the direction of the Vela supernova remnant (SNR), a few lines of sight showed dramatic changes in low-velocity absorption components with ...

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