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Browsing by Author "Lambert, D. L"

Browsing by Author "Lambert, D. L"

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  • Elemental abundance survey of the galactic thick disc 
    Reddy, B. E; Lambert, D. L; Prieto, Carlos Allende (Blackwell Publishing, 2006-04)
    We have performed an abundance analysis for F- and G- dwarfs of the Galactic thick-disc component. A sample of 176 nearby (d≤ 150 pc) thick-disc candidate stars was chosen from the Hipparcos catalogue and subjected to a ...
  • Emission-line spectra of XX Ophiuchi in 1996 and 1997 
    Goswami, A; Kameswara Rao, N; Lambert, D. L (The Observatory, 2001-04)
  • 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 ...
  • Epsilon Aurigae in eclipse. I - Ultraviolet spectroscopy during INGRESS and totality 
    Parthasarathy, M; Lambert, D. L (Astronomical Society of the Pacific, 1983-12)
    Epsilon Aurigae is a long-period eclipsing system containing a F0 Ia supergiant and an unseen slightly less-massive secondary. A primary eclipse began in mid-1982 with the unseen companion passing in front of the supergiant. ...
  • The evolution of the Milky Way: new insights from open clusters 
    Reddy, A. B. S; Lambert, D. L; Giridhar, S (Oxford University Press on behalf of the Royal Astronomical Society, 2016-12)
    We have collected high-dispersion echelle spectra of red giant members in the 12 open clusters (OCs) and derived stellar parameters and chemical abundances for 26 species by either line equivalent widths or synthetic ...
  • FG Sagittae: A Newborn R Coronae Borealis Star? 
    Gonzalez, G; Lambert, D. L; Wallerstein, G; Kameswara Rao, N; Smith, V. V; McCarthy, J. K (The American Astronomical Society, 1998-01)
    We have monitored FG Sge's spectroscopic changes since the time just prior to its dramatic fading in 1992 August. The most significant qualitative changes in the spectrum include large variations in the strength of the C2 ...
  • Fluorine detection in hot extreme helium stars 
    Bhowmick, A; Pandey, G; Lambert, D. L (Springer, 2020-12)
    The origin and evolution of hydrogen-deficient stars are not yet adequately understood. Their chemical peculiarities, along with hydrogen-deficiency, makes them stand out from the rest and sheds light on their possible ...
  • Fluorine in R Coronae Borealis Stars 
    Pandey, G; Lambert, D. L; Kameswara Rao, N (Astronomical Society of the Pacific, 2008)
    Neutral fluorine lines are identified in the optical spectra of several R Coronae Borealis stars (RCBs) at maximum light. These lines provide the first measurement of the fluorine abundance in these stars. Fluorine is ...
  • Fluorine in R Coronae Borealis Stars 
    Pandey, G; Lambert, D. L; Kameswara Rao, N (University of Chicago Press, 2008-02)
    Neutral fluorine (F i) lines are identified in the optical spectra of several R Coronae Borealis stars (RCBs) at maximum light. These lines provide the first measurement of the fluorine abundance in these stars. Fluorine ...
  • Galactic chemical evolution and chemical tagging with open clusters 
    Reddy, A. B. S; Giridhar, S; Lambert, D. L (Indian Academy of Sciences, 2020-12)
    The article presents the consolidated results drawn from the chemical composition studies of Reddy et al. (2012, 2013, 2015, 2016) and Reddy & Lambert (2019), who through the high-dispersion echelle spectra (R=60000) of ...
  • The galactic R coronae borealis stars and the final he-shell flash object V4334Sgr (Sakurai’s object): a comparison 
    Hema, B. P; Pandey, G; Lambert, D. L (Proceedings of Science, 2012-08)
    The high resolution optical spectra of H-deficient stars, R Coronae Borealis stars and H-deficient carbon stars are analyzed by synthesizing the C2 Swan bands (0,1), (0,0), and (1,0) using our detailed line-list and ...
  • The Galactic R Coronae Borealis Stars: The C2 Swan Bands, the Carbon Problem, and the 12C/13C Ratio 
    Hema, B. P; Pandey, G; Lambert, D. L (IOP Publishing, 2012-03-10)
    Observed spectra of R Coronae Borealis (RCB) and hydrogen-deficient carbon (HdC) stars are analyzed by synthesizing the C2 Swan bands (1, 0), (0, 0), and (0, 1) using our detailed line list and the Uppsala model atmospheres. ...
  • A high resolution spectroscopic study of XX Ophiuchi 
    Goswami, A; Kameswara Rao, N; Lambert, D. L (Astronomical Society of India, 2001)
    The star XX Oph has been known to exhibit peculiar spectral variabilities since the work of Merrill in 1924. A high resolution spectroscopic study of the XX Oph spectra taken in July 1996 and later in June 1997 also exhibit ...
  • High Resolution Spectroscopy of QY Sge 
    Kameswara Rao, N; Goswami, A; Lambert, D. L (Astronomical Society of India, 2002-09)
    High resolution spectral analysis of QY Sge, a post AGB star is presented here. The spectrum of QY Sge is characterized by three major components: absorption lines representative of a G supergiant, sharp emission lines ...
  • High resolution spectroscopy of R Coronae Borealis during the 1988-1989 minimum 
    Lambert, D. L; Kameswara Rao, N; Giridhar, S (Indian Academy of Sciences, 1990-12)
    Moderate-resolution spectra of the C2 Swan 0-1 bandhead, the Na I D lines and the K I resonance lines near 7660 A obtained at minimum light during the 1988-1989 decline of R CrB are discussed and interpreted in terms of a ...
  • High resolution spectroscopy of the R Coronae Borealis star, V854 Centauri, during a deep minimum 
    Kameswara Rao, N; Lambert, D. L (American Astronomical Society, 1993-05)
    The R Coronae Borealis star V854 Cen was observed at minimum light (V about 15) at high spectral resolution from 5480 to 7070 A. The spectrum consists of three components: a continuum devoid of photospheric lines, a ...
  • High Resolution Spectroscopy of the Semi-Regular Variable LR Sco 
    Giridhar, S; Kameswara Rao, N; Lambert, D. L (Indian Academy of Sciences, 1992)
    A detailed spectroscopic investigation of LR Sco which was earlier misclassified as R CrB star is made. Atmospheric parameters and elemental abundances are determined using detailed depth-dependent model atmospheres and ...
  • High-resolution Optical Spectroscopy of DY Cen: Diffuse Interstellar Bands in a Proto-fullerene Circumstellar Environment? 
    Garcia-Hernandez, D. A; Kameswara Rao, N; Lambert, D. L (IOP Publishing, 2012-11-01)
    We search high-resolution and high-quality VLT/UVES optical spectra of the hot R Coronae Borealis star DY Cen for electronic transitions of the C60 molecule and diffuse interstellar bands (DIBs). We report the non-detection ...
  • High-Resolution Optical Spectroscopy of the R Coronae Borealis Star V532 Ophiuchi at Maximum Light* 
    Kameswara Rao, N; Lambert, D. L; Woolf, V. M; Hema, B. P (IOP Publishing, 2014-09)
    High-resolution optical spectra of the R Coronae Borealis (RCB) star V532 Oph at light maximum are discussed. The absolute visual magnitude M V of the star is found to be 4 : 9 0 : 5 . The elemental ...
  • A high-resolution spectroscopic analysis of the suspected spectroscopic binary HD 165553 
    Goswami, A; Kameswara Rao, N; Lambert, D. L (The Observatory, 2004-02)
    The results of an analysis of a high-resolution spectrum of the possible spectroscopic binary HD 165553, obtained with a spectral resolving power of ~ 60 000, are presented. A detailed chemical-composition study indicates ...

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