IIA Institutional Repository

Browsing by Author "Lambert, D. L"

Browsing by Author "Lambert, D. L"

Sort by: Order: Results:

  • High-resolution spectroscopy of QY Sge: an obscured RV Tauri variable? 
    Kameswara Rao, N; Goswami, A; Lambert, D. L (Blackwell Publising Ltd, 2002-07)
    The first high-resolution optical spectra of QY Sge are presented and discussed. Menzies & Whitelock, on the basis of photometry and low-resolution spectra, suggested that this G0I supergiant was obscured by dust and seen ...
  • High-resolution spectroscopy of R CrB - pulsations, shells and mass loss 
    Kameswara Rao, N; Lambert, D. L (The Royal Astronomical Society, 1997-01)
    High spectral resolution observations obtained in 1994 and spanning three pulsation cycles of R CrB are discussed along with available UBV photometric observations for the same epochs. Model atmosphere based analyses of ...
  • High-resolution spectroscopy of the R Coronae Borealis and Other Hydrogen Deficient Stars 
    Kameswara Rao, N; Lambert, D. L (Springer, 2010)
    High-resolution spectroscopy is a very important tool for studying stellar physics, perhaps, particularly so for such enigmatic objects like the R Coronae Borealis and related Hydrogen deficient stars that produce carbon ...
  • High-resolution spectroscopy of the R Coronae Borealis star V Coronae Australis 
    Kameswara Rao, N; Lambert, D. L (Blackwell Synergy, 2008-02)
    Optical high-resolution spectra of the R Coronae Borealis star V CrA at light maximum and during minimum light are discussed. Abundance analysis confirms previous results showing that V CrA has the composition of the small ...
  • High-resolution spectroscopy of V854 Cen in decline - absorption and emission lines of C2 molecules 
    Kameswara Rao, N; Lambert, D. L (Royal Astronomical Society, 2000-04)
    High-resolution optical spectra of the R Coronae Borealis (RCB) star V854 Centauri in the early stages of a decline show, in addition to the features reported for other RCBs in decline, narrow absorption lines from the C2 ...
  • A High-Resolution Spectrum of the R Coronae Borealis Star V2552 Ophiuchi 
    Kameswara Rao, N; Lambert, D. L (The Astronomical Society of the Pacific, 2003-11)
    Photometry and low-resolution spectroscopy have added V2552 Oph to the rare class of R Coronae Borealis variables. We confirm this classification of V2552 Oph through a comparison of our high-resolution optical spectrum ...
  • The hot R Coronae Borealis star DY Centauri: Nebular and photospheric lines 
    Kameswara Rao, N; Giridhar, S; Lambert, D. L (The European Southern Observatory, 1993-12)
    High resolution spectra in the red region of the hot R CrB star DY Cen show the following characteristics: a strong absorption line spectrum dominated by lines of C II, N II, and Ne I inverse P-Cygni type profiles of some ...
  • Hydrogen-deficient nature of Z UMi 
    Goswami, A; Kameswara Rao, N; Gonzalez, G; Lambert, D. L (Astronomical Society of the Pacific, 1996)
  • Infrared Space Observatory Spectra of R Coronae Borealis Stars. I. Emission Features in the Interval 3-25 Microns 
    Lambert, D. L; Kameswara Rao, N; Pandey, G; Ivans, I. I (American Astronomical Society, 2001-07)
    Infrared Space Observatory 3-25 μm spectra of the R Coronae Borealis stars V854 Cen, R CrB, and RY Sgr are presented and discussed. Sharp emission features coincident in wavelength with the well-known unidentified emission ...
  • Is DZ Andromedae an R Coronae Borealis variable? 
    Goswami, A; Kameswara Rao, N; Lambert, D. L (The Observatory, 1998-08)
    The variable star DZ Andromedae has been suspected to be an R Coronae Borealis variable. Our analysis of a high-resolution spectrum shows that the star has been misclassified: the spectrum resembles that of a K giant. We ...
  • Is LR SCO and RCB star? 
    Giridhar, S; Kameswara Rao, N; Lambert, D. L (The Observatory, 1990-08)
  • Is the Post-AGB Star SAO 40039 Mildly Hydrogen-Deficient? 
    Sumangala Rao, S; Pandey, G; Lambert, D. L; Giridhar, S (IOP Publishing, 2011-08-10)
    We have conducted an LTE abundance analysis for SAO 40039, a warm post-AGB star whose spectrum is known to show surprisingly strong He I lines for its effective temperature and has been suspected of being H-deficient and ...
  • Li Abundance Survey in Galactic Thin Disk 
    Lambert, D. L; Reddy, B. E (Astronomical Society of the Pacific, 2005-09)
    Lithium abundances for a sample of 451 F and G dwarfs including 181 new stars all belonging to the Galactic thin disk are discussed. Lithium abundances, metallicities ([Fe/H]), masses, and ages are determined (Lambert & ...
  • Lithium abundances and asteroseismology of red giants: understanding the evolution of lithium in giants based on asteroseismic parameters 
    Deepak; Lambert, D. L (Oxford University Press on behalf of the Royal Astronomical Society, 2021-07)
    In this study, we explore the evolution of lithium in giant stars based on data assembled from the literature on asteroseismology and Li abundances for giants. Our final sample of 187 giants consists of 44 red giant branch ...
  • 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 abundances of the local thin disc stars 
    Lambert, D. L; Reddy, B. E (Royal Astronomical Society, 2004-04-01)
    Lithium abundances are presented for a sample of 181 nearby F and G dwarfs with accurate Hipparcos parallaxes. The stars are on circular orbits about the Galactic centre and, hence, are identified as belonging to the thin ...
  • Lithium in red giants: the roles of the He-core flash and the luminosity bump 
    Deepak; Lambert, D. L (Oxford University Press on behalf of the Royal Astronomical Society, 2021-10)
    Lithium abundances for red giants in the GALAH DR3 survey are studied. The rare examples of Li-enriched stars with abundances A(Li) ≥1.5 are confirmed to be He-core burning stars belonging to or evolved from the red clump ...
  • Mid-infrared variations of R Coronae Borealis stars 
    Kameswara Rao, N; Lambert, D. L (Oxford University Press on behalf of the Royal Astronomical Society, 2015-03-11)
    Mid-infrared (IR) photometry of R Coronae Borealis stars obtained from various satellites from Infrared Astronomical Satellite (IRAS) to Wide-field Infrared Survey Explorer (WISE) has been utilized in studying the ...
  • Neon and CNO Abundances for Extreme Helium Stars—A Non-LTE Analysis 
    Pandey, G; Lambert, D. L (IOP Publishing, 2011-02)
    A non-LTE (NLTE) abundance analysis was carried out for three extreme helium stars (EHes): BD+10° 2179, BD–9° 4395, and LS IV+6° 002, from their optical spectra with NLTE model atmospheres. NLTE TLUSTY model atmospheres ...

Search DSpace

Browse

My Account