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Browsing by Subject "Stars: Variables: Other"

Browsing by Subject "Stars: Variables: Other"

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  • The 1995-96 decline of R Coronae Borealis: high-resolution optical spectroscopy 
    Kameswara Rao, N; Lambert, D. L; Adams, M. T; Doss, D. R; Gonzalez, G; Hatzes, A. P; James, C. R; Johns-Krull, C. M; Luck, R. E; Pandey, G; Reinsch, K; Tomkin, J; Woolf, V. M (The Royal Astronomical Society, 1999-12)
    A set of high-resolution optical spectra of R CrB acquired before, during and after its 1995-96 decline is discussed. All of the components reported from earlier declines are seen. This novel data set provides new information ...
  • The Chemical Compositions of the SRD Variable Stars. III. KK Aquilae, AG Aurigae, Z Aurigae, W Leo Minoris, and WW Tauri 
    Giridhar, S; Lambert, D. L; Gonzalez, G (The Astronomical Society of the Pacific, 2000-12)
    Chemical compositions are derived from high-resolution spectra for five field SRd variables. These supergiants not previously analyzed are shown to be metal poor: KK Aql with [Fe/H]=-1.2, AG Aur with [Fe/H]=-1.8, Z Aur ...
  • Do hydrogen-deficient carbon stars have winds? 
    Geballe, T. R; Kameswara Rao, N; Clayton, G. C (Institute of Physics, 2009-06)
    We present high resolution spectra of the five known hydrogen-deficient carbon (HdC) stars in the vicinity of the 10830 Å line of neutral helium. In R Coronae Borealis (RCB) stars the He I line is known to be strong and ...
  • Fading of light maximum and linear polarization variation in the carbon Mira R Leporis 
    Raveendran, A. V (Royal Astronomical Society, 2002-11)
    Polarimetry of R Lep obtained over the years 1991-2002 is presented. During this period the star underwent an episode of fading of the brightness at light maximum, after an interval of about 35 yr. An analysis of the data ...
  • 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 ...
  • 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 ...
  • A new search for variable stars in the globular cluster NGC 6366 
    Ferro, A. A; Giridhar, S; Lopez, V. R; Figuera, R; Bramich, D. M; Rosenzweig, P (Instituto de Astronomía, 2008-10)
    New CCD photometry of NGC 6366 has lead to the discovery of some variable stars. Two possible Anomalous Cepheids (or Pop II Cepheids), three long period variables, one SX Phe and one eclipsing binary have been found. Also, ...
  • On the hydrogen-deficient nature of Z Ursae Minoris 
    Goswami, A; Kameswara Rao, N; Lambert, D. L; Gonzalez, G (The Astronomical Society of the Pacific, 1997-05)
    Z Ursa Minoris was classified by Benson et al. (1994) a a R Coronae Borealis (RCB) variable star from its light variations. Hydrogen deficiency, which is a defining feature of RCB stars, was not established. To investigate ...
  • 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 ...
  • 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 ...
  • 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 ...

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