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Browsing by Author "Giridhar, S"

Browsing by Author "Giridhar, S"

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  • Spectral Analysis of Selected Cepheids and the Galactic Distribution of Metalicity 
    Giridhar, S (Indian Institute of Astrophysics, Bangalore, 1982-10)
  • Spectral Classification: Old and Contemporary 
    Giridhar, S (Springer, 2010)
    Beginning with a historical account of the spectral classification, its refinement through additional criteria is presented. The line strengths and ratios used in two dimensional classifications of each spectral class are ...
  • 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 ...
  • Spectroscopic analysis of four post-AGB candidates 
    Molina, R. E; Giridhar, S; Pereira, C. B; Arellano Ferro, A; Muneer, S (Institute de Astronomia, 2014-10)
    We have done a detailed abundance analysis of four unexplored cand idate post- Asymptotic Giant Branch(AGB) stars IRAS 13110- 6629, IRAS 175 79 - 3121, IRAS 18321- 1401 and IRAS 18489- 0629 using high resolution spectra. ...
  • Spectroscopic studies of R CrB during light minima - Absorption spectrum 
    Kameswara Rao, N; Giridhar, S; Ashoka, B. N (Royal Astronomical Society, 1990-05)
    R CrB was observed during the 1986 shallow minimum to study the spectral changes taking place during light minimum as compared with the spectrum at maximum light. The absorption spectrum at this minimum is very similar to ...
  • Spectroscopic studies of selected F-G supergiants 
    Giridhar, S; Arellano, F. A; Parrao, L (Astronomical Society of India, 1998)
  • Spectroscopic studies of the southern Cepheid β Dor 
    Giridhar, S (Universidad Nacional Autonoma De Mexico, 1987-05)
    Fine analysis of the southern Cepheid β Dor has been conducted at different phases with the aim to derive atmospheric parameters at those phases. Atmospheric abundances have been derived for Fe group elements and s-process ...
  • Spectroscopic survey of field stars : A search for metal-poor stars 
    Giridhar, S; Goswami, A (Astronomical Society of India, 2002)
    We have undertaken a spectroscopic survey of field stars to fine metal-poor objects among them. Though the main objective of the survey is to find new metal-poor stars, stellar parameterization is carried out for all the ...
  • The stellar parametrization using Artificial Neural Network 
    Giridhar, S; Goswami, A; Kunder, A; Muneer, S; Selvakumar, G (Astronomical Society of India, 2012)
    An update on recent methods for automated stellar parametrization is given. We present preliminary results of the ongoing program for rapid parametrization of field stars using medium resolution spectra obtained using Vainu ...
  • Surface compositional changes observed during last stages of stellar evolution 
    Giridhar, S (Astronomical Society of India, 1999)
  • The unusually large population of Blazhko variables in the globular cluster NGC 5024 (M53) 
    Arellano Ferro, A; Bramich, D. M; Figuera Jaimes, R; Giridhar, S; Kuppuswamy, K (Wiley-Blackwell, 2012-02)
    We report the discovery of amplitude and phase modulations typical of the Blazhko effect in 22 RRc and nine RRab type RR Lyrae stars in NGC 5024 (M53). This brings the confirmed Blazhko variables in this cluster to 23 RRc ...
  • The UV spectrum of the WC 11 star CPD -56 deg 8032 
    Kameswara Rao, N; Giridhar, S; Nandy, K (The European Southern Observatory, 1990-08)
    UV observations of the WC 11 central star of the compact planetary nebula CPD -56 deg 8032 show that the continuum flux is variable. This variability appears to be caused by a change in the circumstellar extinction properties. ...
  • THE VARIABLE STAR POPULATION IN THE GLOBULAR CLUSTER NGC 6934 
    Yepez, M. A; Ferro, A. A; Muneer, S; Giridhar, S (Instituto de Astronomia, 2018-04)
    We report an analysis of new V and I CCD time-series photometry of the globular cluster NGC 6934. Through the Fourier decomposition of the RR Lyrae light curves the mean values of [Fe/H] and the distance of the cluster ...
  • Variable stars in NGC 4147 revisited: RR Lyrae stars new CCD VI photometry and physical parameters 
    Arellano Ferro, A; Rojas Galindo, F. C; Muneer, S; Giridhar, S (Universidad Nacional Autonoma De Mexico, 2018-10)
    We have calculated the physical parameters of the RR Lyrae stars in the globular cluster NGC 4147 via the Fourier decomposition of their light curves, using new data and well-established semi-empirical calibrations and ...
  • Variable stars in Palomar 13; an evaporating globular cluster 
    Yepez, M. A; Ferro, A. A; Schoeder, K. P; Muneer, S; Giridhar, S; Allen, C (Elsevier B.V, 2019-08)
    We present new CCD VI photometry of the distant globular cluster Pal 13. Fourier decomposition of the light curves of the three cluster member RRab stars lead to estimations of [Fe/H] = −1.65, and a distance of 23.67 ± ...
  • Variable Stars in the Globular Cluster NGC 288: [Fe/H] and Distance 
    Ferro, A. A; Bramich, D.M; Giridhar, S; Jaimes, R. F; Kains, N; Kuppuswamy, K (Copernicus Foundation for Polish Astronomy, 2013-12)
    A search for variable stars in the globular cluster NGC 288 was carried out using a time-series of CCD images in the V and I filters. The photometry of all stellar sources in the field of view of our images, down to V≈19 ...
  • Variable stars in the globular cluster NGC 7492. New discoveries and physical parameter determination 
    Figuera Jaimes, R; Arellano Ferro, A; Bramich, D. M; Giridhar, S; Kuppuswamy, K (EDP Sciences, 2013-08)
    Aims. We have performed a photometric V,R,I CCD time-series analysis with a baseline of about eight years of the outer-halo globular cluster NGC 7492 with the aim of searching for new variables and using these (and the ...
  • Violet absorption edges of C IV lines in Wolf-Rayet spectra: possible superposition with diffuse interstellar bands at 5780 Å and 5797 Å 
    Giridhar, S; Bappu, M. K. V (Indian Institute of Astrophysics, 1978)
    It is shown that the violet edges normally seen in Wolf-Rayet stars around 5800Å are principally due to displaced C IV absorption. The diffuse interstellar bands are seldom of comparable strength and can be seen separately ...

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