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Browsing by Author "Giridhar, S"

Browsing by Author "Giridhar, S"

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  • Commission 45: Stellar Classification 
    Corbally, C; Giridhar, S; Bailer-Jones, C; Humphreys, R; Kirkpatrick, D; Lloyd Evans, T; Luri, X; Minniti, D; Pasinetti, L; Straižys, V; Weiss, W (Cambridge University Press, 2007)
    This report, like its predecessors, focuses on areas which have been especially active since the last General Assembly. Two major developments have been the unification of the T-dwarf standards and the new general catalogue ...
  • Comprehensive abundance analysis of red giants in the open clusters NGC 1342, 1662, 1912, 2354 and 2447 
    Reddy, A. B. S; Giridhar, S; Lambert, D. L (Oxford University Press on behalf of the Royal Astronomical Society, 2015-07-11)
    We have observed high-dispersion echelle spectra of red giant members in the five open clusters (OCs) NGC 1342, NGC 1662, NGC 1912, NGC 2354 and NGC 2447 and determined their radial velocities and chemical compositions. ...
  • Comprehensive abundance analysis of red giants in the open clusters NGC 2527, 2682, 2482, 2539, 2335, 2251 and 2266 
    Reddy, A. B. S; Giridhar, S; Lambert, D. L (Oxford University Press on behalf of the Royal Astronomical Society, 2013-06-01)
    We have analysed high-resolution echelle spectra of red giant members for seven open clusters in the Galactic anticentre direction to explore their chemical compositions. Cluster membership has been confirmed by radial ...
  • Comprehensive abundance analysis of red giants in the open clusters NGC 752, 1817, 2360 and 2506 
    Reddy, A. B. S; Giridhar, S; Lambert, D. L (Wiley-Blackwell, 2012-01)
    We have analysed high-dispersion echelle spectra (R ≳ 50 000) of red giant members for four open clusters to derive abundances for many elements. The spread in temperatures and gravities being very small among the red ...
  • Constraining the parameters of globular cluster NGC 1904 from its variable star population 
    Kains, N; Bramich, D. M; Figuera Jaimes, R; Arellano Ferro, A; Giridhar, S; Kuppuswamy, K (EDP Sciences, 2012-12)
    Aims. We present the analysis of 11 nights of V and I time-series observations of the globular cluster NGC 1904 (M 79). Using this we searched for variable stars in this cluster and attempted to refine the periods of known ...
  • Coronal photography at H alpha 
    Rangarajan, K. E; Giridhar, S (Indian National Science Academy, 1981)
  • A critical compilation of oscillator strengths for Fe II lines. 
    Giridhar, S; Arellano Ferro, A (Mexicana de Astronomia y Astrofisica, 1995-04)
    We have compiled oscillator strengths for 848 Fe II lines of astrophysical interest. The Oscillator strengths from various sources like laboratory measurements, semi-empirical estimates and those derived using solar Fe II ...
  • Detailed analysis of the variable star population in the globular cluster NGC 7006 
    Arellano Ferro, A; Rojas Galindo, F. C; Bustos Fierro, I. H; Muneer, S; Yepez, M. A; Giridhar, S (Oxford University Press on behalf of Royal Astronomical Society, 2023-02)
    A 5-yr CCD photometric VI time series of NGC 7006 is employed to perform a detailed analysis of the known population of variable stars. In the process, we have corrected inconsistent classifications, sky coordinates and ...
  • A detailed census of variable stars in the globular cluster NGC 6333 (M9) from CCD differential photometry 
    Arellano Ferro, A; Bramich, D. M; Jaimes, R. F; Giridhar, S; Kains, N; Kuppuswamy, K; Jorgensen, U. G; Alsubai, K. A; Andersen, J. M; Bozza, V; Browne, P; Novati, S. C; Damerdji, Y; Diehl, C; Dominik, M; Dreizler, S; Elyiv, A; Giannini, E; Harpsoe, K; Hessman, F. V; Hinse, T. C; Hundertmark, M; Juncher, D; Kerins, E; Korhonen, H; Liebig, C; Mancini, L; Mathiasen, M; Penny, M. T; Rabus, M; Rahvar, S; Ricci, D; Scarpetta, G; Skottfelt, J; Snodgrass, C; Southworth, J; Surdej, J; Tregloan-Reed, J; Vilela, C; Wertz, O (Oxford University Press on behalf of the Royal Astronomical Society, 2013-09-11)
    We report CCD V and I time series photometry of the globular cluster NGC 6333 (M9). The technique of difference image analysis has been used, which enables photometric precision better than 0.05 mag for stars brighter than ...
  • Difference image analysis: extension to a spatially varying photometric scale factor and other considerations 
    Bramich, D. M; Horne, Keith; Albrow, M. D; Tsapras, Y; Snodgrass, C; Street, R. A; Hundertmark, M; Kains, N; Arellano Ferro, A; Figuera Jaimes, R; Giridhar, S (Oxford University Press on behalf of the Royal Astronomical Society, 2013-01-21)
    We present a general framework for matching the point-spread function (PSF), photometric scaling and sky background between two images, a subject which is commonly referred to as difference image analysis (DIA). We introduce ...
  • Elemental Abundances and Atmospheric Parameters of Seven F-G Supergiants 
    Giridhar, S; Ferro, A; Parrao, L (Astronomical Society of the Pacific, 1997-10)
    Spectroscopic abundance determinations for a sample of seven F-G stars have been carried out. The majority of them have large galactic latitudes. One objective in deriving spectroscopic abundances is to differentiate evolved ...
  • Emission Spectrum of Hot R CrB star Mv Sgr 
    Kameswara Rao, N; Houziaux, L; Giridhar, S (Indian Academy Sciences, 1990-03)
    The new spectroscopic observation of MV Sgr obtained at ESO in 1987july shows enhanced emission lines of He I , λ 3889, [S II ] λ 4068 relative to the observations discussed by Jeffrey et al. (1988). The presence of [SII] ...
  • Estimating the parameters of globular cluster M 30 (NGC 7099) from time-series photometry 
    Kains, N; Bramich, D. M; Ferro, A. A; Jaimes, R. F; Jorgensen, U. G; Giridhar, S; Penny, M. T; Alsubai, K. A; Andersen, J. M; Bozza, V; Browne, P; Burgdorf, M; Novati, S. C; Damerdji, Y; Diehl, C; Dodds, P; Dominik, M; Elyiv, A; Fang, X.-S; Giannini, E; Gu, S.-H; Hardis, S; Harpsoe, K; Hinse, T. C; Hornstrup, A; Hundertmark, M; Jessen-Hansen, J; Juncher, D; Kerins, E; Kjeldsen, H; Korhonen, H; Liebig, C; Lund, M. N; Lundkvist, M; Mancini, L; Martin, R; Mathiasen, M; Rabus, M; Rahvar, S; Ricci, D; Sahu, D. K; Scarpetta, G; Skottfelt, J; Snodgrass, C; Southworth, J; Surdej, J; Tregloan-Reed, J; Vilela, C; Wertz, O; Williams, A (EDP Sciences, 2013-07)
    Aims. We present the analysis of 26 nights of V and I time-series observations from 2011 and 2012 of the globular cluster M 30 (NGC 7099). We used our data to search for variable stars in this cluster and refine the periods ...
  • 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 ...
  • Evolution of the optical spectrum of SN 1987a in the Large Magellanic Cloud 
    Ashoka, B. N; Anupama, G. C; Prabhu, T. P; Giridhar, S; Ghosh, K. K; Jain, S. K; Pati, A. K; Kameswara Rao, N (Indian Academy of Sciences, 1987-06)
    The evolution of the spectrum of SN 1987a is traced from 1987 February 26 to March 31. Based on the low-resolution spectroscopic data the authors identify the lines of H, He I, Na I, Fe II, Sc II, Ca II which are known to ...
  • Exploiting large surveys for galactic astronomy 
    Corbally, C. J; Bailer-Jones, C. A. L; Giridhar, S; Lloyd Evans, T. H (Cambridge University Press, 2007-08)
    This summary of JD13, Exploiting large surveys for Galactic astronomy, is based on the talks that were given during the meeting and/or submitted to the full proceedings which appeared in MemSAI 77 no. 4, 2006. The electronic ...
  • Exploring the variable stars in the globular cluster NGC 5024 (M53): new RR Lyrae and SX Phoenicis stars 
    Arellano Ferro, A; Figuera Jaimes, R; Giridhar, S; Bramich, D. M; Hernández Santisteban, J. V; Kuppuswamy, K (Wiley-Blackwell, 2011-09)
    We report CCD V and I time series photometry of the globular cluster NGC 5024 (M53). The technique of difference image analysis has been used which enables photometric precisions better than 10 mmag for stars brighter than ...
  • Fiber-fed echelle spectrometer of the 2.34 meter Vainu Bappu Telescope 
    Kameswara Rao, N; Sriram, S; Gabriel, F; Prasad, B. R; Samson, J. P. A; Jayakumar, K; Srinivasan, R; Mahesh, P. K; Giridhar, S (Anita Publications, 2004-12)
    The optical design and performance of high resolution fiber-fed echelle spectrometer for the 2.34 meter Vainu Bappu Telescope (VBT) is described. An optical fiber of core 100 J-Lm and length 45 meter is used to link the ...
  • Further spectroscopic observations of SN 1987A 
    Anupama, G. C; Prabhu, T. P; Ghosh, K. K; Ashoka, B. N; Giridhar, S (Elsevier, 1988)
    Spectroscopic observations of SN 1987a obtained during 1987 August 30 – September 8 from Vainu Bappu Observatory, Kavalur, are presented; the spectrum is compared and contrasted with the spectra recorded at earlier epochs. ...
  • 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 ...

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