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Browsing by Author "Sivarani, T"

Browsing by Author "Sivarani, T"

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  • The [Fe/H], [C/Fe], and [α/Fe] Distributions of the Boötes I Dwarf Spheroidal Galaxy 
    Lai, D. K; Lee, Y. S; Bolte, M; Lucatello, S; Beers, T. C; Johnson, J. A; Sivarani, T; Rockosi, C. M (IOP Publishing, 2011-09-01)
    We present the results of a low-resolution spectral abundance study of 25 stars in the Boötes I dwarf spheroidal (dSph) galaxy. The data were obtained with the low resolution imaging spectrometer instrument at Keck Observatory ...
  • Field blue straggler stars: discovery of white dwarf companions to blue metal-poor stars using UVIT/AstroSat 
    Panthi, Anju; Subramaniam, A; Vaidya, Kaushar; Jadhav, Vikrant V; Sharmila Rani; Sivarani, T; Pandey, Sindhu (Oxford University Press on behalf of Royal Astronomical Society, 2023-10)
    Blue metal-poor (BMP) stars are the main-sequence stars that appear bluer and more luminous than normal turn-off stars of metal-poor globular clusters. They are believed to be either field blue straggler stars (FBSS) formed ...
  • First stars. XIII. Two extremely metal-poor RR Lyrae stars 
    Hansen, C. J; Nordström, B; Bonifacio, P; Spite, M; Andersen, J; Beers, T. C; Cayrel, R; Spite, F; Molaro, P; Barbuy, B; Depagne, E; François, P; Hill, V; Plez, B; Sivarani, T (EDP Sciences, 2011-03)
    Context. The chemical composition of extremely metal-poor stars (EMP stars; [Fe/H] < ~ −3) is a unique tracer of early nucleosynthesis in the Galaxy. As such stars are rare, we wish to find classes of luminous stars ...
  • Flexure compensation simulation tool for TMT-WFOS spectrograph 
    Surya, Arun; Radovan, Matthew; Sivarani, T; Sriram, S; Devika, Divakar; Fucik, Jason (SPIE--The International Society for Optical Engineering, 2018-07)
    The Wide Field Optical Spectrograph (WFOS) is one of the first-light instruments of Thirty Meter Telescope. It is a medium resolution, multi object, wide field optical spectrograph. Since 2005 the conceptual design of the ...
  • Galactic Chemical Evolution of Exoplanet Hosting Stars: Are High-mass Planetary Systems Young? 
    Swastik, C; Banyal, R. K; Narang, Mayank; Manoj, P; Sivarani, T; Rajaguru, S. P; Athira Unni; Banerjee, Bihan (American Astronomical Society, 2022-08-01)
    The imprints of stellar nucleosynthesis and chemical evolution of the galaxy can be seen in different stellar populations, with older generation stars showing higher α-element abundances and the later generations ...
  • Globular Cluster UVIT Legacy Survey (GlobULeS) – I. FUV–optical colour–magnitude diagrams for eight globular clusters 
    Sahu, Snehalata; Subramaniam, A; Singh, Gaurav; Yadav, Ramakant; Valcarce, Aldo R; Choudhury, Samyaday; Sharmila Rani; Deepthi, S. Prabhu; Chung, Chul; Cote, Patrick; Leigh, Nathan; Geller, Aaron M; Chatterjee, Sourav; Kameswara Rao, N; Bandyopadhyay, Avrajit; Shara, Michael; Dalessandro, Emanuele; Pandey, G; Postma, Joesph E; Hutchings, John; Simunovic, Mirko; Stetson, Peter B; Sivarani, T; Puzia, Thomas; Sohn, Young-Jong (Oxford University Press on behalf of the Royal Astronomical Society, 2022-07)
    We present the first results of eight globular clusters (GCs) from the AstroSat/UVIT Legacy Survey programme GlobULeS based on the observations carried out in two far-ultraviolet (FUV) filters (F148W and F169M). The ...
  • Globular Cluster UVIT Legacy Survey (GlobULeS). III. Omega Centauri in Far-ultraviolet 
    Deepthi, S. Prabhu; Subramaniam, A; Sahu, Snehalata; Chung, Chul; Leigh, Nathan W. C; Dalessandro, Emanuele; Chatterjee, Sourav; Kameswara Rao, N; Shara, Michael; Cote, Patrick; Choudhury, Samyaday; Pandey, G; Valcarce, Aldo A. R; Singh, G; Postma, Joesph E; Sharmila Rani; Bandyopadhyay, Avrajit; Geller, Aaron M; Hutchings, John; Puzia, Thomas; Simunovic, Mirko; Sohn, Young-Jong; Sivarani, T; Yadav, Ramakant Singh (American Astronomical Society, 2022-11-10)
    We present the first comprehensive study of the most massive globular cluster, Omega Centauri, in the farultraviolet (FUV), extending from the center to ∼28% of the tidal radius using the Ultraviolet Imaging Telescope on ...
  • The Hamburg/ESO R-process Enhanced Star survey (HERES) VIII. The r+s star HE 1405 0822 
    Cui, W. Y; Sivarani, T; Christlieb, N (EDP Sciences, 2013-10)
    Aims. The aim of this study is a detailed abundance analysis of the newly discovered r-rich star HE 1405−0822, which has [Fe/H] = −2.40. This star shows enhancements of both r- and s-elements, [Ba/Fe] = + 1.95 and [Eu/Fe] ...
  • Hanle echelle spectrograph: design and performance 
    Sriram, S; Amit Kumar; Arun Surya; Sivarani, T; Giridhar, S; Kathiravan, S; Anand, M. N; Jones, D; Grobler, D; Jakobsson, R; Anantha, Ch; Athira Unni; Angchuk, D; Tsewang, D; Gyalson, T (SPIE-The International Society for Optical Engineering, 2018-07-06)
    Hanle echelle spectrograph (HESP) is a high resolution, bench mounted, fiber-fed spectrograph at visible wavelengths. The instrument was recently installed at the 2m Himalayan Chandra Telescope (HCT), located at Indian ...
  • HD 105262: a high latitude metal-poor post-AGB. A supergiant with large proper motion 
    Reddy, B. E; Parthasarathy, M; Sivarani, T (European Southern Observatory, 1996-09)
    The large proper motion post-AGB supergiant stars are very rare. HD 105262 is a high galactic latitude (+72deg) A-type star with large proper motion (0.057arcsec/year) and high c1-index. Earlier, it was classified as a ...
  • High resolution spectroscopy of the high latitude rapidly evolving post-AGB star SAO 85766 (= IRAS 18062+2410) 
    Parthasarathy, M; García-Lario, P; Sivarani, T; Manchado, A; Sanz Fernández de Córdoba, L (European Southern Observatory, 2000-05)
    SAO 85766 (b = +20o) is an IRAS source with far-infrared colours similar to planetary nebulae. According to the HDE catalogue, its spectrum in 1940 was that of an A5 star. The UV fluxes and colours derived from data obtained ...
  • High-resolution Infrared Spectrograph for Exoplanet Characterization with the Keck and Thirty Meter Telescopes 
    Mawet, Dimitri; Fitzgerald, Michael; Konopacky, Quinn; Beichman, Charles; Jovanovic, Nemanja; Dekany, Richard; Hover, David; Chisholm, Eric; Ciardi, David; Artigau, Etienne; Banyal, Ravinder; Beatty, Thomas; Benneke, Bjorn; Blake, Geoffrey A; Burgasser, Adam; Canalizo, Gabriela; Chen, Guo; Do, Tuan; Doppmann, Greg; Doyon, Rene; Dressing, Courtney; Fang, Min; Greene, Thomas; Hillenbrand, Lynne; Howard, Andrew; Kane, Stephen; Kataria, Tiffany; Kempton, Eliza; Knutson, Heather; Kotani, Takayuki; Lafreniere, David; Liu, Chao; Nishiyama, Shogo; Pandey, G; Plavchan, Peter; Prato, Lisa; Rajaguru, S. P; Robertson, Paul; Salyk, Colette; Sato, Bun’ei; Schlawin, Everett; Sengupta, S; Sivarani, T; Skidmore, Warren; Tamura, Motohide; Terada, Hiroshi; Vasisht, Gautam; Wang, Ji; Zhang, Hui (American Astronomical Society, 2019-09)
    HISPEC (High-resolution Infrared Spectrograph for Exoplanet Characterization) is a proposed diffractionlimited spectrograph for the W.M. Keck Observatory, and a pathfinder for the MODHIS facility project (Multi-Object ...
  • A high-resolution spectroscopic study of two new Na- and Al-rich field giants–likely globular cluster escapees in the galactic halo 
    Bandyopadhyay, A; Sivarani, T; Beers, T. C; Susmitha Rani, A (Oxford University Press on behalf of the Royal Astronomical Society, 2020-05)
    The stars SDSS J0646+4116 and SDSS J1937+5024 are relatively bright stars that were initially observed as a part of the SDSS/MARVELS pre-survey. They were selected, on the basis of their weak CH G bands, along with a total ...
  • High-resolution spectroscopy of extremely metal-poor stars from SDSS/SEGUE. I. Atmospheric parameters and chemical compositions 
    Aoki, W; Beers, T. C; Lee, Young Sun; Honda, S; Ito, H; Takada-Hidai, M; Frebel, A; Suda, T; Fujimoto, M. Y; Carollo, D; Sivarani, T (IOP Publishing, 2013-01)
    Chemical compositions are determined based on high-resolution spectroscopy for 137 candidate extremely metalpoor (EMP) stars selected from the Sloan Digital Sky Survey (SDSS) and its first stellar extension, the ...
  • Horizons: nuclear astrophysics in the 2020s and beyond 
    Schatz, H; Becerril Reyes, A. D; Best, A; Brown, E. F; Chatziioannou, K; Chipps, K. A; Deibel, C. M; Ezzeddine, R; Galloway, D. K; Hansen, C. J; Herwig, F; Gibson, B. K; Gorda, T; Gourgouliatos, K. N; Graber, V; Gupta, M; Haxton, W. C; Heger, A; Nevins, B; Hix, W. R; Ho, W. C. G; Rebeiro, B. M; Holmbeck, E. M; Hood, A. A; Huth, S; Imbriani, G; Izzard, R. G; Jain, R; Jayatissa, H; Johnston, Z; Newton, W. G; Kajino, T; Reifarth, R; Kankainen, A; Kiss, G. G; Kwiatkowski, A; La Cognata, M; Laird, A. M; Lamia, L; Landry, P; Laplace, E; Launey, K. D; Nguyen, L. Q; Richard, A. L; Leahy, D; Leckenby, G; Lennarz, A; Longfellow, B; Lovell, A. E; Lynch, W. G; Lyons, S. M; Maeda, K; Masha, E; Matei, C; Rijal, N; Nishikawa, K; Merc, J; Messer, B; Montes, F; Mukherjee, A; Nishimura, N; Nunes, F. M; O'Connor, E; O'Shea, B. W; Ji, A. P; Roederer, I. U; Ong, W. J; Pain, S. D; Pajkos, M. A; Pignatari, M; Pizzone, R. G; Placco, V. M; Plewa, T; Pritychenko, B; Psaltis, A; Puentes, D; Rojo, J. S; Lugaro, M; Qian, Y-Z; Radice, D; Rapagnani, D; J. S. K; Meisel, Z; Saito, Y; Schwenk, A; Cote, B; Sergi, M. L; Sidhu, R. S; Simon, A; Sivarani, T; Skuladottir, A; Smith, M. S; Spiridon, A; Sprouse, T. M; Norman, D; Starrfield, S; Caplan, M. E; Steiner, A. W; Strieder, F; Sultana, I; Surman, R; Szucs, T; Tawfik, A; Thielemann, F; Trache, L; Trappitsch, R; Read, J. S; Champagne, A. E; Tsang, M. B; Tumino, A; Upadhyayula, S; Valle Martínez, J. O; Van der Swaelmen, M; Viscasillas Vazquez, C; Watts, A; Wehmeyer, B; Wiescher, M; Wrede, C; Clark, J. A; Roberts, L. F; Yoon, J; Zegers, R. G. T; Zermane, M. A; Zingale, M; Spyrou, A; Timmes, F. X; Travaglio, C; Vassh, V; Abia, C; Couder, M; Adsley, P; Agarwal, S; Aliotta, M; Aoki, W; Arcones, A; Aryan, A; Bandyopadhyay, A; Banu, A; Bardayan, D. W; Barnes, J; Couture, A; Bauswein, A; Beers, T. C; Bishop, J; Boztepe, T; de Mink, S. E; Debnath, S; deBoer, R. J; den Hartogh, J; Mumpower, M. R; Denissenkov, P; Dexheimer, V; Dillmann, I; Escher, J. E; Famiano, M. A; Farmer, R; Fisher, R; Frohlich, C; Frebel, A; Fryer, C; Neto, D; Fuller, G; Ganguly, A. K; Ghosh, S (IOP Publishing, 2022-11)
    Nuclear astrophysics is a field at the intersection of nuclear physics and astrophysics, which seeks to understand the nuclear engines of astronomical objects and the origin of the chemical elements. This white paper ...
  • Host star metallicity of directly imaged wide-orbit planets: implications for planet formation 
    Swastik, C; Banyal, R. K; Narang, Mayank; Manoj, P; Sivarani, T; Reddy, B. E; Rajaguru, S. P (IOP Publishing, 2021-03-01)
    Directly imaged planets (DIPs) are self-luminous companions of pre-main-sequence and young main-sequence stars. They reside in wider orbits (~tens to thousands of astronomical units) and generally are more massive compared ...
  • IIA Newsletter, Vol.15, No.2, June 2010 
    Rajaguru, S. P; Sivarani, T; Rajiva, S (Indian Institute of Astrophysics, 2010-06)
  • IIA Newsletter, Vol.15, No.3, September 2010 
    Rajaguru, S. P; Sivarani, T; Rajiva, S (Indian Institute of Astrophysics, 2010-09)
  • IIA Newsletter, Vol.15, No.4, December 2010 
    Rajaguru, S. P; Sivarani, T; Rajiva, S (Indian Institute of Astrophysics, 2010-12)
  • IIA Newsletter, Vol.16, No.1, March 2011 
    Rajaguru, S. P; Sivarani, T; Rajiva, S (Indian Institute of Astrophysics, 2011-03)

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