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Browsing by Author "Sivarani, T"

Browsing by Author "Sivarani, T"

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  • Carbon Abundance of Stars in the LAMOST-Kepler Field 
    Athira Unni; Narang, Mayank; Sivarani, T; Puravankara, Manoj; Banyal, R. K; Surya, Arun; Rajaguru, S. P; Swastik, C (American Astronomical Society, 2022-11-01)
    The correlation between host star iron abundance and the exoplanet occurrence rate is well established and arrived at in several studies. Similar correlations may be present for the most abundant elements, such as carbon ...
  • Carbon Abundances From SDSS Globular Clusters: Exploring the Origin in the Large Spread in [C/Fe] 
    Fiorenza, S. L; Sivarani, T; Susmitha, A; Lee, Y. S; Beers, T. C (Societa Astronomica Italiana, 2013)
    Globular clusters were once thought to be chemically homogeneous systems with a single stellar population. However, recent results suggest the presence of more than one stellar population among most all globular clusters. ...
  • Carbon-Enhanced Metal-Poor Stars in SDSS/Segue. I. Carbon Abundance Estimation and Frequency of CEMP Star 
    Lee, Y. S; Beers, T. C; Masseron, T; Plez, B; Rockosi, C. M; Sobeck, J; Yanny, B; Lucatello, S; Sivarani, T; Placco, V. M; Carollo, D (IOP Publishing, 2013-11)
    We describe a method for the determination of stellar [C/Fe] abundance ratios using low-resolution (R = 2000) stellar spectra from the Sloan Digital Sky Survey (SDSS) and its Galactic sub-survey, the Sloan Extension for ...
  • Carbon-enhanced Metal-poor Stars in the Inner and Outer Halo Components of the Milky Way 
    Carollo, D; Beers, T. C; Bovy, Jo; Sivarani, T; Norris, J. E; Freeman, K. C; Aoki, W; Lee, Young Sun; Kennedy, C. R (IOP Publishing, 2012-01-10)
    Carbon-enhanced metal-poor (CEMP) stars in the halo components of the Milky Way are explored, based on accurate determinations of the carbon-to-iron ([C/Fe]) abundance ratios and kinematic quantities for over 30,000 ...
  • The Case for the Dual Halo of the Milky Way 
    Beers, T. C; Carollo, D; Ivezic, Z; An, D; Chiba, M; Norris, J. E; Freeman, K. C; Lee, Young Sun; Munn, J. F; Re Fiorentin, P; Sivarani, T; Wilhelm, R; Yanny, B; York, D. G (IOP Publishing, 2012-02-10)
    Carollo et al. have recently resolved the stellar population of the Milky Way halo into at least two distinct components, an inner halo and an outer halo. This result has been criticized by Schönrich et al., who claim that ...
  • Chemical Composition of Two Bright, Extremely Metal-poor Stars from the SDSS MARVELS Pre-survey 
    Bandyopadhyay, A; Sivarani, T; Susmitha, A; Beers, T. C; Giridhar, S; Arun Surya; Masseron, T (IOP Publishing, 2018-06-01)
    SDSS J082625.70+612515.10 (V = 11.4; [Fe/H] = −3.1) and SDSS J134144.60+474128.90 (V = 12.4; [Fe/H] = −3.2) were observed with the SDSS 2.5m telescope as part of the SDSS MARVELS spectroscopic pre-survey and identified ...
  • Decoding the compositions of four bright r-process-enhanced stars 
    Saraf, Pallavi; Prieto, Carlos Allende; Sivarani, T; Bandyopadhyay, A; Beers, Timothy C.; Susmitha, A (Oxford University Press on behalf of Royal Astronomical Society, 2023-10)
    There has been a concerted effort in recent years to identify the astrophysical sites of the r-process that can operate early in the galaxy. The discovery of many r-process-enhanced (RPE) stars (especially by the R-process ...
  • Design and development of WFOS, the Wide-Field Optical Spectrograph for the Thirty Meter Telescope 
    Steidel, Charles; Peng, Eric; Fucik, Jason; Nash, Reston; Kaye, Stephen; Jacoby, George; Delabre, Bernard; Ramya, S; Divakar, Devika; Varshney, Hari Mohan; Sivarani, T; Uraguchi, Fumihiro; Ozaki, Shinobu; Ji, Hangxin; Tao, L V; Chiu, Kent; Zhu, Qinfeng; Andersen, David; Miles, John; Lasi, Davide (SPIE-The International Society for Optical Engineering, 2022-08)
    We present the current design of WFOS, a wide-field UV/optical (0.31-1.0 µm) imaging spectrograph planned for first-light on the TMT International Observatory 30 m telescope. WFOS is optimized for high sensitivity across ...
  • Design of an IR imaging channel for the Keck Observatory SCALES instrument 
    Banyal, R. K; Hasan, Armirul; Kupke, Reni; Varshney, Hari Mohan; Prakaesh, Ajin; Sivarani, T; Skemer, Andy J; MacDonald, Nick; Sallum, Steph; Deich, Will; Fitzgerald, Michael P; Govinda, K. V; Ratliff, Chris; Ramya, S; Stelter, Deno; Surya, Arun; Wang, Eric (SPIE-The International Society for Optical Engineering, 2022-08)
    A next-generation instrument named, Slicer Combined with Array of Lenslets for Exoplanet Spectroscopy (SCALES), is being planned for the W. M. Keck Observatory. SCALES will have an integral field spectrograph (IFS) and a ...
  • Design of SCALES: a 2-5 micron coronagraphic integral field spectrograph for Keck Observatory 
    Skemer, Andrew J; Stelter, R. Deno; Sallum, Stephanie; MacDonald, Nicholas; Kupke, Renate; Ratliff, Christopher; Banyal, R. K; Hasan, Amirul; Varshney, Hari Mohan; Surya, Arun; Prakaesh, Ajin; Sivarani, T; Ramya, S; Govinda, K. V; Fitzgerald, Michael P; Wang, Eric; Kassis, Marc; Absil, Olivier; Alvarez, Carlos; Batalha, Natasha; Boucher, Marc-Andre; Bourgenot, Cyril; Brandt, Timothy; Briesemeister, Zackery; Kleer, Katherine de; Pater, Imke de; Deich, William; Divakar, Devika; Filion, Guillaume; Gauvin, Etienne; Gonzales, Michael; Greene, Thomas; Hinz, Philip; Jensen-Clem, Rebecca; Johnson, Christopher; Kain, Isabel; Kruglikov, Gabriel; Lach, Mackenzie; Landry, Jean-Thomas; Li, Jialin; Liu, Michael C; Lyke, James; Magnon, Kenneth; Marin, Eduardo; Martin, Emily; Martinez, Raquel; Mawet, Dimitri; Miles, Brittany; Sandford, Dale; Sheehan, Patrick; Sohn, Ji Man; Stone, Jordan (SPIE-The International Society for Optical Engineering, 2022-08)
    We present the design of SCALES (Slicer Combined with Array of Lenslets for Exoplanet Spectroscopy) a new 2-5 micron coronagraphic integral field spectrograph under construction for Keck Observatory. SCALES enables ...
  • Designing custom medium resolution observing modes to trace planet accretion with SCALES 
    Martinez, Raquel A; Sallum, Steph; Banyal, R. K; Batalha, Natalie; Batalha, Natasha; Blake, Geoff; Brandt, Tim; Briesemeister, Zack; Kleer, Katherine de; Pater, Imke de; Desai, Aditi; Eisner, Josh; Fong, Wen-fai; Greene, Tom; Honda, Mitsuhiko; Kain, Isabel; Kilpatrick, Charlie; Kupke, Renate; Lach, Mackenzie; Liu, Mike; Macintosh, Bruce; Mawet, Dimitri; Miles, Brittany; Morley, Caroline; Powell, Diana; Sheehan, Patrick; Skemer, Andrew J; Spilker, Justin; Stelter, Deno; Stone, Jordan; Surya, Arun; Sivarani, T; Wagner, Kevin; Zhou, Yifan (SPIE-The International Society for Optical Engineering, 2023-10)
    The Slicer Combined with Array of Lenslets for Exoplanet Spectroscopy (SCALES) is an under-construction thermal infrared high-contrast integral field spectrograph that will be located at the W. M. Keck Observatory. SCALES ...
  • Detecting Outliers in SDSS using Convolutional Neural Network 
    Sharma, K; Kembhavi, Ajit; Kembhavi, Aniruddha; Sivarani, T; Abraham, S. (Societe Royale des Sciences de Liege, 2019-10)
    We propose an automated algorithm based on Convolutional Neural Network (CNN) for the detection of peculiar objects in large databases using their spectral observations. A convolutional neural network is a class of ...
  • Development of a stabilized fabry-perot based wavelength calibrator for precision doppler spectroscopy 
    Tanya, Das; Banyal, R. K; Kathiravan, S; Sivarani, T; Ravindra, B (SPIE-The International Society for Optical Engineering, 2018-07-06)
    Precision Doppler spectroscopy serves as an important tool for Radial Velocity (RV) observations of stars. High precision spectroscopy is bound by two major challenges, first being the instrument instability which is ...
  • The development of HISPEC for Keck and MODHIS for TMT: science cases and predicted sensitivities 
    Konopacky, Quinn M; Baker, Ashley D; Mawet, Dimitri; Fitzgerald, Michael P; Jovanovic, Nemanja; Beichman, Charles; Ruane, Garreth; Bertz, Rob; Terada, Hiroshi; Dekany, Richard; Lingvay, Larry; Kassis, Marc; Anderson, David; Tamura, Motohide; Benneke, Bjorn; Beatty, Thomas; Do, Tuan; Nishiyama, Shogo; Plavchan, Peter; Wang, Jason; Wang, Ji; Burgasser, Adam; Ruffio, Jean-Baptiste; Zhang, Huihao; Brown, Aaron; Fucik, Jason; Gibbs, Aidan; Gibson, Rose; Halverson, Sam; Johnson, Christopher; Karkar, Sonia; Kotani, Takayuki; Kress, Evan; Leifer, Stephanie; Magnone, Kenneth; Maire, Jerome; Pahuja, Rishi; Porter, Michael; Roberts, Mitsuko; Sappey, Ben; Thorne, Jim; Wang, Eric; Artigau, Etienne; Blake, Geoffrey A; Canalizo, Gabriela; Chen, Guo; Doppmann, Greg; Doyon, Rene; Dressing, Courtney; Fang, Min; Greene, Thomas; Herczeg, Greg; Hillenbrand, Lynne; Howard, Andrew; Kane, Stephen; Kataria, Tiffany; Kempton, Eliza; Knutson, Heather; Lafrenière, David; Liu, Chao; Metchev, Stanimir; Millar-Blanchaer, Max; Narita, Norio; Pandey, G; Rajaguru, S. P; Robertson, Paul; Salyk, Colette; Sato, Bun’ei; Schlawin, Evertt; Sengupta, S; Sivarani, T; Skidmore, Warren; Vasisht, Gautam; Yasui, Chikako; Zhang, Hui (SPIE-The International Society for Optical Engineering, 2023-10)
    HISPEC is a new, high-resolution near-infrared spectrograph being designed for the W.M. Keck II telescope. By offering single-shot, R 100,000 spectroscopy between 0.98 – 2.5 µm, HISPEC will enable spectroscopy of transiting ...
  • Discovery of a Low-mass Companion to a Metal-rich F Star with the MARVELS Pilot Project 
    Fleming, S. W; Ge, J; Mahadevan, S; Lee, B; Eastman, J. D; Siverd, R. J; Gaudi, B. S; Niedzielski, A; Sivarani, T; Stassun, K. G; Wolszczan, A; Barnes, R; Gary, B; Nguyen, Duy Cuong; Morehead, R. C; Wan, X; Zhao, B; Liu, J; Guo, P; Kane, S. R; van Eyken, J. C; Lee, N. M. D; Crepp, J. R; Shelden, A. C; Laws, C; Wisniewski, J. P; Schneider, D. P; Pepper, J; Snedden, S. A; Pan, K; Bizyaev, D; Brewington, H; Malanushenko, O; Malanushenko, V; Oravetz, D; Simmons, A; Watters, S (IOP Publishing, 2010-08-01)
    We report the discovery of a low-mass companion orbiting the metal-rich, main sequence F star TYC 2949-00557-1 during the Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS) pilot project. The host star ...
  • Early time optical spectroscopy of supernova SN 1998S 
    Anupama, G. C; Sivarani, T; Pandey, G (EDP Sciences, 2001-02)
    We present medium-resolution optical spectra of the type II supernova SN 1998S obtained during the pre-maximum, maximum and early decline phases. The early decline spectra show complex Balmer line profiles: a narrow P-Cygni ...
  • The Eighth Data Release of the Sloan Digital Sky Survey: First Data from SDSS-III 
    Aihara, H; Allende Prieto, C; An, D; Anderson, S. F; Aubourg, E; Balbinot, E; Beers, T. C; Berlind, A. A; Bickerton, S. J; Bizyaev, D; Blanton, M. R; Gillespie, B. A; Pan, K; Gilmore, G; González Hernández, J. I; Bochanski, J. J; Gott, J. R; Gould, A; Grebel, E. K; Mullally, F; Gunn, J. E; Phleps, S; Hamilton, J; Harding, P; Carr, M. A; Harris, D. W; Hawley, S. L; Hearty, F. R; Nichol, R. C; Ho, S; Hogg, D. W; Holtzman, J. A; Davenport, J. R. A; Honscheid, K; Muna, D; Inada, N; Pandey, P; Ivans, I. I; Jiang, L; Johnson, J. A; Jordan, C; O'Connell, R. W; Jordan, W. P; Pichon, C; Kazin, E. A; Kirkby, D; Klaene, M. A; Knapp, G. R; Paris, I; Munn, J. A; Kneib, J; Kochanek, C. S; Koesterke, L; Kollmeier, J. A; Pieri, M. M; Ogando, R. L. C; Kron, R. G; Lampeitl, H; Lang, D; Le Goff, J; Bolton, A. S; Lee, Y. S; Lin, Y; Murayama, H; Long, D. C; Chen, Y; Loomis, C. P; Lucatello, S; Olmstead, M. D; Lundgren, B; Lupton, R. H; Ma, Z; Percival, W. J; MacDonald, N; Mahadevan, S; Maia, M. A. G; Prada, F; Makler, M; Myers, A. D; Malanushenko, E; Malanushenko, V; Oravetz, D. J; Mandelbaum, R; Maraston, C; Petitjean, P; Margala, D; Masters, K. L; Price-Whelan, A. M; McBride, C. K; McGehee, P. M; McGreer, I. D; Ménard; Naugle, T; Fausti Neto, A; Padmanabhan, N; Palanque-Delabrouille, N; Pfaffenberger, R; Pforr, J; Raddick, M. J; Bovy, J; Ramos, B. H. F; Esposito, M; Reyle, C; Rich, J; Miralda-Escudé, J; Richards, G. T; Rix, H; Robin, A. C; Chiappini, C; Rocha-Pinto, H. J; Rockosi, C. M; Roe, N. A; Cuong Nguyen, D; Rollinde, E; Brandt, W. N; Ross, A. J; Dawson, K; Ross, N. P; Rossetto, B. M; Sánchez, A. G; Sayres, C; Comparat, J; Schlegel, D. J; Evans, M. L; Schlesinger, K. J; Schmidt, S. J; Schneider, D. P; Sheldon, E; Dhital, S; Brinkmann, J; Shu, Y; Simmerer, J; Simmons, A. E; Sivarani, T; Fan, X; Connolly, N; Snedden, S. A; Sobeck, J. S; Steinmetz, M; Strauss, M. A; Ealet, A; Szalay, A. S; Tanaka, M; Brown, P. J; Thakar, A. R; Morrison, H. L; Thomas, D; Tinker, J. L; Cortes, M; Tofflemire, B. M; Tojeiro, R; Tremonti, C. A; Ebelke, G. L; Vandenberg, J; Vargas Magaña, M; Verde, L; Femenía Castellá, B; Vogt, N. P; Brownstein, J. R; Wake, D. A; Wang, J; Croft, R. A. C; Weaver, B. A; Weinberg, D. H; Edmondson, E. M; White, M; White, S. D. M; Font-Ribera, A; Yanny, B; Yasuda, N; Yeche, C; Zehavi, I; Busca, N. G; Campbell, H; Cuesta, A. J; da Costa, L. N; Eisenstein, D. J; Escoffier, S; Frinchaboy, P. M; Ge, J (IOP Publishing, 2011-04)
    The Sloan Digital Sky Survey (SDSS) started a new phase in 2008 August, with new instrumentation and new surveys focused on Galactic structure and chemical evolution, measurements of the baryon oscillation feature in the ...
  • The eleventh and twelfth data releases of the sloan digital sky survey: final data from SDSS-III 
    Alam, S; Albareti, F. D; Prieto, C. A; Anders, F; Anderson, S. F; Anderton, T; Andrews, B. H; Armengaud, E; Aubourg, E; Bailey, S; Basu, S; Bautista, J. E; Beaton, R. L; Beers, T. C; Bender, C. F; Berlind, A. A; Beutler, F; Bhardwaj, V; Bird, J. C; Bizyaev, D; Blake, C. H; Blanton, M. R; Blomqvist, M; Bochanski, J. J; Bolton, A. S; Bovy, J; Bradley, A. S; Brandt, W. N; Brauer, D. E; Brinkmann, J; Brown, P. J; Brownstein, J. R; Burden, A; Burtin, E; Busca, N. G; Cai, Z; Capozzi, D; Rosell, A. C; Carr, M. A; Carrera, R; Chambers, K. C; Chaplin, W. J; Chen, Y-C; Chiappini, C; Chojnowski, S. D; Chuang, C-H; Clerc, N; Comparat, J; Covey, K; Croft, R. A. C; Cuesta, A. J; Cunha, K; da Costa, L. N; Da Rio, N; Davenport, J. R. A; Dawson, K. S; De Lee, N; Delubac, T; Deshpande, R; Dhital, S; Dutra-Ferreira, L; Dwelly, T; Ealet, A; Ebelke, G. L; Edmondson, E. M; Eisenstein, D. J; and 237 coauthors; Sivarani, T (IOP Publishing, 2015-07-20)
    The third generation of the Sloan Digital Sky Survey (SDSS-III) took data from 2008 to 2014 using the original SDSS wide-field imager, the original and an upgraded multi-object fiber-fed optical spectrograph, a new ...
  • Erratum: "The Eighth Data Release of the Sloan Digital Sky Survey: First Data from SDSS-III" (2011, ApJS, 193, 29) 
    Aihara, H and 178 coauthors; Sivarani, T (IOP Publishing, 2011-08)
  • 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 ...

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