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Browsing by Author "Sivarani, T"

Browsing by Author "Sivarani, T"

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  • SDSS-III: Massive Spectroscopic Surveys of the Distant Universe, the Milky Way, and Extra-Solar Planetary Systems 
    Eisenstein, D. J and 243 coauthors; Sivarani, T (IOP Publishing, 2011-09)
    Building on the legacy of the Sloan Digital Sky Survey (SDSS-I and II), SDSS-III is a program of four spectroscopic surveys on three scientific themes: dark energy and cosmological parameters, the history and structure of ...
  • A Search for Unrecognized Carbon-Enhanced Metal-Poor Stars 
    Placco, V. M; Kennedy, C. R; Rossi, S; Beers, T. C; Christlieb, N; Sivarani, T (Cambridge University Press, 2010-03)
    We have developed a new procedure to search for Carbon-Enhanced Metal-Poor (CEMP) stars from the Hamburg/ESO (HES) prism-survey plates. This method uses an extended line index for the CH G-band, which we demonstrate to ...
  • A search for unrecognized carbon-enhanced metal-poor stars in the galaxy 
    Placco, V. M; Kennedy, C. R; Rossi, S; Beers, T. C; Lee, Y. S; Christlieb, N; Sivarani, T; Reimers, D; Wisotzki, L (Institute of Physics, 2010-03)
    We have developed a new procedure to search for carbon-enhanced metal-poor (CEMP) stars from the Hamburg/ESO (HES) prism-survey plates. This method employs an extended line index for the CH G band, which we demonstrate to ...
  • Searches for Metal-poor Stars from the Hamburg/ESO Survey Using the CH G Band 
    Placco, V. M; Kennedy, C. R; Beers, T. C; Christlieb, N; Rossi, S; Sivarani, T; Lee, Young Sun; Reimers, D; Wisotzki, L (IOP Publishing, 2011-12)
    We describe a new method to search for metal-poor candidates from the Hamburg/ESO objective-prism survey (HES) based on identifying stars with apparently strong CH G-band strengths for their colors. The hypothesis we exploit ...
  • The SEGUE Stellar Parameter Pipeline. IV. Validation with an Extended Sample of Galactic Globular and Open Clusters 
    Smolinski, J. P; Lee, Y. S; Beers, T. C; An, D; Bickerton, S. J; Johnson, J. A; Loomis, C. P; Rockosi, C. M; Sivarani, T; Yanny, B (IOP Publishing, 2011-03)
    Spectroscopic and photometric data for likely member stars of five Galactic globular clusters (M3, M53, M71, M92, and NGC 5053) and three open clusters (M35, NGC 2158, and NGC 6791) are processed by the current version of ...
  • The SEGUE Stellar Parameter Pipeline. V. Estimation of Alpha-element Abundance Ratios from Low-resolution SDSS/SEGUE Stellar Spectra 
    Lee, Y. S; Beers, T. C; Prieto, C. A; Lai, D. K; Rockosi, C. M; Morrison, H. L; Johnson, J. A; An, D; Sivarani, T; Yanny, B (IOP Publishing, 2011-03)
    We present a method for the determination of [α/Fe] ratios from low-resolution (R = 2000) SDSS/SEGUE stellar spectra. By means of a star-by-star comparison with degraded spectra from the ELODIE spectral library and with a ...
  • Simulating medium-spectral-resolution exoplanet characterization with SCALES angular/reference differential imaging 
    Desai, Aditi; Sallum, Stephanie E; Banyal, R. K; Batalha, Natalie; Batalha, Natasha; Blake, Geoff; Brandt, Tim; Briesemeister, Zack; Kleer, Katherine de; Pater, Imke de; Eisner, Josh; Fong, Wen-fai; Greene, Tom; Honda, Mitsuhiko; Kain, Isabel; Kilpatrick, Charlie; Lach, Mackenzie; Liu, Mike; Macintosh, Bruce; Martinez, Raquel A; Mawet, Dimitri; Miles, Brittany; Morley, Caroline; Powell, Diana; Sheehan, Patrick; Skemer, Andrew J; Spilker, Justin; Stelter, R. Deno; Stone, Jordan; Surya, Arun; Sivarani, T; Wagner, Kevin; Zhou, Yifan (SPIE-The International Society for Optical Engineering, 2023-10)
    SCALES (Slicer Combined with Array of Lenslets for Exoplanet Spectroscopy) is a 2 - 5 micron high-contrast lenslet-based integral field spectrograph (IFS) designed to characterize exoplanets and their atmospheres. The SCALES ...
  • The slicer combined with array of lenslets for exoplanet spectroscopy (SCALES): driving science cases and expected outcomes 
    Sallum, Steph; Skemer, Andrew; Stelter, Deno; 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; Jensen-Clem, Rebecca; Kain, Isabel; Kilpatrick, Charlie; Kupke, Renate; Lach, Mackenzie; Liu, Michael C; Macintosh, Bruce; Martinez, Raquel A; Mawet, Dimitri; Miles, Brittany; Morley, Caroline; Powell, Diana; Sethuram, Ramya; Sheehan, Patrick; Spilker, Justin; Stone, Jordan; Surya, Arun; Sivarani, T; Unni, Athira; 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 a 2 − 5 µm, high-contrast integral field spectrograph (IFS) currently being built for Keck Observatory. With both low (R ≲ 250) and medium ...
  • Spectroscopic observations of first ISOGAL sources 
    Ojha, D. K; Sivarani, T; Parthasarathy, M; Omont, A; Ganesh, S; Simon, G (Astronomical Society of India, 2000)
    Infrared Space Observatory Galactic (ISOGAL) survey at 7 and 15 μm of ~ 22 deg2 of the inner galactic disk and bulge, has detected several hundred thousand sources. Combining ISOGAL survey with I, J, H, Ks data of DENIS ...
  • Spectroscopic study of stars with dusty disks 
    Sivarani, T; Parthasarathy, M (2004)
    We have selected several stars with far-IR (IRAS)fluxes indicating the presence of circumstellar dust shells and disks. In this paper we present an analysis of the spectra of these stars. In several of these stars we find ...
  • Spectroscopy of HD 168625 (IRAS 18184-1623) 
    García, L. P; Sivarani, T; Parthasarathy, M; Manchado, A (Kluwer Academic Publishers, 2001-08)
    HD 168625 (B9-A0 Ia) was classified as a post-AGB star and also as a luminous blue variable. We have analysed the high resolution optical spectra of HD 168625 and derived the atmospheric parameters and the chemical ...
  • Spectroscopy of post-AGB a-supergiant HD 101584 (IRAS 11385-5517) 
    Sivarani, T; Parthasarathy, M; García, L. P; Manchado, A; Pottasch, S. R (Kluwer Academic Publishers, 2001-08)
    In the high resolution optical spectra we identified forbidden lines of [OI] and [CI], which indicate the presence of low excitation nebula. There are many emission lines due forbidden and permitted lines of neutral and ...
  • Spectroscopy of post-AGB candidate HD 331319 (IRAS 19475+3119) 
    Sivarani, T; Parthasarathy, M; García, L. P; Manchado, A (Kluwer Academic Publishers, 2001-08)
    HD 331319 is a F3 Ib star with a detached cold circumstellar dust shell with far-IR colours similar to planetary nebulae. From an analysis of high resolution spectra using LTE stellar atmospheric models, we have derived ...
  • Spectroscopy of post-AGB candidate IRAS 10215-5916 
    Sivarani, T; Parthasarathy, M; García, L. P; Manchado, A (Kluwer Academic Publishers, 2001-08)
    IRAS 10215-5916 was classified as a post-AGB star and also as a massive red supergiant. It was also found to be a spectroscopic binary. In our high resolution spectra we found molecular features from a cool star of Teff = ...
  • Spectroscopy of the post-AGB star HD 101584 (IRAS 11385-5517) 
    Sivarani, T; Parthasarathy, M; García-Lario, P; Manchado, A; Pottasch, S. R (The European Southern Observatory, 1999-06)
    From an analysis of the spectrum (4000 Ä to 8800 Ä) of HD 101584 it is found that most of the neutral and single ionized metallic lines are in emission. The forbidden emission lines of [OI] 6300 Ä and 6363 Ä and [CI] 8727 ...
  • The Stability of Fiber Spectrographs in the Faint-source Regime 
    Bundy, Kevin; Law, David; MacDonald, Nick; Westfall, Kyle B.; Sivarani, T; Divakar, Devika; Bershady, Matthew; Gu, Meng; Yan, Renbin; Roy, Namrata; Poppett, Claire; Drory, Niv (American Astronomical Society, 2022-09-01)
    The use of optical fibers in astronomical instrumentation offers high-multiplex and light-gathering flexibility. However, with most previous fiber spectrographs optimized for large fields of view on modest-aperture telescopes, ...
  • Stellar Relics from the Early Galaxy 
    Sivarani, T (Indian Academy of Sciences, 2013-03)
    We reviewed the recent progress in the field of stellar/galactic archeology, which is a study of the relics from the early galaxy. The oldest and most pristine objects that can be observed in the galaxy are the low mass ...
  • Target selection for the SDSS-III marvels survey 
    Paegert, M; Stassun, K. G; De Lee, N; Pepper, J; Fleming, S. W; Sivarani, T; Mahadevan, S; Mack, C. E; Dhital, S; Hebb, L; Ge, J (IOP Publishing, 2015-06)
    We present the target selection process for the Multi-object APO Radial Velocity Exoplanets Large-area Survey (MARVELS), which is part of the Sloan Digital Sky Survey (SDSS) III. MARVELS is a medium-resolution (R ∼ 11,000) ...
  • The TESS-Keck Survey. VIII. Confirmation of a Transiting Giant Planet on an Eccentric 261 Day Orbit with the Automated Planet Finder Telescope 
    Dalba, Paul A; Kane, Stephen R; Dragomir, Diana; Villanueva Jr, Steven; Collins, Karen A; Jacobs, Thomas Lee; LaCourse, Daryll M; Gagliano, Robert; Kristiansen, Martti H; Omohundro, Mark; Schwengeler, Hans M; Terentev, Ivan A; Vanderburg, Andrew; Fulton, Benjamin; Isaacson, Howard; Zandt, Judah Van; Howard, Andrew W; Thorngren, Daniel P; Howell, Steve B; Batalha, Natalie M; Chontos, Ashley; Crossfield, Ian J. M; Dressing, Courtney D.; Huber, Daniel; Petigura, Erik A.; Robertson, Paul; Roy, Arpita; Weiss, Lauren M; Behmard, Aida; Beard, Corey; Brinkman, Casey L; Giacalone, Steven; Hil, Michelle L; Lubin, Jack; Mayo, Andrew W; Mocnik, Teo; Murphy, Joseph M. Akana; Polanski, Alex S; Rice, Malena; Rosenthal, Lee J; Rubenzahl, Ryan A; Scarsdale, Nicholas; Turtelboom, Emma V; Tyler, Dakotah; Benni, Paul; Boyce, Pat; Esposito, Thomas M; Girardin, E; Laloum, Didier; Lewin, Pablo; Mann, Christopher R; Marchis, Franck; Schwarz, Richard P; Srdoc, Gregor; Steuer, Jana; Sivarani, T; Athira Unni; Eisner, Nora L; Fetherolf, Tara; Li, Zhexing; Yao, Xinyu; Pepper, Joshua; Ricker, George R.; Vanderspek, Roland; Latham, David W; Seager, S.; Winn, Joshua N; Jenkins, Jon M; Burke, Christopher J; Eastman, Jason D; Lund, Michael B; Rodriguez, David R; Rowden, Pamela; Ting, Eric B; Villaseñor, Jesus Noel (American Astronomical Society, 2022-02-01)
    We report the discovery of TOI-2180 b, a 2.8 MJ giant planet orbiting a slightly evolved G5 host star. This planet transited only once in Cycle 2 of the primary Transiting Exoplanet Survey Satellite (TESS) mission. Citizen ...
  • Towards the development of the Infrared Guide Star Catalogue for the adaptive optics observations by the Thirty Meter Telescope 
    Shah, Sarang; Subramanian, S; Anupama, G. C; Delgado, Francisco; Gillies, Kim; Maheswar, G; Narayanan, Rajalakshmi; Ramaprakash, A. N; Rao, Suhasini; Reddy, B. E; Skidmore, Warren; Sivarani, T; Subramaniam, A (SPIE-The International Society for Optical Engineering, 2022-08)
    At first light, the NIR instruments of TMT will be assisted by a multi-conjugate adaptive optics instrument, known as the Narrow Field Infrared Adaptive Optics System (NFIRAOS). NFIRAOS will use laser guide stars for ...

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