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Browsing by Author "Sivarani, T"

Browsing by Author "Sivarani, T"

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  • A 10-m class national large optical-IR telescope 
    Anupama, G. C; Maheswar, G; Sriram, S; Sivarani, T; Parihar, P. S; Nagabhushana, S; Angchuk, D; Barway, Sudhanshu; Bhatt, B. C; Banyal, R. K; Basheer, Alikhan; Prasanna, Deshmukh; Divakar, D. K; Dorjai, T; Goswami, A; Govinda, K. V; Jorphail, S; Kamath, U. S; Kemkar, P. M. M; Mahay, T. T; Muneer, S; Muthumariappan, C; Shantikumar, N. S; Pandey, G; Reddy, B. E; Sahu, D. K; Sandeep, D. S; Ramya, S; Stalin, C. S; Subramanian, S; Tsewang, Stanzin; Subramaniam, A (Indian Academy of Science, 2022-06)
    An observatory class national large optical-IR telescope (NLOT), is proposed to be built and located in the country. The telescope consists of a 10–12 m segmented primary. In order to cater to a diversity of observational ...
  • Abundance analysis of a CEMP-no star in the Carina dwarf spheroidal galaxy 
    Susmitha Rani, A; Koch, A; Sivarani, T (EDP Sciences, 2017-10)
    Carbon-enhanced metal-poor (CEMP) stars bear important imprints of the early chemical enrichment of any stellar system. While these stars are known to exist in copious amounts in the Milky Way halo, detailed chemical ...
  • Abundance analysis of new r-process-enhanced stars from the HESP–GOMPA survey 
    Bandyopadhyay, A; Sivarani, T; Beers, C. T (IOP Publishing, 2020-08-10)
    We present a study on the detailed chemical abundances of five new relatively bright r-process-enhanced stars that were initially observed as part of the SDSS/MARVELS pre-survey. These stars were selected, on the basis ...
  • Abundance analysis of SDSS J134338.67+484426.6; an extremely metal-poor star from the MARVELS pre-survey 
    Susmitha Rani, A; Sivarani, T; Beers, T. C; Fleming, S; Mahadevan, S; Ge, J (Oxford University Press on behalf of the Royal Astronomical Society, 2016-05)
    We present an elemental-abundance analysis of an extremely metal-poor (EMP; [Fe/H] <−3.0) star, SDSS J134338.67+484426.6, identified during the course of the Multi-object Apache Point Observatory Radial Velocity Exoplanet ...
  • Activity of the first interstellar comet 2I/Borisov around perihelion: results from Indian observatories 
    Aravind, K; Ganesh, Shashikiran; Venkataramani, Kumar; Sahu, D. K; Angchuk, D; Sivarani, T; Unni, Athira (Oxford University Press on behalf of the Royal Astronomical Society, 2021-04)
    Comet 2I/Borisov is the first true interstellar comet discovered. Here, we present results from observational programs at two Indian observatories, 2 m Himalayan Chandra Telescope at the Indian Astronomical Observatory, ...
  • Age Distribution of Exoplanet Host Stars: Chemical and Kinematic Age Proxies from GAIA DR3 
    Swastik, C; Banyal, R. K; Narang, Mayank; Unni, Athira; Banerjee, Bihan; Manoj, P; Sivarani, T (American Astronomical Society, 2023-09-01)
    The GAIA space mission is impacting astronomy in many significant ways by providing a uniform, homogeneous, and precise data set for over 1 billion stars and other celestial objects in the Milky Way and beyond. Exoplanet ...
  • A and F stars with circumstellar dust 
    Sivarani, T (Indian Institute of Astrophysics, Bangalore, 2000-03)
  • Application of convolutional neural networks for stellar spectral classification 
    Sharma, K; Kembhavi, Ajit; Kembhavi, Aniruddha; Sivarani, T; Abraham, Sheelu; Vaghmare, Kaustubh (Oxford University Press on behalf of the Royal Astronomical Society, 2020-01)
    Due to the ever-expanding volume of observed spectroscopic data from surveys such as SDSS and LAMOST, it has become important to apply artificial intelligence (AI) techniques for analysing stellar spectra to solve spectral ...
  • Atmospheric dispersion corrector for a multi-object spectroscopic mode of HROS-TMT 
    Manjunath, B; Hasan, Amirul; Divakar, Devika; Surya, Arun; Sriram, S; Sivarani, T; Prakash, A; Parvathy, M; Yadav, Sudharsan (SPIE-The International Society for Optical Engineering, 2023-10)
    Highly multiplexed spectroscopic surveys have changed the astronomy landscape in recent years. However, these surveys are limited to low and medium spectral resolution. High spectral resolution spectroscopy is often photon ...
  • 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 ...

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