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Browsing by Author "Beers, T. C"

Browsing by Author "Beers, T. C"

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  • 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 ...
  • 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 ...
  • 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 ...
  • 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 ...
  • A high-resolution spectral analysis of three carbon-enhanced metal-poor stars 
    Goswami, A; Aoki, W; Beers, T. C; Christlieb, N; Norris, J. E; Ryan, S. G; Tsangarides, S (Blackwell Publishing, 2006-09)
    We present results of an analysis of high-resolution spectra obtained with the Subaru Telescope High Dispersion Spectrograph, of two Carbon-Enhanced Metal-Poor stars, HE 1305+0007 and HE 1152-0355, and of the classical CH ...
  • 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 ...
  • Making Good Use of Bad Weather: Finding Extremely Metal-Poor Stars in the Clouds 
    Placco, V. M; Beers, T. C; Rossi, S; Kennedy, C; Christlieb, N; Lee, Y. S; Sivarani, T (Astronomical Society of the Pacific, 2012-12)
    Current results are presented for a new survey effort to search for Extremely Metal-Poor (EMP) and Carbon Enhanced Metal-Poor (CEMP) stars from the Hamburg / ESO objective-prism survey (HES). These stars are important ...
  • The metal-poor end of the Spite plateau I. Stellar parameters, metallicities, and lithium abundances 
    Sbordone, L; Bonifacio, P; Caffau, E; Ludwig, H. -G; Behara, N. T; González Hernández, J. I; Steffen, M; Cayrel, R; Freytag, B; Van’t Veer, C; Molaro, P; Plez, B; Sivarani, T; Spite, M; Spite, F; Beers, T. C; Christlieb, N; François, P; Hill, V (EDP Sciences, 2010-11)
    Context. The primordial nature of the Spite plateau is at odds with the WMAP satellite measurements, implying a primordial Li production at least three times higher than observed. It has also been suggested that A(Li) might ...
  • The metal–poor end of the Spite plateau 
    Sbordone, L; Bonifacio, P; Caffau, E; Ludwig, H. -G; Behara, N; Gonzalez-Hernandez, J. I; Steffen, M; Cayrel, R; Freytag, B; Van't Veer, C; Molaro, P; Plez, B; Sivarani, T; Spite, M; Spite, F; Beers, T. C; Christlieb, N; François, P; Hill, V (Cambridge University Press, 2010-03)
    We present the largest sample available to date of lithium abundances in extremely metal poor (EMP) Halo dwarfs. Four Teff estimators are used, including IRFM and Hα wings fitting against 3D hydrodynamical synthetic ...
  • The metal–poor end of the Spite plateau: gravity sensitivity of the Hα wings fitting. 
    Sbordone, L; Bonifacio, P; Caffau, E; Ludwig, H. -G; Behara, N; Gonzalez-Hernandez, J. I; Steffen, M; Cayrel, R; Freytag, B; Van't Veer, C; Molaro, P; Plez, B; Sivarani, T; Spite, M; Spite, F; Beers, T. C; Christlieb, N; François, P; Hill, V (Cambridge University Press, 2010-04)
    We recently presented (Sbordone et al., 2009a) the largest sample to date of lithium abundances in extremely metal-poor (EMP) Halo dwarf and Turn-Off (TO) stars. One of the most crucial aspects in estimating Li abundances ...
  • The Milky Way Tomography with SDSS. III. Stellar Kinematics 
    Bond, N. A; Ivezić, Z; Sesar, B; Jurić, M; Munn, J. A; Kowalski, A; Loebman, S; Roškar, R; Beers, T. C; Dalcanton, J; Rockosi, C. M; Yanny, B; Newberg, H. J; Prieto, C. A; Wilhelm, R; Lee, Y. S; Sivarani, T; Majewski, S. R; Norris, J. E; Bailer-Jones, C. A. L; Fiorentin, P. R; Schlegel, D; Uomoto, A; Lupton, R. H; Knapp, G. R; Gunn, J. E; Covey, K. R; Smith, J. A; Miknaitis, G; Doi, M; Tanaka, M; Fukugita, M; Kent, S; Finkbeiner, D; Quinn, T. R; Hawley, S; Anderson, S; Kiuchi, F; Chen, A; Bushong, J; Sohi, H; Haggard, D; Kimball, A; McGurk, R; Barentine, J; Brewington, H; Harvanek, M; Kleinman, S; Krzesinski, J; Long, D; Nitta, A; Snedden, S; Lee, B; Pier, J. R; Harris, H; Brinkmann, J; Schneider, D. P (IOP Publishing, 2010-06-10)
    We study Milky Way kinematics using a sample of 18.8 million main-sequence stars with r < 20 and proper-motion measurements derived from Sloan Digital Sky Survey (SDSS) and POSS astrometry, including ~170,000 stars with ...
  • Near-IR Spectroscopy of CEMP Stars with SOAR/OSIRIS 
    Kennedy, C. R; Sivarani, T; Beers, T. C; Rossi, S; Placco, V. M; Johnson, J; Masseron, T (Cambridge University Press, 2010-03)
    We report on medium-resolution near-IR spectroscopy of a sample of over 60 Carbon- Enhanced Metal-Poor (CEMP) stars observed with SOAR/OSIRIS, selected from the HK survey of Beers and colleagues and the Hamburg/ESO Survey ...
  • A New Technique for Solar Imaging Spectro-polarimetry using Shack-Hartmann and Fabry-Perot 
    Placco, V. M; Beers, T. C; Rossi, S; Kennedy, C; Christlieb, N; Lee, Y. S; Sivarani, T (Astronomical Society of the Pacific, 2012-02)
    A new technique for solar imaging spectro-polarimetry is presented. Using the combination of a Shack-Hartmann (SH) and a Fabry-Pérot (FP) interferometer, high-cadence spectroscopic observations can be obtained at discrete ...

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