Browsing by Author "Casey, Andrew R."

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    KINEMATICS AND CHEMISTRY OF RECENTLY DISCOVERED RETICULUM 2 AND HOROLOGIUM 1 DWARF GALAXIES
    (2015) Koposov, Sergey E.; Casey, Andrew R.; Belokurov, Vasily; Lewis, James R.; Gilmore, Gerard; Worley, Clare; Hourihane, Anna; Randich, S.; Bensby, T.; Bragaglia, A.; Bergemann, M.; Carraro, G.; Costado, M. T.; Flaccomio, E.; Francois, P.; Heiter, U.; Hill, V.; Jofre, P.; Lando, C.; Lanzafame, A. C.; de Laverny, P.; Monaco, L.; Morbidelli, L.; Sbordone, L.; Mikolaitis, S.; Ryde, N.
    We report on VLT/GIRAFFE spectra of stars in two recently discovered ultra-faint satellites, Reticulum 2 and Horologium 1, obtained as part of the Gaia-ESO Survey. We identify 18 members in Reticulum 2 and five in Horologium 1. We find Reticulum 2 to have a velocity dispersion of 3.22(-0.49)(+1.64) km s(-1) , implying a mass-to-light ratio (M/L) of similar to 500. The mean metallicity of Reticulum 2 is [Fe/H] = -2.46, with an intrinsic dispersion of similar to 0.3 dex and alpha-enhancement of similar to 0.4 dex. We conclude that Reticulum 2 is a dwarf galaxy. We also report on the serendipitous discovery of four stars in a previously unknown stellar substructure near Reticulum 2 with [Fe/H] similar to -2 and V-hel similar to 220 km s(-1), far from the systemic velocity of Reticulum 2. For Horologium 1 we infer a velocity dispersion of sigma (V) = 4.9(-0.9)(+2.8) km s(-1) and a M/L ratio of similar to 600, leading us to conclude that Horologium 1 is also a dwarf galaxy. Horologium 1 is slightly more metal-poor than Reticulum 2 ([Fe/H] = -2.76) and is similarly alpha-enhanced: [alpha/Fe] similar to 0.3 dex with a significant spread of metallicities of 0.17 dex. The line-of-sight velocity of Reticulum 2 is offset by 100 km s(-1) from the prediction of the orbital velocity of the Large Magellanic Cloud (LMC), thus making its association with the Cloud uncertain. However, at the location of Horologium 1, both the backward-integrated orbit of the LMC and its halo are predicted to have radial velocities similar to that of the dwarf. Therefore, it is possible that Horologium 1 is or once was a member of the Magellanic family.
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    The Eighteenth Data Release of the Sloan Digital Sky Surveys: Targeting and First Spectra from SDSS-V
    (2023) Almeida, Andres; Anderson, Scott F.; Argudo-Fernandez, Maria; Badenes, Carles; Barger, Kat; Barrera-Ballesteros, Jorge K.; Bender, Chad F.; Benitez, Erika; Besser, Felipe; Bird, Jonathan C.; Bizyaev, Dmitry; Blanton, Michael R.; Bochanski, John; Bovy, Jo; Brandt, William Nielsen; Brownstein, Joel R.; Buchner, Johannes; Bulbul, Esra; Burchett, Joseph N.; Diaz, Mariana Cano; Carlberg, Joleen K.; Casey, Andrew R.; Chandra, Vedant; Cherinka, Brian; Chiappini, Cristina; Coker, Abigail A.; Comparat, Johan; Conroy, Charlie; Contardo, Gabriella; Cortes, Arlin; Covey, Kevin; Crane, Jeffrey D.; Cunha, Katia; Dabbieri, Collin; Davidson, James W.; Davis, Megan C.; de Andrade Queiroz, Anna Barbara; De Lee, Nathan; Mendez Delgado, Jose Eduardo; Demasi, Sebastian; Di Mille, Francesco; Donor, John; Dow, Peter; Dwelly, Tom; Eracleous, Mike; Eriksen, Jamey; Fan, Xiaohui; Farr, Emily; Frederick, Sara; Fries, Logan; Frinchaboy, Peter; Gaensicke, Boris T.; Ge, Junqiang; Gonzalez Avila, Consuelo; Grabowski, Katie; Grier, Catherine; Guiglion, Guillaume; Gupta, Pramod; Hall, Patrick; Hawkins, Keith; Hayes, Christian R.; Hermes, J. J.; Hernandez-Garcia, Lorena; Hogg, David W.; Holtzman, Jon A.; Ibarra-Medel, Hector Javier; Ji, Alexander; Jofre, Paula; Johnson, Jennifer A.; Jones, Amy M.; Kinemuchi, Karen; Kluge, Matthias; Koekemoer, Anton; Kollmeier, Juna A.; Kounkel, Marina; Krishnarao, Dhanesh; Krumpe, Mirko; Lacerna, Ivan; Lago, Paulo Jakson Assuncao; Laporte, Chervin; Liu, Chao; Liu, Ang; Liu, Xin; Lopes, Alexandre Roman; Macktoobian, Matin; Majewski, Steven R.; Malanushenko, Viktor; Maoz, Dan; Masseron, Thomas; Masters, Karen L.; Matijevic, Gal; McBride, Aidan; Medan, Ilija; Merloni, Andrea; Morrison, Sean; Myers, Natalie; Meszaros, Szabolcs; Negrete, C. Alenka; Nidever, David L.; Nitschelm, Christian; Oravetz, Daniel; Oravetz, Audrey; Pan, Kaike; Peng, Yingjie; Pinsonneault, Marc H.; Pogge, Rick; Qiu, Dan; Ramirez, Solange V.; Rix, Hans-Walter; Rosso, Daniela Fernandez; Runnoe, Jessie; Salvato, Mara; Sanchez, Sebastian F.; Santana, Felipe A.; Saydjari, Andrew; Sayres, Conor; Schlaufman, Kevin C.; Schneider, Donald P.; Schwope, Axel; Serna, Javier; Shen, Yue; Sobeck, Jennifer; Song, Ying-Yi; Souto, Diogo; Spoo, Taylor; Stassun, Keivan G.; Steinmetz, Matthias; Straumit, Ilya; Stringfellow, Guy; Sanchez-Gallego, Jose; Taghizadeh-Popp, Manuchehr; Tayar, Jamie; Thakar, Ani; Tissera, Patricia B.; Tkachenko, Andrew; Toledo, Hector Hernandez; Trakhtenbrot, Benny; Fernandez-Trincado, Jose G.; Troup, Nicholas; Trump, Jonathan R.; Tuttle, Sarah; Ulloa, Natalie; Vazquez-Mata, Jose Antonio; Alfaro, Pablo Vera; Villanova, Sandro; Wachter, Stefanie; Weijmans, Anne-Marie; Wheeler, Adam; Wilson, John; Wojno, Leigh; Wolf, Julien; Xue, Xiang-Xiang; Ybarra, Jason E.; Zari, Eleonora; Zasowski, Gail
    The eighteenth data release (DR18) of the Sloan Digital Sky Survey (SDSS) is the first one for SDSS-V, the fifth generation of the survey. SDSS-V comprises three primary scientific programs or "Mappers": the Milky Way Mapper (MWM), the Black Hole Mapper (BHM), and the Local Volume Mapper. This data release contains extensive targeting information for the two multiobject spectroscopy programs (MWM and BHM), including input catalogs and selection functions for their numerous scientific objectives. We describe the production of the targeting databases and their calibration and scientifically focused components. DR18 also includes & SIM;25,000 new SDSS spectra and supplemental information for X-ray sources identified by eROSITA in its eFEDS field. We present updates to some of the SDSS software pipelines and preview changes anticipated for DR19. We also describe three value-added catalogs (VACs) based on SDSS-IV data that have been published since DR17, and one VAC based on the SDSS-V data in the eFEDS field.