GHOST Commissioning Science Results: Identifying a New Chemically Peculiar Star in Reticulum II
Christian R. Hayes, Kim A. Venn, Fletcher Waller, Jaclyn Jensen, Alan W. McConnachie, John Pazder, Federico Sestito, André Anthony, Gabriella Baker, John Bassett, J. Bento, Trystyn A. M. Berg, Gregory Burley, Jurek Brzeski, Scott W. Case, Edward L. Chapin, Timothy Chin, Eric M. Chisholm, Vladimir Churilov, A. Densmore, Rubén Díaz, Jennifer B. Dunn, Michael L. Edgar, Tony Farrell, V. Firpo, Joeleff Fitzsimmons, Juan Font-Serra, Javier Fuentes, Colin Ganton, Manuel Gómez-Jiménez, Tim Hardy, David K. Henderson, Alexis Hill, Brian Hoff, Michael Ireland, V. M. Kalari, Neal Kelly, Urs Klauser, Yuriy Kondrat, Kathleen Labrie, Sam Lambert, Lance Luvaul, Jon Lawrence, Jordan Lothrop, G. Scott Macdonald, Slavko Mali, S. Margheim, Richard M. McDermid, Helen McGregor, Bryan W. Miller, F. Miranda, Rolf Müller, Jon Nielsen, Ryan Norbury, Oliver Oberdorf, Naveen Pai, Gabriel Pérez, Pablo Prado, Ian Price, Carlos Quiroz, В. А. Решетов, Gordon Robertson, Roque Ruiz-Carmona, R. Salinas, Kim M. Sebo, Andrew Sheinis, Matthew Shetrone, Keith Shortridge, Katherine Silversides, Karleyne M. G. Silva, Chris Simpson, Greg Smith, Kei Szeto, Julia Tims, Eduardo Domı́nguez del Toro, Cristian Urrutia, Sudharshan Venkatesan, Lewis Waller, Ivan Wevers, Ramunas Wierzbicki, Marc White, Peter R. Young, Ross Zhelem
Abstract
Abstract The Gemini High-resolution Optical SpecTrograph (GHOST) is the newest high-resolution spectrograph to be developed for a large-aperture telescope, recently deployed and commissioned at the Gemini-South telescope. In this paper, we present the first science results from the GHOST spectrograph taking during its commissioning runs. We have observed the bright metal-poor benchmark star HD 122563, along with two stars in the ultrafaint dwarf galaxy Reticulum II (Ret ii ), one of which was previously identified as a candidate member, but did not have a previous detailed chemical abundance analysis. We find that this candidate (GDR3 0928) to be a bona fide member of Ret ii , and from a spectral synthesis analysis it is also revealed to be a CEMP- r star, with significant enhancements in several light elements (C, N, O, Na, Mg, and Si), in addition to featuring an r -process enhancement like many other Ret ii stars. The light-element enhancements in this star resemble the abundance patterns seen in the CEMP-no stars of other ultrafaint dwarf galaxies, and are thought to have been produced by an independent source from the r -process. These unusual abundance patterns are thought to be produced by faint supernovae, which may be produced by some of the earliest generations of stars.