GHOST Commissioning Science Results: Identifying a New Chemically Peculiar Star in Reticulum II
Simpson, Chris; Hayes, Christian R.; Sestito, Federico; Jensen, Jaclyn; McConnachie, Alan W.; Venn, Kim A.; Bento, Joao; Ireland, Michael; Shetrone, Matthew; McDermid, Richard; Miller, Bryan; Price, Ian; Salinas, Ricardo; Margheim, Steve; Diaz, Ruben; Gomez-Jimenez, Manuel; Henderson, David; Prado, Pablo; Quiroz, Carlos; Ruiz-Carmona, Roque; Urrutia, Cristian; Waller, Fletcher; Berg, Trystyn; Burley, Gregory; Perez, Gabriel; Lawrence, Jon; Young, Peter; Sebo, Kim M.; Anthony, André; Pazder, John; Baker, Gabriella; Bassett, John; Brzeski, Jurek; Case, Scott; Chapin, Edward; Chin, Timothy; Chisholm, Eric; Churilov, Vladimir; Densmore, Adam; Dunn, Jennifer; Edgar, Michael; Farrell, Tony; Firpo, Veronica; Fitzsimmons, Joeleff; Font-Serra, Juan; Fuentes, Javier; Ganton, Colin; Hardy, Tim; Hill, Alexis; Hoff, Brian; Kalari, Venu; Kelly, Neal; Klauser, Urs; Kondrat, Yuriy; Labrie, Kathleen; Lambert, Sam; Luvaul, Lance; Lothrop, Jordan; Macdonald, G. Scott; Mali, Slavko; McGregor, Helen; Miranda, Felipe; Muller, Rolf; Nielsen, Jon; Norbury, Ryan; Oberdorf, Oliver; Pai, Naveen; Reshetov, Vladimir; Robertson, Gordon; Sheinis, Andrew; Shortridge, Keith; Silversides, Katherine; Silva, Karleyne; Smith, Greg; Szeto, Kei; Tims, Julia; Toro, Eduardo; Venkatesan, Sudharshan; Waller, Lewis; Wevers, Ivan; Wierzbicki, Ramunas; White, Marc; Zhelem, Ross
Canada, Australia, Chile, United States
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.