Journal Article

GHOST Commissioning Science Results: Identifying a New Chemically Peculiar Star in Reticulum II

Burley, Gregory, Tims, Julia, Smith, Greg, Fitzsimmons, Joeleff, Labrie, Kathleen, Lambert, Sam, Henderson, David, Silversides, Katherine, Churilov, Vladimir, Kondrat, Yuriy, Shetrone, Matthew, Kelly, Neal, Salinas, Ricardo, Jensen, Jaclyn, Margheim, Steve, Mali, Slavko, Miranda, Felipe, Berg, Trystyn, Perez, Gabriel, Venn, Kim A, McConnachie, Alan W, Hill, Alexis, McGregor, Helen, Zhelem, Ross, Reshetov, Vladimir, Ireland, Michael, Font-Serra, Juan, Price, Ian, Waller, Lewis, Ganton, Colin, Baker, Gabriella, Oberdorf, Oliver, Venkatesan, Sudharshan, McDermid, Richard, Urrutia, Cristian, Sheinis, Andrew, Chin, Timothy, Hardy, Tim, Pazder, John, Luvaul, Lance, Dunn, Jennifer, Sestito, Federico, Gomez-Jimenez, Manuel, Quiroz, Carlos, Edgar, Michael, Fuentes, Javier, Hoff, Brian, Young, Peter, Bassett, John, Lawrence, Jon, Bento, Joao, Silva, Karleyne, Case, Scott, Farrell, Tony, Robertson, Gordon, Wierzbicki, Ramunas, Shortridge, Keith, Chapin, Edward, Klauser, Urs, Macdonald, G. Scott, Norbury, Ryan, Brzeski, Jurek, Pai, Naveen, White, Marc, Szeto, Kei, Simpson, Chris, Lothrop, Jordan, Ruiz-Carmona, Roque, Anthony, Andr

2023

Overview

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.

• Publisher: IOP Publishing
• Subject: Abundance / Astronomy / Astrophysics / Chemical analysis / Commissioning / Dwarf galaxies / High resolution / Light elements / Metallicity / Neutron stars / Observatories / Peculiar stars / Science / Spectrum analysis / Star & galaxy formation / Stars / Stars & galaxies / Supernovae / Telescopes