The Astrophysical Journal (Jan 2023)

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,
  • Joao Bento,
  • Trystyn Berg,
  • Gregory Burley,
  • Jurek Brzeski,
  • Scott Case,
  • Edward Chapin,
  • Timothy Chin,
  • Eric Chisholm,
  • Vladimir Churilov,
  • Adam Densmore,
  • Ruben Diaz,
  • Jennifer Dunn,
  • Michael Edgar,
  • Tony Farrell,
  • Veronica Firpo,
  • Joeleff Fitzsimmons,
  • Juan Font-Serra,
  • Javier Fuentes,
  • Colin Ganton,
  • Manuel Gomez-Jimenez,
  • Tim Hardy,
  • David Henderson,
  • Alexis Hill,
  • Brian Hoff,
  • Michael Ireland,
  • Venu Kalari,
  • Neal Kelly,
  • Urs Klauser,
  • Yuriy Kondrat,
  • Kathleen Labrie,
  • Sam Lambert,
  • Lance Luvaul,
  • Jon Lawrence,
  • Jordan Lothrop,
  • G. Scott Macdonald,
  • Slavko Mali,
  • Steve Margheim,
  • Richard McDermid,
  • Helen McGregor,
  • Bryan Miller,
  • Felipe Miranda,
  • Rolf Muller,
  • Jon Nielsen,
  • Ryan Norbury,
  • Oliver Oberdorf,
  • Naveen Pai,
  • Gabriel Perez,
  • Pablo Prado,
  • Ian Price,
  • Carlos Quiroz,
  • Vladimir Reshetov,
  • Gordon Robertson,
  • Roque Ruiz-Carmona,
  • Ricardo Salinas,
  • Kim M. Sebo,
  • Andrew Sheinis,
  • Matthew Shetrone,
  • Keith Shortridge,
  • Katherine Silversides,
  • Karleyne Silva,
  • Chris Simpson,
  • Greg Smith,
  • Kei Szeto,
  • Julia Tims,
  • Eduardo Toro,
  • Cristian Urrutia,
  • Sudharshan Venkatesan,
  • Lewis Waller,
  • Ivan Wevers,
  • Ramunas Wierzbicki,
  • Marc White,
  • Peter Young,
  • Ross Zhelem

DOI
https://doi.org/10.3847/1538-4357/acebc0
Journal volume & issue
Vol. 955, no. 1
p. 17

Abstract

Read online

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.

Keywords