TY - JOUR
T1 - GHOST commissioning science results - II
T2 - A very metal-poor star witnessing the early galactic assembly
AU - Sestito, Federico
AU - Hayes, Christian R.
AU - Venn, Kim A.
AU - Jensen, Jaclyn
AU - McConnachie, Alan W.
AU - Pazder, John
AU - Waller, Fletcher
AU - Ardern-Arentsen, Anke
AU - Jablonka, Pascale
AU - Martin, Nicolas F.
AU - Matsuno, Tadafumi
AU - Navarro, Julio F.
AU - Starkenburg, Else
AU - Vitali, Sara
AU - Bassett, John
AU - Berg, Trystyn A.M.
AU - Diaz, Ruben
AU - Edgar, Michael L.
AU - Firpo, Veronica
AU - Gomez-Jimenez, Manuel
AU - Kalari, Venu
AU - Lambert, Sam
AU - Lawrence, Jon
AU - Robertson, Gordon
AU - Ruiz-Carmona, Roque
AU - Salinas, Ricardo
AU - Sebo, Kim M.
AU - Venkatesan, Sudharshan
N1 - Publisher Copyright:
© 2024 Oxford University Press. All rights reserved.
PY - 2024/3/1
Y1 - 2024/3/1
N2 - This study focuses on Pristine 180956.78−294759.8 (hereafter P180956, [Fe/H] = −1.95 ± 0.02), a star selected from the Pristine Inner Galaxy Survey (PIGS), and followed-up with the recently commissioned Gemini High-resolution Optical SpecTrograph (GHOST) at the Gemini South telescope. The GHOST spectrograph’s high efficiency in the blue spectral region (3700−4800 Å) enables the detection of elemental tracers of early supernovae (e.g. Al, Mn, Sr, and Eu). The star exhibits chemical signatures resembling those found in ultrafaint dwarf (UFD) systems, characterized by very low abundances of neutron-capture elements (Sr, Ba, and Eu), which are uncommon among stars in the Milky Way halo. Our analysis suggests that P180956 bears the chemical imprints of a small number (2 or 4) of low-mass hypernovae (∼ 10−15 M⃝), which are needed to mostly reproduce the abundance pattern of the light-elements (e.g. [Si, Ti/Mg, Ca] ∼0.6), and one fast-rotating intermediate-mass supernova (∼ 300 km s−1, ∼ 80−120 M⃝), which is the main channel contributing to the high [Sr/Ba] (∼+1.2). The small pericentric (∼ 0.7 kpc) and apocentric (∼ 13 kpc) distances and its orbit confined to the plane (2 kpc) indicate that this star was likely accreted during the early Galactic assembly phase. Its chemo-dynamical properties suggest that P180956 formed in a system similar to a UFD galaxy accreted either alone, as one of the low-mass building blocks of the proto-Galaxy, or as a satellite of Gaia–Sausage–Enceladus. The combination of Gemini’s large aperture with GHOST’s high efficiency and broad spectral coverage makes this new spectrograph one of the leading instruments for near-field cosmology investigations.
AB - This study focuses on Pristine 180956.78−294759.8 (hereafter P180956, [Fe/H] = −1.95 ± 0.02), a star selected from the Pristine Inner Galaxy Survey (PIGS), and followed-up with the recently commissioned Gemini High-resolution Optical SpecTrograph (GHOST) at the Gemini South telescope. The GHOST spectrograph’s high efficiency in the blue spectral region (3700−4800 Å) enables the detection of elemental tracers of early supernovae (e.g. Al, Mn, Sr, and Eu). The star exhibits chemical signatures resembling those found in ultrafaint dwarf (UFD) systems, characterized by very low abundances of neutron-capture elements (Sr, Ba, and Eu), which are uncommon among stars in the Milky Way halo. Our analysis suggests that P180956 bears the chemical imprints of a small number (2 or 4) of low-mass hypernovae (∼ 10−15 M⃝), which are needed to mostly reproduce the abundance pattern of the light-elements (e.g. [Si, Ti/Mg, Ca] ∼0.6), and one fast-rotating intermediate-mass supernova (∼ 300 km s−1, ∼ 80−120 M⃝), which is the main channel contributing to the high [Sr/Ba] (∼+1.2). The small pericentric (∼ 0.7 kpc) and apocentric (∼ 13 kpc) distances and its orbit confined to the plane (2 kpc) indicate that this star was likely accreted during the early Galactic assembly phase. Its chemo-dynamical properties suggest that P180956 formed in a system similar to a UFD galaxy accreted either alone, as one of the low-mass building blocks of the proto-Galaxy, or as a satellite of Gaia–Sausage–Enceladus. The combination of Gemini’s large aperture with GHOST’s high efficiency and broad spectral coverage makes this new spectrograph one of the leading instruments for near-field cosmology investigations.
KW - Galaxy: abundances
KW - Galaxy: bulge
KW - Galaxy: evolution
KW - Galaxy: formation
KW - stars: kinematics and dynamics
KW - stars: Population II
UR - http://www.scopus.com/inward/record.url?scp=85185509583&partnerID=8YFLogxK
U2 - 10.1093/mnras/stae244
DO - 10.1093/mnras/stae244
M3 - Article
SN - 0035-8711
VL - 528
SP - 4838
EP - 4851
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 3
ER -