TY - JOUR
T1 - Probing the early Milky Way with GHOST spectra of an extremely metal-poor star in the Galactic disk
AU - Dovgal, Anya
AU - Venn, Kim A.
AU - Sestito, Federico
AU - Hayes, Christian R.
AU - McConnachie, Alan W.
AU - Navarro, Julio F.
AU - Placco, Vinicius M.
AU - Starkenburg, Else
AU - Martin, Nicolas F.
AU - Pazder, John S.
AU - Chiboucas, Kristin
AU - Deibert, Emily
AU - Gamen, Roberto
AU - Heo, Jeong-Eun
AU - Kalari, Venu M.
AU - Martioli, Eder
AU - Xu, Siyi
AU - Diaz, Ruben
AU - Gomez-Jiminez, Manuel
AU - Henderson, David
AU - Prado, Pablo
AU - Quiroz, Carlos
AU - Robertson, J. Gordon
AU - Ruiz-Carmona, Roque
AU - Simpson, Chris
AU - Urrutia, Cristian
AU - Waller, Fletcher
AU - Berg, Trsytyn
AU - Burley, Gregory
AU - Hartman, Zachary
AU - Ireland, Michael
AU - Margheim, Steve
AU - Perez, Gabriel
AU - Thomas-Osip, Joanna
N1 - 16 pages, 10 figures, 6 tables. Accepted by MNRAS November 22; Revisions include comparisons to more EMP stars, results unchanged
PY - 2023/10/4
Y1 - 2023/10/4
N2 - Pristine_183.6849+04.8619 (P1836849) is an extremely metal-poor ([Fe/H]$=-3.3\pm0.1$) star on a prograde orbit confined to the Galactic disk. Such stars are rare and may have their origins in protogalactic fragments that formed the early Milky Way, in low mass satellites accreted later, or forming in situ in the Galactic plane. Here we present a chemo-dynamical analysis of the spectral features between $3700-11000$\r{A} from a high-resolution spectrum taken during Science Verification of the new Gemini High-resolution Optical SpecTrograph (GHOST). Spectral features for many chemical elements are analysed (Mg, Al, Si, Ca, Sc, Ti, Cr, Mn, Fe, Ni), and valuable upper limits are determined for others (C, Na, Sr, Ba). This main sequence star exhibits several rare chemical signatures, including (i) extremely low metallicity for a star in the Galactic disk, (ii) very low abundances of the light $\alpha$-elements (Na, Mg, Si) compared to other metal-poor stars, and (iii) unusually large abundances of Cr and Mn, where [Cr, Mn/Fe]$_{\rm NLTE}>+0.5$. A comparison to theoretical yields from supernova models suggests that two low mass Population III objects (one 10 M$_\odot$ supernova and one 17 M$_\odot$ hypernova) can reproduce the abundance pattern well (reduced $\chi^2
AB - Pristine_183.6849+04.8619 (P1836849) is an extremely metal-poor ([Fe/H]$=-3.3\pm0.1$) star on a prograde orbit confined to the Galactic disk. Such stars are rare and may have their origins in protogalactic fragments that formed the early Milky Way, in low mass satellites accreted later, or forming in situ in the Galactic plane. Here we present a chemo-dynamical analysis of the spectral features between $3700-11000$\r{A} from a high-resolution spectrum taken during Science Verification of the new Gemini High-resolution Optical SpecTrograph (GHOST). Spectral features for many chemical elements are analysed (Mg, Al, Si, Ca, Sc, Ti, Cr, Mn, Fe, Ni), and valuable upper limits are determined for others (C, Na, Sr, Ba). This main sequence star exhibits several rare chemical signatures, including (i) extremely low metallicity for a star in the Galactic disk, (ii) very low abundances of the light $\alpha$-elements (Na, Mg, Si) compared to other metal-poor stars, and (iii) unusually large abundances of Cr and Mn, where [Cr, Mn/Fe]$_{\rm NLTE}>+0.5$. A comparison to theoretical yields from supernova models suggests that two low mass Population III objects (one 10 M$_\odot$ supernova and one 17 M$_\odot$ hypernova) can reproduce the abundance pattern well (reduced $\chi^2
KW - astro-ph.GA
KW - astro-ph.SR
U2 - 10.1093/mnras/stad3673
DO - 10.1093/mnras/stad3673
M3 - Article
SN - 0035-8711
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
ER -