J/A+A/696/A122 BPS CS 29529-0089 and TYC 9219-2422-1 abund. (da Silva+, 2025)
Discovery of a pair of very metal-poor stars enriched in neutron-capture
elements: The proto-disk r-II star BPS CS 29529-0089 and
the Gaia-Sausage-Enceladus r-I star TYC 9219-2422-1.
da Silva A.R., Smiljanic R.
<Astron. Astrophys. 696, A122 (2025)>
=2025A&A...696A.122D 2025A&A...696A.122D (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, halo ; Stars, metal-deficient ; Abundances
Keywords: stars: abundances - stars: chemically peculiar -
stars: Population II - Galaxy: disk - Galaxy: halo -
Galaxy: stellar content
Abstract:
R-process enhanced metal-poor stars ([Eu/Fe]≥+0.3 and [Fe/H]≤-1.0)
are rare objects, the study of which can provide clues as to the
astrophysical sites of the rapid neutron capture process. Aims. In
this study, we investigate the detailed chemical abundance patterns of
two of these anomalous stars, originally identified among stars
observed by the GALAH survey. Our aim is to obtain the detailed
chemical abundance pattern of these stars with spectroscopy at a
higher resolution and signal-to-noise ratio.
We used a calibration of the infrared flux method to determine
accurate effective temperatures, and Gaia parallaxes together with
broadband photometry and theoretical bolometric corrections to
determine surface gravity. Metallicities and chemical abundances were
determined with model atmospheres and spectrum synthesis. We also
integrated stellar orbits for a complete chemodynamic analysis.
We determined abundances for up to 47 chemical species (44 elements),
of which 27 are neutron-capture elements. Corrections because of
deviations from the local thermodynamical equilibrium were applied to
the metallicities and 12 elements. We find that one of the stars, BPS
CS 29529-0089, is a proto-disk star of the Milky Way of r-II type,
with [Eu/Fe]=+1.79dex. The second star, TYC 9219-2422-1, is part of
the halo and associated with the Gaia-Sausage-Enceladus merger event.
It is of r-I type with [Eu/Fe]=+0.54. Abundances of Th are also
provided for both stars.
BPS CS 29529-0089 is the most extreme example of an r-process enhanced
star known with disk-like kinematics and not carbon enhanced. TYC
9219-2422-1 is found to be an archetypal Gaia-Sausage-Enceladus star.
Their abundances of C, Mg, Ni, Sc, Mn, and Al seem consistent with
expectations for stars enriched by a single population III core
collapse supernova, despite their relatively high metallicities
([Fe/H]~-2.4).
Description:
Here are the abundances by line. As the analysis was done by grid,
some species and lines have the same abundance as it was done
together.
Objects:
--------------------------------------------------------------
RA (2000) DE Designation(s)
--------------------------------------------------------------
04 14 16.24 -60 09 04.7 BPS CS 29529-0089 = TIC 38573564
10 36 22.32 -71 30 09.8 TYC 9219-2422-1 = TIC 397725420
14 02 31.84 +09 41 09.9 HD 122563 = TIC 457862177
--------------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablee1.dat 38 567 Abundances by line for BPS CS 29529-0089,
TYC 9219-2422-1 and HD 122563
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablee1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- Species Chemical Species
7- 13 F7.2 0.1nm lambda Line Wavelength in Angstroems
15- 20 F6.2 --- loggf Oscillator strength
22- 26 F5.2 --- Abund1 ? BPS CS 29529-0089 abundance in [X/Fe]
28- 32 F5.2 --- Abund2 ? TYC 9219-2422-1 abundance in [X/Fe]
34- 38 F5.2 --- Abund3 ? HD 122563 abundance in [X/Fe]
--------------------------------------------------------------------------------
Acknowledgements:
Andre Rodrigo da Silva, arodrigo(at)camk.edu.pl
(End) Patricia Vannier [CDS] 27-Mar-2025