J/A+A/697/A75 BPM 3066 line list (Monaco+, 2025)
A Sequoia stellar candidate with very high 7Li and 9Be.
Monaco L., Caffau E., Molaro P., Bonifacio P., Cescutti G.
<Astron. Astrophys. 697, A75 (2025)>
=2025A&A...697A..75M 2025A&A...697A..75M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, population II ; Abundances ; Spectroscopy
Keywords: nuclear reactions, nucleosynthesis, abundances -
stars: abundances - planetary systems stars: Population II -
Galaxy: stellar content - Galaxy: structure
Abstract:
The metal-poor star BPM 3066 belongs to the retrograde halo and
presents unexpectedly strong spectral features of lithium. To gain
insight into the origin of this peculiar abundance, we investigate the
chemistry and kinematic properties of this star.
We performed a local thermodynamic equilibrium chemical abundance
analysis of UVES/VLT high-resolution spectra of BPM 3066 using ATLAS9
and ATLAS12 model atmospheres and the MyGIsFOS code. We further
characterised the orbital properties of the star by integrating its
orbit and analysing its integrals of motion using the galpy code.
The star BPM 3066 shows an exceptional overabundance of both lithium
and beryllium. The abundances are A(Li)=3.0 and A(Be)=2.1, which are
respectively about 0.8 and 2.2dex higher than the Li and Be abundances
expected at [Fe/H]=-1.5, the metallicity of the star. The observed
ratio 7Li/9Be is 7.9, which is close to that expected from a
synthesis by spallation processes. Overabundances of Si, Al, and of
the neutron capture elements Sr,Y, Zr, and Ba are also measured.
Kinematically, BPM 3066 has an eccentric, strongly retrograde orbit,
confined to a height lower than 1 kpc from the galactic plane, and it
is a candidate member of the Sequoia/Thamnos accreted galaxy.
The processes leading to the 7Li and 9Be synthesis could have
occurred in the environment of a hypernova. This is supported by some
abundance anomalies like the high value of Si, [Si/Fe]=1.2 and
[Si/O]=1.1. However, the simultaneous high values of N, Na, Al, Sc,
Ti, and Cu are at odds with the expectations from a hypernova.
Alternatively, the abundances of BPM 3066 could result from the
engulfing of rocky planets that were rich in spallated Li and Be. In
both cases, it is remarkable that such an extreme abundance pattern
has been found in a star belonging to the Sequoia/Thamnos accreted
galaxy.
Description:
We observed the dwarf, metal-poor star BPM 3066 with the UVES
Spectrograph at the ESO Very Large Telescope (Paranal, Chile), on the
night between the 17 and the 18 July, 2023. We adopted the DIC1
346+580 UVES setting, which covers the 304.4-391.7nm and 472.6-683.5nm
spectral ranges with the blue and red arm, respectively. BPM 3066
presents an exceptional overabundance of both lithium and beryllium.
Objects:
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RA (2000) DE Designation(s)
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03 35 55.23 -68 33 45.6 BPM 3066 = WISE J033555.39-683346.6
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
linelist.dat 31 544 List of lines used for the chemical abundance
analysis of star BPM 3066
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Byte-by-byte Description of file: linelist.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Element Element (I for neutral, II for ionized)
6- 13 F8.4 nm lambda Line wavelength
15- 20 F6.3 [-] loggf Oscillator strength
22- 31 F10.3 cm-1 lep Lower Excitation potential
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Acknowledgements:
Lorenzo Monaco, lorenzo.monaco(at)unab.cl
(End) Patricia Vannier [CDS] 14-Apr-2025