J/A+A/673/A123 Phosphorus-rich stars (Brauner+, 2023)
Unveiling the chemical fingerprint of phosphorus-rich stars
I. In the infrared region of APOGEE-2.
Brauner M., Masseron T., Garcia-Hernandez D.A., Pignatari M., Womack K.A.,
Lugaro M., Hayes C.R.
<Astron. Astrophys. 673, A123 (2023)>
=2023A&A...673A.123B 2023A&A...673A.123B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, peculiar ; Abundances, peculiar ; Spectra, infrared
Keywords: nuclear reactions, nucleosynthesis, abundances - stars: abundances -
stars: chemically peculiar - surveys
Abstract:
The origin of phosphorus, one of the essential elements for life on
Earth, is currently unknown. Prevalent models of Galactic chemical
evolution (GCE) systematically underestimate the amount of P compared
to observations, especially at low metallicities. The recently
discovered P-rich ([P/Fe]≳1.2dex) and metal-poor ([Fe/H]~-1.0dex)
giants further challenge the GCE models, calling current theories on
stellar nucleosynthesis into question. Since the observed low-mass
giants are not expected to produce their high P contents themselves,
our primary goal is to find clues on their progenitor or polluter. By
increasing the number of known P-rich stars, we aim to narrow down a
statistically reliable chemical abundance pattern that defines these
peculiar stars. In this way, we place more robust constraints on the
nucleosynthetic mechanism responsible for the unusually high P
abundances. In the long term, identifying the progenitor of the P-rich
stars may contribute to the search for the source of P in our Galaxy.
We performed a detailed chemical abundance analysis based on the high
resolution near-infrared (H-band) spectra from the latest data release
(DR17) of the APOGEE-2 survey. Employing the BACCHUS code, we measured
the abundances of 13 elements in the inspected sample, which is mainly
composed of a recent collection of Si-enhanced giants. We also
analyzed the orbital motions and compared the abundance results to
possible nucleosynthetic formation scenarios, as well as to detailed
GCE models. These models were produced with the OMEGA+ chemical
evolution code, using four different massive star yield sets to
investigate different scenarios for massive star evolution. We
enlarged the sample of confirmed P-rich stars from 16 to a group of 78
giants, representing the largest sample of P-rich stars to date,
including the first detection of a P-rich star in a Galactic globular
cluster. Significant enhancements in O, Al, Si and Ce, as well as
systematic correlations among the studied elements, unveil the unique
chemical fingerprint of the P-rich stars. In contrast, the high
[Mg/Fe] and [(C+N)/Fe] found in some of the P-rich stars with respect
to P-normal stars is, due to the present uncertainties, not confirmed
over the full sample. Strikingly, the strong over-abundance in the
alpha-element Si is accompanied by normal Ca and S abundances, at odds
with present stellar nucleosynthesis models of massive stars. Our
analysis of the orbital motion showed that the P-rich stars do not
belong to a locally specific population in the Galaxy. In addition, we
confirm that the majority of the sample stars are not part of binary
systems.
Description:
Basic stellar parameters from ASPCAP (DR16 or DR17) used to obtain the
synthetic spectra, elemental abundances and standard deviations of the
full sample of 87 metal-poor P-rich giant stars derived with BACCHUS.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 223 87 Stellar parameters and elemental abundances of
the full sample of P-rich stars
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See also:
https://www.sdss4.org/dr16/irspec/aspcap : ASPCAP DR16 Home page
https://www.sdss4.org/dr17/irspec/aspcap : ASPCAP DR17 Home page
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 18 A18 --- APOGEE APOGEE identifier (APOGEE_ID)
20- 23 A4 --- Source Source of the parameters (DR16 or DR17)
25- 29 F5.2 [-] [M/H] Uncalibrated [M/H] from ASPCAP analysis of
combined spectrum
31- 35 F5.1 --- S/N Signal-to-Noise ratio from ASPCAP analysis
of combined spectrum
37- 42 F6.1 K Teff Effective Temperature from ASPCAP analysis
of combined spectrum (MH)
44- 47 F4.2 [-] logg Surface Gravity from ASPCAP analysis of
combined spectrum (MH)
49- 53 F5.2 [-] [C/Fe] ? [C/Fe] from BACCHUS analysis of
combined spectrum
54- 55 A2 --- n_[C/Fe] [*+: ] Note on [C/Fe] (1)
57- 60 F4.2 [-] s_[C/Fe] ? Standard deviation of [C/Fe]
62 I1 --- l_[C/Fe] [0/1] Indicator of upper limits in [C/Fe] (2)
64- 68 F5.2 [-] [N/Fe] ? [N/Fe] from BACCHUS analysis of
combined spectrum
69- 70 A2 --- n_[N/Fe] [*+: ] Note on [N/Fe] (1)
72- 75 F4.2 [-] s_[N/Fe] ? Standard deviation of [N/Fe]
77 I1 --- l_[N/Fe] [0/1] Indicator of upper limits in [N/Fe] (2)
79- 82 F4.2 [-] [O/Fe] ? [O/Fe] from BACCHUS analysis of
combined spectrum
83- 84 A2 --- n_[O/Fe] [*+: ] Note on [O/Fe] (1)
86- 89 F4.2 [-] s_[O/Fe] ? Standard deviation of [O/Fe]
91 I1 --- l_[O/Fe] [0/1] Indicator of upper limits in [O/Fe] (2)
93- 97 F5.2 [-] [Na/Fe] ? [Na/Fe] from BACCHUS analysis of
combined spectrum
98- 99 A2 --- n_[Na/Fe] [*+: ] Note on [Na/Fe] (1)
101-104 F4.2 [-] s_[Na/Fe] ? Standard deviation of [Na/Fe]
106 I1 --- l_[Na/Fe] [0/1] Indicator of upper limits in [Na/Fe] (2)
108-112 F5.2 [-] [Mg/Fe] ? [Mg/Fe] from BACCHUS analysis of
combined spectrum
113-114 A2 --- n_[Mg/Fe] [*: ] Note on [Mg/Fe] (1)
116-119 F4.2 [-] s_[Mg/Fe] ? Standard deviation of [Mg/Fe]
121-124 F4.2 [-] [Al/Fe] ? [Al/Fe] from BACCHUS analysis of
combined spectrum
125 A1 --- n_[Al/Fe] [*: ] Note on [Al/Fe] (1)
127-130 F4.2 [-] s_[Al/Fe] ? Standard deviation of [Al/Fe]
132-135 F4.2 [-] [Si/Fe] ? [Si/Fe] from BACCHUS analysis of
combined spectrum
136 A1 --- n_[Si/Fe] [: ] Note on [Si/Fe] (1)
138-141 F4.2 [-] s_[Si/Fe] ? Standard deviation of [Si/Fe]
143-146 F4.2 [-] [P/Fe] ? [P/Fe] from BACCHUS analysis of
combined spectrum
147-148 A2 --- n_[P/Fe] [*+: ] Note on [P/Fe] (1)
150-153 F4.2 [-] s_[P/Fe] ? Standard deviation of [P/Fe]
155 I1 --- l_[P/Fe] [0/1] Indicator of upper limits in [P/Fe] (2)
157-160 F4.2 [-] [S/Fe] ? [S/Fe] from BACCHUS analysis of
combined spectrum
161-162 A2 --- n_[S/Fe] [*+: ] Note on [S/Fe] (1)
164-167 F4.2 [-] s_[S/Fe] ? Standard deviation of [S/Fe]
169 I1 --- l_[S/Fe] [0/1] Indicator of upper limits in [S/Fe] (2)
171-174 F4.2 [-] [Ca/Fe] ? [Ca/Fe] from BACCHUS analysis of
combined spectrum
175-176 A2 --- n_[Ca/Fe] [*+: ] Note on [Ca/Fe] (1)
178-181 F4.2 [-] s_[Ca/Fe] ? Standard deviation of [Ca/Fe]
183 I1 --- l_[Ca/Fe] [0/1] Indicator of upper limits in [Ca/Fe] (2)
185-189 F5.2 [-] [Fe/H] ? [Fe/H] from BACCHUS analysis of
combined spectrum
190 A1 --- n_[Fe/H] [: ] Note on [Fe/H] (1)
192-195 F4.2 [-] s_[Fe/H] Standard deviation of [Fe/H]
197-200 F4.2 [-] [Ce/Fe] ? [Ce/Fe] from BACCHUS analysis of
combined spectrum
201-202 A2 --- n_[Ce/Fe] [*+: ] Note on [Ce/Fe] (1)
204-207 F4.2 [-] s_[Ce/Fe] ? Standard deviation of [Ce/Fe]
209 I1 --- l_[Ce/Fe] [0/1] Indicator of upper limits in [Ce/Fe] (2)
211-214 F4.2 [-] [Nd/Fe] ? [Nd/Fe] from BACCHUS analysis of
combined spectrum
215-216 A2 --- n_[Nd/Fe] [*+: ] Note on [Nd/Fe] (1)
218-221 F4.2 [-] s_[Nd/Fe] ? Standard deviation of [Nd/Fe]
223 I1 --- l_[Nd/Fe] [0/1] Indicator of upper limits in [Nd/Fe] (2)
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Note (1): Notes as follows:
+ = value is an upper limit
* = value is based on one line only
: = no clear measurement was possible
Note (2): Indicator of upper limits as follows:
1 = upper limit
0 = real measurement
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Acknowledgements:
Maren Brauner, maren.brauner(at)iac.es
(End) Maren Brauner [IAC, Spain], Patricia Vannier [CDS] 24-Mar-2023