J/A+A/690/A262 Phosphorus-rich stars. II. (Brauner+, 2024)
Unveiling the chemical fingerprint of phosphorus-rich stars
II. Heavy elemental abundances from UVES@VLT spectra.
Brauner M., Pignatari M., Masseron T., Garcia-Hernandez D.A., Lugaro M.
<Astron. Astrophys. 690, A262 (2024)>
=2024A&A...690A.262B 2024A&A...690A.262B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, peculiar ; Abundances, peculiar ; Spectroscopy
Keywords: nuclear reactions, nucleosynthesis, abundances - stars: abundances -
stars: chemically peculiar
Abstract:
The atmospheres of phosphorus-rich (P-rich) stars have been shown to
contain between 10 and 100 times more P than our Sun. Given its
crucial role as an essential element for life, it is especially
necessary to uncover the origin of P-rich stars to gain insights into
the still unknown nucleosynthetic formation pathways of P in our
Galaxy. Our objective is to obtain the extensive chemical abundance
inventory of four P-rich stars, covering a large range of heavy (Z>30)
elements. This characterization will serve as a milestone for the
nuclear astrophysics community to uncover the processes responsible
for the formation of the unique chemical fingerprint of P-rich stars.
We performed a detailed 1D LTE abundance analysis on the optical UVES
spectra of four P-rich stars. The abundance measurements, complemented
with upper limit estimates, included 48 light and heavy elements. Our
focus lies on the neutron-capture elements (Z>30), in particular on
the elements between Sr and Ba, as well as Pb, as they provide
valuable constraints to nucleosynthesis calculations. In past works,
we showed that the heavy elements observations from the first P-rich
stars are not compatible with either classical s-process or r-process
abundance patterns. In this work, we compare the obtained abundances
with three different nucleosynthetic scenarios: a single i-process, a
double i-process and a combination of s- and i-process. We have
performed the most extensive abundance analysis of P-rich stars to
date, including the elements between Sr and Ba, such as Ag, which are
rarely measured in any kind of stars. Constraining upper limits could
also be estimated for CdI, InI, and SnI. We found overabundances
with respect to solar in the s-process peak elements, accompanied by
an extremely high Ba abundance and slight enhancements in some
elements between Rb and Sn. Regarding the nucleosynthetic origin of
the pattern, no global solution explaining all four stars could be
found. The model that produces the least number of discrepancies in
three of the four stars is a combination of s- and i-process, but the
current lack of extensive multi-dimensional hydrodynamic simulations
to follow the occurrence of the i-process in different types of stars
makes this scenario highly uncertain.
Description:
Wavelength, excitation potential E.P. and oscillator strength log(gf)
for all absorption lines of elements with Z>30 extracted from the
VALD. This line list was used to derived the abundances of the
elements with Z>30 using BACCHUS. Some of the oscillator strengths
have been modified to improve the agreement with the synthetic
spectrum. The abundances of the heavy (Z>30) elements are given in the
paper as they are in the focus of this work. Nevertheless, the
abundances of the light (Z<30) elements have been calculated as well
and we give their abundances in an additional table. For the heavy
(Z>30) elements, we also provide the systematic uncertainties
associated with deviations in the stellar parameters.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
lines.dat 38 1661 Line list of the light and heavy elements
including wavelength, excitation potential and
oscillator strength
modif.dat 49 32 Modifications applied on the original VALD
log(gf) of transitions close to a line of
interest
lightabu.dat 53 132 Abundances of the light (Z<30) elements
uncert.dat 27 22 *Uncertainties associated with the heavy (Z>30)
elements due to deviations in atmospheric
parameters
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Note on uncert.dat: The calculation was performed on 2M00044180, as this star
has the least number of upper limits. For the uncertainty in the Ga I
abundance, 2M22480199 was used.
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See also:
J/A+A/673/A123 : Phosphorus-rich stars (Brauner+, 2023)
Byte-by-byte Description of file: lines.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- El Element symbol + excitation state
7- 14 F8.3 0.1nm lambda Wavelength in angstrom
15 A1 --- n_lambda [*] Note on lambda (1)
17- 21 F5.3 eV EP Excitation potential of the line
23- 29 F7.3 [-] log(gf) Oscillator strength of the line
31- 38 A8 --- Mol/Isotope? Is line a molecular line, indicating
the molecule; or from isotope(s)
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Note (1): Asterisks in wavelength highlight the lines with modified log(gf),
see table modif.dat for more details on the modifications applied
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Byte-by-byte Description of file: modif.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- El Element symbol + excitation state
of the element to improve
6- 13 F8.3 0.1nm Line-to-improve ? Wavelength in angstrom of the line
to improve
15- 19 A5 --- Species-modified Element symbol + excitation state
of the modified species
21- 28 F8.3 0.1nm lambda Wavelength in angstrom of the
modified species
30- 34 F5.3 eV EP Excitation potential of modified line
36- 41 F6.3 [-] log(gf)VALD Oscillator strength of the line
before modification
43- 48 F6.3 [-] log(gf)MOD Oscillator strength of the line
after modification
49 A1 --- n_log(gf)MOD [+] Note on log(gf)MOD (1)
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Note (1): Plus signs in column log(gf)MOD denote that the value of log(gf) was
taken from Sneden et al., 2003ApJ...591..936S 2003ApJ...591..936S; Ernandes et al.,
2023MNRAS.524..656E 2023MNRAS.524..656E.
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Byte-by-byte Description of file: lightabu.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- El Element symbol + excitation state (1)
9- 18 A10 --- Molecule? Is abundance derived from molecular
lines, indicating the molecule
20- 37 A18 --- Star ID of the Star, 2MHHMMSSss+DDMMSSs
39 A1 --- l_[X/Fe] Limit flag on [X/Fe]
40- 44 F5.2 [-] [X/Fe] ?=- Abundance compared to solar
46- 49 F4.2 [-] sigma-std ?=- Line-to-line standard deviation
51- 53 I3 --- N ?=- Number of lines
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Note (1): The measurements of C are based on molecular lines of
CH (Masseron et al., 2014A&A...571A..47M 2014A&A...571A..47M, Cat. J/A+A/571/A47),
C2 (Yurchenko et al., 2018MNRAS.480.3397Y 2018MNRAS.480.3397Y, Cat. J/MNRAS/480/3397),
and CN (Sneden et al., 2014ApJS..214...26S 2014ApJS..214...26S, Cat. J/ApJS/214/26),
and the measurements of C are based on molecular lines of
CN (Sneden et al., 2014ApJS..214...26S 2014ApJS..214...26S, Cat. J/ApJS/214/26).
The average over all lines independent from the ionization state are
indicated with "I+II".
For Li I, the A(Li)=log(epsilon(Li)) value is given.
For Fe I and Fe II, the [X/Fe] column corresponds to [Fe/H].
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Byte-by-byte Description of file: uncert.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- El Element symbol + excitation state
9- 12 F4.2 [-] deltaTeff Systematic uncertainty related to
effective temperature
14- 17 F4.2 [-] deltalogg Systematic uncertainty related to
surface gravity
19- 22 F4.2 [-] deltamicrovel Systematic uncertainty related to
microturbulence velocity
24- 27 F4.2 [-] sigmaparam The total uncertainty equal to the
square root of the sum of the
parameter deviations squared
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Acknowledgements:
Maren Brauner, maren.brauner(at)iac.es
References:
Brauner et al., Paper I 2023A&A...673A.123B 2023A&A...673A.123B, Cat. J/A+A/673/A123
(End) Maren Brauner [IAC, Spain], Patricia Vannier [CDS] 12-Aug-2024