J/A+A/668/A88 38 K giants phosphorus abundance (Nandakumar+, 2022)
The Galactic chemical evolution of phosphorus observed with IGRINS.
Nandakumar G., Ryde N., Montelius M., Thorsbro B., Joensson H., Mace G.
<Astron. Astrophys. 668, A88 (2022)>
=2022A&A...668A..88N 2022A&A...668A..88N (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, K-type ; Stars, giant ; Abundances ;
Spectra, infrared ; Effective temperatures
Keywords: stars: abundances - stars: late-type - Galaxy: evolution -
Galaxy: disk - infrared: stars
Abstract:
Phosphorus (P) is considered to be one of the key elements for life,
making it an important element to look for in the abundance analysis
of spectra of stellar systems. Yet, only a select number of
spectroscopic studies exist to estimate the phosphorus abundances and
investigate its trend across a range of metallicities. This is due to
the lack of good phosphorus lines in the optical wavelength region and
the requirement of careful manual analysis of the blended phosphorus
lines in near-infrared H-band spectra obtained with individual
observations and surveys such as the Apache Point Observatory Galactic
Evolution Experiment (APOGEE).
Based on a consistent and systematic analysis of high-resolution,
near-infrared Immersion GRating INfrared Spectrograph (IGRINS) spectra
of 38 K giant stars in the Solar neighborhood, we present and
investigate the phosphorus abundance trend in the metallicity range of
-1.2dex<[Fe/H]<0.4dex. Furthermore, we compare this trend with
the available chemical evolution models to shed some light on the
origin and evolution of phosphorus.
We have observed full H- and K-band spectra at a spectral resolving
power of R=45000 with IGRINS mounted on the Gemini South telescope,
the Discovery Channel Telescope, and the Harlan J Smith Telescope at
McDonald Observatory. Abundances were determined from spectral lines
by modeling the synthetic spectrum that best matches the observed
spectrum by chi-square minimization. For this task, we used the
Spectroscopy Made Easy (SME) tool in combination with one-dimensional
(1D) Model Atmospheres in a Radiative and Convective Scheme (MARCS)
stellar atmosphere models. The investigated sample of stars have
reliable stellar parameters estimated using optical FIber-fed Echelle
Spectrograph (FIES) spectra obtained in a previous study of a set of
stars called GIants in the Local Disk (GILD). In order to determine
the phosphorus abundances from the 16482.92 Angstrom phosphorus line,
we needed to take special care blending the CO(7-4) line. With the
stellar parameters known, we thus determined the C, N, and O
abundances from atomic carbon and a range of nonblended molecular
lines (CO, CN, and OH) which are plentiful in the H-band region of K
giant stars, assuring an appropriate modeling of the blending CO(7-4)
line.
We present the [P/Fe] versus [Fe/H] trend for K giant stars in the
metallicity range of -1.2dex<[Fe/H]<0.4dex and enhanced phosphorus
abundances for two metal-poor s-rich stars. We find that our trend
matches well with the compiled literature sample of prominently dwarf
stars and the limited number of giant stars. Our trend is found to be
higher by 0.05-0.1dex compared to the theoretical chemical evolution
trend resulting from the core collapse supernova (type II) of massive
stars with the phosphorus yields arbitrarily increased by a factor of
2.75. Thus the enhancement factor might need to be 0.05-0.1dex higher
to match our trend. We also find an empirically determined primary
behavior for phosphorus. Furthermore, the phosphorus abundance is
found to be elevated by 0.6-0.9dex in the two s-enriched stars
compared to the theoretical chemical evolution trend.
Description:
We present phosphorus abundances measured from the infrared H band for
38 K giants in the solar neighbourhood. The spectra were obtained with
the spectrograph IGRINS at HJST and DCT. The spectra have R=45000. The
S/N of the spectra is generally high, with the majority of them having
values above 150.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 64 38 Stellar parameters and phosphorus abundances
for sample
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Star Name (HD, HIP, KIC, 2M)
14 A1 --- n_Star [a] Note on Star (1)
16- 26 A11 --- Pop Designated stellar population (2)
28- 31 I4 K Teff Effective temperature
33- 35 F3.1 [cm/s2] logg Surface gravity
37- 41 F5.2 [-] [Fe/H] Relative iron abundance
43- 45 F3.1 km/s vmicro Microturbulence velocity
47- 49 F3.1 km/s vmacro Macroturbulence velocity
51- 55 F5.2 [-] [P/Fe] Relative phosphorus abundance
57- 60 F4.2 [-] e_[P/Fe] Uncertainty in the relative phosphorus abundance
62- 64 I3 --- S/N Signal-to-noise ratio
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Note (1): a: Infrared atlas spectrum of Arcturus (Hinkle et al.,
1995PASP..107.1042H 1995PASP..107.1042H, Cat. J/PASP/107/1042).
Note (2): Based on kinematics and [Mg/Fe], see Sect. 3.2. S-rich designation
from s-element abundances in Jonsson et al. (in prep.)
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Acknowledgements:
Govind Nandakumar, govind.iist(at)gmail.com
(End) Patricia Vannier [CDS] 10-Nov-2022