| Issue |
A&A
Volume 701, September 2025
|
|
|---|---|---|
| Article Number | A153 | |
| Number of page(s) | 18 | |
| Section | Stellar atmospheres | |
| DOI | https://doi.org/10.1051/0004-6361/202555466 | |
| Published online | 15 September 2025 | |
Chemical composition of planetary hosts
II. Abundances of neutron-capture elements★
Vilnius University, Faculty of Physics, Institute of Theoretical Physics and Astronomy,
Sauletekio av. 3,
10257
Vilnius,
Lithuania
★★ Corresponding author: ashutosh.sharma@ff.vu.lt
Received:
9
May
2025
Accepted:
22
July
2025
Aims. This study seeks to determine abundances of neutron-capture elements (Sr, Y, Zr, Ba, La, Ce, Nd, Pr, and Eu) in a large and homogeneous sample of F, G, and K-type planet-host stars (PHSs) located in the northern hemisphere. The sample includes 160 stars, 32 of which are in multi-planetary systems. These stars host a total of 175 high-mass planets and 47 Neptunian and Super-Earth planets. We investigated potential correlations between stellar chemical compositions and the presence of orbiting planets.
Methods. Spectra were obtained using the 1.65-metre telescope at the Moletai Astronomical Observatory and a fibre-fed high-resolution spectrograph covering the entire visible wavelength range (4000–8500 Å). The abundances of neutron-capture elements were determined by differential line-by-line spectrum synthesis using the TURBOSPECTRUM code with the MARCS stellar model atmospheres.
Results. We analysed neutron-capture elements relative to iron ([El/Fe]) and found that the abundances of the majority of chemical elements in exoplanet host stars align with the Galactic chemical evolution. However, [Zr/Fe], [La/Fe], and [Ce/Fe] are overabundant in stars with planets compared to reference stars at a given [Fe/H]. When examining [El/Fe] against planet mass, most elements show positive correlations with higher mass planets, excluding strontium, yttrium, and barium, which exhibit insignificant correlations across all sub-samples. The ∆[El/H] versus Tcond slope distribution shows a positive skewness for planet-hosting stars, suggesting an enrichment of refractory elements compared to analogues. While ∆[El/H]–Tcond slopes and stellar and planetary parameters do not show strong correlations, trends suggest that older dwarf stars with multiple planets have smaller or even negative ∆[El/H]–Tcond slopes compared to younger dwarf stars, which show larger positive slopes. Our results also show that multi-planetary systems are more common around metal-rich stars.
Key words: techniques: spectroscopic / stars: abundances / stars: atmospheres / planetary systems
This work is based on observations collected with the VUES spectrograph installed on a 1.65 m telescope set up at the Moletai Astronomical Observatory, Institute of Theoretical Physics and Astronomy, Vilnius University, Lithuania (A facility that belongs to the Euro-planet Telescope Network; https://www.europlanet-society.org/europlanet-2824-ri/europlanet-telescope-network/).
© The Authors 2025
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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