![Kiel diagram for 290 stars with 5000 K ≤ Teff ≤ 6500 K and log g ≥ 4.0 dex analyzed in this work. The dashed black lines present the solar values obtained for the Ceres 2009-02-08 solar spectrum, Teff = 5759±18 K, log g = 4.43±0.05 dex and [Fe/H] = 0.00±0.01 dex. -- astro-ph.EP](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/07/Chemical-Abundances.png?fit=1200%2C675&ssl=1)
[astro-ph.EP] We determined atmospheric and evolutionary parameters, along with chemical abundances of C, O, S, Fe, and Ni for 290 solar-type exoplanet hosting stars using high-resolution HARPS-North and HARPS-South spectra, and radii for 373 exoplanets using literature transit depths.
We find that stars hosting giant exoplanets (Rpl>4 R⊕) show enhanced [X/H] abundances compared to small exoplanet hosts for all elements analyzed. When considering only exoplanets with Porb≤30 days, there is a statistically significant anti-correlation between host star [Fe/H] and Porb.
However, [Fe/H] does not continue to decline as the orbital period increases, but rather rises again for exoplanets with larger orbital periods. Stars hosting only small exoplanets or hosting at least one sub-Saturn show significant differences between the populations of hot and warm exoplanets for all elements.
In contrast, stars hosting at least one Jupiter-sized planet show no abundance differences. The host star C/O ratios obtained vary from 0.17 to 0.95, with giant exoplanet hosts exhibiting the lowest median C/O ratios (0.43+0.02−0.03), while the 3 — 4 R⊕ sub-Neptune hosts in our sample exhibit the highest median C/O ratios (0.55+0.05−0.01). Our sample has 199 exoplanets with estimated masses and we find correlations between host star [O/H] and [S/H] and log(Mpl/M⊕).
When segregating the sample into hot and warm exoplanet hosts, these trends are only found for warm exoplanets. Dividing the sample between low- (91 exoplanets) and high-[α/Fe] (20 exoplanets) stars, there are trends between host star [O/H], [S/H], [Fe/H] and [Ni/H] and log(Mpl/M⊕) only for the low-[α/Fe] sample.
Fe and Ni, in Solar-type Exoplanet-hosting Stars from HARPS North and South
E. Costa-Almeida, L. Ghezzi, K. Cunha, V. V. Smith, J. J. Fortney
Comments: 45 pages, 21 figures
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2606.30722 [astro-ph.EP] (or arXiv:2606.30722v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2606.30722
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Submission history
From: Ellen Costa-Almeida
[v1] Mon, 29 Jun 2026 18:00:02 UTC (7,712 KB)
https://arxiv.org/abs/2606.30722
Astrobiology, Astrochemistry,
