The RoPES Project With HARPS and HARPS-N III. Two Candidate Planets Orbiting The G-type Star HD 161098

Context. The development of refined instruments and techniques for a detailed analysis of the radial velocities (RVs) of stars other than the Sun allows the presence of planetary signals of amplitude below 1 ms⁻¹ to be investigated. Long-term RV surveys allow the detection of Earth-like and super-Earth-like planets in the habitable zones of Sun-like stars, prime targets for future missions for the atmospheric characterization of exoplanets.

Aims. We present the analysis of the nearby G8 V-type star HD 161098 (V = 7.68 mag, d = 29.75 pc). We searched for terrestrial planets in the habitable zone.

Methods. We combined historical datasets with new data collected in an ongoing blind search program with HARPS, HARPS-N, and ESPRESSO. We utilized recently developed tools to extract RVs and to deal with the analysis of stellar activity. We performed a joint analysis of RVs and activity indicators to separate the planetary signals from those related to activity.

Results. We detected two sub-ms⁻¹ signals that we claim as candidate planets. We are not able to confirm their nature with certainty. Candidate HD 161098 b has an orbital period of 72.578+0.059−0.060 d and a minimum mass of 3.63 ± 0.59 M_Earth. HD 161098 c has an orbital period of 682.5+9.5−9.9 d and a minimum mass of 7.8+1.5−1.4 this http URL confirmed, candidate HD 161098 c would reside in the optimistic habitable zone of the star.

We find a magnetic cycle of 4090+140−130 d period and a rotation period of 28.22+0.30−0.35 d. Our analysis sets the stage for future observing campaigns of the star, finalized for the confirmation of our results.

Conclusions. We are entering the sub-ms⁻¹ era at long orbital periods with a combination of stellar activity treatment and long-term campaigns.

N. Nari, A. Suárez Mascareño, J. I. González Hernández, A. K. Stefanov, R. Rebolo, J. M. Mestre, X. Dumusque, M. Cretignier, V. M. Passegger, L. Mignon, F. Manni, R. G. S. B. De Amorim

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2604.11516 [astro-ph.EP](or arXiv:2604.11516v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2604.11516
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Submission history
From: Nicola Nari
[v1] Mon, 13 Apr 2026 14:20:19 UTC (2,376 KB)
https://arxiv.org/abs/2604.11516

Astrobiology,