J/A+A/709/A123 HD 161098 RVs and activity indicators (Nari+, 2026)
The RoPES project with HARPS and HARPS-N.
III. Two candidate planets orbiting the G-type star HD 161098.
Nari N., Suarez Mascareno A., Gonzalez Hernandez J.I., Stefanov A.K.,
Rebolo R., Mestre J.M., Dumusque X., Cretignier M., Passegger V.M.,
Mignon L., Manni F., De Amorim R.G.S.B.
<Astron. Astrophys. 709, A123 (2026)>
=2026A&A...709A.123N 2026A&A...709A.123N (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Radial velocities ;
Optical
Keywords: planets and satellites: detection -
planets and satellites: terrestrial planets
Abstract:
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 1m/s 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.
We present the analysis of the nearby G8 V-type star HD 161098
(V=7.68mag, d=29.75pc). We searched for terrestrial planets in the
habitable zone.
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.
We detected two sub-m/s1 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 72.578-0.060+0.059d and a
minimum mass of 3.63±0.59M⊕. HD 161098 c has an orbital
period of 682.5-9.9+9.5d and a minimum mass of
7.8-1.4+1.5M⊕. If confirmed, candidate HD 161098 c would
reside in the optimistic habitable zone of the star. We find a
magnetic cycle of 4090-130+140d period and a rotation period of
28.22-0.35+0.30d. Our analysis sets the stage for future observing
campaigns of the star, finalized for the confirmation of our results.
We are entering the sub-m/s era at long orbital periods with a
combination of stellar activity treatment and long-term campaigns.
Description:
Tables contain RV and activity indicators used in our analysis.
Objects:
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RA (2000) DE Designation(s)
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17 43 44.25 -03 55 04.3 HD 161098 = HIP 86765
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablee1.dat 207 51 ESPRESSO time series of RV and activity
indicators
tablee2.dat 373 301 HARS-N, HARPS-03 and HARPS-15 time series of RV
and activity indicators
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Byte-by-byte Description of file: tablee1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 F18.12 d JD Reduced Julian date (JD-240000)
20- 32 F13.6 m/s RV Radial velocity
34- 41 F8.6 m/s e_RV Radial velocity error
43- 53 F11.6 m/s FWHM Full width at half maximum
55- 62 F8.6 m/s e_FWHM Full width at half maximum
64- 73 F10.6 km/s BisSpan Bisector span
75- 82 F8.6 km/s e_BisSpan Bisector span error
84- 92 F9.6 % Contrast Contrast
94-101 F8.6 % e_Contrast Contrast error
103-112 F10.6 --- SMW Mt. Wilson chromospheric activity index index
114-121 F8.6 --- e_SMW Mt. Wilson chromospheric activity index index
error
123-130 F8.6 --- Halpha H-alpha indicator
132-139 F8.6 --- e_Halpha H-alpha indicator error
141-148 F8.6 --- Na Na indicator
150-157 F8.6 --- e_Na Na indicator error
159-166 F8.6 --- Ca Ca indicator
168-175 F8.6 --- e_Ca Ca indicator error
177-185 F9.6 --- RHK RHK activity indicator
187-194 F8.6 --- e_RHK RHK activity indicator error
196-205 F10.6 km/s BERV Barycentric Earth Radial Velocity
207 I1 --- Weight Weight
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Byte-by-byte Description of file: tablee2.dat
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Bytes Format Units Label Explanations
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1- 12 F12.6 d JD Reduced Julian rdate (JD-240000)
17- 31 E15.9 km/s RV Radial velocity
33- 46 E14.9 km/s e_RV Radial velocity error
49- 62 E14.9 km/s FWHM Full width at half maximum
65- 78 E14.9 km/s e_FWHM Full width at half maximum
81- 94 E14.9 km/s BisSpan Bisector span
97-110 E14.9 km/s e_BisSpan Bisector span error
113-126 E14.9 % Contrast Contrast
129-142 E14.9 % e_Contrast Contrast error
145-159 E15.9 --- SMW Mt. Wilson chromospheric activity index index
161-174 E14.9 --- e_SMW Mt. Wilson chromospheric activity index index
error
177-190 E14.9 --- Halpha H-alpha indicator
193-206 E14.9 --- e_Halpha H-alpha indicator error
209-222 E14.9 --- Na Na indicator
225-238 E14.9 --- e_Na Na indicator error
241-254 E14.9 --- Ca Ca indicator
257-270 E14.9 --- e_Ca Ca indicator error
273-287 E15.9 --- RHK RHK activity indicator
289-302 E14.9 --- e_RHK RHK activity indicator error
305-319 E15.9 km/s BERV Barycentric Earth Radial Velocity
321-334 E14.9 --- snCaII CaII S/N
337-351 E15.9 --- model Model
353-365 A13 --- Inst Instrument name
369-373 A5 --- Ver insdrsversion
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Acknowledgements:
Nicola Nari, nicola.nari(at)lightbridges.es
License: CC-BY-4.0
(End) Patricia Vannier [CDS] 12-May-2026