J/A+A/702/A118 HD224018 HARPS-N data (Damasso+, 2025)
Discovery of a multi-planetary system orbiting the aged Sun-like star HD224018.
Damasso M., Naponiello L., Anna John A., Egger J.A., Cretignier M.,
Mortier A., Bonomo A.S., Collier Cameron A., Dumusque X., Wilson T.,
Buchhave L., Nicholson B., Stalport M., Ghedina A., Latham D.W.,
Livingston J., Malavolta L., Sozzetti A., Jenkins J.M., Mantovan G.,
Martinez Fiorenzano A.F., Palethorpe L., Tronsgaard R., Udry S., Watson C.A.
<Astron. Astrophys. 702, A118 (2025)>
=2025A&A...702A.118D 2025A&A...702A.118D (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Radial velocities ;
Spectroscopy ; Optical
Keywords: techniques: photometric - techniques: radial velocities -
planets and satellites: detection -
planets and satellites: fundamental parameters -
stars: individual: HD 224018
Abstract:
Exoplanetary systems show a large diversity of architectures and
planet types. Among the increasing number of exodemographics studies,
those exploring correlations between the presence of close-in small
planets and cold Jupiters are the object of particular attention.
In 2016, Kepler-K2 detected a system of two sub-Neptunes transiting
the star HD 224018, one of them showing a mono-transit event. In 2017,
we began a spectroscopic follow-up with HARPS-N to measure the
dynamical masses of the planets using radial velocities, and collected
additional transit observations using CHEOPS.
We measured the fundamental physical parameters of the host star,
which is an old Sun analogue. We analysed radial velocities and
photometric time series, also including data by TESS, to provide
precise ephemerides, radii, masses, and bulk densities of the two
planets, and possibly modeling their internal structure and
composition.
The system turned out to be more crowded than shown by K2. Radial
velocities revealed the presence of two additional bodies: a candidate
cold companion on an eccentric orbit with a minimum mass nearly half
that of Jupiter (eccentricity 0.60+0.07_-0.08); semi-major axis
8.6+1.5-1.6au), and an innermost super-Earth (orbital period
10.6413±0.0028d; mass 4.1±0.8M⊕) for which we discovered
previously undetected transit events in K2 photometry. TESS data
revealed a second transit of one of the two companions originally
observed by K2. This allowed us to constrain its orbital period to a
grid of values, the most likely being nearly 138 days, which would
imply a mass less than 9M⊕, at a 3-sigma significance level.
Given the level of precision of our measurements, we were able to
constrain the internal structure and composition of the second-most
distant planet from the host star, a warm sub-Neptune with a bulk
density of 3.9±0.5g/cm3.
HD 224018 hosts three close-in transiting planets in the
super-Earth-to- sub-Neptune regime, and a candidate cold and eccentric
massive companion. Additional follow-up is needed to better
characterise the physical properties of the planets and their
architecture, and to study the evolutionary history of the system.
Description:
HARPS-N radial velocities, CCF-based activity indicators, S-index
values, and SCALPELS decorrelation vector basis (from U0 to U2) of
HD224018.
Objects:
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RA (2000) DE Designation(s)
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23 54 33.47 -04 43 23.8 HD 224018 = TIC 248608315
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablee1.dat 81 206 Full list of RVs and activity indicators
tablee2.dat 43 177 Analysed RVs and SCALPELS decorrelation vector basis
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Byte-by-byte Description of file: tablee1.dat
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Bytes Format Units Label Explanations
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1- 12 F12.6 d Time Time (BJD-2450000)
14- 22 F9.2 m/s RV Radial velocity
24- 28 F5.2 m/s e_RV Radial velocity error
30- 36 F7.2 m/s FWHM FWHM
38- 42 F5.2 m/s e_FWHM FWHM error
44- 49 F6.2 m/s BIS Bisector span
51- 55 F5.2 m/s e_BIS Bisector span error
57- 61 F5.2 --- Cont Contrast of cross-correlation function
63- 66 F4.2 --- e_Cont Contrast of cross-correlation function error
68- 74 F7.4 --- Sindex S-index
76- 81 F6.4 --- e_Sindex S-index error
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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 Time Time (BJD-2450000)
14- 19 F6.2 m/s RV Relative radial velocity
21- 24 F4.2 m/s e_RV Relative radial velocity error
26- 31 F6.2 m/s U0 SCALPELS vector basis U0
33- 37 F5.2 m/s U1 SCALPELS vector basis U1
39- 43 F5.2 m/s U2 SCALPELS vector basis U2
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Acknowledgements:
Mario Damasso, mario.damasso(at)inaf.it
(End) Patricia Vannier [CDS] 19-Aug-2025