J/MNRAS/548/G520 HARPS-N RV data of six planetary systems (Palethorpe+, 2026)
Constraining small planet compositions for future missions.
Palethorpe L., Mortier A., Egger J.A., Rice K., Wilson T.G., Vanderburg A.,
Bonomo A.S., Boschin W., Cameron A.C., Eschen Y.N.E., Harutyunyan A.,
Malavolta L., Fiorenzano A.F.M., Sozzetti A., Stalport M., Van Eylen V.,
Watson C.A.
<Mon. Not. R. Astron. Soc. 548, stag520 (2026)>
=2026MNRAS.548g.520P 2026MNRAS.548g.520P (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Radial velocities ;
Optical
Keywords: techniques: photometric - techniques: spectroscopic - exoplanets -
planets and satellites: composition
Abstract:
Accurate mass and radius measurements of small transiting exoplanets
are essential for probing their compositions, formation histories, and
potential habitability. We present a uniform analysis of six planetary
systems (each hosting at least one small transiting planet): K2-79,
K2-106, K2-111, K2-222, K2-263, and TOI-1634. Our study combines new
CHEOPS transit observations with archival photometry from K2, TESS,
and ground-based facilities, alongside new and archival radial
velocity data from HARPS-N, HIRES, ESPRESSO, and others. For each
system, we perform joint transit and RV modelling, achieving typical
precisions better than 15 per cent and 5 per cent for mass and radius,
respectively, and thus enabling precise bulk density determinations.
These reveal a range of compositions, including rocky planets near the
radius valley (e.g. K2-106 b, TOI-1634 b), intermediate-density
planets requiring steam-rich or mixed volatile envelopes (e.g. K2-111
b, K2-263 b), and low-density regimes, consistent with gas dwarfs or
water-worlds (e.g. K2-79 b, K2-222 b). Several systems show evidence
of additional companions detectable via RVs but not seen in transit.
The results highlight the value of coordinated CHEOPS and HARPS-N
observations in delivering some of the most precise bulk densities for
small planets to date and support the preparation for future
atmospheric characterization missions.
Description:
HARPS-N radial velocities for the K2-79, K2-106, K2-111, K2-222,
K2-263 and TOI-1634 systems.
Objects:
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RA (2000) DE Designation(s) (file)
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03 41 01.41 +13 31 09.71 K2-79 = TOI-6962 (tablea1.dat)
00 52 19.14 +10 47 40.91 K2-106 = TIC 266015990 (tablea2.dat)
03 59 33.54 +21 17 55.24 K2-111 = TIC 14227229 (tablea3.dat)
01 05 50.95 +11 45 12.34 K2-222 = TOI-4648 (tablea4.dat)
08 38 43.77 +15 40 50.25 K2-263 = TIC 21276520 (tablea5.dat)
03 45 33.64 +37 06 44.00 TOI-1634 = TIC 201186294 (tablea6.dat)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 50 80 HARPS-N RV DRS reduced data for K2-79
tablea2.dat 50 45 HARPS-N RV DRS reduced data for K2-106
tablea3.dat 60 116 HARPS-N RV DRS reduced data for K2-111
tablea4.dat 50 74 HARPS-N RV DRS reduced data for K2-222
tablea5.dat 50 96 HARPS-N RV DRS reduced data for K2-263
tablea6.dat 47 32 HARPS-N RV TERRA reduced data for TOI-1634
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Byte-by-byte Description of file: tablea?.dat
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Bytes Format Units Label Explanations
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1- 20 F20.12 d BJD Barycentric Julian Day
22- 40 F19.12 m/s RV Radial Velocity (relative radial velocity
for table 6)
42- 60 F19.16 m/s e_RV Error in radial velocity
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Acknowledgements:
Larissa Palethorpe, larissa.palethorpe(at)bristol.ac.uk
License: CC-BY-4.0
(End) Patricia Vannier [CDS] 19-Jun-2026