J/A+A/699/A185 TOI-2427 HARPS RVs and activity indicators (Schmerling+, 2025)
The TOI-2427 system: Two close-in planets orbiting a late K-dwarf star.
Schmerling H., Goffo E., Grziwa S., Persson C.M., Gandolfi D., Paetzold M.,
Hatzes A., Hellier C., Livingston J., Acuna L., Aguichine A., Costanza E.,
Deeg H.J., Masseron T., Palle E., Cochran W., Nowak G., Jankowski D.,
Gozdziewski K., Luque R., Mathur S., Palakkatharappil D.B., Garcia R.A.
<Astron. Astrophys. 699, A185 (2025)>
=2025A&A...699A.185S 2025A&A...699A.185S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Stars, K-type ;
Radial velocities ; Optical
Keywords: instrumentation: photometers - techniques: radial velocities -
planets and satellites: atmospheres -
planets and satellites: detection - planets and satellites: interiors
Abstract:
Using high-precision photometry, NASA's TESS space mission has
discovered many intriguing transiting planet candidates. These
discoveries require ground-based follow-up observations, including
high-precision Doppler spectroscopy, to rule out false positive
scenarios and measure the mass of the transiting planets. In this
study, we present an intensive Doppler follow-up campaign of the TESS
object of interest TOI-2427, carried out with the High Accuracy Radial
velocity Planet Searcher (HARPS) spectrograph to determine the mass of
the previously validated transiting planet (TOI-2427 b) and search for
additional orbiting companions. By analyzing TESS transit photometry
alongside our HARPS radial velocity measurements, we spectroscopically
confirmed the transiting planet TOI-2427 b, which orbits its host star
every ∼1.3d. We also discovered the presence of a second
non-transiting planetary companion with an orbital period of ∼5.15d,
which is very close to four times the orbital period of the inner
transiting planet. We found that TOI-2427 b is a short-period,
high-density super-Earth with a mass of Mb=5.69-0.50+0.51M⊕
and a radius of Rb=1.64-0.11+0.12R⊕, implying a mean
density of ρb=7.1-0.4+0.8g/cm3. Its interior seems to be
composed of a predominantly iron core and a silicate mantle and crust.
Despite its high density, it is unlikely that TOI-2427 b can sustain
any atmosphere composed of lighter gases; however, it could still
retain heavier gases. The outer non-transiting planet TOI-2427 c has a
minimum mass of Mc sin ic = 6.46-0.78+0.79 M⊕. Assuming that
TOI-2427 b and c are coplanar, a statistical analysis suggests that
planets with a mass of ∼6.5M⊕ tend to have radii around
2.7-0.8+1.1R⊕. This would place TOI-2457 c near the
sub-Neptune regime, while also leaving open the possibility of it
being a super-Earth.
Description:
We present the HARPS data obtained as part of a study on the system
TOI 2427 (RA = 03:29:09.83, DE = -31:21:46.96). The observations were
carried out between September 2021 and February 2022.
A significant radial velocity signature was found which we explain as
the signature of two planets orbiting the target star. Thus, we were
able to determine the presence of the planets as well as their minimum
masses.
Barycentric Julian dates in Barycentric dynamical time (BJD_TDB)
dependent Measurements of the HARPS DRS (RV_DRS), TERRA (RV_TERRA),
and SERVAL (RV_SERVAL) radial velocity measurements together with
their respective uncertainties. The rest pf the data lists measurements
of several different activity indicators and their uncertainties.
These are the bisector inverse slope (BIS) and the full width at
half-maximum (FWHM) of the cross-correlation function (CCF) as
extracted by the DRS, Contrast, the differential line width (dLW,
edLW), the chromatic RV index (crx, ecrx), the S-Index, and emissions
in the Halpha, Na D1, and Na D2 activity-related lines, and the S/N
ratio per pixel at 550nm.
Objects:
----------------------------------------------------
RA (2000) DE Designation(s)
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03 29 09.83 -31 21 46.9 TOI-2427 = CD-31 1415
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 175 100 HARPS RV measurements
tablea2.dat 234 100 HARPS activity indicators
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 16 F16.8 d BJD Barycentric Julian date (TDB)
18- 35 F18.15 km/s RV-DRS HARPS DRS radial velocity
37- 53 F17.15 km/s e_RV-DRS HARPS DRS radial velocity uncertainty
55- 75 F21.18 km/s RV-TERRA TERRA relative radial velocity
77- 96 F20.18 km/s e_RV-TERRA TERRA relative radial velocity uncertainty
98-118 F21.18 km/s RV-SERVAL SERVAL relative radial velocity
120-139 F20.18 km/s e_RV-SERVAL SERVAL relative radial velocity uncertainty
141-157 F17.15 km/s BIS Bisector inverse slope
159-175 F17.15 km/s FWHM Full width at half-maximum
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 16 F16.8 d BJD Barycentric Julian date (TDB)
18- 35 F18.15 % Contrast Depth of cross-correlation function
as percentage
37- 58 F22.18 m2/s2 dLW Differential line width
60- 79 F20.18 m2/s2 e_dLW dLW uncertainty
81-102 F22.18 m/s CRX Chromatic Index of the Radial Velocity
104-124 F21.18 m/s e_CRX CRX uncertainty
126-145 F20.18 --- SIndex Chromosperic activity index
147-166 F20.18 --- e_SIndex S-Index uncertainty
168-187 F20.18 0.1nm Halpha Emission in the H-alpha line
189-208 F20.18 0.1nm NaD1 Emission in the NaD1 line
210-229 F20.18 0.1nm NaD2 Emission in the NaD2 line
231-234 F4.1 --- SNR Signal to noise ratio at 550nm
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Acknowledgements:
Hendrik Schmerling, h.schmerling(at)uni-koeln.de
(End) Hendrik Schmerling [RIU, Germany], Patricia Vannier [CDS] 30-May-2025