J/A+A/700/A174 ESPRESSO's RVs down to the 10cm/s level (Figueira+, 2025)
A comprehensive study on radial velocity signals using ESPRESSO:
Pushing precision to the 10 cm/s level.
Figueira P., Faria J.P., Silva A.M., Castro-Gonzalez A., Gomes da Silva J.,
Sousa S.G., Bossini D., Zapatero-Osorio M.R., Balsalobre-Ruza O.,
Lillo-Box J., Tabernero H.M., Adibekyan V., Allart R., Benatti S.,
Bouchy F., Cabral A., Cristiani S., Dumusque X., Gonzalez-Hernandez J.I.,
Hara N., Lo Curto G., Lovis C., Mehner A., Molaro P., Pepe F., Santos N.C.,
Segransan D., Sosnowska D., Rebolo R., Suarez Mascareno A., Sozzetti A.,
Udry S., Wehbe B.
<Astron. Astrophys. 700, A174 (2025)>
=2025A&A...700A.174F 2025A&A...700A.174F (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Radial velocities ;
Optical
Keywords: instrumentation: spectrographs - methods: observational -
techniques: radial velocities
Abstract:
We analyse the ESPRESSO data for the stars HD10700, HD20794, HD102365,
and HD304636 acquired via its Guaranteed Time Observations (GTO)
programme. We characterise the stars' radial velocity (RV) signals
down to a precision of 10cm/s on timescales ranging from minutes to
planetary periods falling within the host's habitable zone (HZ). We
study the RV signature of pulsation, granulation, and stellar
activity, inferring the potential presence of planets around these
stars. Thus, we outline the population of planets that while
undetectable, remains compatible with the data.
We derived the stellar parameters through different methods for a
complete characterisation of the star. We used these parameters to
model the effects of stellar pulsations on intra-night RV variations
and of stellar activity on nightly averaged values. The RVs were
derived both with the cross-correlation method and template matching,
as well as over the blue and red ESPRESSO detectors independently to
identify colour-dependent parasitic effects that were of an
instrumental or a stellar nature. The study of RVs was complemented by
an investigation of stellar activity indicators variation using
photospheric information and chromospheric indexes.
A simple model of stellar pulsations successfully reproduced the
intra-night RV scatter of HD10700 down to a few cm/s. For HD102365 and
HD20794 an additional source of scatter at the level of several 10cm/s
is required to explain the data. A kima analysis was used to evaluate
the number of planets supported by the nightly averaged time series of
each of these three stars, under the assumption that a quasi-periodic
Gaussian process (GP) regression is able to model the activity signal.
While a frequency analysis of HD10700 RVs identifies a periodic signal
at 20d, when it is modelled along with the activity signal the signal
is formally non-significant. Moreover, its physical origin remains
uncertain due to the similarity with the first harmonic of the stellar
rotation. ESPRESSO data on their own do not provide conclusive
evidence to support the existence for planets around HD10700, HD102365
or HD304636. In addition, the comparison of RVs with the
contemporaneous indicators display a strong correlation for HD102365.
The direct interpretation is that half of the RV variance on this star
is directly attributed to activity.
ESPRESSO is shown to reach an on-sky RV precision of better than
10cm/s on short timescales (<1h) and of 40cm/s over 3.5yr. A
subdivision of the datasets showcases a precision reaching 20-30cm/s
over one year. These results provide stringent constraints on the
impact of granulation mechanisms on RV. In spite of no detections, our
analysis of HD10700 RVs demonstrates a sensitivity to planets with a
mass of 1.7M⊕ for periods of up to 100d, and with a mass of
2-5M⊕ for the star's HZ.
Description:
ESPRESSO Radial Velocities for the three stars HD10700, HD102365, and
HD304636 divided into the two datasets ESPR18 and ESPR19, as used
throughout the paper.
For each of these stars we present RVs calculated with the CCF, TM,
TMb, and TMr methods, corresponding to Cross Correlation Function and
Template Matching using the whole wavelength range or only blue and
red detectors, respectively.
For the star HD10700 we also include RVs calculated using
telluric-corrected spectra, with the above datasets and RV methods.
For further details, please refer to the paper.
Objects:
-------------------------------------------------
RA (2000) DE Designation(s)
-------------------------------------------------
11 46 31.07 -40 30 01.2 HD102365 = HR 4523
01 44 04.08 -15 56 14.9 HD10700 = HR 509
09 21 37.60 -60 16 55.0 HD304636 = HIP 45908
-------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
list.dat 121 32 List of velocity curve files
vc/* . 32 Individual velocity curves
--------------------------------------------------------------------------------
Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 32 A32 --- FileName Name of the velocity curve file
in subdirectory vc
34-121 A88 --- Title Title of the file
--------------------------------------------------------------------------------
Byte-by-byte Description of file: vc/*
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 F11.5 d BJD Barycentric Julian Date (BJD-2400000)
18- 25 F8.5 m/s RV Radial Velocity (average-value subtracted)
35- 41 F7.5 m/s e_RV Radial Velocity uncertainty
--------------------------------------------------------------------------------
Acknowledgements:
Pedro Figueira, Pedro.Figueira(at)unige.ch
(End) Pedro Figueira [UNIGE], Patricia Vannier [CDS] 11-Jul-2025