arXiv subjects

Francesco Pepe

Publications and source records attributed to Francesco Pepe.

At least 37 records · Page 2Linked to original sources

arXiv2025

NIRPS joining HARPS at ESO 3.6 m. On-sky performance and science objectives

The Near-InfraRed Planet Searcher (NIRPS) is a high-resolution, high-stability near-infrared (NIR) spectrograph equipped with an AO system. Installed on the ESO 3.6-m telescope, it was developed to enable radial velocity (RV) measurements of low-mass exoplanets around M dwarfs and to characterise exoplanet atmospheres in the NIR. This paper provides a comprehensive design overview and characterisation of the NIRPS instrument, reporting on its on-sky performance, and presenting its GTO programme. The instrument started its operations on 1 Apr 2023 after intensive on-sky testing phases. The spectral range continuously covers the Y, J, and H bands from 972.4 to 1919.6 nm. The thermal control system maintains 1 mK stability over several months. The NIRPS AO-assisted fibre link improves coupling efficiency and offers a unique high-angular resolution capability with a fibre acceptance of only 0.4 arcsec. A high spectral resolving power of 90 000 and 75 000 is provided in HA and HE modes, respectively. The overall throughput from the top of the atmosphere to the detector peaks at 13 percent. The RV precision, measured on the bright star Proxima with a known exoplanetary system, is 77 cm/s. NIRPS and HARPS can be used simultaneously, offering unprecedented spectral coverage for spectroscopic characterisation and stellar activity mitigation. Modal noise can be aptly mitigated by the implementation of fibre stretchers and AO scanning mode. Initial results confirm that NIRPS opens new possibilities for RV measurements, stellar characterisation, and exoplanet atmosphere studies with high precision and high spectral fidelity. NIRPS demonstrated stable RV precision at the level of 1 m/s over several weeks. The instrument high throughput offers a notable improvement over previous spectrographs, enhancing our ability to detect small exoplanets.

astro-ph.IM↗

arXiv2025

Diving into the planetary system of Proxima with NIRPS -- Breaking the metre per second barrier in the infrared

We obtained 420 high-resolution spectra of Proxima, over 159 nights, using the Near Infra Red Planet Searcher (NIRPS). We derived 149 nightly binned radial velocity measurements with a standard deviation of 1.69 m/s and a median uncertainty of 55 cm/s, and performed a joint analysis combining radial velocities, spectroscopic activity indicators, and ground-based photometry, to model the planetary and stellar signals present in the data, applying multi-dimensional Gaussian process regression to model the activity signals. We detect the radial velocity signal of Proxima b in the NIRPS data. All planetary characteristics are consistent with those previously derived using visible light spectrographs. In addition, we find evidence of the presence of the sub-Earth Proxima d in the NIRPS data. When combining the data with the HARPS observations taken simultaneous to NIRPS, we obtain a tentative detection of Proxima d and parameters consistent with those measured with ESPRESSO. By combining the NIRPS data with simultaneously obtained HARPS observations and archival data, we confirm the existence of Proxima d, and demonstrate that its parameters are stable over time and against change of instrument. We refine the planetary parameters of Proxima b and d, and find inconclusive evidence of the signal attributed to Proxima c (P = 1900 d) being present in the data. We measure Proxima b and d to have minimum masses of 1.055 $\pm$ 0.055 Me, and 0.260 $\pm$ 0.038 Me, respectively. Our results show that, in the case of Proxima, NIRPS provides more precise radial velocity data than HARPS, and a more significant detection of the planetary signals. The standard deviation of the residuals of NIRPS after the fit is 80 cm/s, showcasing the potential of NIRPS to measure precise radial velocities in the near-infrared.

astro-ph.EP↗

arXiv2025

NIRPS detection of delayed atmospheric escape from the warm and misaligned Saturn-mass exoplanet WASP-69b

Near-infrared high-resolution echelle spectrographs unlock access to fundamental properties of exoplanets, from their atmospheric escape and composition to their orbital architecture, which can all be studied simultaneously from transit observations. We present the first results of the newly commissioned ESO near-infrared spectrograph, NIRPS, from three transits of WASP-69b. We used the RM Revolutions technique to better constrain the orbital architecture of the system. We extracted the high-resolution helium absorption profile to study its spectral shape and temporal variations. Then, we made 3D simulations from the EVE code to fit the helium absorption time series. We measure a slightly misaligned orbit for WASP-69b (psi of 28.7+/-5.7 deg). We confirm the detection of helium with an average excess absorption of 3.17+/-0.05%. The helium absorption is spectrally and temporally resolved, extends to high altitudes and has a strong velocity shift up to -29.5+/-2.5 km/s 50 minutes after egress. EVE simulations put constraints on the mass loss of 2.25 10^11 g/s and hint at reactive chemistry within the cometary-like tail and interaction with the stellar winds that allow the metastable helium to survive longer than expected. Our results suggest that WASP-69b is undergoing a transformative phase in its history, losing mass while evolving on a misaligned orbit. This work shows how combining multiple observational tracers such as orbital architecture, atmospheric escape, and composition, is critical to understand exoplanet demographics and their formation and evolution. We demonstrate that NIRPS can reach precisions similar to HARPS for RM studies, and the high data quality of NIRPS leads to unprecedented atmospheric characterization. The high stability of NIRPS combined with the large GTO available for its consortium, enables in-depth studies of exoplanets as well as large population surveys.

astro-ph.EP↗

arXiv2025

Studying the variability of the He triplet to understand the detection limits of evaporating exoplanet atmospheres

With more than a dozen significant detections, the helium triplet has emerged as a key tracer of evaporating exoplanet atmospheres. This near-infrared feature can be observed from the ground and holds great promise, especially with upcoming observations provided by new-generation instruments such as the Near Infrared Planet Searcher (NIRPS). However, as the helium triplet is also present in stellar spectra, careful removal of the average stellar contribution is necessary to accurately characterize the atmospheres of transiting exoplanets. In this study, we analyze multi-epoch observations of the Sun obtained with NIRPS to investigate the temporal variability of the helium triplet. Our findings reveal significant variability across different timescales, ranging from minutes to days. We identify telluric contamination and stellar activity as likely sources for the short-term and long-term variability, respectively. Importantly, we demonstrate that this variability has minimal impact on the retrieval of planetary parameters crucial to the study of atmospheric escape.

astro-ph.EP↗

arXiv2025

The ESPRESSO Redshift Drift Experiment I -- High-resolution spectra of the Lyman-$α$ forest of QSO J052915.80-435152.0

The measurement of the temporal evolution in the redshift of distant objects, the redshift drift, is a probe of universal expansion and cosmology. We perform the first steps towards a measurement of such effect using the Lyman-$α$ forest in the spectra of bright quasars as a tracer of cosmological expansion. Our goal is to determine to which precision a velocity shift measurement can be carried out with the signal-to-noise (S/N) level currently available and whether this precision aligns with previous theoretical expectations. A precise assessment of the achievable measurement precision is fundamental for estimating the time required to carry out the whole project. We acquire 12 hours of ESPRESSO observations distributed over 0.875 years of the brightest quasar known, J052915.80-435152.0 (z=3.962), to obtain high-resolution spectra of the Lyman-$α$ forest, with median S/N of ~86 per 1 km/s pixel at the continuum. We divide the observations into two epochs and analyse them using both a pixel-by-pixel method and a model-based approach. This comparison allows us to estimate the velocity shift between the epochs, as well as the velocity precision that can be achieved at this S/N. The model-based method is calibrated using high-resolution simulations of the intergalactic medium, and it provides greater accuracy compared to the pixel-by-pixel approach. We measure a velocity drift of the Lyman-$α$ forest consistent with zero: $Δv = -1.25\pm 4.45 {\rm ms^{-1}}$, equivalent to a cosmological drift of $\dot{v}=-1.43\pm 5.09 {\rm ms^{-1}yr^{-1}}$ or $\dot{z}= (-2.19\pm7.77) \times 10^{-8}{\rm yr^{-1}}$. The measurement uncertainties are on par with the expected precision. We estimate that reaching a 99% detection of the cosmic drift requires a monitoring campaign of 5400 hours of integration time over 54 years with an ELT and an ANDES-like high-resolution spectrograph.

astro-ph.CO↗

arXiv2025

High-resolution, high-efficiency narrowband spectroscopy with an s-p-phased holographic grating in double pass

High-resolution spectroscopy (R>50,000) in astronomy typically uses echelle-type spectrographs, which excel for exoplanet detection via radial velocity but compromise throughput for atmospheric characterization. We propose and test a novel method to achieve very high spectral resolution with significantly higher throughput within a limited bandpass using a tuned, high fringe-density volume phase holographic (VPH) grating in double pass. Using a wavelength-tunable laser, we measured the dispersion and diffraction efficiency of this setup, finding that our tested VPH grating reaches a diffraction-limited resolving power >140,000 in double pass with a peak diffraction efficiency of 79% for unpolarized light. Based on current manufacturing capabilities, we estimate double-pass diffraction efficiencies >50% with resolving powers >200,000 are achievable from visible to near-infrared wavelengths, limited only by detector size.

astro-ph.IM↗

arXiv2025

PoET: the Paranal solar ESPRESSO Telescope

The detection and characterisation of other "Earths", orbiting other suns, is a bold objective of present-day astrophysics. However, this quest is severely challenged by astrophysical "noise" from the host stars, whose signatures distort the observed spectra. Motivated by this problem, we are building a dedicated facility, the Paranal solar ESPRESSO Telescope (PoET). PoET will collect solar light and channel it into the ESPRESSO spectrograph, allowing us to use the Sun as a proxy to unambiguously identify and understand the sources of relevant variability in solar-type stars.

astro-ph.SR↗

arXiv2024

Ultraviolet astronomical spectrograph calibration with laser frequency combs from nanophotonic lithium niobate waveguides

Astronomical precision spectroscopy underpins searches for life beyond Earth, direct observation of the expanding Universe and constraining the potential variability of physical constants across cosmological scales. Laser frequency combs can provide the critically required accurate and precise calibration to the astronomical spectrographs. For cosmological studies, extending the calibration with such astrocombs to the ultraviolet spectral range is highly desirable, however, strong material dispersion and large spectral separation from the established infrared laser oscillators have made this exceedingly challenging. Here, we demonstrate for the first time astronomical spectrograph calibrations with an astrocomb in the ultraviolet spectral range below 400 nm. This is accomplished via chip-integrated highly nonlinear photonics in periodically-poled, nano-fabricated lithium niobate waveguides in conjunction with a robust infrared electro-optic comb generator, as well as a chip-integrated microresonator comb. These results demonstrate a viable route towards astronomical precision spectroscopy in the ultraviolet and may contribute to unlocking the full potential of next generation ground- and future space-based astronomical instruments.

physics.optics↗

arXiv2024

The Near-Infrared Gatherer of Helium Transits (NIGHT)

This paper provides a comprehensive overview of the subsystems of the NIGHT instrument. NIGHT (the Near Infrared Gatherer of Helium Transits) is a narrowband, high-resolution spectrograph, marking the first dedicated survey instrument for exoplanetary atmosphere observations. Developed through a collaboration between the Observatory of Geneva and the Universite de Montreal, NIGHT aims to conduct an extensive statistical survey of helium atmospheres around 100+ exoplanets over several years. The instrument will report new detections of helium in exoplanet atmospheres and perform temporal monitoring of a subset of these. NIGHT measures absorption from the metastable helium state during exoplanet transits, observable in a triplet of lines around 1083nm. The instrument comprises a vacuum enclosure housing the spectrograph, a front end unit for fiber injection at the telescope's focal plane, and a calibration and control rack containing calibration light sources and control hardware. The spectrograph is optimized for efficiency, achieving a uniform throughput of approximately 71%. The primary disperser employs a VPH grating in a unique double-pass configuration, enabling a spectral resolution of 75,000 while maintaining high throughput. The detector is a HAWAII-1 infrared array, cooled to 85K, with the spectrograph operating at room temperature. Thanks to its relatively high throughput, NIGHT on a 2m class telescope is predicted to be as sensitive as existing instruments on 4m class telescopes. The front end unit injects starlight and sky background into two separate fibers leading to the spectrograph. It also performs near-infrared guiding and includes a mechanism for injecting calibration light. The assembly and optical alignment of NIGHT's spectrograph and front end unit are scheduled for July to September 2024, with the first light anticipated before early 2025.

astro-ph.IM↗

arXiv2024

Improving Earth-like planet detection in radial velocity using deep learning

Many novel methods have been proposed to mitigate stellar activity for exoplanet detection as the presence of stellar activity in radial velocity (RV) measurements is the current major limitation. Unlike traditional methods that model stellar activity in the RV domain, more methods are moving in the direction of disentangling stellar activity at the spectral level. The goal of this paper is to present a novel convolutional neural network-based algorithm that efficiently models stellar activity signals at the spectral level, enhancing the detection of Earth-like planets. We trained a convolutional neural network to build the correlation between the change in the spectral line profile and the corresponding RV, full width at half maximum (FWHM) and bisector span (BIS) values derived from the classical cross-correlation function. This algorithm has been tested on three intensively observed stars: Alpha Centauri B (HD128621), Tau ceti (HD10700), and the Sun. By injecting simulated planetary signals at the spectral level, we demonstrate that our machine learning algorithm can achieve, for HD128621 and HD10700, a detection threshold of 0.5 m/s in semi-amplitude for planets with periods ranging from 10 to 300 days. This threshold would correspond to the detection of a $\sim$4$\mathrm{M}_{\oplus}$ in the habitable zone of those stars. On the HARPS-N solar dataset, our algorithm is even more efficient at mitigating stellar activity signals and can reach a threshold of 0.2 m/s, which would correspond to a 2.2$\mathrm{M}_{\oplus}$ planet on the orbit of the Earth. To the best of our knowledge, it is the first time that such low detection thresholds are reported for the Sun, but also for other stars, and therefore this highlights the efficiency of our convolutional neural network-based algorithm at mitigating stellar activity in RV measurements.

astro-ph.EP↗

arXiv2024

Fundamental physics with ESPRESSO: a new determination of the D/H ratio towards PKS1937-101

Primordial abundances of light elements are sensitive to the physics of the early Universe and can directly constrain cosmological quantities, such as the baryon-to-photon ratio $η_{10}$, the baryon density and the number of neutrino families. Deuterium is especially suited for these studies: its primordial abundance is sensitive and monotonically dependent on $η_{10}$, allowing an independent measurement of the cosmic baryon density that can be compared, for instance, against the Planck satellite data. The primordial deuterium abundance can be measured in high $H_I$ column density absorption systems towards distant quasars. We report here a new measurement, based on high-resolution ESPRESSO data, of the primordial $D_I$ abundance of a system at redshift $z \sim 3.572$, towards PKS1937-101. Using only ESPRESSO data, we find a D/H ratio of $2.638\pm0.128 \times 10^{-5}$, while including the available UVES data improves the precision, leading to a ratio of $2.608 \pm 0.102 \times 10^{-5}$. The results of this analysis agree with those of the most precise existing measurements. We find that the relatively low column density of this system ($\log{N_{\rm H_I}/ {\rm cm}^{-2}}\sim18 $) introduces modelling uncertainties, which become the main contributor to the error budget.

astro-ph.CO↗

arXiv2024

Probing the small scale structure of the Inter-Galactic Medium with ESPRESSO: spectroscopy of the lensed QSO UM673

The gravitationally lensed quasar J014516.6-094517 at z=2.719 has been observed with the ESPRESSO instrument at the ESO VLT to obtain high-fidelity spectra of the two images A and B with a resolving power R=70000. At the redshifts under investigation (2.1 < z < 2.7), the Lyman forests along the two sightlines are separated by sub-kiloparsec physical distances and exhibit a strong correlation. We find that the two forests are indistinguishable at the present level of signal-to-noise ratio and do not show any global velocity shift, with the cross-correlation peaking at $Δv = 12 \pm 48$ m/s. The distribution of the difference in velocity of individual Lyman-$α$ features is compatible with a null average and a mean absolute deviation of 930 m/s. Significant differences in NHI column density are not detected, putting a limit to the RMS fluctuation in the baryon density on $\leq 1$ proper kpc scales of $Δρ/ ρ< 3$%. On the other hand, metal lines show significant differences both in velocity structure and in column density. A toy model shows that the difference in velocity of the metal features between the two sightlines is compatible with the the motions of the baryonic component associated to dark matter halos of typical mass $M\simeq 2\times 10^{10} M_\odot$, also compatible with the observed incidence of the metal systems. The present observations confirm the feasibility of the Sandage test of the cosmic redshift drift with high-fidelity spectroscopy of the Lyman forest of distant, bright quasars, but also provide an element of caution about the intrinsic noise associated to the usage of metal features for the same purpose.

astro-ph.CO↗

arXiv2024

ESPRESSO on VLT: An Instrument for Exoplanet Research

ESPRESSO (Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations) is a VLT ultra-stable high resolution spectrograph installed at ESO's Paranal Observatory in Chile at the end of 2017 and that started regular operations in October 2018. The spectrograph is located at the VLT Combined-Coudé Laboratory and is able to operate with one or (simultaneously) four 8.2m Unit Telescopes (UTs) through four optical Coudé trains. Combining efficiency and extreme spectroscopic precision, ESPRESSO has demonstrated to gain about two magnitudes with respect to its predecessor HARPS. ESPRESSO has improved the instrumental radial-velocity precision getting close to the aimed 10 cm/s level, thus opening the possibility to explore new frontiers in the search for Earth-mass exoplanets in the habitable zone of quiet, nearby G to M-dwarfs. ESPRESSO will be certainly an important development step towards high-precision ultra-stable spectrographs on the next generation of giant telescopes such as the ELT.

astro-ph.IM↗

arXiv2023

New Mass and Radius Constraints on the LHS 1140 Planets -- LHS 1140 b is Either a Temperate Mini-Neptune or a Water World

The two-planet transiting system LHS 1140 has been extensively observed since its discovery in 2017, notably with $Spitzer$, HST, TESS, and ESPRESSO, placing strong constraints on the parameters of the M4.5 host star and its small temperate exoplanets, LHS 1140 b and c. Here, we reanalyse the ESPRESSO observations of LHS 1140 with the novel line-by-line framework designed to fully exploit the radial velocity content of a stellar spectrum while being resilient to outlier measurements. The improved radial velocities, combined with updated stellar parameters, consolidate our knowledge on the mass of LHS 1140 b (5.60$\pm$0.19 M$_{\oplus}$) and LHS 1140 c (1.91$\pm$0.06 M$_{\oplus}$) with unprecedented precision of 3%. Transits from $Spitzer$, HST, and TESS are jointly analysed for the first time, allowing us to refine the planetary radii of b (1.730$\pm$0.025 R$_{\oplus}$) and c (1.272$\pm$0.026 R$_{\oplus}$). Stellar abundance measurements of refractory elements (Fe, Mg and Si) obtained with NIRPS are used to constrain the internal structure of LHS 1140 b. This planet is unlikely to be a rocky super-Earth as previously reported, but rather a mini-Neptune with a $\sim$0.1% H/He envelope by mass or a water world with a water-mass fraction between 9 and 19% depending on the atmospheric composition and relative abundance of Fe and Mg. While the mini-Neptune case would not be habitable, a water-abundant LHS 1140 b potentially has habitable surface conditions according to 3D global climate models, suggesting liquid water at the substellar point for atmospheres with relatively low CO$_2$ concentration, from Earth-like to a few bars.

astro-ph.EP↗

arXiv2023

The magnetically quiet solar surface dominates HARPS-N solar RVs during low activity

Using images from the Helioseismic and Magnetic Imager aboard the \textit{Solar Dynamics Observatory} (SDO/HMI), we extract the radial-velocity (RV) signal arising from the suppression of convective blue-shift and from bright faculae and dark sunspots transiting the rotating solar disc. We remove these rotationally modulated magnetic-activity contributions from simultaneous radial velocities observed by the HARPS-N solar feed to produce a radial-velocity time series arising from the magnetically quiet solar surface (the 'inactive-region radial velocities'). We find that the level of variability in the inactive-region radial velocities remains constant over the almost 7 year baseline and shows no correlation with well-known activity indicators. With an RMS of roughly 1 m/s, the inactive-region radial-velocity time series dominates the total RV variability budget during the decline of solar cycle 24. Finally, we compare the variability amplitude and timescale of the inactive-region radial velocities with simulations of supergranulation. We find consistency between the inactive-region radial-velocity and simulated time series, indicating that supergranulation is a significant contribution to the overall solar radial velocity variability, and may be the main source of variability towards solar minimum. This work highlights supergranulation as a key barrier to detecting Earth twins.

astro-ph.SR↗

arXiv2023

Masses, Revised Radii, and a Third Planet Candidate in the "Inverted" Planetary System Around TOI-1266

Is the population of close-in planets orbiting M dwarfs sculpted by thermally driven escape or is it a direct outcome of the planet formation process? A number of recent empirical results strongly suggest the latter. However, the unique architecture of the TOI-1266 system presents a challenge to models of planet formation and atmospheric escape given its seemingly "inverted" architecture of a large sub-Neptune ($P_b=10.9$ days, $R_{p,b}=2.62\pm 0.11\, \mathrm{R}_{\oplus}$) orbiting interior to that of the system's smaller planet ($P_c=18.8$ days, $R_{p,c}=2.13\pm 0.12\, \mathrm{R}_{\oplus}$). Here we present revised planetary radii based on new TESS and diffuser-assisted ground-based transit observations, and characterize both planetary masses using a set of 145 radial velocity measurements from HARPS-N ($M_{p,b}=4.23\pm 0.69\, \mathrm{M}_{\oplus}, M_{p,c}=2.88\pm 0.80\, \mathrm{M}_{\oplus}$). Our analysis also reveals a third planet candidate ($P_d=32.3$ days, $M_{p,d}\sin{i} = 4.59^{+0.96}_{-0.94}\, \mathrm{M}_{\oplus}$), which if real, would form a chain of near 5:3 period ratios, although the system is likely not in a mean motion resonance. Our results indicate that TOI-1266 b and c are among the lowest density sub-Neptunes around M dwarfs and likely exhibit distinct bulk compositions of a gas-enveloped terrestrial ($X_{\mathrm{env},b}=5.5\pm 0.7$%) and a water-rich world (WMF$_c=59\pm 14$%), which is supported by hydrodynamic escape models. If distinct bulk compositions are confirmed through atmospheric characterization, the system's unique architecture would represent an interesting test case of inside-out sub-Neptune formation at pebble traps.

astro-ph.EP↗

arXiv2023

The Extreme Stellar-Signals Project III. Combining Solar Data from HARPS, HARPS-N, EXPRES, and NEID

We present an analysis of Sun-as-a-star observations from four different high-resolution, stabilized spectrographs -- HARPS, HARPS-N, EXPRES, and NEID. With simultaneous observations of the Sun from four different instruments, we are able to gain insight into the radial velocity precision and accuracy delivered by each of these instruments and isolate instrumental systematics that differ from true astrophysical signals. With solar observations, we can completely characterize the expected Doppler shift contributed by orbiting Solar System bodies and remove them. This results in a data set with measured velocity variations that purely trace flows on the solar surface. Direct comparisons of the radial velocities measured by each instrument show remarkable agreement with residual intra-day scatter of only 15-30 cm/s. This shows that current ultra-stabilized instruments have broken through to a new level of measurement precision that reveals stellar variability with high fidelity and detail. We end by discussing how radial velocities from different instruments can be combined to provide powerful leverage for testing techniques to mitigate stellar signals.

astro-ph.EP↗

arXiv2023

TOI-4010: A System of Three Large Short-Period Planets With a Massive Long-Period Companion

We report the confirmation of three exoplanets transiting TOI-4010 (TIC-352682207), a metal-rich K dwarf observed by TESS in Sectors 24, 25, 52, and 58. We confirm these planets with HARPS-N radial velocity observations and measure their masses with 8 - 12% precision. TOI-4010 b is a sub-Neptune ($P = 1.3$ days, $R_{p} = 3.02_{-0.08}^{+0.08}~R_{\oplus}$, $M_{p} = 11.00_{-1.27}^{+1.29}~M_{\oplus}$) in the hot Neptune desert, and is one of the few such planets with known companions. Meanwhile, TOI-4010 c ($P = 5.4$ days, $R_{p} = 5.93_{-0.12}^{+0.11}~R_{\oplus}$, $M_{p} = 20.31_{-2.11}^{+2.13}~M_{\oplus}$) and TOI-4010 d ($P = 14.7$ days, $R_{p} = 6.18_{-0.14}^{+0.15}~R_{\oplus}$, $M_{p} = 38.15_{-3.22}^{+3.27}~M_{\oplus}$) are similarly-sized sub-Saturns on short-period orbits. Radial velocity observations also reveal a super-Jupiter-mass companion called TOI-4010 e in a long-period, eccentric orbit ($P \sim 762$ days and $e \sim 0.26$ based on available observations). TOI-4010 is one of the few systems with multiple short-period sub-Saturns to be discovered so far.

astro-ph.EP↗