Search

Zeldovich amplification of classic waves carrying orbital angular momentum (OAM) from a rotating absorber is an extension of Penrose superradiance from a rotating black hole. The demonstration of Zeldovich amplification in recently published experiments showed the possibility of extracting energy from a spinning black hole or a rotating absorber. However, it remains unclear whether extracting energy from non-absorbent bodies is possible. Here, we experimentally demonstrate the amplification of acoustic OAM from rotating impellers made of non-absorbent materials. We develop a multichannel least-mean-square algorithm to emit high-charge acoustic OAM beams into three types of impellers. The acoustic gains (more than 20 dB) have been measured by both a static microphone and a microphone array working as a virtual rotating receiver. The results indicate that the acoustic gain from the impeller with a large windward area is much higher than the ones with a small area. Our work is worthwhile in proposing the experimental method to study the phenomenon of acoustic OAM amplification and showing prospects in industrial applications such as amplifying acoustic signals by commonly used impellers. Our work also discusses a possible way of extracting energy from non-absorbent celestial systems, such as the orbiting planets of the Solar system, which are much less absorbent to light but much closer to the Earth than a black hole. [ABSTRACT FROM AUTHOR]

Several groups have recently suggested that small planets orbiting very closely around white dwarf stars could be promising locations for life to arise, even after stellar death. There are still many uncertainties, however, regarding the existence and habitability of these worlds. Here we consider the retention of water during post-main-sequence evolution of a Sun-like star and during the subsequent migration of planets to the white dwarf's habitable zone. This inward migration is driven by dynamical mechanisms such as planet–planet interactions in packed systems, which can excite planets to high eccentricities, setting the initial conditions for tidal migration into short-period orbits. In order for water to persist on the surfaces of planets orbiting white dwarfs, the water must first survive the asymptotic giant branch phase of stellar evolution, then avoid being lost as a result of photoevaporation due to X-ray and extreme-ultraviolet radiation from the newly formed white dwarf, and finally survive the tidal migration of the planet inward to the habitable zone. We find that while this journey will likely desiccate large swaths of post-main-sequence planetary systems, planets with substantial reservoirs of water may retain some surface water, especially if their migration occurs at later white dwarf cooling ages. Therefore, although stellar evolution may pose a challenge for the retention of water on exoplanet surfaces, it is possible for planets to retain surface oceans even as their host stars die and their orbits evolve. [ABSTRACT FROM AUTHOR]

There is increasing evidence for the presence and variability of circumstellar dust and gas around white dwarfs that are polluted with exoplanetary material, although the origin of this dust and gas remains debated. This paper presents the first near-simultaneous observations of both circumstellar dust (via broad-band emission) and gas (via emission lines) around a polluted white dwarf. From the optical spectra the gaseous emission lines, notably the calcium infrared triplet and magnesium lines, show significant increases and decreases in their strength over time-scales of weeks, while the oxygen and iron lines remain relatively stable. Near-infrared JHK |$_{\rm s}$| photometry reveals dust emission changes of up to 0.2 magnitudes in the K |$_{\rm s}$| band over similar time-scales, marking the shortest variability time-scales observed to date. The two epochs with the strongest emission were correlated between the dust (K |$_{\rm s}$| -band brightening) and gas (strengthened calcium and magnesium lines), showing for the first time that the dust and gas must be produced near-simultaneously with a common origin, likely in collisions. [ABSTRACT FROM AUTHOR]

The AU Microscopii planetary system is only 24 Myr old, and its geometry may provide clues about the early dynamical history of planetary systems. Here, we present the first measurement of the Rossiter–McLaughlin effect for the warm sub-Neptune AU Mic c, using two transits observed simultaneously with the European Southern Observatory's (ESO's) Very Large Telescope (VLT)/Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO), CHaracterising ExOPlanet Satellite (CHEOPS), and Next-Generation Transit Survey (NGTS). After correcting for flares and for the magnetic activity of the host star, and accounting for transit-timing variations, we find the sky-projected spin–orbit angle of planet c to be in the range |$\lambda _{\mathrm{c}}=67.8_{-49.0}^{+31.7}$|  degrees (1 |$\sigma$|⁠). We examine the possibility that planet c is misaligned with respect to the orbit of the inner planet b (⁠|$\lambda _{\mathrm{b}}=-2.96_{-10.30}^{+10.44}$|⁠), and the equatorial plane of the host star, and discuss scenarios that could explain both this and the planet's high density, including secular interactions with other bodies in the system or a giant impact. We note that a significantly misaligned orbit for planet c is in some degree of tension with the dynamical stability of the system, and with the fact that we see both planets in transit, though these arguments alone do not preclude such an orbit. Further observations would be highly desirable to constrain the spin–orbit angle of planet c more precisely. [ABSTRACT FROM AUTHOR]

The significant brightness contrast between stars and orbiting planets often hinders the detection of exoplanets. This paper presents the development and validation of an experimental setup and digital filtering techniques for a rotational shearing interferometer (RSI) aimed at enhancing exoplanet detection. The method leverages controlled phase shifts and spatial frequency modulation through Risley and Dove prisms to isolate faint planetary signals from dominant starlight. Laboratory experiments use HeNe lasers to simulate a star-planet system, and spatial filters ensure precise wavefront alignment. The interferometer's rotational shearing capabilities enhance the accuracy of phase alignment, allowing for significant suppression of starlight and improved detection of planetary signals. Additionally, applying Fourier-based digital filtering techniques further enhances detection sensitivity by reducing background noise. Experimental results demonstrate an 80% reduction in noise and up to a 20% increase in detection sensitivity compared to traditional interferometric methods. The RSI's performance represents a significant advancement in interferometric techniques, suggesting its potential for real-world astronomical applications. However, further optimization is required to address challenges associated with space-based observations. This work sets the foundation for future research aimed at refining optical configurations and digital filtering techniques for exoplanet detection. [ABSTRACT FROM AUTHOR]

Eccentric planets may spend a significant portion of their orbits at large distances from their host stars, where low temperatures can cause atmospheric CO2 to condense out onto the surface, similar to the polar ice caps on Mars. The radiative effects on the climates of these planets throughout their orbits would depend on the wavelength-dependent albedo of surface CO2 ice that may accumulate at or near apoastron and vary according to the spectral energy distribution of the host star. To explore these possible effects, we incorporated a CO2 ice-albedo parameterization into a one-dimensional energy balance climate model. With the inclusion of this parameterization, our simulations demonstrated that F-dwarf planets require 29% more orbit-averaged flux to thaw out of global water ice cover compared with simulations that solely use a traditional pure water ice-albedo parameterization. When no eccentricity is assumed, and host stars are varied, F-dwarf planets with higher bond albedos relative to their M-dwarf planet counterparts require 30% more orbit-averaged flux to exit a water snowball state. Additionally, the intense heat experienced at periastron aids eccentric planets in exiting a snowball state with a smaller increase in instellation compared with planets on circular orbits; this enables eccentric planets to exhibit warmer conditions along a broad range of instellation. This study emphasizes the significance of incorporating an albedo parameterization for the formation of CO2 ice into climate models to accurately assess the habitability of eccentric planets, as we show that, even at moderate eccentricities, planets with Earth-like atmospheres can reach surface temperatures cold enough for the condensation of CO2 onto their surfaces, as can planets receiving low amounts of instellation on circular orbits. [ABSTRACT FROM AUTHOR]

A sub-Earth-mass planet orbiting Barnard's star, designated as Barnard b, has recently been announced. At almost the same time, the first photometric data of Barnard's star by the Transit Exoplanet Survey Satellite (TESS) was released in Sector 80. We explore the possibility of emergent transits of Barnard b in TESS photometry. The detrended 2 min light curve appears to be flat, with a flux root mean square of 0.411 parts per thousand. Attempts of blind and informed transit curve model inference suggest no evidence of transiting Barnard b, or any other body. This provides a 3σ upper bound of 87.9 degrees for the orbital inclination of Barnard b. [ABSTRACT FROM AUTHOR]

A large sample of planet–planet scattering events for three planet systems with different orbital separations and masses is analysed with a multiple regression model. The dependence of the time for the onset of instability on the masses of the planets and on their initial orbital separations is modelled with a quadratic function. The same analysis is applied to the timespan of the chaotic evolution dominated by mutual close encounters. The configurations with the less massive planet on an outside orbit are stable over longer time-scales. The same configuration leads to shorter chaotic evolution times before the ejection of one planet. In about 70  per cent of the cases, the lighter planet is the one escaping from the system. If a different separation is assumed between the inner and outer planet pairs, then the dominant effect on the instability time is due to the pair with the smaller separation, as a first approximation. [ABSTRACT FROM AUTHOR]

An accurate knowledge of the orientation, the tidal deformability, and the gravity field of a celestial body is fundamental to provide constraints on its internal structure. These quantities may be retrieved by processing radiometric tracking and altimetry data from a probe in orbit around such body. This paper presents a method to combine altimetry crossovers with two-way Doppler tracking observations at normal equation level, using the Bernese GNSS Software and the pyXover software library. This method was applied to a proposed 200 km altitude orbiter around Callisto, a privileged destination for the upcoming phase of Solar System exploration. Enhancing "standard" Doppler tracking with altimetry generally benefited both orbit determination and a joint estimation of the orientation of the north pole and of planetary librations. The retrieval of low-degree gravity field parameters was also improved by the addition of altimetry data. However, the improvements on the estimated parameters were highly dependent on the characteristics of the simulation, e.g., the underlying topography roughness. Overall, combining radioscience with altimetry data accounted for a visible reduction of correlations among estimated parameters, while also allowing for a consistent estimation of the "vertical" Love number h 2 along with gravity. • An original method to combine altimetry crossovers and Doppler data is presented. • Applied to Callisto, this combination improves the orbit of a low altitude probe. • Low-degree gravity and orientation parameters benefit from the combination. • Combining observations allows for consistent estimations of Love numbers k 2 and h 2. [ABSTRACT FROM AUTHOR]

Major space agencies such as NASA and the ESA have long reported the growing dangers caused by resident space objects orbiting our planet. These objects continue to grow in number as satellites are imploded and space debris impacts each other, causing fragmentation. As a result, significant efforts by both the public and private sectors are geared towards enhancing space domain awareness capabilities to protect future satellites and astronauts from impact by these orbiting debris. Current approaches and standards implement very large radar arrays, telescopes, and laser ranging systems to detect and track such objects. These systems are very expensive, may take significant amounts of time to develop, and are still only sparingly able to efficiently track debris targets less than 10 cm in diameter. This work proposes a theoretical passive-radar-based method using illuminators of opportunity for detecting space debris while estimating motion direction and Doppler. We show that by using a signal processing chain based on the self-mixing technique and digital filters, Doppler information can be extracted and continuously tracked by a uniform linear receiver array. This can be achieved by a passive sensor system, which has the advantage of lower cost without the need to emit signals that constrain the spectrum sharing issues. [ABSTRACT FROM AUTHOR]

The ground-based solar telescope THEMIS performed several observations of Mercury's sodium exosphere in years 2011–2013, when the MESSENGER spacecraft was orbiting around the planet. Typical two-peak exospheric patterns were frequently identified. In previous studies, some specific cases of THEMIS Na two-peak observations were characterized and related to IMF conditions, during specific extreme cases, in the occasion of CME arrival. The present study aims to perform a statistical analysis of Na two-peak emissions in nominal IMF conditions at Mercury, as measured by MESSEGER. The comparison between parameters of Na two-peak exospheric patterns (relative distances and intensities) versus the IMF intensity and Z-component is analysed, demonstrating, in average conditions, the existance of a direct relationship between Na peaks distance/intensity and IMF intensity. Moreover, only when IMF is very low, the shear angle seems to detrmine the occurrence of dayside reconnection when IMF-Z is negative (similarly to the Earth's case), whereas at higher IMF, it seems that reconnection may occur independently from shear angle. This study supports the idea that particle precipitation is a significant driver of the shaping of Na exosphere morphology, and that only when IMF intensity is particularly low, the dayside magnetospheric structure appears to be more similar to the Earth's configuration. These results allow to better understand the way the planet reacts to IMF conditions, thus providing interesting clues for the incoming BepiColombo measurement objectives. [ABSTRACT FROM AUTHOR]

This work investigated the dynamics of planets in binary systems and provided insights into the stability and evolution of these systems. We explored the influence of a nearby secondary star on planetary growth and evolution, focusing on S -type configurations. We tracked the orbits of the planets and analysed their stability over long time-scales, considering various parameters such as mass, eccentricity, and inclination. Our results show that the presence of a secondary star can significantly impact the growth and evolution of planets, leading to changes in their orbits and potential ejection from the system, however, it was possible to identify stable planets even in systems experiencing multiple disturbances. One of the most significant results of the work was the analysis of the increased material in the disc near the primary star, which contributes to planet growth, driven by the density spirals influenced by the binary star. These findings have important implications for the search for habitable exoplanets and emphasize the need for further studies of planetary systems in binary star environments. [ABSTRACT FROM AUTHOR]

Achieving resolution in the sub-Rayleigh regime (superresolution) is one of the rapidly developing topics in quantum optics and metrology. Recently, it was shown that perfect measurement based on spatial mode demultiplexing (SPADE) in Hermite–Gauss modes allows one to reach the quantum limit of precision for estimation of separation between two weak incoherent stationary sources. Since then, different imperfections such as misalignment or crosstalk between modes have been studied to check how this result translates into more realistic experimental setups. In this paper, we consider another deviation from the perfect setup by discarding the assumption about the stationarity of the sources. This is relevant for example for astrophysical applications where planets necessarily orbit around the star. We analyze two examples of dynamics: rotations and oscillations, showing the robustness of the SPADE-based measurement against them. The analysis is based on Fisher information, which allows one to obtain the precision limit through Cramér–Rao bound. Furthermore, we formulate a measurement algorithm that allows for the reduction of one parameter for estimation (system orientation angle) in the stationary sources scenario, maintaining the measurement precision despite the lack of knowledge about this parameter. [ABSTRACT FROM AUTHOR]

We report JWST Mid-Infrared Instrument (MIRI) Medium Resolution Spectrograph (MRS) observations of the β Pic moving-group member, η Tel A, along with its brown dwarf binary companion, η Tel B. Following point-spread-function subtraction, we recover the spatially resolved flux from the debris disk around η Tel A, along with the position of the companion exterior to the disk. We present a new 5–26 μ m epoch of spectroscopy for the disk, in which we discover a 20 μ m silicate feature, and the first ever 11–21 μ m spectrum of η Tel B, which indicates a bare photosphere. We derive a new epoch of relative astrometry for the companion, extending the baseline of measurements to 25 yr, and find that it is currently located near the apocenter of an eccentric long-period orbit. The companion's orbit is close enough to the disk that it should significantly perturb the planetesimals within it, resulting in a detectable mid-IR pericenter glow and near alignment with the companion. Contrary to expectations, however, we find that the disk appears to be axisymmetric and potentially misaligned with the companion in the MIRI MRS data. We posit that this may be due to the presence of an additional, as-yet-undetected ∼0.7–30 M J planet orbiting interior to the disk, with a semimajor axis of ∼3–19 au. [ABSTRACT FROM AUTHOR]

Mercury's surface undergoes large temperature gradients between day and night, which repeats periodically over the same longitudes due to its 3:2 spin‐orbit resonance. This effect combined with the orbit's eccentricity, creates hot and cold geographic longitudes. The planet is covered with a highly porous regolith, allowing exospheric atoms to diffuse in depth. By using a 1‐D diffusion model, we studied the subsurface precipitation of gas over the cold and hot longitudes to understand gas retention. This work identifies the cold longitudes as favorable regions to form subsurface reservoirs closer to the surface. Moreover, subsurface reservoirs of adsorbates increase two to three times faster over cold longitudes than over hot longitudes, depending on the surface binding energy distribution of the atoms. We suggest that this result may be related to the observation that Mercury's sodium exosphere persists at later local times over the cold pole. Plain Language Summary: The surface of Mercury experience large temperature differences between day and night, and this repeatedly occurs over the same geographic positions as an orbit of the planet around the Sun lasts exactly one and half Mercury day. Additionally, Mercury's orbit is highly elliptic, causing the planet‐Sun distance to vary. This creates cold and hot geographic longitudes on the planet surface. Mercury's surface is porous and covered with very fine grains which allows gas to diffuse through it. By using a one dimensional model, we study how gases can penetrate Mercury's surface depending on the geographic position. We identify that colder regions are favorable to the formation of shallow gas reservoirs, which grow two to three times faster than over the hottest regions, depending on the gas‐surface interactions. This result may be related to the higher measurements of sodium over the cold geographic longitudes of Mercury, which last through each local afternoon. Key Points: Subsurface diffusion of sodium forms shallow reservoir in the first meter of regolith, which is denser at the cold longitudesGreater surface binding energies increase the amount of sodium retained in the regolith per synodic cycleConvergence of the sodium accumulation should happen on timescales of billions of years, which could lead to the saturation of the regolith [ABSTRACT FROM AUTHOR]

Circumbinary planets, orbiting both stars in a binary system, offer the opportunity to study planet formation and orbital migration in an environment different from that around single stars. However, despite the fact that |$\gt 90~\% $| of binary systems in the solar neighbourhood are spectrally resolved double-lined binaries, there has been only one detection of a circumbinary planet orbiting a double-lined binary using the radial velocity method so far. Spectrally disentangling binary components is challenging due to blending of spectral lines and inaccuracies in spectral modelling. These inaccuracies add scatter to the measurements, which can hide the weak radial velocity signature of circumbinary exoplanets. We have obtained new high signal-to-noise, high-resolution spectra with the SOPHIE spectrograph, mounted on the 193 cm telescope at Observatoire de Haute-Provence (OHP), for six bright, double-lined binaries for which circumbinary exoplanet detection has been attempted in the past. To extract radial velocities, we use the DOLBY code, a recent method of spectral disentangling using Gaussian processes to model the time-varying components. We analyse the resulting radial velocities with a diffusive nested sampler to seek planets, and compute sensitivity limits. We do not detect any new circumbinary planet. However, we show that the combination of new data, new radial velocity extraction methods, and improved statistical methods to determine a data set's sensitivity to planets leads to an approximately one order of magnitude improvement compared to previous results. This improvement brings us into the range of known circumbinary exoplanets and paves the way for future observation campaigns targeting double-lined binaries. [ABSTRACT FROM AUTHOR]

Recent observations of giant planets have revealed unexpected bulk densities. Hot Jupiters, in particular, appear larger than expected for their masses compared to planetary evolution models, while warm Jupiters seem denser than expected. These differences are often attributed to the influence of the stellar incident flux, but it has been unclear if they also result from different planet formation processes, and if there is a trend linking the planetary density to the chemical composition of the host star. In this work, we present the confirmation of three giant planets in orbit around solar analogue stars. TOI-2714 b (P ≃ 2.5 d, Rp ≃ 1.22 RJ, Mp = 0.72 MJ) and TOI-2981 b (P ≃ 3.6 d, RP ≃ 1.2 RJ, MP = 2 MJ) are hot Jupiters on nearly circular orbits, while TOI-4914 b (P ≃ 10.6 d, RP ≃ 1.15 RJ, Mp = 0.72 MJ) is a warm Jupiter with a significant eccentricity (e = 0.41 ± 0.02) that orbits a star more metal-poor ([Fe/H] = −0.13) than most of the stars known to host giant planets. Similarly, TOI-2981 b orbits a metal-poor star ([Fe/H] = −0.11), while TOI-2714 b orbits a metal-rich star ([Fe/H] = 0.30). Our radial velocity follow-up with the HARPS spectrograph allows us to detect their Keplerian signals at high significance (7, 30, and 23σ, respectively) and to place a strong constraint on the eccentricity of TOI-4914 b (18σ). TOI-4914 b, with its large radius (Rp ≃ 1.15 RJ) and low insolation flux (F⋆ < 2 × 108 erg s−1 cm−2), appears to be more inflated than what is supported by current theoretical models for giant planets. Moreover, it does not conform to the previously noted trend that warm giant planets orbiting metal-poor stars have low eccentricities. This study thus provides insights into the diverse orbital characteristics and formation processes of giant exoplanets, in particular the role of stellar metallicity in the evolution of planetary systems. [ABSTRACT FROM AUTHOR]

Context. Protoplanetary disks surrounding young stars are the birth places of planets. Among them, transition disks with inner dust cavities of tens of au are sometimes suggested to host massive companions. Yet, such companions are often not detected. Aims. Some transition disks exhibit a large amount of gas inside the dust cavity and relatively high stellar accretion rates, which contradicts typical models of gas-giant-hosting systems. Therefore, we investigate whether a sequence of low-mass planets can create the appearance of cavities in the dust disk. Methods. We evolve the disks with low-mass growing embryos in combination with 1D dust transport and 3D pebble accretion, to investigate the reduction of the pebble flux at the embryos' orbits. We vary the planet and disk properties to understand the resulting dust profile. Results. We find that multiple pebble-accreting planets can efficiently decrease the dust surface density, resulting in dust cavities consistent with transition disks. The number of low-mass planets necessary to sweep up all pebbles decreases with decreasing turbulent strength and is preferred when the dust Stokes number is 10−2 − 10−4. Compared to dust rings caused by pressure bumps, those by efficient pebble accretion exhibit more extended outer edges. We also highlight the observational reflections: the transition disks with rings featuring extended outer edges tend to have a large gas content in the dust cavities and rather high stellar accretion rates. Conclusions. We propose that planet-hosting transition disks consist of two groups. In Group A disks, planets have evolved into gas giants, opening deep gaps in the gas disk. Pebbles concentrate in pressure maxima, forming dust rings. In Group B, multiple Neptunes (unable to open deep gas gaps) accrete incoming pebbles, causing the appearance of inner dust cavities and distinct ring-like structures near planet orbits. The morphological discrepancy of these rings may aid in distinguishing between the two groups using high-resolution ALMA observations. [ABSTRACT FROM AUTHOR]

Of over 5000 exoplanets identified so far, only a few hundred possess sub-Earth radii. The formation processes of these sub-Earths remain elusive, and acquiring additional samples is essential for investigating this unique population. In our study, we employ the GPFC method, a novel GPU phase folding algorithm combined with a convolutional neural network, on the Kepler photometry data. This method enhances the transit search speed significantly over the traditional Box-fitting Least Squares method, allowing a complete search of the known Kepler KOI data within days using a commercial GPU card. To date, we have identified five new ultra-short-period planets (USPs): Kepler-158d, Kepler-963c, Kepler-879c, Kepler-1489c, and KOI-4978.02. Kepler-879c with a radius of 0.4 R |$_{\oplus }$| completes its orbit around a G dwarf in 0.646716 d, Kepler-158d with a radius of 0.43 R |$_{\oplus }$| orbits a K dwarf star every 0.645088 d, Kepler-1489c with a radius of 0.51 R |$_{\oplus }$| orbits a G dwarf in 0.680741 d, Kepler-963c with a radius of 0.6 R |$_{\oplus }$| revolves around a G dwarf in 0.919783 d, and KOI-4978.02 with a radius of 0.7 R |$_{\oplus }$| circles a G dwarf in 0.941967 d. Among our findings, Kepler-879c, Kepler-158d, and Kepler-963c rank as the first, the third, and the fourth smallest USPs identified to date. Notably, Kepler-158d stands as the smallest USP found orbiting K dwarfs, while Kepler-963c, Kepler-879c, Kepler-1489c, and KOI-4978.02 are the smallest USPs found orbiting G dwarfs. Kepler-879c, Kepler-158d, Kepler-1489c, and KOI-4978.02 are among the smallest planets that are closest to their host stars, with orbits within 5 stellar radii. In addition, these discoveries highlight GPFC's promising capability in identifying small, new transiting exoplanets within the photometry data from Kepler, TESS , and upcoming space transit missions PLATO and ET. [ABSTRACT FROM AUTHOR]

Giant planets on long-period orbits around the nearest stars are among the easiest to directly image. Unfortunately these planets are difficult to fully constrain by indirect methods, e.g. transit and radial velocity (RV). In this study, we present the discovery of a super-Jupiter, HD 222237 b, orbiting a star located |$11.445\pm 0.002$|  pc away. By combining RV data, Hipparcos , and multi-epoch Gaia astrometry, we estimate the planetary mass to be |${5.19}_{-0.58}^{+0.58}\, M_{\rm Jup}$|⁠ , with an eccentricity of |${0.56}_{-0.03}^{+0.03}$| and a period of |${40.8}_{-4.5}^{+5.8}$|  yr, making HD 222237 b a promising target for imaging using the Mid-Infrared Instrument (MIRI) of JWST. A comparative analysis suggests that our method can break the inclination degeneracy and thus differentiate between prograde and retrograde orbits of a companion. We further find that the inferred contrast ratio between the planet and the host star in the F 1550 C filter (⁠|$15.50\, \mu \rm m$|⁠) is approximately |$1.9\times 10^{-4}$|⁠ , which is comparable with the measured limit of the MIRI coronagraphs. The relatively low metallicity of the host star (⁠|$\rm -0.32\, dex$|⁠) combined with the unique orbital architecture of this system presents an excellent opportunity to probe the planet–metallicity correlation and the formation scenarios of giant planets. [ABSTRACT FROM AUTHOR]

Transiting planets in multiple-star systems, especially high-order multiples, make up a small fraction of the known planet population but provide unique opportunities to study the environments in which planets would have formed. Planet-hosting binaries have been shown to have an abundance of systems in which the stellar orbit aligns with the orbit of the transiting planet, which could give insights into the planet formation process in such systems. We investigate here if this trend of alignment extends to planet-hosting triple-star systems. We present long-term astrometric monitoring of a novel sample of triple-star systems that host Kepler transiting planets. We measured orbit arcs in 21 systems, including 12 newly identified triples, from a homogeneous analysis of our Keck adaptive optics data and, for some systems, Gaia astrometry. We examine the orbital alignment within the nine most compact systems (⁠|$\lesssim 500$|  au), testing if either (or both) of the stellar orbits align with the edge-on orbits of their transiting planets. Our statistical sample of triple systems shows a tendency toward alignment, especially when assessing the alignment probability using stellar orbital inclinations computed from full orbital fits, but is formally consistent with isotropic orbits. Two-population tests where half of the stellar orbits are described by a planet-hosting-binary-like moderately aligned distribution give the best match when the other half (non-planet-hosting) has a Kozai-like misaligned distribution. Overall, our results suggest that our sample of triple-star planet-hosting systems are not fully coplanar systems and have at most one plane of alignment. [ABSTRACT FROM AUTHOR]

In this paper, we have analyzed the properties of the photometric and spectral variability of young star V718 Per, a member of the cluster IC 348, in terms of its possible binarity. The most realistic is the model where the main component of the V718 Per A system—with an effective temperature of 5200 K—is periodically shielded by two extended dust structures consisting of large particles and moving around the star in resonance with two planets. Their orbital periods are 4.7 years and 213 days. Their ratio with high accuracy is equal to 1 : 8, and the ratio of the large semi-axes is 1 : 4. The masses of the planets have not exceeded . At the moments of total eclipses V718 Per A, the radiation of the system has been dominated by a colder component with an effective temperature of K, which has explained the reddening of the star observed in the brightness minima, as well as its spectral changes during brightness weakening. Speckle interferometric observations performed using the 2.5-m telescope of the Sternberg Astronomical Institute have made it possible to estimate the upper limit of the angular distance between the components of the system: ≤0.1 , which is equivalent to a projection distance of ≤30 AU. The unique feature of this system has been that the planes of the planetary orbits practically coincide with the line of sight. Such an orientation of the system has been most favorable for measuring fluctuations in the radial velocity of a star caused by the orbital motion of planets, as well as for observing planetary transits along the disk of the main component of the system. [ABSTRACT FROM AUTHOR]

In previous works, entropic gravity and ungravity have been considered as possible solutions to the dark energy and dark matter problems. To test the viability of these models, modifications to planetary orbits are calculated for ungravity and different models of entropic gravity. Using the gravitational sector of unparticles, an equation for the contribution to the effect of orbital precession is obtained. We conclude that the estimated values for the ungravity parameters from planetary orbits are inconsistent with the values needed for the cosmological constant. The same ideas are explored for entropic gravity arising from a modified entropy–area relationship. [ABSTRACT FROM AUTHOR]

This paper examines the dynamic evolution of the compact three-planet system Kepler-51. Possible resonant states of the system are analyzed and a search for potential chains of mean motion resonances is carried out. Using the Posidonius software package the dynamic evolution of the system is studied over a time interval of 100 Myr, taking into account tidal interaction. Also, for various initial values of eccentricities, inclinations, arguments of periapsis and longitudes of the ascending nodes of orbits, modeling of the dynamic evolution of the planetary system is carried out within the framework of the semi-analytical theory of motion. It is shown that the compact planetary system Kepler-51 is not resonant. Under initial conditions corresponding to the masses and elements of the planets' orbits, determined from observations taking into account their errors, the evolution of the system is stable and regular over the studied interval of 100 Myr. [ABSTRACT FROM AUTHOR]

The Mars Sample Return campaign is an endeavor of unprecedented technological complexity and coordination that attempts to answer fundamental questions about the habitability of Mars by returning the first samples of Martian material to Earth for analysis. The third mission in the campaign consists of the NASA-provided Capture, Containment, and Return System (CCRS) onboard the European Space Agency's Earth Return Orbiter, which will retrieve the Orbiting Sample (OS) container from its orbit around Mars. Retrieving a passive sample container from a planetary orbit has never been attempted by any spacecraft and requires the development of new technology to succeed in this ambitious task. This paper introduces the high-reliability Capture Sensor Suite (CSS), a novel optical detection system that provides CCRS with the capability to autonomously detect the OS as it is captured. This article will discuss the challenges and requirements for the fault-tolerant design of the CSS. [ABSTRACT FROM AUTHOR]

Context. Hot and warm Jupiters might have undergone the same formation and evolution path, but the two populations exhibit different distributions of orbital parameters. This challenges our understanding of their actual origin. Aims. We report the results of our warm Jupiters survey, which was carried out with the CHIRON spectrograph within the KESPRINT collaboration. We addressed the question of the population origin by studying two planets that might help to bridge the gap between the two populations. Methods. We confirm two planets and determine their mass. One is a hot Jupiter (with an orbital period shorter than 10 days), TOI-2420 b, and the other is a warm Jupiter, TOI-2485 b. We analyzed them using a wide variety of spectral and photometric data in order to characterize these planetary systems. Results. We found that TOI-2420 b has an orbital period of Pb=5.8 days, a mass of Mb=0.9 MJ, and a radius of Rb=1.3 RJ, with a planetary density of 0.477 g cm−3. TOI-2485 b has an orbital period of Pb=11.2 days, a mass of Mb=2.4 MJ, and a radius of Rb=1.1 RJ with a density of 2.36 g cm−3. Conclusions. With the current parameters, the migration history for TOI-2420 b and TOI-2485 b is unclear: Scenarios of a high-eccentricity migration cannot be ruled out, and the characteristics of TOI-2485 b even support this scenario. [ABSTRACT FROM AUTHOR]

Context. ESPRESSO guaranteed time observations (GTOs) at the 8.2m VLT telescope were performed to look for Earth-like exoplanets in the habitable zone of nearby stars. Barnard's star is a primary target within the ESPRESSO GTO as it is the second closest neighbour to our Sun after the α Centauri stellar system. Aims. We present here a large set of 156 ESPRESSO observations of Barnard's star carried out over four years with the goal of exploring periods of shorter than 50 days, thus including the habitable zone (HZ). Methods. Our analysis of ESPRESSO data using Gaussian process (GP) to model stellar activity suggests a long-term activity cycle at 3200 d and confirms stellar activity due to rotation at 140 d as the dominant source of radial velocity (RV) variations. These results are in agreement with findings based on publicly available HARPS, HARPS-N, and CARMENES data. ESPRESSO RVs do not support the existence of the previously reported candidate planet at 233 d. Results. After subtracting the GP model, ESPRESSO RVs reveal several short-period candidate planet signals at periods of 3.15 d, 4.12 d, 2.34 d, and 6.74 d. We confirm the 3.15 d signal as a sub-Earth mass planet, with a semi-amplitude of 55 ± 7 cm s−1, leading to a planet minimum mass mp sin i of 0.37 ± 0.05 M⊕, which is about three times the mass of Mars. ESPRESSO RVs suggest the possible existence of a candidate system with four sub-Earth mass planets in circular orbits with semi-amplitudes from 20 to 47 cm s−1, thus corresponding to minimum masses in the range of 0.17–0.32 M⊕. Conclusions. The sub-Earth mass planet at 3.1533 ± 0.0006 d is in a close-to circular orbit with a semi-major axis of 0.0229 ± 0.0003 AU, thus located inwards from the HZ of Barnard's star, with an equilibrium temperature of 400 K. Additional ESPRESSO observations would be required to confirm that the other three candidate signals originate from a compact short-period planet system orbiting Barnard's star inwards from its HZ. [ABSTRACT FROM AUTHOR]

The sub-Jovian desert is a region in the mass-period and radius-period parameter space that typically encompasses short-period ranges between super-Earths and hot Jupiters, and exhibits an intrinsic dearth of planets. This scarcity is likely shaped by photoevaporation caused by the stellar irradiation received by giant planets that have migrated inward. We report the detection and characterization of TOI-3568 b, a transiting super-Neptune with a mass of 26.4 ± 1.0 M⊕, a radius of 5.30 ± 0.27 R⊕, a bulk density of 0.98 ± 0.15 g cm−3, and an orbital period of 4.417965 (5) d situated in the vicinity of the sub-Jovian desert. This planet orbiting a K dwarf star with solar metallicity was identified photometrically by the Transiting Exoplanet Survey Satellite (TESS). It was characterized as a planet by our high-precision radial-velocity (RV) monitoring program using MAROON-X at Gemini North, supplemented with additional observations from the SPICE large program with SPIRou at CFHT. We performed a Bayesian MCMC joint analysis of the TESS and ground-based photometry, and MAROON-X and SPIRou RVs, to measure the orbit, radius, and mass of the planet, as well as a detailed analysis of the high-resolution flux and polarimetric spectra to determine the physical parameters and elemental abundances of the host star. Our results reveal TOI-3568 b to be a hot super-Neptune rich in hydrogen and helium, with a core of heavier elements of between 10 and 25 M⊕ in mass. We analyzed the photoevaporation status of TOI-3568 b and find that it experiences one of the highest extreme-ultraviolet (EUV) luminosities among planets with a mass of Mp < 2 MNep, yet it has an evaporation lifetime exceeding 5 Gyr. Positioned in the transition between two significant populations of exoplanets on the mass-period and energy diagrams, this planet presents an opportunity to test theories concerning the origin of the sub-Jovian desert. [ABSTRACT FROM AUTHOR]

Many circumbinary gas giant planets have been recently discovered. The formation mechanism of circumbinary planets on wide orbits is unclear. We investigate the formation of Delorme 1 (AB)b, a |$13 \pm 5 \ \mathrm{ M_J}$| planet, orbiting its host binary at 84 au. The planet is accreting while having an estimated age of 40 Myr, which is unexpected, as this process should have ceased due to the dissipation of the protoplanetary disc. Using the smoothed particle hydrodynamics code seren , we model three formation scenarios for this planet. In Scenario I, the planet forms in situ on a wide orbit in a massive disc (by gravitational instability), in Scenario II closer to the binary in a massive disc (by gravitational instability), and in Scenario III much closer to the binary in a less massive disc (by core accretion). Planets in Scenario I stay at the observed separation and have mass accretion rates consistent with observed value, but their final mass is too high. In Scenario II, the planet reaches the observed separation through outward migration or scattering by the binary, and has mass accretion rate comparable to the observed; however, the planet mass is above the observed value. In Scenario III, the planet's final mass and mass accretion rate are comparable to the observed ones, but the planet's separation is smaller. We conclude that all models may explain some features of the observations but not all of them, raising questions about how gas is accreted on to the planet from its circumplanetary disc, and the presumed age of the system. [ABSTRACT FROM AUTHOR]

Recent observations have demonstrated that some subsets of even moderately wide-separation planet-hosting binaries are preferentially configured such that planetary and binary orbits appear to lie within the same plane. In this work, we explore dissipation during the protoplanetary disk phase, induced by disk warping as the system is forced into nodal recession by an inclined binary companion as a possible avenue of achieving orbit–orbit alignment. We analytically model the coupled evolution of the disk angular momentum vector and stellar spin vector under the influence of a distant binary companion. We find that a population of systems with random initial orientations can appear detectably more aligned after undergoing dissipative precession, and that this process can simultaneously produce an obliquity distribution that is consistent with observations. While dissipative precession proceeds efficiently in close binaries, favorable system properties (e.g., r out ≳ 100 au, α ≳ 0.05, and/or M b / M * ≳ 1) are required to reproduce observed alignment trends at wider binary separations a b ≳ 450 au. Our framework further predicts that circum-primary planets in systems with high stellar mass ratios should be preferentially less aligned than planets in equal mass stellar binary systems. We discover tentative evidence for this trend in Gaia DR3 and Transiting Exoplanet Survey Satellite data. Our findings suggest that dissipative precession may play a significant role in sculpting orbital configurations in a subset of moderately wide planet-hosting binaries, but is likely not solely responsible for their observed population-level alignment. [ABSTRACT FROM AUTHOR]

WASP-107 b seems to be a poster child of the long-suspected high-eccentricity migration scenario. It is on a 5.7 day, polar orbit. The planet is Jupiter-like in radius but Neptune-like in mass with exceptionally low density. WASP-107 c is on a 1100 day, e = 0.28 orbit with at least Saturn mass. Planet b may still have a residual eccentricity of 0.06 ± 0.04: the ongoing tidal dissipation leads to the observed internally heated atmosphere and hydrodynamic atmospheric erosion. We present a population synthesis study coupling octupole Lidov–Kozai oscillations with various short-range forces, while simultaneously accounting for the radius inflation and tidal disruption of the planet. We find that a high-eccentricity migration scenario can successfully explain nearly all observed system properties. Our simulations further suggest that the initial location of WASP-107 b at the onset of migration is likely within the snowline (<0.5 au). More distant initial orbits usually lead to tidal disruption or orbit crossing. WASP-107 b most likely lost no more than 20% of its mass during the high-eccentricity migration, i.e., it did not form as a Jupiter-mass object. More vigorous tidally induced mass loss leads to disruption of the planet during migration. We predict that the current-day mutual inclination between the planets b and c is substantial: at least 25°–55°, which may be tested with future Gaia astrometric observations. Knowing the current-day mutual inclination may further constrain the initial orbit of planet b. We suggest that the proposed high-eccentricity migration scenario of WASP-107 may be applicable to HAT-P-11, GJ-3470, HAT-P-18, and GJ-436, which have similar orbital architectures. [ABSTRACT FROM AUTHOR]

Numerous numerical studies have been carried out in recent years that simulate different aspects of exoplanets' magnetosphere and stellar winds. These studies have focused primarily on hot Jupiters with sun-like stars. This study addresses the challenges inherent in utilizing existing MHD codes to model hot Jupiter-star systems. Due to the scaling of the system and the assumption of a uniformly flowing stellar wind at the outer boundary of the simulation, MHD codes necessitate a minimum distance of greater than 0.4 au for a Jupiter-like planet orbiting a sun-like star to avoid substantial violations of the code's assumptions. Additionally, employing the GAMERA (Grid Agnostic MHD for Extended Research Applications) MHD code, we simulate star-planet interactions considering various stellar types (Sun-like and M Dwarf stars) with both Jupiter-like and rocky planets positioned at varying orbital distances. Furthermore, we explore the impact of tidal locking on the total power within the magnetosphere-ionosphere systems. [ABSTRACT FROM AUTHOR]

Irregular satellites (ISs) are believed to have been captured during the Solar system's dynamical history and provide clues for the Solar system's formation and evolution. ISs occupy a large fraction of the Hill sphere of their host planet and their orbits are highly perturbed by the Sun. We use a novel formalism developed in Paper I to characterize their orbits in terms of an effective secular Hamiltonian (the Brown Hamiltonian) that accounts for their large orbital separations. We find that prograde satellites generally follow the Brown Hamiltonian, while retrograde satellites (which extend further) deviate more significantly. Nevertheless, the phase portrait is much better described by the Brown Hamiltonian for all satellites. We construct a semi-analytical criterion that predicts the librating orbit based on the effective energy due to the Brown Hamiltonian. We also check our results with highly accurate N -body integrations of satellite orbits, where initial conditions are loaded directly from the updated ephemeris from the NASA Horizons data base. Although the retrograde librating orbits occupy more area in the parameter space, the vast majority of librating ISs are prograde. Using our method, we find 13 librating satellites, 8 of them previously known to librate, and the rest shown to librate for the first time. Further observations of existing and new satellites could shed more light on the dynamical history of the Solar system and satellite formation and test our results. [ABSTRACT FROM AUTHOR]

We study the evolution of eccentricity and inclination of massive planets in low-density cavities of protoplanetary discs using three-dimensional (3D) simulations. When the planet's orbit is aligned with the equatorial plane of the disc, the eccentricity increases to high values of 0.7–0.9 due to the resonant interaction with the inner parts of the disc. For planets on inclined orbits, the eccentricity increases due to the Kozai–Lidov mechanism, where the disc acts as an external massive body, which perturbs the planet's orbit. At small inclination angles, |${\lesssim}30^\circ$|⁠ , the resonant interaction with the inner disc strongly contributes to the eccentricity growth, while at larger angles, eccentricity growth is mainly due to the Kozai–Lidov mechanism. We conclude that planets inside low-density cavities tend to acquire high eccentricity if favourable conditions give sufficient time for growth. The final value of the planet's eccentricity after the disc dispersal depends on the planet's mass and the properties of the cavity and protoplanetary disc. [ABSTRACT FROM AUTHOR]

Numerical modeling of the interaction of giant planets and the planetesimal disk was carried out for the Nice model, in which the initial orbits of the planets are in resonant configurations. In addition to the standard Nice model, planetesimals in the planetary region were considered and the self-gravity of the planetesimal disk was taken into account. The dynamic evolution of planetary systems has been studied over time intervals on the order of the lifetime of the Solar System. Options have been found in which planetary systems are preserved over billions of years, the final orbits of the planets are close to modern orbits and distant trans-Neptunian objects exist. [ABSTRACT FROM AUTHOR]

We report the discovery of two transiting planets detected by the Transiting Exoplanet Survey Satellite (TESS), TOI-2374 b and TOI-3071 b, orbiting a K5V and an F8V star, respectively, with periods of 4.31 and 1.27 d, respectively. We confirm and characterize these two planets with a variety of ground-based and follow-up observations, including photometry, precise radial velocity monitoring and high-resolution imaging. The planetary and orbital parameters were derived from a joint analysis of the radial velocities and photometric data. We found that the two planets have masses of (57 ± 4) M ⊕ or (0.18 ± 0.01) MJ , and (68 ± 4) M ⊕ or (0.21 ± 0.01) MJ , respectively, and they have radii of (6.8 ± 0.3) R ⊕ or (0.61 ± 0.03) RJ and (7.2 ± 0.5) R ⊕ or (0.64 ± 0.05) RJ , respectively. These parameters correspond to sub-Saturns within the Neptunian desert, both planets being hot and highly irradiated, with T eq ≈ 745 K and T eq ≈ 1812 K, respectively, assuming a Bond albedo of 0.5. TOI-3071 b has the hottest equilibrium temperature of all known planets with masses between 10 and 300  M ⊕ and radii less than 1.5  RJ. By applying gas giant evolution models we found that both planets, especially TOI-3071 b, are very metal-rich. This challenges standard formation models which generally predict lower heavy-element masses for planets with similar characteristics. We studied the evolution of the planets' atmospheres under photoevaporation and concluded that both are stable against evaporation due to their large masses and likely high metallicities in their gaseous envelopes. [ABSTRACT FROM AUTHOR]

In circumstellar disks around young stars, the gravitational influence of nascent planets produces telltale patterns in density, temperature, and kinematics. To better understand these signatures, we first performed 3D hydrodynamical simulations of a 0.012 M⊙ disk with a Saturn-mass planet orbiting circularly in-plane at 40 au. We tested four different disk thermodynamic prescriptions (in increasing order of complexity: local isothermality, β cooling, two-temperature radiation hydrodynamics, and three-temperature radiation hydrodynamics), finding that β cooling offers a reasonable approximation for the three-temperature approach when the planet is not massive or luminous enough to substantially alter the background temperature and density structure. Thereafter, using the three-temperature scheme, we relaxed this assumption, simulating a range of different planet masses (Neptune-mass, Saturn-mass, and Jupiter-mass) and accretion luminosities (0 and 10−3L⊙) in the same disk. Our investigation revealed that signatures of disk–planet interaction strengthen with increasing planet mass, with circumplanetary flows becoming prominent in the high-planet-mass regime. Accretion luminosity, which adds pressure support around the planet, was found to weaken the midplane Doppler flip, which is potentially visible in optically thin tracers such as C18O, while strengthening the spiral signature, particularly in upper disk layers sensitive to thicker lines, such as those of 12CO. [ABSTRACT FROM AUTHOR]

Context. The mean motion resonance is the most important mechanism that may dominate the dynamics of a planetary system. In a multi-planetary system consisting of N ≥ 3 planets, the planets may form a resonant chain when the ratios of orbital periods of planets can be expressed as the ratios of small integers T1: T2: ⋯ : TN = k1: k2: ⋯ : kN. Due to the high degree of freedom, the motion in such systems could be complex and difficult to depict. Aims. In this paper, we investigate the dynamics and possible formation of the resonant chain in a triple-planet system. Methods. We defined the appropriate Hamiltonian for a three-planet resonant chain and numerically averaged it over the synodic period. The stable stationary solutions – apsidal corotational resonances (ACRs) – of this averaged system, corresponding to the local extrema of the Hamiltonian function, can be searched out numerically. The topology of the Hamiltonian around these ACRs reveals their stabilities. We further constructed the dynamical maps on different representative planes to study the dynamics around the stable ACRs, and we calculated the deviation (χ2) of the resonant angle in the evolution from the uniformly distributed values, by which we distinguished the behaviour of critical angles. Finally, the formation of the resonant chain via convergent planetary migration was simulated and the stable configurations associated with ACRs were verified. Results. We find that the stable ACR families arising from circular orbits always exist for any resonant chain, and they may extend to a high eccentricity region. Around these ACR solutions, regular motion can be found, typically in two types of resonant configurations. One is characterised by libration of both the two-body resonant angles and the three-body Laplace resonant angle, and the other by libration of only two-body resonant angles. The three-body Laplace resonance does not seem to contribute to the stability of the resonant chain much. The resonant chain can be formed via convergent migration, and the resonant configuration evolves along the ACR families to eccentric orbits once the planets are captured into the chain. Ideally, our methods introduced in this paper can be applied to any resonant chain of any number of planets at any eccentricity. [ABSTRACT FROM AUTHOR]

Context. Cold planets, including all habitable planets, produce only scattered light emission in the visual to near-infrared wavelength range. For this reason it is highly desirable to adapt the technique for the direct imaging of reflected light from extra-solar planets. Aims. For the nearby system ε Eri, we want to set much deeper detection limits for the expected scattered radiation from the radial velocity planet candidate (≈0.7 MJ) and the warm dust using the VLT/SPHERE adaptive optics (AO) instrument with the ZIMPOL imaging polarimeter. Methods. We carried out very deep imaging polarimetry of ε Eri based on 38.5 h of integration time with a broad-band filter (λc = 735 nm) for the search of the polarization signal from a planet or from circumstellar dust using AO, coronagraphy, high precision differential polarimetry, and angular differential imaging. The data were collected during 12 nights within four epochs distributed over 14 months and we searched for a signal in the individual epochs. We also combined the full data set to achieve an even higher contrast limit considering the Keplerian motion using the K-Stacker software. All data were also combined for the search of the scattering signal from extended dust clouds. We improved various data reduction and post-processing procedures and also developed new ones to enhance the sensitivity of SPHERE/ZIMPOL further. The final detection limits were quantified and we investigated the potential of SPHERE/ZIMPOL for deeper observations. Results. The data of ε Eridani provide unprecedented contrast limits but no significant detection of a point source or an extended signal from circumstellar dust. For each observing epoch, we achieved a 5 σ풩 point source contrast for the polarized intensity CP = Qϕ/I★ between 2 × 10−8 and 4 × 10−8 at a separation of ρ ≈ 1″, which is as expected for the proposed radial velocity planet at a quadrature phase. The polarimetric contrast limits are close to the photon noise limits for ρ > 0.6″ or about six times to 50 times better than the intensity limits because polarimetric imaging is much more efficient for speckle suppression. Combining the data for the search of a planet moving on a Keplerian orbit with the K-Stacker technique improves the contrast limits further by about a factor of two, when compared to an epoch, to about CP = 0.8 × 10−8 at ρ = 1″. This would allow the detection of a planet with a radius of about 2.5 RJ. Should future astrometry provide strong constraints on the position of the planet, then a 3 σ풩 detection at 1″ with CP ≈ 5 × 10−9 would be within reach of our data. The surface brightness contrast limits achieved for the polarized intensity from an extended scattering region is about 15 mag arcsec−2 at 1″ or up to 3 mag arcsec−2 deeper than previous limits. For ε Eri, these limits exclude the presence of a narrow dust ring and they constrain the dust properties. The photon statistics would allow deeper limits but we find a very weak systematic noise pattern probably introduced by polarimetric calibration errors. Conclusions. This ε Eri study shows that the polarimetric contrast limits for reflecting planets with SPHERE/ZIMPOL can be improved to a level below Cp < 10−8 by just collecting more data during many nights using software such as K-Stacker, which can combine all data considering the expected planet orbit. Contrast limits of Cp ≈ 10−9 are within reach for ε Eri if the search can be optimized for a planet with a well-known orbit. This limit is also attainable for other bright nearby stars, such as α Cen or Sirius A. Such data also provide unprecedented sensitivity for the search of extended polarized emission from warm circumstellar dust. [ABSTRACT FROM AUTHOR]

Aims. We investigate whether volcanic exomoons can be detected in thermal wavelength light curves due to their phase variability along their orbit. The method we use is based on the photometric signal variability that volcanic features or hotspots would cause in infrared (IR) wavelengths, when they are inhomogeneously distributed on the surface of a tidally heated exomoon (THEM). Methods. We simulated satellites of various sizes around an isolated planet and modeled the system's variability in two IR wavelengths, taking into account photon shot noise. The moon's periodic signal as it orbits the planet introduces a peak in the frequency space of the system's time-variable flux. We investigated the THEM and system properties that would make a moon stand out in the frequency space of its host's variable flux. Results. The moon's signal can produce a prominent feature in its host's flux periodogram at shorter IR wavelengths for hotspots with temperatures similar to the ones seen on the Jovian moon, Io, while the same moon would not be identifiable in longer IR wavelengths. By comparing observations at two different wavelengths, we are able to disentangle the signal of an exomoon with transiting and non-transiting orbital inclinations from the planet's signal in the frequency domain for system distances up to ~10 pc for Mars-sized exomoons and even further for Earth-sized ones. Conclusions. This method enlarges the parameter space of detectable exomoons around isolated planetary mass objects and directly imaged exoplanets, as it is sensitive to Io- to Earth-sized exomoons with hot volcanic features for a wide range of non-transiting orbital inclinations. Exomoon transits and the detection of outgassed volcanic molecules can subsequently confirm a putative detection. [ABSTRACT FROM AUTHOR]

One of the main goals of the NASA Transiting Exoplanet Survey Satellite (TESS) mission is the discovery of Earth-like planets around nearby M-dwarf stars. We present the discovery and validation of three new short-period Earth-sized planets orbiting nearby M dwarfs: TOI-5720 b, TOI-6008 b, and TOI-6086 b. We combined TESS data, ground-based multicolor light curves, ground-based optical and near-infrared spectroscopy, and Subaru/IRD radial velocity data to validate the planetary candidates and constrain the physical parameters of the systems. In addition, we used archival images, high-resolution imaging, and statistical validation techniques to support the planetary validation. TOI-5720 b is an Earth-sized planet with a radius of Rp = 1.09 ± 0.07 R⊕. It orbits a nearby (36 pc) M 2.5 host with an orbital period of P = 1.4344555 ± 0.0000036 days. It has an equilibrium temperature of Teq = 708 ± 19 K (assuming a null albedo) and an incident flux of Sp = 41.7 ± 4.5 S⊕. TOI-6008 b is a short-period planet of P = 0.8574347 ± 0.0000424 day. It has a radius of Rp = 1.03 ± 0.05 R⊕, an equilibrium temperature of Teq = 707 ± 19 K, and an incident flux of Sp = 41.5 ± 4.5 S⊕. The host star (TOI-6008) is a nearby (23 pc) M 5 with an effective temperature of Teff = 3075 ± 75 K. Based on the radial velocity measurements collected with Subaru/IRD, we set a 3σ upper limit of Mp < 4 M⊕, thus ruling out a star or brown dwarf as the transiting companion. TOI-6086 b orbits its nearby (32 pc) M 3 host star (Teff = 3200 ± 75 K) every 1.3888725 ± 0.0000827 days and has a radius of Rp = 1.18 ± 0.07 R⊕, an equilibrium temperature of Teq = 634 ± 16 K, and an incident flux of Sp = 26.8 ± 2.7 S⊕. Additional high-precision radial velocity measurements are needed to derive the planetary masses and bulk densities and to search for additional planets in the systems. Moreover, short-period Earth-sized planets orbiting around nearby M dwarfs are suitable targets for an atmospheric characterization with the James Webb Space Telescope through transmission and emission spectroscopy and phase-curve photometry. [ABSTRACT FROM AUTHOR]

Aims. We report the confirmation of a new transiting exoplanet orbiting the star TOI-5076. Methods. We present our vetting procedure and follow-up observations which led to the confirmation of the exoplanet TOI-5076b. In particular, we employed high-precision TESS photometry, high-angular-resolution imaging from several telescopes, and high-precision radial velocities from HARPS-N. Results. From the HARPS-N spectroscopy, we determined the spectroscopic parameters of the host star: Teff = (5070±143) K, log 푔 = (4.6±0.3), [Fe/H] = (+0.20±0.08), and [α/Fe] = 0.05±0.06. The transiting planet is a warm sub-Neptune with a mass mp = (16±2) M⊙, a radius rp =(3.2±0.l) R⊙ yielding a density ρp = (2.8±0.5) g cm−3. It revolves around its star approximately every 23.445 days. Conclusions. The host star is a metal-rich, K2V dwarf, located at about 82 pc from the Sun with a radius of R⋆ = (0.78±0.01) R⊙ and a mass of M⋆ = (0.80±0.07) M⊙. It forms a common proper motion pair with an M-dwarf companion star located at a projected separation of 2178 au. The chemical analysis of the host-star and the Galactic-space velocities indicate that TOI-5076 belongs to the old population of thin-to-thick-disk transition stars. The density of TOI-5076b suggests the presence of a large fraction by volume of volatiles overlying a massive core. We found that a circular orbit solution is marginally favored with respect to an eccentric orbit solution for TOI-5076b. [ABSTRACT FROM AUTHOR]

We present the detection of nine new planet candidates orbiting M dwarfs, identified using an independent search and vetting pipeline applied to TESS Full-Frame Image data from Sectors 1 to 63. Our candidates include planets as small as 1.4  |$\mathrm{ R}_{{\oplus }}$|⁠ , with orbital periods up to 20 d. Among the nine new candidates, we identified five gas giants, which represent a rare and unexpected outcome of planet formation. Our findings add to the growing sample of giant planets around M dwarfs found by TESS. We discuss their follow-up potential for mass measurements through radial velocity observations and atmospheric characterization through transmission spectroscopy. We highlight TIC 12999193.01 as a particularly unique gas giant candidate in an eccentric orbit and excellent potential for atmospheric characterization. [ABSTRACT FROM AUTHOR]

Planets orbiting binary systems are relatively unexplored compared to those around single stars. Detections of circumbinary planets and planetary systems offer a first detailed view into our understanding of circumbinary planet formation and dynamical evolution. The BEBOP (binaries escorted by orbiting planets) radial velocity survey plays a special role in this adventure as it focuses on eclipsing single-lined binaries with an FGK dwarf primary and M dwarf secondary allowing for the highest radial velocity precision using the HARPS and SOPHIE spectrographs. We obtained 4512 high-resolution spectra for the 179 targets in the BEBOP survey which we used to derive the stellar atmospheric parameters using both equivalent widths and spectral synthesis. We furthermore derive stellar masses, radii, and ages for all targets. With this work, we present the first homogeneous catalogue of precise stellar parameters for these eclipsing single-lined binaries. [ABSTRACT FROM AUTHOR]

The radius valley, i.e. a dearth of planets with radii between 1.5 and 2 Earth radii, provides insights into planetary formation and evolution. Using homogenously revised planetary parameters from Kepler 1-min short cadence light curves, we remodel transits of 72 small planets mostly orbiting low-mass stars, improving the precision and accuracy of planet parameters. By combining this sample with a similar sample of planets around higher mass stars, we determine the depth of the radius valley as a function of stellar mass. We find that the radius valley is shallower for low-mass stars compared to their higher mass counterparts. Upon comparison, we find that theoretical models of photoevaporation underpredict the number of planets observed inside the radius valley for low-mass stars: with decreasing stellar mass, the predicted fraction of planets inside the valley remains approximately constant whereas the observed fraction increases. We argue that this provides evidence for the presence of icy planets around low-mass stars. Alternatively, planets orbiting low-mass stars undergo more frequent collisions and scatter in the stars' high-energy output may also cause planets to fill the valley. We predict that more precise mass measurements for planets orbiting low-mass stars would be able to distinguish between these scenarios. [ABSTRACT FROM AUTHOR]

Galileo's book, "Dialogue on the two greatest world systems, the Ptolemaic and the Copernican," is a significant work that discusses the two astronomical systems and their mathematical models. The book also delves into ideas about how bodies move on Earth, which were not part of the Copernican or Ptolemaic systems. Galileo's book caused controversy and led to his trial and conviction for heresy. The book was banned by the Roman Catholic Church until 1835. The new translation of the book by Mark Davie provides readers with an excellent opportunity to explore Galileo's work. [Extracted from the article]

Long live the vis-viva equation. There is sometimes more than one way of telling a story with the same ending, and this is particularly true in the field of applied mathematics where there are often different ways of obtaining the same result to a given problem, so that what might be lost or not appreciated in one approach can be found and appreciated in another. It is the purpose here to illustrate this by presenting a well-known example drawn from the field of orbital dynamics, namely the development of what is called the Vis-viva equation. This equation is simply an expression relating the square of the velocity of an orbiting object, for example a planet orbiting a sun, to orbit parameters and scientific constants. It is a standard workhorse equation that is used extensively today by orbit control specialists wishing to determine and affect velocities of spacecraft orbiting significantly larger masses, and it was developed from work carried out centuries ago by Gottfried Leibniz (1646 – 1716). The first story will simply acknowledge the equation and how it arose. The second story will present an alternative approach based on calculus, trigonometry, algebra and computations set against the backdrop of an ellipse geometry. This second story leads to the vis-viva equation in disguise, so to speak, and examples of the speeds of two planets, Earth and Mercury, orbiting the Sun will be discussed. Where relevant, the nomenclature of orbit dynamics will be acknowledged. The discussion will involve primarily a planet's orbit velocity of translation and detailed considerations will not be given to effects due to its speed of rotation. [ABSTRACT FROM AUTHOR]

Spacecraft‐to‐spacecraft radio occultations experiments are being conducted at Mars between Mars Express (MEX) and Trace Gas Orbiter (TGO), the first ever extensive inter‐spacecraft occultations at a planet other than Earth. Here we present results from the first 83 such occultations, conducted between 2 Nov 2020 and 5th of July 2023. Of these, 44 observations have to‐date resulted in the extraction of vertical electron density profiles. These observations are the successful results of a major feasibility study conducted by the European Space Agency to use pre‐existing relay communication equipment for radio science purposes. Mutual radio occultations have numerous advantages over traditional spacecraft‐to‐ground station occultations. In this work, we demonstrate how raw data are transformed into electron density values and validated with models and other instruments. Plain Language Summary: Radio occultation is a measuring technique involving the passage of a signal through an atmosphere, during which we observe how much the signal bends. This bending effect is precisely measured as a frequency shift. Typically, this technique is employed by transmitting a signal from a satellite orbiting a planet to a ground station on Earth. However, in this article, we explore an alternative on this measurement approach known as mutual RO. Here, both the transmitter and receiver of the signal are positioned in orbit around the same foreign planet, creating a unique scenario. Specifically, we utilized two European Space Agency satellites: Mars Express and ExoMars Trace Gas Orbiter, and have conducted a total of 83 experiments. Within this article, we present the methodology, processing and outcomes of select experiments, underlining their reliability through comparisons with models and data from other instruments. Key Points: Many vertical electron density profiles have been successfully acquired via mutual radio occultation (RO) measurementsConducting RO mutually provides many advantages over conventional spacecraft‐Earth occultationsThis is an example of data‐relay equipment being repurposed for Radio Science [ABSTRACT FROM AUTHOR]