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Internal temperature-pressure profiles for planets with different masses as labeled in the figure, at 5.2 AU from the Sun, and an age between 4 and 5 Gyrs. The core masses of the planets are about 33 Earth masses, except for the 0.14M (44.5 M ⊕ ) planet which has a core of about 18 M ⊕ .
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The research of exoplanets has entered an era in which we characterize
extrasolar planets. This has become possible with measurements of radii and
luminosities. Meanwhile, radial velocity surveys discover also very low-mass
planets. Uniting all this observational data into one coherent picture to
better understand planet formation is an important,...
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Over the last twenty years, the search for extrasolar planets revealed us the
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The growing body of observational data on extrasolar planets and protoplanetary disks has stimulated intense research on planet formation and evolution in the past few years. The extremely diverse, sometimes unexpected physical and orbital characteristics of exoplanets lead to frequent updates on the mainstream scenarios for planet formation and ev...
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The search and characterization of extrasolar planets is one of the hot topic of astrophysical research. The italian community is beginning to contribute to this field. Main activities concern: the study of protoplanetary disks; the studies of planet formation, dynamical stability and evolution of their orbits; the search for planets in binary syst...
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... A higher temperature is possible, but the disk would need to cool down to this temperature to form particles (dust); therefore, this is the most relevant temperature to assess the effect of streaming instability. The thermal state of the disk formed by icy planetary collisions is estimated based on an equation of state of water (Senft & Stewart 2008 for icy planets are assumed (Kipping et al. 2013;Mordasini et al. 2012). At M planet = 1-6 M ⊕ , these parameters makeG 0.42 0.67 = for rocky planets andG 0.25 = for icy planets, which are similar to the ranges covered in our hydrodynamic simulations (Section 2.3). ...
It is generally accepted that the Moon accreted from the disk formed by an impact between the proto-Earth and impactor, but its details are highly debated. Some models suggest that a Mars-sized impactor formed a silicate melt-rich (vapor-poor) disk around Earth, whereas other models suggest that a highly energetic impact produced a silicate vapor-rich disk. Such a vapor-rich disk, however, may not be suitable for the Moon formation, because moonlets, building blocks of the Moon, of 100 m–100 km in radius may experience strong gas drag and fall onto Earth on a short timescale, failing to grow further. This problem may be avoided if large moonlets (≫100 km) form very quickly by streaming instability, which is a process to concentrate particles enough to cause gravitational collapse and rapid formation of planetesimals or moonlets. Here, we investigate the effect of the streaming instability in the Moon-forming disk for the first time and find that this instability can quickly form ∼100 km-sized moonlets. However, these moonlets are not large enough to avoid strong drag, and they still fall onto Earth quickly. This suggests that the vapor-rich disks may not form the large Moon, and therefore the models that produce vapor-poor disks are supported. This result is applicable to general impact-induced moon-forming disks, supporting the previous suggestion that small planets (<1.6 R ⊕ ) are good candidates to host large moons because their impact-induced disks would likely be vapor-poor. We find a limited role of streaming instability in satellite formation in an impact-induced disk, whereas it plays a key role during planet formation.
... Probing the atmospheres of Earth-mass exoplanets will help to constrain the lower mass limit for the capture and loss of planetary envelopes. These data will provide an opportunity to test our understanding of terrestrial planet formation, as well as prevailing theories of Earth's formation (e.g., Hayashi et al. 1979;Rogers et al. 2011;Mordasini et al. 2012;Stökl et al. 2016). TEMPO data may show that young exoplanets around low-mass stars have begun to lose their envelopes on timescales of a few Myr. ...
The TEMPO (Transiting Exosatellites, Moons, and Planets in Orion) Survey is a proposed 30-day observational campaign using the Nancy Grace Roman Space Telescope. By providing deep, high-resolution, short-cadence infrared photometry of a dynamic star-forming region, TEMPO will investigate the demographics of exosatellites orbiting free-floating planets and brown dwarfs -- a largely unexplored discovery space. Here, we present the simulated detection yields of three populations: extrasolar moon analogs orbiting free-floating planets, exosatellites orbiting brown dwarfs, and exoplanets orbiting young stars. Additionally, we outline a comprehensive range of anticipated scientific outcomes accompanying such a survey. These science drivers include: obtaining observational constraints to test prevailing theories of moon, planet, and star formation; directly detecting widely separated exoplanets orbiting young stars; investigating the variability of young stars and brown dwarfs; constraining the low-mass end of the stellar initial mass function; constructing the distribution of dust in the Orion Nebula and mapping evolution in the near-infrared extinction law; mapping emission features that trace the shocked gas in the region; constructing a dynamical map of Orion members using proper motions; and searching for extragalactic sources and transients via deep extragalactic observations reaching a limiting magnitude of $m_{AB}=29.7$\,mag (F146 filter).
... The results of core accretion models are also known to be significantly impacted by disc metallicity (Mordasini et al., 2012;Hasegawa & Pudritz, 2014). The global disc dust-to-gas ratio is impacted by disc metallicity, which also has an impact on the solid accretion time scale during planet formation. ...
Since molecules are ubiquitous in space, the study of the 'Molecular Universe' could unfold the mystery of the existing Interstellar medium. Star formation is linked to the chemical evolution processes. Thus, an analysis of the formation of stars coupled with the chemical evolution would give a clear insight into the entire process. For example, various evolutionary stages of star formation could be probed by observing various molecules. Chemical diagnostics of these regions could be used to extract the physical properties (e.g., density, temperature, ionization degree, etc.) of these regions. Radiative transfer calculations are worthwhile in estimating physical parameters of the region where molecules are detected. However, the radiative transfer calculations are limited due to insufficient molecular data, such as spectroscopic information or collisional excitation probabilities of many interstellar species. Complex organic molecules are detected in various environments ranging from the cold gas in prestellar cores to the warm gas on solar system scales close to individual protostars. A comparative study of the relative abundances of molecules could provide insights into the beginning of chemical complexity and the link to our solar system. In my thesis, I would mainly investigate the physical properties and kinematics of different star-forming regions using radiative transfer modeling. The observed spatial differentiation between various key molecules is used to explain their physical structure or evolution and various microphysical effects. In addition, some key molecules are used to study the various evolutionary phases. This simulated data is useful for interpreting the observed data of different telescopes like IRAM 30m, GBT, ALMA, Herschel, SOFIA, etc.
... As of 2024, it remains the preferred technique for confirming transiting planet candidates and the most prolific method for detecting non-transiting planets. It provides one of the most fundamental parameters of an exoplanet, its mass, crucial to constrain its inner composition (Mordasini et al. 2012) and to characterise its atmosphere (Batalha et al. 2019). Since the detection of 51 Pegasi b by Mayor & Queloz (1995), the radial velocity (RV) accuracy of optical high-resolution échelle spectrographs has dramatically increased, to the point where planets with RV semi-amplitudes below 1 m s −1 can be reliably detected (e.g. ...
Stellar magnetic activity induces both distortions and Doppler-shifts in the absorption line profiles of Sun-like stars. Those effects produce apparent radial velocity (RV) signals which greatly hamper the search for potentially habitable, Earth-like planets. In this work, we investigate these distortions in the Sun using cross-correlation functions (CCFs), derived from intensive monitoring with the high-precision spectrograph HARPS-N. We show that the RV signal arising from line-shape variations on time-scales associated with the solar rotation and activity cycle can be robustly extracted from the data, reducing the RV dispersion by half. Once these have been corrected, activity-induced Doppler-shifts remain, that are modulated at the solar rotation period, and that are most effectively modelled in the time domain, using Gaussian Processes (GPs). Planet signatures are still best retrieved with multi-dimensonal GPs, when activity is jointly modelled from the raw RVs and indicators of the line width or of the Ca II H and K emission. After GP modelling, the residual RVs exhibit a dispersion of 0.6-0.8 m/s, likely to be dominated by signals induced by super-granulation. Finally, we find that the statistical properties of the RVs evolve significantly over time, and that this evolution is primarily driven by sunspots, which control the smoothness of the signal. Such evolution, which reduces the sensitivity to long-period planet signatures, is no longer seen in the activity-induced Doppler-shifts, which is promising for long term RV monitoring surveys such as the Terra Hunting Experiment or the PLATO follow-up campaign.
... We vary the water budgets, running sets of simulations with initial water masses of 1, 10, and 100 TO following the procedures of Morbidelli et al. (2000), Raymond et al. (2006), Chassefière et al. (2012), , and do Amaral et al. (2022) in order to account for the possibility of the planets forming in situ, or migrating in from further out in the disk where more water may have been available at planet formation (Mordasini et al. 2012;Tian & Ida 2015;Unterborn et al. 2018;Pidhorodetska et al. 2021). Our parameter variation method is further discussed in Section 3.1.4. ...
A critically important process affecting the climate evolution and potential habitability of an exoplanet is atmospheric escape, in which high-energy radiation from a star drives the escape of hydrogen atoms and other light elements from a planet’s atmosphere. L 98-59 is a benchmark system for studying such atmospheric processes, with three transiting terrestrial-sized planets receiving Venus-like instellations (4–25 S ⊕ ) from their M3 host star. We use the VPLanet model to simulate the evolution of the L 98-59 system and the atmospheric escape of its inner three small planets, given different assumed initial water quantities. We find that, regardless of their initial water content, all three planets accumulate significant quantities of oxygen due to efficient water photolysis and hydrogen loss. All three planets also receive enough strong X-ray and extreme-ultraviolet flux to drive rapid water loss, which considerably affects their developing climates and atmospheres. Even in scenarios of low initial water content, our results suggest that the JWST will be sensitive to observations of retained oxygen on the L 98-59 planets in its future scheduled observations, with planets b and c being the most likely targets to possess an extended atmosphere. Our results constrain the atmospheric evolution of these small rocky planets, and they provide context for current and future observations of the L 98-59 system to generalize our understanding of multiterrestrial planet systems.
... Understanding the orbital eccentricity demographics is important for constraining formation and migration models, as different evolutionary tracks predict different distributions.Figure 10shows all known exoplanets around solar-analog stars, including the solar system giant planets, in a mass-radius diagram, allowing for study of their bulk densities. Shown in dashed lines are nominal density curves corresponding to 0.1, 0.3, 1, 3, and 10 g cm −3 , while exoplanet composition models fromMordasini et al. (2012),Zeng et al. (2019), andEmsenhuber et al. (2021b) are shown as solid lines of varying colors. For the latter model, we fitted their synthetic planet population with orbital periods shorter than 30 days and masses larger than 100 M earth using the same functional form as Mordasini et al. found b = 1.061 ± 0.002 R jup , M 0 = 3.85 ± 0.10 M jup , w = 2.0 ± 0.2, and p = 2.5 ± 0.2. ...
We report the discovery and characterization of three giant exoplanets orbiting solar-analog stars, detected by the TESS space mission and confirmed through ground-based photometry and radial velocity measurements taken at La Silla observatory with FEROS. TOI-2373 b is a warm Jupiter orbiting its host star every ∼13.3 days, and is one of the most massive known exoplanet with a precisely determined mass and radius around a star similar to the Sun, with an estimated mass of m p = 9.3 − 0.2 + 0.2 M jup and a radius of r p = 0.93 − 0.2 + 0.2 R jup . With a mean density of ρ = 14.4 − 1.0 + 0.9 g cm − 3 , TOI-2373 b is among the densest planets discovered so far. TOI-2416 b orbits its host star on a moderately eccentric orbit with a period of ∼8.3 days and an eccentricity of e = 0.32 − 0.02 + 0.02 . TOI-2416 b is more massive than Jupiter with m p = 3.0 − 0.09 + 0.10 M jup , however is significantly smaller with a radius of r p = 0.88 − 0.02 + 0.02 , R jup , leading to a high mean density of ρ = 5.4 − 0.3 + 0.3 g cm − 3 . TOI-2524 b is a warm Jupiter near the hot Jupiter transition region, orbiting its star every ∼7.2 days on a circular orbit. It is less massive than Jupiter with a mass of m p = 0.64 − 0.04 + 0.04 M jup , and is consistent with an inflated radius of r p = 1.00 − 0.03 + 0.02 R jup , leading to a low mean density of ρ = 0.79 − 0.08 + 0.08 g cm − 3 . The newly discovered exoplanets TOI-2373 b, TOI-2416 b, and TOI-2524 b have estimated equilibrium temperatures of 860 − 10 + 10 K, 1080 − 10 + 10 K, and 1100 − 20 + 20 K, respectively, placing them in the sparsely populated transition zone between hot and warm Jupiters.
... A common result from exoplanet demographic studies is that Jupitersized/mass planets are less common than their sub-Jovian counterparts (e.g. Howard et al. 2012 ;Wittenmyer et al. 2016 ;He, Ford & Ragozzine 2019 ), a result also supported by theoretical simulations of planet formation (Mordasini et al. 2012 ). Despite this, one might argue that WD 1856 b's giant radius is not surprising though because giant planets typically have much deeper transits, as well as longer durations and enhanced transit probabilities (Beatty & Gaudi 2008 ). ...
White dwarfs (WDs) have roughly Earth-sized radii - a fact long recognized to facilitate the potential discovery of sub-Earth sized planets via transits, as well atmospheric characterization including biosignatures. Despite this, the first (and still only) transiting planet discovered in 2020 was a roughly Jupiter-sized world, found using TESS photometry. Given the relative paucity of giant planets compared to terrestrials indicated by both exoplanet demographics and theoretical simulations (a “bottom-heavy” radius distribution), this is perhaps somewhat surprising. Here, we quantify the surprisingness of this fact accounting for geometric bias and detection bias assuming 1) a bottom-heavy Kepler derived radius distribution, and 2) a top-heavy radial velocity inspired radius distribution. Both are concerning, with the latter implying rocky planets are highly unusual and the former implying WD 1856 b would have to be highly surprising event at the <0.5% level. Using an HBM, we infer the implied power-law radius distribution conditioned upon WD 1856 b and arrive at a top-heavy distribution, such that 0.1-2 R⊕ planets are an order-of-magnitude less common than 2-20 R⊕ planets in the period range of 0.1-10 days. The implied hypothesis is that transiting WD rocky planets are rare. We discuss ways to reconcile this with other evidence for minor bodies around WDs, and ultimately argue that it should be easily testable.
... Distribution of core mass fraction (CMF) and core radius fraction (CRF) of each type from 1 M e systems at 5 Gyr in synthetic data. For comparison, we also overplot the M-R relation from Mordasini et al. (2012), which gives the M turning at 4.12 M J from another function consistent with our result well. Exceeding this critical mass, the planetʼs cold interior pressure cannot sustain its gravity and begins shrinking its volume. ...
Classification is an essential method and has been developed widely in astronomy. However, planets still lack a universal classification framework, because the solar system planet sample is too small for statistical analysis. Fortunately, exoplanets supply large samples to help build up synthetic planetary populations then support a classification framework. In this study, we use synthetic populations to explore the diversity and evolution relations of planets. We detect six outstanding clusters in mass–radius space with the kernel density estimation and extract typical planets for each type. The first four types are gas-poor planets, and the last two are gas-rich. For an intermediate type, the light gas envelopes contribute to the observable radius but not the mass. Once the planet is massive enough (3.9 M J ), its size shrinks with increasing mass due to self-gravity. Based on the evolution tracks and the gas envelopes’ properties, the environment is linked strongly to the gas properties, and it controls which type can form at a specific location. The system with gas giants will be different from those without, including total planet mass and the number of planets in the system. Giant planets shape the whole system by orbital resonance. Each type of planets’ period ratios are different, and gas giants have the most outstanding accumulation peak at 2:1 resonance. In the future, the patterns of observed planets’ retrieved interior structures can help to confirm the suggested classification. However, the structure degeneracy induces high uncertainty, such that the framework will still profit from additional theoretical constraints.
... With = r R 1.9 min J , the shock that defines the planet surface is usually at R p ≈ 2 R J , changing only slowly during the simulation. This commonly used size is thought to be appropriate for forming or young planets (Marley et al. 2007;Mordasini et al. 2012a;Zhu 2015). ...
Surveys have looked for H α emission from accreting gas giants but found very few objects. Analyses of the detections and nondetections have assumed that the entire gas flow feeding the planet is in radial freefall. However, hydrodynamical simulations suggest that this is far from reality. We calculate the H α emission from multidimensional accretion onto a gas giant, following the gas flow from Hill sphere scales down to the circumplanetary disk (CPD) and the planetary surface. We perform azimuthally symmetric radiation hydrodynamics simulations around the planet and use modern tabulated gas and dust opacities. Crucially, contrasting with most previous simulations, we do not smooth the gravitational potential but do follow the flow down to the planetary surface, where grid cells are 0.01 Jupiter radii small. We find that roughly only 1% of the net gas inflow into the Hill sphere directly reaches the planet. As expected for ballistic infall trajectories, most of the gas falls at too large a distance on the CPD to generate H α . Including radiation transport removes the high-velocity subsurface flow previously seen in hydrodynamics-only simulations, so that only the free planet surface and the inner regions of the CPD emit substantial H α . Unless magnetospheric accretion, which we neglect here, additionally produces H α , the corresponding H α production efficiency is much smaller than usually assumed, which needs to be taken into account when analyzing (non)detection statistics.
... A notable example is the V1298 Tau system (∼20 Myr; David et al. 2019). Core accretion models for giant planet formation predict that gaseous planets will contract as they cool (e.g., Fortney et al. 2007;Mordasini et al. 2012). However, Suárez Mascareño et al. ...
Developments in the stability of modern spectrographs have led to extremely precise instrumental radial velocity (RV) measurements. For most stars, the detection limit of planetary companions with these instruments is expected to be dominated by astrophysical noise sources such as starspots. Correlated signals caused by rotationally modulated starspots can obscure or mimic the Doppler shifts induced by even the closest, most massive planets. This is especially true for young, magnetically active stars where stellar activity can cause fluctuation amplitudes of ≳0.1 mag in brightness and ≳100 m s ⁻¹ in RV semiamplitudes. Techniques that can mitigate these effects and increase our sensitivity to young planets are critical to improving our understanding of the evolution of planetary systems. Gaussian processes (GPs) have been successfully employed to model and constrain activity signals in individual cases. However, a principled approach of this technique, specifically for the joint modeling of photometry and RVs, has not yet been developed. In this work, we present a GP framework to simultaneously model stellar activity signals in photometry and RVs that can be used to investigate the relationship between both time series. Our method, inspired by the FF ′ framework of Aigrain et al., models spot-driven activity signals as the linear combinations of two independent latent GPs and their time derivatives. We also simulate time series affected by starspots by extending the starry software to incorporate time evolution of stellar features. Using these synthetic data sets, we show that our method can predict spot-driven RV variations with greater accuracy than other GP approaches.
