Search

We measure the dependence of planet frequency on host star mass, M L, and distance from the Galactic center, R L, using a sample of planets discovered by gravitational microlensing. We compare the two-dimensional distribution of the lens-source proper motion, μ rel, and the Einstein radius crossing time, t E, measured for 22 planetary events from Suzuki et al. with the distribution expected from Galactic model. Assuming that the planet-hosting probability of a star is proportional to M L m R L r , we calculate the likelihood distribution of (m, r). We estimate that r = 0.10 − 0.37 + 0.51 and m = 0.50 − 0.70 + 0.90 under the assumption that the planet-hosting probability is independent of the mass ratio. We also divide the planet sample into subsamples based on their mass ratio, q, and estimate that m = − 0.08 − 0.65 + 0.95 for q < 10−3 and 1.25 − 1.14 + 1.07 for q > 10−3. Although uncertainties are still large, this result implies a possibility that, in orbits beyond the snowline, massive planets are more likely to exist around more massive stars whereas low-mass planets exist regardless of their host star mass. [ABSTRACT FROM AUTHOR]

Abstract The Andrade rheological model is often employed to describe the response of solar system or extra‐solar planets to tidal perturbations, especially when their properties are still poorly constrained. While for uniform planets with steady‐state Maxwell rheology the analytical form of the Love numbers was established long ago, for the transient Andrade rheology no closed‐form solutions have been yet determined, and the planetary response is usually studied either semi‐analitically in the frequency domain or numerically in the time domain. Closed‐form expressions are potentially important since they could provide insight into the dependence of Love numbers upon the model parameters and the time‐scales of the isostatic readjustment of the planet. First, we focus on the Andrade rheological law in 1‐D and we obtain a previously unknown explicit form, in the time domain, for the relaxation modulus in terms of the higher Mittag‐Leffler transcendental function Eα,β(z) that generalizes the exponential function. Second, we consider the general response of an incompressible planetary model — often referred to as the “Kelvin sphere” — studying the Laplace domain, the frequency domain and the time domain Love numbers by analytical methods. Through a numerical approach, we assess the effect of compressibility on the Love numbers in the Laplace and frequency domains. Furthermore, exploiting the results obtained in the 1‐D case, we establish closed‐form — although not elementary — expressions of the time domain Love numbers and we discuss the frequency domain response of the Kelvin sphere with Andrade rheology analytically.

Popular modern diets are often seen as a panacea for improving health and promoting weight reduction. While there is a large body of literature reporting the health benefits of popular diets, few studies have described their planetary benefits. Our investigation aims to evaluate the simultaneous impacts of six popular diets within the United States on both human and planetary health. Using carbon footprint databases and representative meal plans, the environmental and health-related impacts of the Standard American, Mediterranean, vegan, paleo, keto, and climatarian diets are compared using the currently available literature. Results indicate that diets that exhibit lower carbon footprints also have positive effects on human health. The diets found to have the lowest environmental impacts were the vegan, climatarian, and Mediterranean diets. These low-carbon-footprint diets can likely be attributed to a reduced reliance on ruminant meat (cattle and sheep) and processed food consumption, while diets with high carbon footprints are more dependent on ruminant meat and saturated fat. Moderate consumption of meats such as chicken, pork, and fish in conjunction with an emphasis on locally grown fruits and vegetables can be maintained without adversely affecting the planetary carbon footprint and with the added benefit of promoting good health. Thus, making simple substitutions within each individual's diet can be advertised as an effective approach to collectively lower the environmental impact in tandem with improving health and longevity.

Determining compositions of low-mass exoplanets is essential in understanding their origins. The certainty by which masses and radius are measured affects our ability to discern planets that are rocky or volatile rich. In this study, we aim to determine sound observational strategies to avoid diminishing returns. We quantify how uncertainties in mass, radius, and model assumptions propagate into errors in inferred compositions of rocky and water planets. For a target error in a planet's iron-mass fraction or water content, we calculate the corresponding required accuracies in radius and mass. For instance, a rocky planet with a known radius error of 2 per cent (corresponding to TESS detection best errors) demands mass precision to be at 5–11 per cent to attain an 8 wt% precision in iron-mass fraction, regardless of mass. Similarly, a water world of equal radius precision requires 9–20 per cent mass precision to confine the water content within a 10 wt% margin. Lighter planets are more difficult to constrain, especially water-rich versus water-poor worlds. Studying Earth as an exoplanet, we find an ∼±5 point 'error floor' in iron-mass fraction and ∼±7 in core-mass fraction from our lack of knowledge on mineralogy. The results presented here can quickly guide observing strategies to maximize insights into small exoplanet compositions while avoiding overobserving. [ABSTRACT FROM AUTHOR]

One of the leading mechanisms invoked to explain the existence of the radius valley is atmospheric mass-loss driven by X-ray and extreme-ultraviolet irradiation, with this process stripping the primordial envelopes of young, small planets to produce the observed bimodal distribution. We present an investigation into the TOI-431 and ν2 Lupi planetary systems, both of which host planets either side of the radius valley, to determine if their architectures are consistent with evolution by the X-ray/ultraviolet (XUV) mechanism. With XMM–Newton , we measure the current X-ray flux of each star, and see evidence for a stellar flare in the TOI-431 observations. We then simulate the evolution of all of the transiting planets across the two systems in response to the high-energy irradiation over their lifetimes. We use the measured X-ray fluxes as an anchor point for the XUV time evolution in our simulations, and employ several different models of estimating mass-loss rates. While the simulations for TOI-431 b encountered a problem with the initial calculated radii, we estimate a likely short (∼Myr) timespan for primordial envelope removal using reasonable assumptions for the initial planet. ν2 Lupi b is likely harder to strip, but is achieved in a moderate fraction of our simulations. None of our simulations stripped any of the lower density planets of their envelope, in line with prediction. We conclude that both systems are consistent with expectations for generation of the radius valley through XUV photoevaporation. [ABSTRACT FROM AUTHOR]

We analyse a tilt instability of the orbit of an outer planet in a two-planet circumbinary system that we recently reported. The binary is on an eccentric orbit and the inner circumbinary planet is on a circular polar orbit that causes the binary to undergo apsidal precession. The outer circumbinary planet is initially on a circular or eccentric orbit that is coplanar with respect to the binary. We apply a Hamiltonian in quadrupole order of the binary potential to show that the tilt instability is the result of a secular resonance in which the apsidal precession rate of the binary matches the nodal precession rate of the outer planet. A resonance is possible because the polar inner planet causes the apsidal precession of the binary to be retrograde. The outer planet periodically undergoes large tilt oscillations for which we analytically determine the initial evolution and maximum inclination. Following a typically relatively short adjustment phase, the tilt grows exponentially in time at a characteristic rate that is of order the absolute value of the binary apsidal precession rate. The analytic results agree well with numerical simulations. This instability is analogous to the Kozai–Lidov instability, but applied to a circumbinary object. The instability fails to operate if the binary mass ratio is too extreme. The instability occurs even if the outer planet is instead an object of stellar mass and involves tilt oscillations of the inner binary. [ABSTRACT FROM AUTHOR]

Cool gaseous exoplanets (1.75  R ⊕ < R p < 3  R J, 200 K < T eq  < 1000 K) are an as-yet understudied population, with great potential to expand our understanding of planetary atmospheres and formation mechanisms. In this paper, we outline the basis for a homogeneous survey of cool gaseous planets with Twinkle , a 0.45-m diameter space telescope with simultaneous spectral coverage from 0.5–4.5  μ m, set to launch in 2025. We find that Twinkle has the potential to characterise the atmospheres of 36 known cool gaseous exoplanets (11 sub-Neptunian, 11 Neptunian, 14 Jovian) at an SNR ≥ 5 during its 3-yr primary mission, with the capability of detecting most major molecules predicted by equilibrium chemistry to >5σ significance. We find that an injected mass–metallicity trend is well recovered, demonstrating Twinkle 's ability to elucidate this fundamental relationship into the cool regime. We also find that Twinkle will be able to detect cloud layers at 3σ or greater in all cool gaseous planets for clouds at ≤10 Pa pressure level, but will be insensitive to clouds deeper than 104 Pa in all cases. With these results, we demonstrate the capability of the Twinkle mission to greatly expand the current knowledge of cool gaseous planets, enabling key insights and constraints to be obtained for this poorly charted region of exoplanet parameter space. [ABSTRACT FROM AUTHOR]

With more than 5500 detected exoplanets, the search for life is entering a new era. Using life on Earth as our guide, we look beyond green landscapes to expand our ability to detect signs of surface life on other worlds. While oxygenic photosynthesis gives rise to modern green landscapes, bacteriochlorophyll-based anoxygenic phototrophs can also colour their habitats and could dominate a much wider range of environments on Earth-like exoplanets. Here, we characterize the reflectance spectra of a collection of purple sulfur and purple non-sulfur bacteria from a variety of anoxic and oxic environments. We present models for Earth-like planets where purple bacteria dominate the surface and show the impact of their signatures on the reflectance spectra of terrestrial exoplanets. Our research provides a new resource to guide the detection of purple bacteria and improves our chances of detecting life on exoplanets with upcoming telescopes. Our biological pigment data base for purple bacteria and the high-resolution spectra of Earth-like planets, including ocean worlds, snowball planets, frozen worlds, and Earth analogues, are available online, providing a tool for modellers and observers to train retrieval algorithms, optimize search strategies, and inform models of Earth-like planets, where purple is the new green. [ABSTRACT FROM AUTHOR]

Context. The formation mechanisms of stellar, brown dwarf, and planetary companions, their dependencies on the environment and their interactions with each other are still not well established. Recently, combining high-contrast imaging and space astrometry we found that Jupiter-like (JL) planets are frequent in the β Pic moving group (BPMG) around those stars where their orbit can be stable, prompting further analysis and discussion. Aims. We broaden our previous analysis to other young nearby associations to determine the frequency, mass and separation of companions in general and JL in particular and their dependencies on the mass and age of the associations. Methods. We collected available data about companions to the stars in the BPMG and seven additional young associations, including those revealed by visual observations, eclipses, spectroscopy and astrometry. Results. We determined search completeness and found that it is very high for stellar companions, while completeness corrections are still large for JL companions. Once these corrections are included, we found a high frequency of companions, both stellar (>0.52 ± 0.03) and JL (0.57 ± 0.11). The two populations are clearly separated by a gap that corresponds to the well-known brown dwarf desert. Within the population of massive companions, we found clear trends in frequency, separation, and mass ratios with stellar mass. Planetary companions pile up in the region just outside the ice line and we found them to be frequent once completeness was considered. The frequency of JL planets decreases with the overall mass and possibly the age of the association. Conclusions. We tentatively identify the two populations as due to disk fragmentation and core accretion, respectively. The distributions of stellar companions with a semi-major axis <1000 au is indeed well reproduced by a simple model of formation by disk fragmentation. The observed trends with stellar mass can be explained by a shorter but much more intense phase of accretion onto the disk of massive stars and by a more steady and prolonged accretion on solar-type stars. Possible explanations for the trends in the population of JL planets with association mass and age are briefly discussed. [ABSTRACT FROM AUTHOR]

Aims. We study the secular evolution of two planets in mutual deep mean-motion resonance (MMR) in the planar elliptic three-body problem framework for different mass ratios. We do not consider any restriction in the eccentricity of the inner planet e1 or in the eccentricity of the outer planet e2. Methods. The method we used is based on a semi-analytical model that consists of calculating the averaged resonant disturbing function numerically. It is assumed for this that all the orbital elements (except for the mean longitudes) of both planets are constant on the resonant timescale. In order to obtain the secular evolution inside the MMR, we make use of the adiabatic invariance principle, assuming a zero-amplitude resonant libration. We constructed two phase portraits, called the ℋ1 and ℋ2 surfaces, in the three-dimensional spaces (e1, Δϖ, σ) and (e2, Δϖ, σ), where Δϖ is the difference between the planetary longitude of perihelia and σ is the critical angle. These surfaces, which are related through the angular moment conservation, allow us to find the apsidal corotation resonances (ACRs) and to predict the secular evolution of e1, e2, Δϖ, and σ (libration center). Results. While studying the 1:1, 2:1, 3:1, and 3:2 MMR, we found that large excursions in eccentricity can exist in some particular cases. We compared the secular variations of e1, e2, Δϖ, and σ predicted by the model with a numerical integration of the exact equations of motion for different mass ratios. We obtained good matches. Finally, the model was applied to study the secular evolution of the resonant exoplanet systems HD 73526 and HD 31527. They both have a pair of planets and are very close to the deep MMR condition. In the first system, we found that the pair of planets that constitutes the system evolves in a symmetrical ACR, whereas in the second system, we found that planets c and d, which are in an unusual 16:3 MMR, are close to an ACR, but outside its dynamical region, where Δϖ circulates. [ABSTRACT FROM AUTHOR]

The number of discovered exoplanets now exceeds 5500 allowing statistical analyses of planetary systems. Multi-planet systems are mini-laboratories of planet formation and evolution, and analysing their system architectures can help us to constrain the physics of these processes. Recent works have found evidence of significant intrasystem uniformity in planet properties such as radius, mass, and orbital spacing, collectively termed 'peas in a pod' trends. In particular, correlations in radius and mass have been interpreted as implying uniformity in planet bulk density and composition within a system. However, the samples used to assess trends in mass tend to be small and biased. In this paper, we re-evaluate correlations in planet properties in a large sample of systems with at least two planets for which mass and radius have been directly measured, and therefore bulk density can be calculated. Our sample was assembled using the most up-to-date exoplanet catalogue data, and we compute the relevant statistics while using a procedure to 'weight' the data points according to measurement precision. We find a moderate correlation in radius and a weak correlation in the densities of adjacent planets. However, masses of neighbouring planets show no overall correlation in our main sample and a weak correlation among pairs of planets similar in size or pairs restricted to Mp<100 M⊕, Rp<10 R⊕. Similarly, we show that the intrasystem dispersion in radius is typically less than that in mass and density. We identify ranges in stellar host properties that correlate with stronger uniformity in pairs of adjacent planets: low Teff for planet masses, and low metallicity and old age for planet densities. Furthermore, we explore whether peas in a pod trends extend into planet compositions or interior structures. For small neighbouring planets with similar radii, we show that their masses and interior structures are often disparate, indicating that even within the same system, similarity in radii is not necessarily a good proxy for similarity in composition or the physical nature of the planets. [ABSTRACT FROM AUTHOR]

We present the detection of three exoplanets orbiting the early M dwarf TOI-663 (TIC 54962195; V = 13.7 mag, J = 10.4 mag, R★ = 0.512 ± 0.015 R⊙, M★ = 0.514 ± 0.012 M⊙, d = 64 pc). TOI-663 b, c, and d, with respective radii of 2.27 ± 0.10 R⊕, 2.26 ± 0.10 R⊕, and 1.92 ± 0.13 R⊕ and masses of 4.45 ± 0.65 M⊕, 3.65 ± 0.97 M⊕, and <5.2 M⊕ at 99%, are located just above the radius valley that separates rocky and volatile-rich exoplanets. The planet candidates are identified in two TESS sectors and are validated with ground-based photometric follow-up, precise radial-velocity measurements, and high-resolution imaging. We used the software package juliet to jointly model the photometric and radial-velocity datasets, with Gaussian processes applied to correct for systematics. The three planets discovered in the TOI-663 system are low-mass mini-Neptunes with radii significantly larger than those of rocky analogs, implying that volatiles, such as water, must predominate. In addition to this internal structure analysis, we also performed a dynamical analysis that confirmed the stability of the system. The three exoplanets in the TOI-663 system, similarly to other sub-Neptunes orbiting M dwarfs, have been found to have lower densities than planets of similar sizes orbiting stars of different spectral types. [ABSTRACT FROM AUTHOR]

Free-floating planets are a new class of planets recently discovered. These planets don't orbit within stellar systems, instead living a nomadic life within the galaxy. How such objects formed remains elusive. Numerous works have explored mechanisms to form such objects, but have not yet provided predictions on their distributions that could differentiate between formation mechanisms. In this work we form these objects within circumbinary systems, where these planets are readily formed and ejected through interactions with the central binary stars. We find significant differences between planets ejected through planet–planet interactions and those by the binary stars. The main differences that arise are in the distributions of excess velocity, where binary stars eject planets with faster velocities. These differences should be observable amongst known free-floating planets in nearby star-forming regions. We predict that targeted observations of directly imaged free-floating planets in these regions should be able to determine their preferred formation pathway, either by planet formation in single or multiple stellar systems, or through processes akin to star formation. Additionally, the mass distributions of free-floating planets can yield important insights into the underlying planet populations. We find that for planets more massive than 20  |$\, {\rm M}_{\hbox{$\oplus $}}$|⁠ , their frequencies are similar to those planets remaining bound and orbiting near the central binaries. This similarity allows for effective and informative comparisons between mass distributions from microlensing surveys, to those of transit and radial velocities. Ultimately, by observing the velocity dispersion and mass distribution of free-floating planets, it will be possible to effectively compare with predictions from planet formation models, and to further understand the formation and evolution of these exotic worlds. [ABSTRACT FROM AUTHOR]

A simple and clear method to calculate the averaged motion of the apsis line in the Moon orbit is proposed. The obtained result is 3°1′12′′$$ {3}^{{}^{\circ}}{1}^{\prime }1{2}^{\prime \prime } $$ for the starry period of the Moon revolution around the Earth or 40°22′48′′$$ {40}^{{}^{\circ}}2{2}^{\prime }4{8}^{\prime \prime } $$ per year. The modern observed value of the latter quantity is 40°41′$$ {40}^{{}^{\circ}}4{1}^{\prime } $$ per year. In "Principia" Newton derived 1°31′28′′$$ {1}^{{}^{\circ}}3{1}^{\prime }2{8}^{\prime \prime } $$ for the Moon month and 20°12′′$$ {20}^{{}^{\circ}}1{2}^{\prime \prime } $$ per year, that is approximately two times less than the observed values. Contrary to the Newton approach, we use a simple and obvious averaging of the Sun disturbing force for the starry period of the Moon revolution around the Earth. The applicability of the obtained formulae to satellites of other planets and to the planets themselves is argued. Comparing Newton's calculation with our method, we reveal the reason, rather convincing, that brought Newton to an imprecise result. [ABSTRACT FROM AUTHOR]

Many studies have analysed planetary occurrence rates and their dependence on the host's properties to provide clues to planet formation, but few have focused on the mutual occurrence ratio of different kinds of planets. Such relations reveal whether and how one type of planet evolves into another, e.g. from a cold Jupiter (CJ) to a warm Jupiter (WJ) or even hot Jupiter (HJ), and demonstrate how stellar properties impact the evolution history of planetary systems. We propose a new classification of giant planets, i.e. CJ, WJ, and HJ, according to their position relative to the snow line in the system. Then, we derive their occurrence rates (ηHJ, ηWJ, ηCJ) with the detection completeness of radial velocity (RV) surveys (HARPS and CORALIE) considered. Finally, we analyse the correlation between the mutual occurrence ratios, i.e. ηCJ/ηWJ, ηCJ/ηHJ, or ηWJ/ηHJ, and various stellar properties, e.g. effective temperature T eff. Our results show that the ηHJ, ηWJ, and ηCJ are increasing with the increasing T eff when T eff ∈ (4600, 6600] K. Furthermore, the mutual occurrence ratio between CJ and WJ, i.e. ηCJ/ηWJ, shows a decreasing trend with the increasing T eff. But, both ηCJ/ηHJ and ηWJ/ηHJ are increasing when the T eff increases. Further consistency tests reveal that the formation processes of WJ and HJ may be dominated by orbital change mechanisms rather than the in situ model. However, unlike WJ, which favours gentle disc migration, HJ favours a more violent mechanism that requires further investigation. [ABSTRACT FROM AUTHOR]

During the final stage of planetary formation, different formation pathways of planetary embryos could significantly influence the observed variations in planetary densities. Of the approximately 5000 exoplanets identified to date, a notable subset exhibits core fractions reminiscent of Mercury, potentially a consequence of high-velocity giant impacts. In order to better understand the influence of such collisions on planetary formation and compositional evolution, we conducted an extensive set of smoothed particle hydrodynamics giant impact simulations between two-layered rocky bodies. These simulations spanned a broad range of impact velocities from 1 to 11 times the mutual escape velocity. We derived novel scaling laws that estimate the mass and core mass fraction of the largest post-collision remnants. Our findings indicate that the extent of core vaporization markedly influences mantle stripping efficiency at low impact angles. We delineate the distinct roles played by two mechanisms – kinetic momentum transfer and vaporization-induced ejection – in mantle stripping. Our research suggests that collisional outcomes for multilayered planets are more complex than those for undifferentiated planetesimal impacts. Thus, a single universal law may not encompass all collision processes. We found a significant decrease in the mantle stripping efficiency as the impact angle increases. To form a 5 M⊕ super-Mercury at 45°, an impact velocity over 200 km s−1 is required. This poses a challenge to the formation of super-Mercuries through a single giant impact, implying that their formation would favour either relatively low-angle single impacts or multiple collisions. [ABSTRACT FROM AUTHOR]

In this work, we present the results from a study using the Giant Meterwave Radio Telescope (GMRT) to search for radio emission from planets around three evolved stars namely α Tau, β UMi, and β Gem. Both α Tau and β UMi host massive ∼ 6 MJ mass planets at about ∼1.4 au from the central star, while β Gem is host to a 2.9 MJ mass planet at 1.7 au from the host star. We observe α Tau and β UMi at two upgraded GMRT bands: band 3 (250–500 MHz) and band 4 (550–900 MHz). We also analysed the archival observations from β Gem at 150 MHz from GMRT. We did not detect any radio signals from these systems. At 400 MHz, the 3σ upper limit is 87 μ Jy beam−1 for α Tau b and 77.4 μ Jy beam−1 for β UMi b. From our observations at 650 MHz, we place a 3σ upper limit of 28.2 μ Jy beam−1 for α Tau b and 33.6 μ Jy beam−1 for β UMi b. For β Gem b, at 150 MHz, we place an upper limit of 2.5 mJy. At 400 and 650 MHz, our observations are the deepest radio images for any exoplanetary system. [ABSTRACT FROM AUTHOR]

Examples of hypotheses about the number of planets are frequently used to introduce the topic of (actual) truthlikeness but never analyzed in detail. In this paper we first deal with the truthlikeness of singular quantity hypotheses, with reference to several 'the number of planets' examples, such as 'The number of planets is 10 versus 10 billion (instead of 8).' For the relevant ratio scale of quantities we will propose two, strongly related, normalized metrics, the proportional metric and the (simplest and hence favorite) fractional metric, to express e.g. the distance from a hypothetical number to the true number of planets, i.e. the distance between quantities. We argue that they are, in view of the examples and plausible conditions of adequacy, much more appropriate, than the standardly suggested, normalized absolute difference, metric. Next we deal with disjunctive hypotheses, such as 'The number of planets is between 7 and 10 inclusive is much more truthlike than between 1 and 10 billion inclusive.' We compare three (clusters of) general ways of dealing with such hypotheses, one from Ilkka Niiniluoto, one from Pavel Tichý and Graham Oddie, and a trio of ways from Theo Kuipers. Using primarily the fractional metric, we conclude that all five measures can be used for expressing the distance of disjunctive hypotheses from the actual truth, that all of them have their strong and weak points, but that (the combined) one of the trio is, in view of principle and practical considerations, the most plausible measure. [ABSTRACT FROM AUTHOR]

The PARST educational tool is a new application that allows users to calculate and visualize the rising and setting times of planets over long periods. It focuses on the rising and setting times of five planets: Mercury, Venus, Mars, Jupiter, and Saturn. The tool displays recurring patterns in these times and can be used as a hands-on activity in astronomy classes. The study conducted by faculty members from Chiang Mai University in Thailand analyzes the rising times of Venus and Mars and creates cycle plots to visualize the variations. It also extends to other planets and provides valuable information for understanding the temporal and geometric relationships between their orbits. [Extracted from the article]

Chondrules probably formed during a small window of time ~1–4 Ma after CAIs, when most solid matter in the asteroid belt was already in the form of km‐sized planetesimals. They are unlikely, therefore, to be "building blocks" of planets or abundant on asteroids, but more likely to be a product of energetic events common in the asteroid belt at that epoch. Laboratory experiments indicate that they could have formed when solids of primitive composition were heated to temperatures of ~1600 K and then cooled for minutes to hours. A plausible heat source for this is magma, which is likely to have been abundant in the asteroid belt at that time, and only that time, due to the trapping of 26Al decay energy in planetesimal interiors. Here, we propose that chondrules formed during low‐speed (≲1kms−1) collisions between large planetesimals when heat from their interiors was released into a stream of primitive debris from their surfaces. Heating would have been essentially instantaneous and cooling would have been on the dynamical time scale, 1/Gρ ~30 min, where ρ is the mean density of a planetesimal. Many of the heated fragments would have remained gravitationally bound to the merged object and could have suffered additional heating events as they orbited and ultimately accreted to its surface. This is a hybrid of the splash and flyby models: We propose that it was the energy released from a body's molten interior, not its mass, that was responsible for chondrule formation by heating primitive debris that emerged from the collision. [ABSTRACT FROM AUTHOR]

Since the notion of the Anthropocene entered the discourse of environmental humanities, it has prompted multiple conceptual innovations. This paper focuses on one such case: the term planetary – and the adjacent genre of planetary thinking – theorized by a broad range of scholars. The original contribution of this paper lies in developing an astronomical concept of the planet, derived from the definition agreed by resolution 5A 2006 of International Astronomical Union, which defines planets based on their dynamical context. By means of philosophical interpretation of the definition's underlying assumptions, this paper articulates standalone philosophical implications of the astronomical concept: the contextualization of the planet in expanded ecology of the solar system, paired with the understanding of the planet as a structure of phase gradients and as a historical natural kind. Furthermore, I position the astronomical concept alongside theorizations of the planet by Latour, Stengers, Clark & Szerszynski as well as Chakrabarty, touching upon the Gaia hypothesis or the concept of geological history. Finally, I encourage deeper disciplinary interaction between astronomy and environmental humanities. The benefits of this interaction are highlighted in the concluding discussion concerning the multiplicity of planetary narratives and applications of the astronomical concept of the planet. [ABSTRACT FROM AUTHOR]

Ultra-short period planets (USPs) have orbital periods of less than 1 d. Since their masses and radii can be determined to a higher precision than long-period planets, they are the preferred targets to determine the density of planets which constrains their composition. The K2-106 system is particularly interesting because it contains two planets of nearly identical masses. One is a high-density USP, the other is a low-density planet that has an orbital period of 13 d. Combining the Gaia DR3 results with new ESPRESSO data allows us to determine the masses and radii of the two planets more precisely than before. We find that the USP K2-106 b has a density consistent with an Earth-like composition, and K2-106 c is a low-density planet that presumably has an extended atmosphere. We measure a radius of |$\rm R_p=1.676_{-0.037}^{+0.037}$| |$\rm R_{{\oplus }}$|⁠ , a mass of |$\rm M_p=7.80_{-0.70}^{+0.71}$| M ⊕, and a density of |$\rm \rho =9.09_{-0.98}^{+0.98}$| |$\rm g\, cm^{-3}$| for K2-106 b. For K2-106 c, we derive |$R_p=2.84_{-0.08}^{+0.10}$| |$\rm R_{{\oplus }}$|⁠ , |$M_p=7.3_{-2.4}^{+2.5}$| |$\rm M_{{\oplus }}$|⁠ , and a density of |$\rm \rho = 1.72_{-0.58}^{+0.66}$| |$\rm g\, cm^{-3}$|⁠. We finally discuss the possible structures of the two planets with respect to other low-mass planets. [ABSTRACT FROM AUTHOR]

We present a study of the detection efficiency for the TESS mission, focusing on the yield of longer period transiting exoplanets (P > 25 d). We created the Transit Investigation and Recoverability Application (TIaRA) pipeline to use real TESS data with injected transits to create sensitivity maps which we combine with occurrence rates derived from Kepler. This allows us to predict longer period exoplanet yields, which will help design follow-up photometric and spectroscopic programs, such as the NGTS (Next Generation Transit Survey) Monotransit Program. For the TESS Years 1 and 3 SPOC (Science Processing Operations Centre) FFI (Full Frame Image) light curves, we find |$2271^{+241}_{-138}$| exoplanets should be detectable around AFGKM dwarf host stars. We find |$215^{+37}_{-23}$| exoplanets should be detected from single-transit events or 'monotransits'. An additional |$113^{+22}_{-13}$| detections should result from 'biennial duotransit' events with one transit in Year 1 and a second in Year 3. We also find that K dwarf stars yield the most detections by TESS per star observed. When comparing our results to the TOI (TESS objects of interest) catalogue, we find our predictions agree within 1σ of the number of discovered systems with periods between 0.78 and 6.25 d and agree to 2σ for periods between 6.25 and 25 d. Beyond periods of 25 d, we predict |$403^{+64}_{-38}$| detections, which is three times as many detections as there are in the TOI catalogue with >3σ confidence. This indicates a significant number of long-period planets yet to be discovered from TESS data as monotransits or biennial duotransits. [ABSTRACT FROM AUTHOR]

Recent studies have suggested the possibility of Hycean worlds, characterized by deep liquid water oceans beneath H2-rich atmospheres. These planets significantly widen the range of planetary properties over which habitable conditions could exist. We conduct internal structure modelling of Hycean worlds to investigate the range of interior compositions, ocean depths and atmospheric mass fractions possible. Our investigation explicitly considers habitable oceans, where the surface conditions are limited to those that can support potential life. The ocean depths depend on the surface gravity and temperature, confirming previous studies, and span 10s to ∼1000 km for Hycean conditions, reaching ocean base pressures up to ∼6 × 104 bar before transitioning to high-pressure ice. We explore in detail test cases of five Hycean candidates, placing constraints on their possible ocean depths and interior compositions based on their bulk properties. We report limits on their atmospheric mass fractions admissible for Hycean conditions, as well as those allowed for other possible interior compositions. For the Hycean conditions considered, across these candidates we find the admissible mass fractions of the H/He envelopes to be ≲10−3. At the other extreme, the maximum H/He mass fractions allowed for these planets can be up to ∼4–8 per cent, representing purely rocky interiors with no H2O layer. These results highlight the diverse conditions possible among these planets and demonstrate their potential to host habitable conditions under vastly different circumstances to the Earth. Upcoming JWST observations of candidate Hycean worlds will allow for improved constraints on the nature of their atmospheres and interiors. [ABSTRACT FROM AUTHOR]

Low-mass planets migrate in the type-I regime. In the inviscid limit, the contrast between the vortensity trapped inside the planet's corotating region and the background disc vortensity leads to a dynamical corotation torque, which is thought to slow down inward migration. We investigate the effect of radiative cooling on low-mass planet migration using inviscid 2D hydrodynamical simulations. We find that cooling induces a baroclinic forcing on material U-turning near the planet, resulting in vortensity growth in the corotating region, which in turn weakens the dynamical corotation torque and leads to 2–3× faster inward migration. This mechanism is most efficient when cooling acts on a time-scale similar to the U-turn time of material inside the corotating region, but is none the less relevant for a substantial radial range in a typical disc (R ∼ 5–50 au). As the planet migrates inwards, the contrast between the vortensity inside and outside the corotating region increases and partially regulates the effect of baroclinic forcing. As a secondary effect, we show that radiative damping can further weaken the vortensity barrier created by the planet's spiral shocks, supporting inward migration. Finally, we highlight that a self-consistent treatment of radiative diffusion as opposed to local cooling is critical in order to avoid overestimating the vortensity growth and the resulting migration rate. [ABSTRACT FROM AUTHOR]

In this work, we develop a rocky planet interior model and use it to investigate the evolution of catastrophically evaporating rocky exoplanets. These planets, detected through the dust tails produced by evaporative outflows from their molten surfaces, can be entirely destroyed in a fraction of their host star's lifetime. To allow for the major decrease in mass, our interior model can simultaneously calculate the evolution of the pressure and density structure of a planet alongside its thermal evolution, which includes the effects of conduction, convection and partial melting. We first use this model to show that the underlying planets are likely to be almost entirely solid. This means that the dusty tails are made up of material sampled only from a thin dayside lava pool. If one wishes to infer the bulk compositions of rocky exoplanets from their dust tails, it is important to take the localized origin of this material into account. Secondly, by considering how frequently one should be able to detect mass loss from these systems, we investigate the occurrence of sub-Earth mass exoplanets, which is difficult with conventional planet detection surveys. We predict that, depending on model assumptions, the number of progenitors of the catastrophically evaporating planets is either in line with, or higher than, the observed population of close-in (substellar temperatures around 2200 K) terrestrial exoplanets. [ABSTRACT FROM AUTHOR]

We present a technique for verifying or refuting exoplanet candidates from the Transiting Exoplanet Survey Satellite (TESS) mission by searching for nearby eclipsing binary stars using higher resolution archival images from ground-based telescopes. Our new system is called Detecting and Evaluating A Transit: finding its Hidden Source in Time-domain Archival Records (DEATHSTAR). We downloaded time series of cutout images from two ground-based telescope surveys (the Zwicky Transient Facility, and the Asteroid Terrestrial-impact Last Alert System, analysed the images to create apertures and measure the brightness of each star in the field, and plotted the resulting light curves using custom routines. Thus far, we have confirmed on-target transits for 17 planet candidates, and identified 35 false positives and located their actual transit sources. With future improvements to automation, DEATHSTAR will be scaleable to run on the majority of TESS Objects of Interest. [ABSTRACT FROM AUTHOR]

This Note from the Field uses the travel metaphor and inquiry format of Elinor Fuchs's well-known pedagogical essay, "EF's Visit to a Small Planet: Some Questions to Ask a Play," to pose questions about a related object of dramatic analysis: the familiar world in which you live. The questions posed in this Note invite readers to imagine their regional, institutional, and local world as a social text that is worth reading before (or alongside) selecting plays for a theatrical season. It is the interplay between familiar and distant planets that can yield, as so many socially engaged artists and educators have found, meaningful choices of plays for local audiences. [ABSTRACT FROM AUTHOR]

It is π‐day 2024 (March 14th) and to celebrate, we ask the question: can π be estimated accurately using the shape of the terrestrial planets and the Moon? We proceed by using models for the planet topographies in slices of constant latitude and computing π as the ratio of the circumference to the diameter in each slice. We define the circumference as the topographically undulating perimeter of the slice (which deviates from the circular section of the reference ellipsoid). We define the diameter as the distance connecting two opposite points on the topography model through the center of the slice. This gives us a distribution of π estimates for each latitude slice and overall for each planetary body. The distribution and accuracy of the π estimates we compute are a representation of how smooth and circular latitude slices of the terrestrial planets are. We find that Mercury and Venus are particularly good at predicting π because they are relatively smooth and the topographic deviations from the reference ellipsoid are small compared with Mars, Earth, and the Moon. In the spirit of π‐day, this mathematical exercise motivates an interest in planetary geophysics and shape. Plain Language Summary: 14th March is π‐day: an annual celebration of the number π and a fun opportunity to raise the profile of mathematics in all fields of science and of numeracy in general. One way to define the number π is by taking the ratio of a circle's circumference to its diameter. And so, to celebrate π‐day this year, we take the terrestrial worlds of our solar system and we cut them into near‐circular slices. We take the ratio of a slice circumference to its diameter to see how close it is to the number π. This results in some good estimates of π, but with inaccuracies because the planets are not perfectly smooth spheres. Nevertheless, it turns out that Mars, Earth, the Moon, Venus, and Mercury all slice up in such a way as to provide accurate estimates of π, and Venus is the best among them all. Key Points: Every year March 14th is international π‐day when we celebrate by finding fun ways to compute the number ∼3.14The topography of the terrestrial planets is variable and can be used to compute π in slices of constant latitudeFun ways to compute π using planetary science methods are educational and can support quantitative learning in a range of fields [ABSTRACT FROM AUTHOR]

Purpose: This study aims to construct the model of Corporate Social Responsibility (CSR) based on Surah Al Mudassir and Kitab Tarbiyah Wa Tahdzib in Islamic boarding schools. Method: This research uses a postmodernist-interpretivist paradigm where the research tries to integrate the meaning of each data obtained through interviews and construct a Corporate Social Responsibility (CSR) model based on Surah Al Mudassir and the Kitab of Tarbiyah Wa Tahdzib. Results: Empirically in Islamic boarding schools, it was found that 1) The application of Corporate Social Responsibility (CSR) towards profits is interpreted as sustenance that arises from a sense of sufficiency and gratitude, 2) The application of Corporate Social Responsibility (CSR) towards people is interpreted as charity service. 3) The implementation of corporate social responsibility (CSR) for the planet is interpreted as mutual concern and responsibility. Implications: this study provides implications for accounting science, especially the concept of CSR in a broader context Novelty: This study focuses on the construction of a CSR model that integrates organizational culture, religion and spirituality into a CSR model based on Surah Al Mudassir and Kitab Tarbiyah Wa Tahdzib

State of the art in the search for extrasolar planets In the last three decades, the study of exoplanets has evolved from a marginal field into a vital area of research with significant implications for other sciences and philosophy. In this article, we review the recent discoveries in the study of Earth-like planets and the prospects of searching for life through astronomical means.

"Fungi on Mars!": a popular news heading that piques public interest and makes scientists' blood boil. While such a statement is laden with misinformation and light on evidence, the search for past and present extraterrestrial life is an ongoing scientific effort. Moreover, it is one that is increasingly gaining momentum with the recent collection of martian rock cores from Jezero Crater by NASA's Perseverance rover. Despite the increasingly sophisticated approaches guiding the search for microbial life on other planets, fungi remain relatively underexplored compared to their bacterial counterparts, highlighting a gap between the astrobiological and fungal research communities. Through a meeting in April 2021, the CIFAR Earth 4D and Fungal Kingdom research programs worked to bridge this divide by uniting experts in each field. CIFAR is a Canadian-based global research organization that convenes researchers across disciplines to address important questions facing science and humanity. The CIFAR Earth 4D: Subsurface Science & Exploration and Fungal Kingdom: Threats & Opportunities research programs were launched by CIFAR in July 2019, each made up of approximately two dozen international researchers who are experts in their fields. The Earth 4D program, led by co-directors John Mustard (Brown University, USA) and Barbara Sherwood Lollar (University of Toronto, Canada), aims to understand the complex chemical, physical, and biological interactions that occur within and between Earth's surface and subsurface to explore questions on the evolution of planets and life. The Fungal Kingdom program, led by co-directors Leah Cowen (University of Toronto, Canada) and Joseph Heitman (Duke University, USA), seeks to tackle the most pressing threats fungi pose to human health, agriculture, and biodiversity and to harness their extraordinary potential. The programs met to explore areas for synergy within four major themes: (1) the origins of life; (2) the evolution and diversification of life; (3) life in diverse and extreme environments; and (4) extinction: lessons learned and threats. This report covers the research discussed during the meeting across these four themes.