"Super-puffs" are planets with anomalously low mean densities ( ). With a low surface gravity, the extended atmosphere is susceptible to extreme hydrodynamic mass loss ("boil-off") on a timescale ...that is much shorter than the system's age. Even more puzzling, super-puffs are estimated to have a scale height of , yet recent observations revealed completely flat transmission spectra for Kepler 51b and 51d. We investigate a new scenario that explains both observations: non-static outflowing ( ) atmospheres that carry very small dust grains (∼10 in size, in mass fraction) to high altitudes ( ). Dust at high altitudes inflates the observed transit radius of the planet while flattening the transmission spectra. Previous static atmospheric models struggle to achieve cloud elevation and production of photochemical haze at such high altitudes. We propose to test this scenario by extending the wavelength coverage of transmission spectra. If true, dusty atmospheric outflows may affect many young ( ), low-mass ( ) exoplanets, thereby limiting our ability to study the atmospheric composition in transmission, and inflate the observed transit radius of a planet, hence obscuring the underlying mass-radius relationship.
Observations of nine transits of WASP-107 during the K2 mission reveal three separate occasions when the planet crossed in front of a starspot. The data confirm the stellar rotation period to be 17 ...days-approximately three times the planet's orbital period-and suggest that large spots persist for at least one full rotation. If the star had a low obliquity, at least two additional spot crossings should have been observed. They were not observed, giving evidence for a high obliquity. We use a simple geometric model to show that the obliquity is likely in the range 40°-140°, i.e., both spin-orbit alignment and anti-alignment can be ruled out. WASP-107 thereby joins the small collection of relatively low-mass stars with a high obliquity. Most such stars have been observed to have low obliquities; all of the exceptions, including WASP-107, involve planets with relatively wide orbits ("warm Jupiters," with ). This demonstrates a connection between stellar obliquity and planet properties, in contradiction to some theories for obliquity excitation.
Abstract 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.
PurposeThe purpose of this paper is to extend the literature on the spillovers across economic policy uncertainty (EPU) and cryptocurrency uncertainty indices.Design/methodology/approachThis paper ...uses cross-country economic policy uncertainty indices and the novel data measuring the cryptocurrency price uncertainties over the period 2013–2021 to construct a sample of 946 observations and applies the time-varying parameter vector autoregression (TVP-VAR) model to do an empirical study.FindingsThe findings suggest that there are cross-country spillovers of economic policy uncertainty. In addition, the total uncertainty spillover between economic policies and cryptocurrency peaked in 2015 before gradually decreasing in the following periods. Concomitantly, the cryptocurrency uncertainty has acted as the “receiver.” More importantly, the authors found the predictive power of economic policy uncertainty to predict the cryptocurrency uncertainty index. This paper’s results hold robust when using alternative measurement of cryptocurrency policy uncertainty.Originality/valueThis study is the first research that deeply investigates the association between two uncertainty indicators, namely economic policy uncertainty and the cryptocurrency uncertainty index. We provide fresh evidence about the dynamic connectedness between country-level economic policy uncertainty and the cryptocurrency index. Our work contributes a new channel driving the variants of uncertainties in the cryptocurrency market.
Carboxylation of easily available alkenes with CO2 is highly important to afford value‐added carboxylic acids. Although dicarboxylation of activated alkenes, especially 1,3‐dienes, has been widely ...investigated, the challenging dicarboxylation of unactivated 1,n‐dienes (n>3) with CO2 remains unexplored. Herein, we report the first dicarboxylation of unactivated skipped dienes with CO2 via electrochemistry, affording valuable dicarboxylic acids. Control experiments and DFT calculations support the single electron transfer (SET) reduction of CO2 to its radical anion, which is followed by sluggish radical addition to unactivated alkenes, SET reduction of unstabilized alkyl radicals to carbanions and nucleophilic attack on CO2 to give desired products. This reaction features mild reaction conditions, broad substrate scope, facile derivations of products and promising application in polymer chemistry.
A powerful electrochemical protocol that enables the first dicarboxylation of unactivated skipped dienes with CO2 is reported. Various valuable tethered adipic acids are formed in moderate‐to‐good yields under mild conditions, showing great potential in synthetic, medicinal and polymer chemistry.
The Kepler mission revealed a population of compact multiple-planet systems with orbital periods shorter than a year, and occasionally even shorter than a day. By analyzing a sample of 102 Kepler and ...K2 multiple-planet systems, we measure the minimum difference ΔI between the orbital inclinations, as a function of the orbital distance of the innermost planet. This is accomplished by fitting all the planetary signals simultaneously, constrained by an external estimate of the stellar mean density. We find ΔI to be larger when the inner orbit is smaller, a trend that does not appear to be a selection effect. We find that planets with a/R < 5 have a dispersion in ΔI of 6 7 0 6, while planets with 5 < a/R < 12 have a dispersion of 2 0 0 1. The planetary pairs with higher mutual inclinations also tend to have larger period ratios. These trends suggest that the shortest-period planets have experienced both inclination excitation and orbital shrinkage.
The Internet of Vehicles (IoV) has gained worldwide attentions as it provides the service of collecting real-time traffic information to improve the road safety. The IoV users can offload their ...computing tasks to the edge computing devices (ECDs) for low latency execution and the cloud can be engaged to process big data with sufficient computing resources. Though galactic convenience brought by the IoV cloud-edge computing system, it remains a challenge to manage the resource of ECDs by reducing the energy and time consumption while avoiding the situation of overload or underload of the ECDs to maintain the system-stability. Moreover, during the movement of the vehicles, the computing tasks and data may be uploaded to different ECDs and the data continuity may be destroyed. In this paper, a multi-objective computation offloading method (MOC) for IoV in cloud-edge computing is proposed to deal with the challenges above. A vehicle-to-vehicle communication-based route obtaining algorithm is designed first. Then, in order to ensure the trustworth of the IoV data, which ECD to upload the computing tasks to is selected. Under the case that all ECDs are overloaded, the computation offloading between ECDs and cloud is considered. In addition, non-dominated sorting genetic algorithm III is adopted to realize the multi-objective optimization of decreasing the load balancing rate and reduce the energy consumption in ECDs and shorten the time during processing the computing tasks. Furthermore, we employ the simple additive weighting and multiple criteria decision making to evaluate the solutions of our proposed method. Finally, experimental evaluations are conducted to validate the efficiency and effectiveness of our proposed method.
Abstract
We report helium absorption from the escaping atmosphere of TOI 560.01 (HD 73583b), an
R
= 2.8
R
⊕
,
P
= 6.4 day mini-Neptune orbiting a young (∼600 Myr) K dwarf. Using Keck/NIRSPEC, we ...detect a signal with an average depth of 0.68% ± 0.08% in the line core. The absorption signal repeats during a partial transit obtained a month later, but is marginally stronger and bluer, perhaps reflecting changes in the stellar wind environment. Ingress occurs on time, and egress occurs within 12 minutes of the white light egress, although absorption rises more gradually than it declines. This suggests that the outflow is slightly asymmetric and confined to regions close to the planet. The absorption signal also exhibits a slight 4 km s
−1
redshift rather than the expected blueshift; this might be explained if the planet has a modest orbital eccentricity, although the radial velocity data disfavors such an explanation. We use XMM-Newton observations to reconstruct the high-energy stellar spectrum and model the planet’s outflow with 1D and 3D hydrodynamic simulations. We find that our models generally overpredict the measured magnitude of the absorption during transit, the size of the blueshift, or both. Increasing the metallicity to 100× solar suppresses the signal, but the dependence of the predicted signal strength on metallicity is non-monotonic. Decreasing the assumed stellar EUV flux by a factor of three likewise suppresses the signal substantially.
This study examines the heterogeneous effects of the COVID‐19 outbreak on stock prices in China. We confirm what is already known, that the pandemic has had a significant negative impact on stock ...market returns. Additionally, we find, this effect is heterogeneous across industries. Second, fear sentiment can directly cause stock prices to fall and panic exacerbates the negative impact of the pandemic on stock returns. Third, and most importantly, we demonstrate the underlying mechanisms of four firm characteristics and find that those with high asset intensity, low labor intensity, high inventory‐to‐revenue ratio, and small market value are more negatively affected than others. For labor‐intensive state‐owned firms, in particular, stock performance worsened because of higher idle labor costs. Finally, we created an index to measure the relative position of an industry in the supply chain, which shows that downstream companies were more vulnerable to the effects of the pandemic.
•A flexible and efficient method for remote sensing ecological index (RSEI) construction based on Google Earth Engine (GEE).•A long-term spatial–temporal change of the ecological environment quality ...assessment approach was discussed.•The variation trend of ecological environment quality in the Erhai Lake Basin, China was revealed.•The traits of homogeneity and heterogeneity of ecological environment quality were observed using geostatistical techniques.
The Erhai Lake Basin is an area with the active economic and social development of agriculture and tourism, facing increasingly prominent environmental problems with rapid urbanization. Assessing spatial–temporal changes in ecological environment quality objectively and quantitatively in a timely fashion is crucial for environmental protection and policymaking. First, we selected the high-quality Landsat imagery acquired at the same time phase in the years of 1999, 2004, 2009, 2014, and 2019 respectively. Second, the remote sensing-based ecological index (RSEI) was constructed by using Landsat 5 TM and Landsat 8 OLI/TIRS imagery based on Google Earth Engine (GEE) platform. Third, we assessed the spatial–temporal changes and spatial autocorrelation of ecological environment quality in our study area based on five RSEI maps. The mean values of RSEI in 1999, 2004, 2009, 2014, and 2019 were 0.513 0.457, 0.462, 0.506, and 0.509, respectively, which indicated that the overall ecological environment quality of the Erhai Lake Basin degraded from 1999 to 2009 and promoted from 2009 to 2019. The worst degradation occurred between 1999 and 2004, about 27.12% of the total area was degraded, and the greatest improvement occurred between 2009 and 2014, about 26.42% of the total area was improved. The Globalmoran's I value ranged from 0.662 to 0.783 in 1999–2019, which indicated that the spatial distribution of ecological environment quality was positively correlated. The cluster map of local indicator of spatial association of RSEI show that the high-high points were mainly located in the western and southern high-altitude area of the study area, and the low-low points were mainly distributed in lakeside area, where populations were dense and human activities were frequent. This study provides a promising approach to assess the spatial–temporal changes in ecological environment quality based on RSEI and GEE, which is critical to investigate the interactions between human activities and ecosystem services in basin systems.
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