arXiv: Earth and Planetary Astrophysics最新文献_第2页

Radio Observations of HD80606 Near Planetary Periastron: II. LOFAR Low Band Antenna Observations at 30-78 MHz HD80606在行星周边的射电观测:II。30-78 MHz LOFAR低频段天线观测

arXiv: Earth and Planetary Astrophysics Pub Date : 2020-11-11 DOI: 10.1051/0004-6361/202038746

F. de Gasperin, T. Lazio, M. Knapp

{"title":"Radio Observations of HD80606 Near Planetary Periastron: II. LOFAR Low Band Antenna Observations at 30-78 MHz","authors":"F. de Gasperin, T. Lazio, M. Knapp","doi":"10.1051/0004-6361/202038746","DOIUrl":"https://doi.org/10.1051/0004-6361/202038746","url":null,"abstract":"All of the giant planets in the solar system generate radio emission via the electron cyclotron maser instability, most notably giving rise to Jupiter's decametric emissions. An interaction with the solar wind is at least partially responsible for all of these solar system electron cyclotron masers. HD80606b is a giant planet with a highly eccentric orbit, leading to predictions that its radio emission may be enhanced substantially near periastron. This paper reports observations with the Low Frequency Array (LOFAR) of HD80606b near its periastron in an effort to detect radio emissions generated by an electron cyclotron maser instability in the planet's magnetosphere. The reported observations are at frequencies between 30 MHz and 78 MHz, and they are distinguished from most previous radio observations of extrasolar planets by two factors: (i) They are at frequencies near 50 MHz, much closer to the frequencies at which Jupiter emits (< 40 MHz) and lower than most previously reported observations of extrasolar planets; and (ii) Sensitivities of approximately a few millijanskys have been achieved, an order of magnitude or more below nearly all previous extrasolar planet observations below 100 MHz. We do not detect any radio emissions from HD80606b and use these observations to place new constraints on its radio luminosity. We also revisit whether the observations were conducted at a time when it was super-Alfvenic relative to the host star's stellar wind, which experience from the solar system illustrates is a state in which an electron cyclotron maser emission can be sustained in a planet's magnetic polar regions.","PeriodicalId":8428,"journal":{"name":"arXiv: Earth and Planetary Astrophysics","volume":"137 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75145948","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 8

GLISSE: A GPU-optimized planetary system integrator with application to orbital stability calculations. GLISSE:一个gpu优化的行星系统集成商，用于轨道稳定性计算。

arXiv: Earth and Planetary Astrophysics Pub Date : 2020-11-06 DOI: 10.1016/J.NEWAST.2021.101659

Kevin Zhang, B. Gladman

引用次数: 5

The statistical reliability of 267-GHz JCMT observations of Venus: no significant evidence for phosphine absorption 金星267-GHz JCMT观测的统计可靠性:没有磷化氢吸收的显著证据

arXiv: Earth and Planetary Astrophysics Pub Date : 2020-10-28 DOI: 10.1093/mnrasl/slaa187

M. Thompson

引用次数: 28

Do instabilities in high-multiplicity systems explain the existence of close-in white dwarf planets? 高多重系统的不稳定性能解释近距离白矮星的存在吗?

arXiv: Earth and Planetary Astrophysics Pub Date : 2020-10-22 DOI: 10.1093/mnrasl/slaa193

R. F. Maldonado, Eva Villaver, Eva Villaver, A. Mustill, Miguel Chávez, E. Bertone

{"title":"Do instabilities in high-multiplicity systems explain the existence of close-in white dwarf planets?","authors":"R. F. Maldonado, Eva Villaver, Eva Villaver, A. Mustill, Miguel Chávez, E. Bertone","doi":"10.1093/mnrasl/slaa193","DOIUrl":"https://doi.org/10.1093/mnrasl/slaa193","url":null,"abstract":"We investigate the origin of close-in planets and related phenomena orbiting white dwarfs (WDs), which are thought to originate from orbits more distant from the star. We use the planetary architectures of the 75 multiple-planet systems (four, five and six planets) detected orbiting main-sequence stars to build 750 dynamically analogous templates that we evolve to the WD phase. Our exploration of parameter space, although not exhaustive, is guided and restricted by observations and we find that the higher the multiplicity of the planetary system, the more likely it is to have a dynamical instability (losing planets, orbit crossing and scattering), that eventually will send a planet (or small object) through a close periastron passage. Indeed, the fraction of unstable four- to six-planet simulations is comparable to the 25-50$%$ fraction of WDs having atmospheric pollution. Additionally, the onset of instability in the four- to six-planet configurations peaks in the first Gyr of the WD cooling time, decreasing thereafter. Planetary multiplicity is a natural condition to explain the presence of close-in planets to WDs, without having to invoke the specific architectures of the system or their migration through the von Zeipel-Lidov-Kozai (ZLK) effect from binary companions.","PeriodicalId":8428,"journal":{"name":"arXiv: Earth and Planetary Astrophysics","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87667430","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 12

Did life originate from low-temperature areas of the Universe? 生命起源于宇宙的低温区域吗?

arXiv: Earth and Planetary Astrophysics Pub Date : 2020-10-21 DOI: 10.1063/10.0003519

S. Krasnokutski

{"title":"Did life originate from low-temperature areas of the Universe?","authors":"S. Krasnokutski","doi":"10.1063/10.0003519","DOIUrl":"https://doi.org/10.1063/10.0003519","url":null,"abstract":"The biological molecules delivered to Earth on the board of meteorites and comets were called one of the possible causes of the origin of life. Therefore, our understanding of the routes of formation of biomolecules in space should shed the light on the possibility of the existence of habitable extrasolar planets. The large abundance of organic molecules is found in the space regions with the lowest temperature. Different routes of the organics formation in these areas were suggested. In this article, we demonstrate that complex organic molecules same as important biological molecules can be formed due to the reaction of C atoms with the mantels of molecular ices covering refractory dust grains present in the interstellar medium (ISM). Having four valence electrons, C atoms act as glue joining simple non-organic molecules and converting them into organic matter. The formation of many molecules is barrierless and thus can happen at low temperature. The barrierless reaction C + NH3 + CO -> NH2CHCO attracts particular interest. The product of this reaction is an isomer of the central residue of a peptide chain and expected to be efficiently formed in the translucent molecular clouds. The polymerization of these molecules leads to the formation of proteins that according to some theories are life's first molecules. Considering a high abundance of atomic carbon in the ISM, we expect a high efficiency of the formation of a large variety of different organic molecules, and show why the amount of organic material formed by condensation of atomic carbon may be underestimated.","PeriodicalId":8428,"journal":{"name":"arXiv: Earth and Planetary Astrophysics","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89972218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 7

Numerical convergence of hot-Jupiter atmospheric flow solutions 热木星大气流动解的数值收敛性

arXiv: Earth and Planetary Astrophysics Pub Date : 2020-10-19 DOI: 10.1093/MNRAS/STAB971

J. W. Skinner, J. Cho

{"title":"Numerical convergence of hot-Jupiter atmospheric flow solutions","authors":"J. W. Skinner, J. Cho","doi":"10.1093/MNRAS/STAB971","DOIUrl":"https://doi.org/10.1093/MNRAS/STAB971","url":null,"abstract":"We perform an extensive study of numerical convergence for hot-Jupiter atmospheric flow solutions in simulations employing a setup commonly-used in extrasolar planet studies, a resting state thermally forced to a prescribed temperature distribution on a short time-scale at high altitudes. Convergence is assessed rigorously with: (i) a highly-accurate pseudospectral model which has been explicitly verified to perform well under hot-Jupiter flow conditions and (ii) comparisons of the kinetic energy spectra, instantaneous (unaveraged) vorticity fields and temporal evolutions of the vorticity field from simulations which are numerically equatable. In the simulations, the (horizontal and vertical) resolutions, dissipation operator order and viscosity coefficient are varied with identical physical and initial setups. All of the simulations are compared against a fiducial, reference simulation at high horizontal resolution and dissipation order (T682 and $nabla^{16}$, respectively) -- as well as against each other. Broadly, the reference solution features a dynamic, zonally (east--west) asymmetric jet with a copious amount of small-scale vortices and gravity waves. Here we show that simulations converge to the reference simulation only at T341 resolution and with $nabla^{16}$ dissipation order. Below this resolution and order, simulations either do not converge or converge to unphysical solutions. The general convergence behaviour is independent of the vertical range of the atmosphere modelled, from $sim! 2!times! 10^{-3}$ MPa to $sim! 2!times! 10^1$ MPa. Ramifications for current extrasolar planet atmosphere modelling and observations are discussed.","PeriodicalId":8428,"journal":{"name":"arXiv: Earth and Planetary Astrophysics","volume":"75 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83291460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 7

The cloudy shape of hot Jupiter thermal phase curves 热木星的云状热相曲线

arXiv: Earth and Planetary Astrophysics Pub Date : 2020-10-14 DOI: 10.1093/mnras/staa3418

V. Parmentier, A. Showman, J. Fortney

{"title":"The cloudy shape of hot Jupiter thermal phase curves","authors":"V. Parmentier, A. Showman, J. Fortney","doi":"10.1093/mnras/staa3418","DOIUrl":"https://doi.org/10.1093/mnras/staa3418","url":null,"abstract":"Hot Jupiters have been predicted to have a strong day/night temperature contrast and a hot spot shifted eastward of the substellar point. This was confirmed by numerous phase curve observations probing the longitudinal brightness variation of the atmosphere. Global circulation models, however, systematically underestimate the phase curve amplitude and overestimate the shift of its maximum. We use a global circulation model including non-grey radiative transfer and realistic gas and cloud opacities to systematically investigate how the atmospheric circulation of hot Jupiters varies with equilibrium temperature from 1000 to 2200K. We show that the heat transport is very efficient for cloudless planets cooler than 1600K and becomes less efficient at higher temperatures. When nightside clouds are present, the day-to-night heat transport becomes extremely inefficient, leading to a good match to the observed low nightside temperatures. The constancy of this low temperature is, however, due to the strong dependence of the radiative timescale with temperature. We further show that nightside clouds increase the phase curve amplitude and decreases the phase curve offset at the same time. This change is very sensitive to the cloud chemical composition and particle size, meaning that the diversity in observed phase curves can be explained by a diversity of nightside cloud properties. Finally, we show that phase curve parameters do not necessarily track the day/night contrast nor the shift of the hot spot on isobars, and propose solutions to to recover the true hot-spot shift and day/night contrast.","PeriodicalId":8428,"journal":{"name":"arXiv: Earth and Planetary Astrophysics","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88809096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 56

Coupled day–night models of exoplanetary atmospheres 系外行星大气的昼夜耦合模型

arXiv: Earth and Planetary Astrophysics Pub Date : 2020-10-14 DOI: 10.1093/mnras/staa3143

S. Gandhi, A. Jermyn

引用次数: 5

Chemical fingerprints of formation in rocky super-Earths’ data 岩石超级地球数据中形成的化学指纹

arXiv: Earth and Planetary Astrophysics Pub Date : 2020-10-13 DOI: 10.1093/mnras/staa2615

Mykhaylo Plotnykov, D. Valencia

{"title":"Chemical fingerprints of formation in rocky super-Earths’ data","authors":"Mykhaylo Plotnykov, D. Valencia","doi":"10.1093/mnras/staa2615","DOIUrl":"https://doi.org/10.1093/mnras/staa2615","url":null,"abstract":"The composition of rocky exoplanets in the context of stars' composition provides important constraints to formation theories. In this study, we select a sample of exoplanets with mass and radius measurements with an uncertainty <25% and obtain their interior structure. We calculate compositional markers, ratios of iron to magnesium and silicon, as well as core-mass fractions (cmf) that fit the planetary parameters, and compare them to the stars'. We find four key results that successful planet formation theories need to predict: (1) In a population sense, the composition of rocky planets spans a wider range than stars. The stars' Fe/Si distribution is close to a Gaussian distribution $1.63^{+0.91}_{-0.85}$, while the planets' distribution peaks at lower values and has a longer tail, $1.15^{+1.43}_{-0.76}$. It is easier to see the discrepancy in cmf space, where primordial stellar composition is $0.32^{+0.14}_{-0.12}$, while rocky planets' follow a broader distribution $0.24^{+0.33}_{-0.18}$. (2) We introduce uncompressed density ($overline{rho_0}$ at reference pressure/temperature) as a metric to compare compositions. With this, we find what seems to be the maximum iron enrichment that rocky planets attain during formation ($overline{rho_0}$ ~ 6 and cmf ~ 0.8). (3) Highly irradiated planets exhibit a large range of compositions. If these planets are the result of atmospheric evaporation, iron enrichment and perhaps depletion must happen before gas dispersal. And (4), we identify a group of highly-irradiated planets that, if rocky, would be 2-fold depleted in Fe/Si with respect to the stars. Without a reliable theory for forming iron-depleted planets, these are interesting targets for follow up.","PeriodicalId":8428,"journal":{"name":"arXiv: Earth and Planetary Astrophysics","volume":"18 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76876541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 22

A physical model for the magnetosphere of Uranus at solstice time 天王星至日磁层的物理模型

arXiv: Earth and Planetary Astrophysics Pub Date : 2020-10-12 DOI: 10.1051/0004-6361/202039143

F. Pantellini

{"title":"A physical model for the magnetosphere of Uranus at solstice time","authors":"F. Pantellini","doi":"10.1051/0004-6361/202039143","DOIUrl":"https://doi.org/10.1051/0004-6361/202039143","url":null,"abstract":"Uranus is the only planet in the Solar System whose rotation axis and orbital plane are nearly parallel to each other. Uranus is also the planet with the largest angle between the rotation axis and the direction of its magnetic dipole (roughly $59^circ$). Consequently, the shape and structure of its magnetospheric tail is very different to those of all other planets in whichever season one may consider. We propose a magnetohydrodynamic model for the magnetic tail of Uranus at solstice time. One of the main conclusions of the model is that all magnetic field lines forming the extended magnetic tail follow the same qualitative evolution from the time of their emergence through the planet's surface and the time of their late evolution after having been stretched and twisted several times downstream of the planet. In the planetary frame, these field lines move on magnetic surfaces that wind up to form a tornado-shaped vortex with two foot points on the planet (one in each magnetic hemisphere). The centre of the vortex (the eye of the tornado) is a simple double helix with a helical pitch (along the symmetry axis $z$) $lambda=tau[v_z+B_z/(mu_0rho)^{1/2}],$ where $tau$ is the rotation period of the planet, $mu_0$ the permeability of vacuum, $rho$ the mass density, $v_z$ the fluid velocity, and $B_z$ the magnetic field where all quantities have to be evaluated locally at the centre of the vortex. In summary, in the planetary frame, the motion of a typical magnetic field of the extended Uranian magnetic tail is a vortical motion, which asymptotically converges towards the single double helix, regardless of the line's emergence point on the planetary surface.","PeriodicalId":8428,"journal":{"name":"arXiv: Earth and Planetary Astrophysics","volume":"46 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80950186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0