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1.
There is a growing population of relativistically relevant minor bodies in the Solar System and a growing population of massive extrasolar planets with orbits very close to the central star where relativistic effects should have some signature. Our purpose is to review how general relativity affects the orbital dynamics of the planetary systems and to define a suitable relativistic correction for Solar System orbital studies when only point masses are considered. Using relativistic formulae for the N body problem suited for a planetary system given in the literature we present a series of numerical orbital integrations designed to test the relevance of the effects due to the general theory of relativity in the case of our Solar System. Comparison between different algorithms for accounting for the relativistic corrections are performed. Relativistic effects generated by the Sun or by the central star are the most relevant ones and produce evident modifications in the secular dynamics of the inner Solar System. The Kozai mechanism, for example, is modified due to the relativistic effects on the argument of the perihelion. Relativistic effects generated by planets instead are of very low relevance but detectable in numerical simulations.  相似文献   

2.
The stars that populate the solar neighbourhood were formed in stellar clusters. Through N -body simulations of these clusters, we measure the rate of close encounters between stars. By monitoring the interaction histories of each star, we investigate the singleton fraction in the solar neighbourhood. A singleton is a star which formed as a single star, has never experienced any close encounters with other stars or binaries, or undergone an exchange encounter with a binary. We find that, of the stars which formed as single stars, a significant fraction is not singletons once the clusters have dispersed. If some of these stars had planetary systems, with properties similar to those of the Solar System, the planets' orbits may have been perturbed by the effects of close encounters with other stars or the effects of a companion star within a binary. Such perturbations can lead to strong planet–planet interactions which eject several planets, leaving the remaining planets on eccentric orbits. Some of the single stars exchange into binaries. Most of these binaries are broken up via subsequent interactions within the cluster, but some remain intact beyond the lifetime of the cluster. The properties of these binaries are similar to those of the observed binary systems containing extrasolar planets. Thus, dynamical processes in young stellar clusters will alter significantly any population of Solar System-like planetary systems. In addition, beginning with a population of planetary systems exactly resembling the Solar System around single stars, dynamical encounters in young stellar clusters may produce at least some of the extrasolar planetary systems observed in the solar neighbourhood.  相似文献   

3.
We discuss the status of ultraviolet knowledge of Solar System objects. We begin with a short historical survey, followed by a review of knowledge gathered so far and of existing observational assets. The survey indicates that UV observations, along with data collected in other spectral bands, are necessary and in some cases essential to understand the nature of our neighbors in the Solar System. By extension, similar observations are needed to explore the nature of extrasolar planets, to support or reject astro-biology arguments, and to compose and test scenarios for the formation and evolution of planetary systems.We propose a set of observations, describing first the necessary instrumental capabilitites to collect these and outlining what would be the expected scientific return. We identify two immediate programmatic requirements: the establishment of a mineralogic database in the ultraviolet for the characterization of planetary, ring, satellite, and minor planet surfaces, and the development and deployment of small orbital solar radiation monitors. The first would extend the methods of characterizing surfaces of atmosphere-less bodies by adding the UV segment. The latter are needed to establish a baseline against which contemporaneous UV observations of Solar System objects must be compared.We identify two types of UV missions, one appropriate for a two-meter-class telescope using almost off-the-shelf technology that could be launched in the next few years, and another for a much larger (5–20 meter class) instrument that would provide the logical follow-up after a decade of utilizing the smaller facility.Michel Festou, our co-author and a very important contributor to this paper, passed away while this paper was being completed. We dedicate it to his memory.Deceased 11 May 2005  相似文献   

4.
The chaotic behaviour of the motion of the planets in our Solar System is well established. In this work to model a hypothetical extrasolar planetary system our Solar System was modified in such a way that we replaced the Earth by a more massive planet and let the other planets and all the orbital elements unchanged. The major result of former numerical experiments with a modified Solar System was the appearance of a chaotic window at κ E ∈ (4, 6), where the dynamical state of the system was highly chaotic and even the body with the smallest mass escaped in some cases. On the contrary for very large values of the mass of the Earth, even greater than that of Jupiter regular dynamical behaviour was observed. In this paper the investigations are extended to the complete Solar System and showed, that this chaotic window does still exist. Tests in different ‘Solar Systems’ clarified that including only Jupiter and Saturn with their actual masses together with a more ‘massive’ Earth (4 < κ E < 6) perturbs the orbit of Mars so that it can even be ejected from the system. Using the results of the Laplace‐Lagrange secular theory we found secular resonances acting between the motions of the nodes of Mars, Jupiter and Saturn. These secular resonances give rise to strong chaos, which is the cause of the appearance of the instability window. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

5.
Knowing the chemical, elemental, and isotopic composition of planetary objects allows the study of their origin and evolution within the context of our Solar System. Landed probes are critical to such an investigation. Instruments on a landed platform can answer a different set of scientific questions than can instruments in orbit or on Earth. Composition studies for elemental, isotopic, and chemical analysis are best performed with dedicated mass spectrometer systems. Mass spectrometers have been part of the early lunar missions, and have been successfully employed to investigate the atmospheres of Mars, Venus, Jupiter, Saturn, Titan, and in comet missions. Improved mass spectrometer systems are foreseen for many planetary missions currently in planning or implementation.  相似文献   

6.
On our way toward the characterization of smaller and more temperate planets, missions dedicated to the spectroscopic observation of exoplanets will teach us about the wide diversity of classes of planetary atmospheres, many of them probably having no equivalent in the Solar System. But what kind of atmospheres can we expect? To start answering this question, many theoretical studies have tried to understand and model the various processes controlling the formation and evolution of planetary atmospheres, with some success in the Solar System. Here, we shortly review these processes and we try to give an idea of the various type of atmospheres that these processes can create. As will be made clear, current atmosphere evolution models have many shortcomings yet, and need heavy calibrations. With that in mind, we will thus discuss how observations with a mission similar to EChO would help us unravel the link between a planet’s environment and its atmosphere.  相似文献   

7.
The formation of the gas giant planets Jupiter and Saturn probably required the growth of massive 15 Earth-mass cores on a time scale shorter than the 107 time scale for removal of nebular gas. Relatively minor variations in nebular parameters could preclude the growth of full-size gas giants even in systems in which the terrestrial planet region is similar to our own. Systems containing failed Jupiters, resembling Uranus and Neptune in their failure to capture much nebular gas, would be expected to contain more densely populated cometary source regions. They will also eject a smaller number of comets into interstellar space. If systems of this kind were the norm, observation of hyperbolic comets would be unexpected. Monte Carlo calculations of the orbital evolution of region of such systems (the Kuiper belt) indicate that throughout Earth history the cometary impact flux in their terrestrial planet regions would be 1000 times greater than in our Solar System. It may be speculated that this could frustrate the evolution of organisms that observe and seek to understand their planetary system. For this reason our observation of these planets in our Solar System may tell us nothing about the probability of similar gas giants occurring in other planetary systems. This situation can be corrected by observation of an unbiased sample of planetary systems.Paper presented at the Conference onPlanetary Systems: Formation, Evolution, and Detection held 7–10 December, 1992 at CalTech, Pasadena, California, U.S.A.  相似文献   

8.
It is shown that by means of elementary assumptions it is possible to obtain models of planetary systems not too different from the observed case. Such assumptions are shown to be the bulk of more detailed models as those by Dole (1970) and Isaacman and Sagan (1977).An accurate fit with the features of the Solar System can be obtained only byad hoc assumptions on various physical quantities and depends also on the possibility of taking into account stochastic processes in the numerical code.We discuss various cases and attempt to derive best fit values for the free parameters of the model. The hypothesis of a moderate mass depletion in the region of outer planets is strongly supported by our results.  相似文献   

9.
The origin of water in the inner Solar System is not well understood. It is believed that temperatures were too high in the accretion disk in the region of the terrestrial planets for hydrous phases to be thermodynamically stable. Suggested sources of water include direct adsorption of hydrogen from the nebula into magma oceans after the terrestrial planets formed, and delivery of asteroidal or cometary material from beyond the zone of the terrestrial planets. We explore a new idea, direct adsorption of water onto grains prior to planetary accretion. This hypothesis is motivated by the observation that the accretion disk from which our planetary system formed was composed of solid grains bathed in a gas dominated by hydrogen, helium, and oxygen. Some of that hydrogen and oxygen combined to make water vapor. We examine quantitatively adsorption of water onto grains in the inner Solar System accretion disk by exploring the adsorption dynamics of water molecules onto forsterite surfaces via kinetic Monte Carlo simulations. We conclude that many Earth oceans of water could be adsorbed.  相似文献   

10.
The study of extrasolar planets and of the Solar System provides complementary pieces of the mosaic represented by the process of planetary formation. Exoplanets are essential to fully grasp the huge diversity of outcomes that planetary formation and the subsequent evolution of the planetary systems can produce. The orbital and basic physical data we currently possess for the bulk of the exoplanetary population, however, do not provide enough information to break the intrinsic degeneracy of their histories, as different evolutionary tracks can result in the same final configurations. The lessons learned from the Solar System indicate us that the solution to this problem lies in the information contained in the composition of planets. The goal of the Atmospheric Remote-Sensing Infrared Exoplanet Large-survey (ARIEL), one of the three candidates as ESA M4 space mission, is to observe a large and diversified population of transiting planets around a range of host star types to collect information on their atmospheric composition. ARIEL will focus on warm and hot planets to take advantage of their well-mixed atmospheres, which should show minimal condensation and sequestration of high-Z materials and thus reveal their bulk composition across all main cosmochemical elements. In this work we will review the most outstanding open questions concerning the way planets form and the mechanisms that contribute to create habitable environments that the compositional information gathered by ARIEL will allow to tackle.  相似文献   

11.
Adrián Brunini 《Icarus》2005,177(1):264-268
The sample of known exoplanets is strongly biased to masses larger than the ones of the giant gaseous planets of the Solar System. Recently, the discovery of two extrasolar planets of considerably lower masses around the nearby Stars GJ 436 and ρ Cancri was reported. They are like our outermost icy giants, Uranus and Neptune, but in contrast, these new planets are orbiting at only some hundredth of the Earth-Sun distance from their host stars, raising several new questions about their origin and constitution. Here we report numerical simulations of planetary accretion that show, for the first time through N-body integrations that the formation of compact systems of Neptune-like planets close to the hosts stars could be a common by-product of planetary formation. We found a regime of planetary accretion, in which orbital migration accumulates protoplanets in a narrow region around the inner edge of the nebula, where they collide each other giving rise to Neptune-like planets. Our results suggest that, if a protoplanetary solar environment is common in the Galaxy, the discovery of a vast population of this sort of ‘hot cores’ should be expected in the near future.  相似文献   

12.
Mean motion resonances(MMRs)are widespread in our Solar System.Moreover,resonant dynamics has always been an essential topic in planetary research.Recently,the research about exoplanets and the potential Planet Nine with large eccentricity has given rise to our interests in the secular dynamics inside MMRs in the elliptic model.In this paper,we study the fixed points of the averaged Hamiltonian and the long-term stable regions of the 1/1 resonance(or co-orbital motion)in the elliptic restricted three-body problem(ERTBP)systematically.Numerical integrations prove those test particles trapped in"apsidal co-rotation",where both the resonant angleφresand the secular angleΔω(or apsidal longitude differences)librate simultaneously,always survive the long-term simulations.Furthermore,utilizing a semianalytical method based on the adiabatic approach,three families of long-term fixed points of the averaged Hamiltonian of the planar ERTBP inside the 1/1 resonance have been found.We call them QS-points,Hpoints,and T-points here,whose values of the(φres,Δω)are(0°,180°),(180°,0°),and(±60°,±60°),respectively.All the fixed points of the averaged Hamiltonian of the co-orbital motion in the ERTBP are presented in the e-e’plane(’represents the elements of the planet in this paper).We find that QS-points and T-points always exist for the arbitrary eccentricity of a planet,while H-points only exist for the cases of low e’and very high e.Furthermore,we measure the libration width in terms of eccentricity,Δe,around these stable equilibrium points in the e-Δωphase-space portraits.The"apsidal co-rotation"around all the stable equilibrium points is presented in the e-e’plane.All these results are effectively confirmed by numerical experiments.The long-term stable zones around these periodic orbits in the e-e’plane are significant for the research of the co-orbital motion in the ERTBP.Above all,these practical approaches that we proposed can also be used to study the secular dynamics of other MMRs.  相似文献   

13.
Solar System Research - In this review we consider the main rotation regimes that are inherent for planetary satellites of the Solar System, satellites of trans-Neptunian objects, and potential...  相似文献   

14.
We study planetary migration in a gas-free disk of planetesimals. In the case of our Solar System we show that Neptune could have had either a damped migration, limited to a few AUs, or a forced migration up to the disk's edge, depending on the disk's mass density. We also study the possibility of runaway migration of isolated planets in very massive disk, which might be relevant for extra-solar systems. We investigate the problem of the mass depletion of the Kuiper belt in the light of planetary migration and conclude that the belt lost its pristine mass well before that Neptune reached its current position. Therefore, Neptune effectively hit the outer edge of the proto-planetary disk. We also investigate the dynamics of massive planetary embryos embedded in the planetesimal disk. We conclude that the elimination of Earth-mass or Mars-mass embryos originally placed outside the initial location of Neptune also requires the existence of a disk edge near 30AU.  相似文献   

15.
A two body, patched conic analysis is presented for a planetary capture mode in which a gravity assist by an existing natural satellite of the planet aids in the capture. An analytical condition sufficient for capture is developed and applied for the following planet/satellite systems: Earth/Moon, Jupiter/Ganymede, Jupiter/Callisto, Saturn/Titan and Neptune/Triton. Co-planar, circular planetary orbits are assumed. Three sources of bodies to be captured are considered: spacecraft launched from Earth, bodies entering the solar system from interstellar space, and bodies already in orbit around the Sun. Results show that the Neptune/Triton system has the most capability for satellite aided capture of those studied. It can easily capture bodies entering the Solar System from interstellar space. Its ability to capture spacecraft launched from Earth is marginal and can only be decided with better definition of physical properties. None of the other systems can capture bodies from these two sources, but all can capture bodies already in orbit around the Sun under appropriate conditions.  相似文献   

16.
R.J. de Kok  D.M. Stam 《Icarus》2012,221(2):517-524
The transmission of light through a planetary atmosphere can be studied as a function of altitude and wavelength using stellar or solar occultations, giving often unique constraints on the atmospheric composition. For exoplanets, a transit yields a limb-integrated, wavelength-dependent transmission spectrum of an atmosphere. When scattering haze and/or cloud particles are present in the planetary atmosphere, the amount of transmitted flux not only depends on the total optical thickness of the slant light path that is probed, but also on the amount of forward-scattering by the scattering particles. Here, we present results of calculations with a three-dimensional Monte Carlo code that simulates the transmitted flux during occultations or transits. For isotropically scattering particles, like gas molecules, the transmitted flux appears to be well-described by the total atmospheric optical thickness. Strongly forward-scattering particles, however, such as commonly found in atmospheres of Solar System planets, can increase the transmitted flux significantly. For exoplanets, such added flux can decrease the apparent radius of the planet by several scale heights, which is comparable to predicted and measured features in exoplanet transit spectra. We performed detailed calculations for Titan’s atmosphere between 2.0 and 2.8 μm and show that haze and gas abundances will be underestimated by about 8% if forward-scattering is ignored in the retrievals. At shorter wavelengths, errors in the gas and haze abundances and in the spectral slope of the haze particles can be several tens of percent, also for other Solar System planetary atmospheres. We also find that the contribution of forward-scattering can be fairly well described by modelling the atmosphere as a plane-parallel slab. This potentially reduces the need for a full three-dimensional Monte Carlo code for calculating transmission spectra of atmospheres that contain forward-scattering particles.  相似文献   

17.
Planets result from a series of processes within a circumstellar disk. Evidence comes from the near planar orbits in the Solar System and other planetary systems, observations of newly formed disks around young stars, and debris disks around main-sequence stars. As planet-hunting techniques improve, we approach the ability to detect systems like the Solar System, and place ourselves in context with planetary systems in general. Along the way, new classes of planets with unexpected characteristics are discovered. One of the most recent classes contains super Earth-mass planets orbiting a few AU from low-mass stars. In this contribution, we outline a semi-analytic model for planet formation during the pre-main sequence contraction phase of a low-mass star. As the star contracts, the “snow line”, which separates regions of rocky planet formation from regions of icy planet formation, moves inward. This process enables rapid formation of icy protoplanets that collide and merge into super-Earths before the star reaches the main sequence. The masses and orbits of these super-Earths are consistent with super-Earths detected in recent microlensing experiments.  相似文献   

18.
We investigate whether Earth-type habitable planets can in principle exist in the planetary system of 47 UMa. The system of 47 UMa consists of two Jupiter-size planets beyond the outer edge of the stellar habitable zone, and thus resembles our own Solar System most closely compared to all exosolar planetary systems discovered so far. Our study of habitability deliberately follows an Earth-based view according to the concept of Franck and colleagues, which assumes the long-term possibility of photosynthetic biomass production under geodynamic conditions. Consequently, a broad variety of climatological, biogeochemical, and geodynamical processes involved in the generation of photosynthesis-driven life conditions is taken into account. The stellar luminosity and the age of the star/planet system are of fundamental importance for planetary habitability. Our study considers different types of planetary continental growth models and takes into account a careful assessment of the stellar parameters. In the event of successful formation and orbital stability, two subjects of intense research, we find that Earth-type habitable planets around 47 UMa are in principle possible! The likelihood of those planets is increased if assumed that 47 UMa is relatively young (?6 Gyr) and has a relatively small stellar luminosity as permitted by the observational range of those parameters.  相似文献   

19.
The steadily growing international interest in the exploration of planets in our Solar System and many advances in the development of space-sensor technology have led to the launch of a multitude of planetary missions to Mercury, Venus, the Earth's moon, Mars and various Outer-Solar System objects, such as the Jovian and Saturnian satellites. Camera instruments carried along on these missions image surfaces in different wavelength ranges and under different viewing angles, permitting additional data to be derived, such as spectral data or digital terrain models. Such data enable researchers to explore and investigate the development of planetary surfaces by analyzing and interpreting the inventory of surface units and structures. Results of such work are commonly abstracted and represented in thematic, mostly geological and geomorphological, maps. In order to facilitate efficient collaboration among different planetary research disciplines, mapping results need to be prepared, described, managed, archived, and visualized in a uniform way. These tasks have been increasingly carried out by means of computer-based geographic information systems (GIS or GI systems) which have come to be widely employed in the field of planetary research since the last two decades. In this paper we focus on the simplification of mapping processes, putting specific emphasis on a cartographically correct visualization of planetary mapping data using GIS-based environments. We present and discuss the implementation of a set of standardized cartographic symbols for planetary mapping based on the Digital Cartographic Standard for Geologic Map Symbolization as prepared by the United States Geological Survey (USGS) for the Federal Geographic Data Committee (FGDC). Furthermore, we discuss various options to integrate this symbol catalog into generic GI systems, and more specifically into the Environmental Systems Research Institute's (ESRI) ArcGIS environment, and focus on requirements for symbol definitions in the field of planetary mapping. A symbology of this type can be embedded into any modular GIS environment capable in dealing with external stand-alone as well as database-driven management of symbol sets. Using such a uniform GIS-based symbol catalog will give the research community access to map results already cartographically elaborated, enabling them to create digital maps as a secondary data source in subsequent studies.  相似文献   

20.
Recent observational and experimental evidence for the presence of complex organics in space is reviewed. Remote astronomical observations have detected \(\sim \)200 gas-phased molecules through their rotational and vibrational transitions. Many classes of organic molecules are represented in this list, including some precursors to biological molecules. A number of unidentified spectral phenomena observed in the interstellar medium are likely to have originated from complex organics. The observations of these features in distant galaxies suggests that organic synthesis had already taken place during the early epochs of the Universe. In the Solar System, almost all biologically relevant molecules can be found in the soluble component of carbonaceous meteorites. Complex organics of mixed aromatic and aliphatic structures are present in the insoluble component of meteorites. Hydrocarbons cover much of the surface of the planetary satellite Titan and complex organics are found in comets and interplanetary dust particles. The possibility that the early Solar System, or even the early Earth, have been enriched by interstellar organics is discussed.  相似文献   

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