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Planetary Systems (planetary + system)

Distribution by Scientific Domains
Physics and Astronomy93%

Kinds of Planetary Systems

  • extrasolar planetary system
    		•

    Selected Abstracts

    Review of the population of impactors and the impact cratering rate in the inner solar system

    METEORITICS & PLANETARY SCIENCE, Issue 11 2007
    Patrick Michel
    The best witness of these events is the lunar surface, which kept the memory of the impacts that it underwent during the last 3.8 Gyr. In this paper, we review the recent studies at the origin of a reliable model of the impactor population in the inner solar system, namely the near-Earth object (NEO) population. Then we briefly expose the scaling laws used to relate a crater diameter to body size. The model of the NEO population and its impact frequency on terrestrial planets is consistent with the crater distribution on the lunar surface when appropriate scaling laws are used. Concerning the early phases of our solar system's history, a scenario has recently been proposed that explains the origin of the Late Heavy Bombardment (LHB) and some other properties of our solar system. In this scenario, the four giant planets had initially circular orbits, were much closer to each other, and were surrounded by a massive disk of planetesimals. Dynamical interactions with this disk destabilized the planetary system after 500,600 Myr. Consequently, a large portion of the planetesimal disk, as well as 95% of the Main Belt asteroids, were sent into the inner solar system, causing the LHB while the planets reached their current orbits. Our knowledge of solar system evolution has thus improved in the last decade despite our still-poor understanding of the complex cratering process. [source]

    A planetary system with an escaping Mars

    ASTRONOMISCHE NACHRICHTEN, Issue 1 2007
    Á. Süli
    Abstract 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 ,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 < ,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) [source]

    Using long-term transit timing to detect terrestrial planets

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2007
    Jeremy S. Heyl
    ABSTRACT We propose that the presence of additional planets in extrasolar planetary systems can be detected by long-term transit timing studies. If a transiting planet is on an eccentric orbit then the presence of another planet causes a secular advance of the transiting planet's pericentre over and above the effect of general relativity. Although this secular effect is impractical to detect over a small number of orbits, it causes long-term differences when future transits occur, much like the long-term decay observed in pulsars. Measuring this transit-timing delay would thus allow the detection of either one or more additional planets in the system or the first measurements of non-zero oblateness (J2) of the central stars. [source]

    A model-independent test of the spatial variations of the Newtonian gravitational constant in some extrasolar planetary systems

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2007
    Lorenzo Iorio
    ABSTRACT In this paper, we directly constrain possible spatial variations of the Newtonian gravitational constant G over the range , 0.01,5 au in various extrasolar multiplanet systems. Using the third Kepler law, we determine the quantity ,XY=GX/GY for each couple of planets X and Y located at different distances from their parent star; deviations of the measured values of , from unity would signal variations of G. The obtained results for ,= 1 ,, are found to be very compatible with zero within the experimental errors (,/,,, 0.2,0.3). We make a comparison with an analogous test previously performed in our Solar system. [source]

    A stability catalogue of the habitable zones in extrasolar planetary systems

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2007
    Zs. Sándor
    ABSTRACT In the near future, space missions will be launched (e.g. COROT, KEPLER) to detect Earth-like extrasolar planets. The orbital elements of these (still hypothetic) planets will contain some uncertainties that can only be eliminated by careful dynamical investigations of the hosting planetary systems. The proportion of extrasolar planetary systems with one known giant planet is high (,90 per cent). Therefore, as a first step we have investigated the possible existence of terrestrial planets in these systems. In this paper, the development of a stability catalogue of the habitable zones of exoplanetary systems is reported. This catalogue is formed by a series of stability maps, which can help to establish where Earth-like planets could exist in extrasolar planetary systems having one giant planet. After a description of the dynamical model and the numerical methods, details of the stability maps are discussed. An application of the stability catalogue to 15 known exoplanetary systems is also shown, and a characterization of the stability properties of their habitable zones is given. [source]

    Long-lived disc accretion in the , Chamaeleontis pre-main sequence star cluster

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2004
    Warrick A. Lawson
    ABSTRACT High-resolution spectroscopic study of late-type members of the ,9-Myr-old , Chamaeleontis star cluster shows that four stars, RECX 5, 9, 11 and ECHA J0843.3,7905, have broad H, profiles indicative of ballistic accretion of material from circumstellar discs first identified by virtue of their infrared (IR) excess emission. Quantitative analysis of the profiles finds accretion in , Cha stars at rates comparable to that derived by Muzerolle et al. for members of the similarly aged TW Hydrae Association (TWA); rates 1,3 orders of magnitude lower than in younger classical T Tauri (CTT) stars. Together these studies indicate that the fraction of long-lived inner discs can be significantly higher than that inferred from study of younger pre-main sequence (PMS) populations, which suggest a disc lifetime of <6 Myr. The detection of long-lived discs may have implications for the formation of planetary systems. If slow accretion processes are the dominant formation mechanism for Jovian planets then long-lived discs may be ideal sites to search for evidence for protoplanets. [source]

    Front and Back Covers, Volume 22, Number 2.

    ANTHROPOLOGY TODAY, Issue 2 2006
    April 200
    Front and back cover caption, volume 22 issue 2 Front & back cover ANTHROPOLOGY AND THE SEARCH FOR EXTRATERRESTRIAL LIFE. The debate around the likelihood of humans encountering extraterrestrial life is based in the broad context of cosmic evolution, which encompasses astronomical, biological and socio-cultural evolution. In this depiction of cosmic evolution from the US National Aeronautics Space Administration (NASA), the upper left portion shows the formation of stars, the production of heavy elements and the formation of planetary systems, including our own. On the lower left-hand side prebiotic molecules, RNA and DNA are formed within the first billion years on the primitive Earth. The centre shows the origin and evolution of life leading to increasing complexity, culminating with intelligence, culture, and the astronomers who contemplate the universe on the upper right. The image was created by David DesMarais, Thomas Scattergood and Linda Jahnke at NASA's Ames Research Center in 1986, and reissued in 1997. In this issue Steven J. Dick, Chief Historian at NASA, recounts the history of anthropological involvement in the search for extraterrestrial intelligence, and discusses SETI's broader relevance to anthropology. Anthropologists are uniquely qualified by knowledge and training to contribute to SETI, since central concerns when and if contact is made will include socio-cultural difference and cross-cultural communication. In turn the extraterrestrial perspective has much to offer anthropology, both in expanding its boundaries, its insights and its tools, and in casting a fresh light on cultures on Earth. Valerie Olson, in her review of the session dedicated to SETI at the 2005 American Anthropological Association Annual Meeting, argues that the SETI vision of a terrestrial/extraterrestrial dichotomy between human and alien ,others' brings older and more recent anthropological ideas into a new juxtaposition, and that SETI has potential for stimulating the anthropological imagination. [source]

    Pulsations and planets: The asteroseismology-extrasolar-planet connection

    ASTRONOMISCHE NACHRICHTEN, Issue 5 2010
    S. Schuh
    Abstract The disciplines of asteroseismology and extrasolar planet science overlap methodically in the branch of high-precision photometric time series observations. Light curves are, amongst others, useful to measure intrinsic stellar variability due to oscillations, as well as to discover and characterize those extrasolar planets that transit in front of their host stars, periodically causing shallow dips in the observed brightness. Both fields ultimately derive fundamental parameters of stellar and planetary objects, allowing to study for example the physics of various classes of pulsating stars, or the variety of planetary systems, in the overall context of stellar and planetary system formation and evolution. Both methods typically also require extensive spectroscopic follow-up to fully explore the dynamic characteristics of the processes under investigation. In particularly interesting cases, a combination of observed pulsations and signatures of a planet allows to characterize a system's components to a very high degree of completeness by combining complementary information. The planning of the relevant space missions has consequently converged with respect to science cases, where at the outset there was primarily a coincidence in instrumentation and techniques. Whether space- or ground-based, a specific type of stellar pulsations can themselves be used in an innovative way to search for extrasolar planets. Results from this additional method at the interface of stellar pulsation studies and exoplanet hunts in a beyond-mainstream area are presented (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Status and future of MUSE

    ASTRONOMISCHE NACHRICHTEN, Issue 9-10 2008
    S. Harfst
    Abstract We present MUSE, a software framework for combining existing computational tools from different astrophysical domains into a single multi-physics, multi-scale application. MUSE facilitates the coupling of existing codes written in different languages by providing inter-language tools and by specifying an interface between each module and the framework that represents a balance between generality and computational efficiency. This approach allows scientists to use combinations of codes to solve highly-coupled problems without the need to write new codes for other domains or significantly alter their existing codes. MUSE currently incorporates the domains of stellar dynamics, stellar evolution and stellar hydrodynamics for studying generalized stellar systems. We have now reached a "Noah's Ark" milestone, with (at least) two available numerical solvers for each domain. MUSE can treat multi-scale and multi-physics systems in which the time- and size-scales are well separated, like simulating the evolution of planetary systems, small stellar associations, dense stellar clusters, galaxies and galactic nuclei. In this paper we describe two examples calculated using MUSE: the merger of two galaxies and an N -body simulation with live stellar evolution. In addition, we demonstrate an implementation of MUSE on a distributed computer which may also include special-purpose hardware, such as GRAPEs or GPUs, to accelerate computations. The current MUSE code base is publicly available as open source at http://muse.li. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Stability of fictitious Trojan planets in extrasolar systems

    ASTRONOMISCHE NACHRICHTEN, Issue 8 2007
    R. Schwarz
    Abstract Our work deals with the dynamical possibility that in extrasolar planetary systems a terrestrial planet may have stable orbits in a 1:1 mean motion resonance with a Jovian like planet. We studied the motion of fictitious Trojans around the Lagrangian points L4/L5 and checked the stability and/or chaoticity of their motion with the aid of the Lyapunov Indicators and the maximum eccentricity. The computations were carried out using the dynamical model of the elliptic restricted three-body problem that consists of a central star, a gas giant moving in the habitable zone, and a massless terrestrial planet. We found 3 new systems where the gas giant lies in the habitable zone, namely HD99109, HD101930, and HD33564. Additionally we investigated all known extrasolar planetary systems where the giant planet lies partly or fully in the habitable zone. The results show that the orbits around the Lagrangian points L4/L5 of all investigated systems are stable for long times (107 revolutions). (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    International team wins first Ambartsumian Prize

    ASTRONOMY & GEOPHYSICS, Issue 5 2010
    Article first published online: 17 SEP 2010
    The first Viktor Ambartsumian International Prize, in memory of the distinguished Armenian theorist, goes to the team led by Prof. Michel Mayor of the Observatory of Geneva, for "their important contribution in the study of relation between planetary systems and their host stars". [source]

    Want to find planets?

    ASTRONOMY & GEOPHYSICS, Issue 6 2009
    Track the lithium
    A spectrographic survey has found that stars with planets , like our Sun , tend to have a lot less lithium in their make-up than comparable stars without planetary systems. It is not yet clear how this comes about, but it points the way to a shortcut to finding new exoplanetary systems. [source]

    Life, the universe and everything, with GAIA

    ASTRONOMY & GEOPHYSICS, Issue 5 2001
    Gerry Gilmore
    Great things are expected of the GAIA Observatory, currently expected to launch in 2011. Gerry Gilmore explains how it will provide accurate measurements that will help us understand the formation of the Milky Way and the distribution of dark matter. The GAIA Observatory, ESA's Cornerstone 6 mission, addresses the origin and evolution of our galaxy, and a host of other scientific challenges. GAIA will provide unprecedented positional and radial velocity measurements with the accuracies needed to produce a stereoscopic and kinematic census of about one billion stars in our galaxy and throughout the Local Group, about 1% of the galactic stellar population. Combined with astrophysical information for each star, provided by on-board multicolour photometry, these data will have the precision and depth necessary to address the three key questions which underlie the GAIA science case: l when did the stars in the Milky Way form? l when and how was the Milky Way assembled? l what is the distribution of dark matter in our galaxy? The accurate stellar data acquired for this purpose will also have an enormous impact on all areas of stellar astrophysics, including luminosity calibrations, structural studies, and the cosmic distance scale. Additional scientific products include detection and orbital classification of tens of thousands of extrasolar planetary systems, a comprehensive survey of objects ranging from huge numbers of minor bodies in our solar system, including near-Earth objects, through galaxies in the nearby universe, to some 500 000 distant quasars. GAIA will also provide several stringent new tests of general relativity and cosmology. [source]