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Showing 1 to 20 of 21 for “"planetesimal"”.
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Planetesimal Belts in Misaligned Wide Stellar Binaries
… companion on a misaligned wide orbit perturbs planetesimals to high eccentricities. First, in order to explain the mys- terious light-curve of KIC 8462852, one component of a wide binary star system in the Kepler field with deep, irregular and aperiodic dips in its light-curve, a Monte Carlo …
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The Structure of Extrasolar Planetesimal Belts in Images
Solid bodies in the form of planets and planetesimal belts familiar to us in the Solar System are also a prevalent feature around other stars. Their great diversity highlights a lack of complete theories for how they formed, which is further complicated by observational challenges to understand …
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Planetesimal and Protoplanet Dynamics in a Turbulent Protoplanetary Disk
… disk subject to magneto-rotational instability, planetesimals and protoplanets undergo diffusive radial migration as well as changes of other orbital properties. The magnitude of the effect on particle orbits has important consequences for planet formation scenarios. To accurately measure the …
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Studying the Formation of Protoplanets : A new Hybrid Code for Planetesimal Dynamics
… auf der Entstehung von Protoplaneten aus Planetesimalen liegt. In diesem Stadium wird die Entwicklung des System von Kollisionen und Zwei-Körper-Streuungen bestimmt, die eine sorgfältige Modellierung der Entwicklung der Geschwindigkeitsdispersion und der Größenverteilung über den ganzen …
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High-resolution studies of exoplanetesimal belt formation and evolution
… the protoplanetary system: planets, and belts of planetesimals (km-sized rocky and icy bodies). Planetesimals within belts readily collide and produce detectable levels of dust and gas, known as debris discs, around 20% of main sequence stars. Despite the ubiquity of planets and planetesimal belt …
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Deciphering the thermal evolution of small planetary bodies.
… In this thesis, I use detailed models of planetesimal thermal evolution to constrain the accretionary histories and structures of a range of different meteorite parent bodies from a variety of observed meteorite properties. This model describes the thermochemical evolution of a …
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GENETICS, AGES, AND CHEMICAL COMPOSITIONS OF IRON METEORITES
… are observed. Results of comparing bulk planetesimal genetic isotopic compositions with bulk planetesimal siderophile element chemical characteristics indicate that the processes responsible for isotopic heterogeneity in the early Solar System are not discerned by the siderophile element …
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The structure and stability of vortices in astrophysical discs
… a barrier to their potential as sites for planetesimal formation. It is challenging to build planetesimals from dust within the lifetime of a protoplanetary disc and before such bodies spiral into the central star. Collecting matter in vortices is a promising mechanism for planetesimal …
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THE CONCENTRATION OF HYDROGEN IN INCOMPLETELY AND WHOLLY MELTED TERRESTRIAL BUILDING BLOCKS
… carbonaceous chondrites. Similarly, all melted planetesimals are commonly assumed to be anhydrous. However, recent analyses of enstatite chondrites (ECs), which are formed in the inner solar system and are the closest match to the nucleosynthetic isotopic composition of the bulk Earth, suggest …
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Hydrocode modeling of oblique impacts into terrestrial planets
… temperature. Recent studies of differentiated planetesimal impacts assume that planetesimal cores survive the impact intact as concentrated masses that passively settle from a zero initial velocity and undergo turbulent entrainment in a global magma ocean; under these conditions, cores greater …
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Remanent magnetization in angrite NWA 4931
… are among the oldest known rocks and may record planetesimal dynamo activity and protoplanetary disk fields in the early solar system. Towards this goal, the natural remanent magnetism and its origin were examined in newly discovered angrite NWA 4931. Measurements were conducted on subsamples cut …
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Experimental Constraints on Melting Processes in the Earth and Small Rocky Bodies
… formation models of a differentiated moon-sized planetesimal accreting in the first 3 Ma of the Solar System are also discussed. In the fourth Chapter, I introduce a new experimental technique for studying melt migration in volcanoes, which allowed me to observe and describe the mechanisms that …
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EXOCOMETS AT LARGE ORBITAL RADII AND THEIR INWARD TRANSPORT IN DEBRIS DISCS
… which I use to set constraints on the underlying planetesimal distribution and mass and orbital distance of unseen planets. Finally, in Chapter 6 I present result obtained from N-body simulations to study the process of inward transport of comets by a multiplanetary system and how these can …
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Magnetic Properties of Iron Meteorites and Their Parent Bodies
… solar system. Similar to Earth, some of these “planetesimals” underwent differentiation into a metallic core and a silicate mantle, and powered magnetic fields by the motion of their liquid cores via dynamo effect. Although most planetesimals no longer exist, records of their magnetic fields are …
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The origin and evolution of Transneptunian binaries
… the potential to elucidate the processes of planetesimal formation and evolution in general. Previous work has shown that gravitational instability is an efficient mechanism for producing these transneptunian binaries, where planetesimals and binaries form directly from the gravitational …
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Dust disks around hot white dwarfs and central stars of planetary nebulae
… mechanisms are: (1) breakup of bodies in planetesimal belts through collisions, (2) formation of circumstellar dust disks through binary interactions. In addition, we have derived basic dust disk parameters using simple blackbody approximations, or optically thin dust disk models with …
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The effects of stochastic forces on the evolution of planetary systems and Saturn's rings
… collapse to form a gravitationally bound planetesimal. Due to the large separation of scales, this process is very hard to model numerically. A scaled method is presented, that allows for the correct treatment of self-gravity for a marginally collisional system by taking into account the …
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Connecting models and observations of disc evolution and planet formation
… conditions to kickstart the formation of planetesimal under streaming instability are met in one of the rings.
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Secular Dynamics of Self-gravitating Debris Discs
… gap within the debris disc through excitation of planetesimal eccentricities. I then characterise the properties of the secular resonances and illustrate how the planet--disc parameters can be constrained for a given system hosting a gapped disc. Then, using a numerical method developed based on …
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Planet formation, resonant drag instabilities, and vortices
… turbulent coagulation, the metre-scale barrier, planetesimal accretion, pebble accretion, cooling-limited gas accretion, and runaway gas accretion. Finally, I present six possible bridges over the metre gap: sturdy grains, pressure bumps, the gravitational instability, the Safronov-Goldreich-Ward …
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