Statistics of collision parameters computed from 2D simulations

There are two popular ways to speed up simulations of planet formation via increasing the collision probability: ({\it i}) confine motion to 2D, ({\it ii}) artificially enhance the physical radii of the bodies by an expansion factor. In this paper I have performed 100 simulations each containing $10^4$ interacting bodies and computed the collision parameters from the results of the runs. Each run was executed for a lower and a higher accuracy parameter. The main goal is to determine the probability distribution functions of the collision parameters and their dependence on the expansion factor. A simple method is devised to improve the determination of the collision parameters from the simulation data. It was shown that the distribution of the impact parameter is uniform and independent of the expansion factor. For real collisions the impact velocity is greater than 1 mutual escape velocity, a finding that can be explained using the two-body problem. The results casts some doubts on simulations of the terrestrial planets' final accretion that have assumed merge. Collision outcome maps were created adopting the fragmentation model of \cite{Leinhardt2012} to estimate the number of different types of collisions. A detailed comparison with earlier works indicates that there are similarities as well as significant differences between the different works. The results indicate that as the planetary disc matures and the masses of the bodies differs progressively than the majority of collisions lead to mass growth either via partial accretion or via graze-and-merge collision.Comment: 20 pages, 17 figure

SPH-based simulation of multi-material asteroid collisions

We give a brief introduction to smoothed particle hydrodynamics methods for continuum mechanics. Specifically, we present our 3D SPH code to simulate and analyze collisions of asteroids consisting of two types of material: basaltic rock and ice. We consider effects like brittle failure, fragmentation, and merging in different impact scenarios. After validating our code against previously published results we present first collision results based on measured values for the Weibull flaw distribution parameters of basalt.Comment: Accepted and to be published in Astronomical Note

Water delivery in the early Solar System

As part of the national scientific network 'Pathways to Habitable Worlds' the delivery of water onto terrestrial planets is a key question since water is essential for the development of life as we know it. After summarizing the state of the art we show some first results of the transport of water in the early Solar System for scattered main belt objects. Hereby we investigate the questions whether planetesimals and planetesimal fragments which have gained considerable inclination due to the strong dynamical interactions in the main belt region around 2 AU can be efficient water transporting vessels. The Hungaria asteroid group is the best example that such scenarios are realistic. Assuming that the gas giants and the terrestrial planets are already formed, we monitor the collisions of scattered small bodies containing water (in the order of a few percent) with the terrestrial planets. Thus we are able to give a first estimate concerning the respective contribution of such bodies to the actual water content in the crust of the Earth

Naprendszeren kívüli bolygók kutatása = Researches on planets beyond the Solar System

Exobolygó-rendszerek megfigyelésével és dinamikájával kapcsolatos kutatásokat folytattunk. A KH 15D születő bolygórendszer fotometriai megfigyelésével hozzájárultunk a csillag körüli anyag bolygókeletkezést megelőző sűrűséghullámainak kimutatásához. IRAS, ISOPHOT és Spitzer adatokat felhasználva összeállítottuk a Nap-rendszer 120 parszek környezetében található legfényesebb törmelékkorongok katalógusát, valamint meghatároztuk fő paramétereiket és fejlődési diagramjaikat. Numerikus módszerek alkalmazásával létrehoztunk egy dinamikai stabilitási katalógust, mely sok millió kezdőfeltételre megadja a pályák stabilitási viszonyait. A katalógus alapján ismert exobolygó-rendszerek lakhatósági zónáinak stabilitási viszonyait határoztuk meg. Exobolygók kialakulásával és dinamikai fejlődésével kapcsolatos modellt dolgoztunk ki. Módszereket dolgoztunk ki hatékony dinamikai vizsgálatokhoz, és tranzit fotometria adatokból pályaelemek meghatározására. | We have conducted researches on the observations and dynamics of exoplanetary systems. By making photometric observations of the planet-forming system KH 15D, we contributed to the detection of the density waves in the circumstellar matter which preceed planet formation. By using IRAS, ISOPHOT and Spitzer data we compiled a catalogue of the brightest debris disks in the 120 pc neighbourhood of the Sun. We also determined their main parameters and evolution diagrams. By using numerical methods we developed a catalogue of dynamical stability giving stability properties of orbits for millions of initial conditions. We determined the stability features of the habitable zones of known exoplanetary systems. We developed a model for the formation and evolution of one class of exoplanets. We developed efficient methods for dynamical investigations and for the estimation of orbital data from transit photometry

The Influence of Giant Planets Near a Mean Motion Resonance on Earth-like Planets in the Habitable Zone of Sun-like Stars

We present a numerical study of several two-planet systems based on the motions of Jupiter and Saturn, in which the two giant planets move in low eccentric orbits close to a mean motion resonance. It is more likely to find two planets with similar characteristics in a system than a clone of the Jupiter-Saturn pair of our solar system. Therefore, we vary the distance between the two planets and their mass ratio by changing Saturn's semimajor axis from 8 to 11 AU and increasing its mass by factors of 2-40. The different two-planets were analyzed for the interacting perturbations due to the mean motion resonances of the giant planets. We select several mass ratios for the gas giants, for which we study their influence on test bodies (with negligible mass) moving in the habitable zone (HZ) of a Sun-like star. The orbits are calculated for 2×107 yr. In all cases the HZ is dominated by a significant curved band, indicating higher eccentricity, which corresponds to a secular resonance with Jupiter. Interesting results of this study are finding (1) an increase of Venus's eccentricity for the real Jupiter and Saturn masses and the actual semimajor axis of Saturn; (2) an increase of the eccentricity of a test planet at Earth's position when Saturn's mass was increased by a factor of 3 or more; and (3) if the two giant planets are in 2:1 resonance, we observe a strong influence on the outer region of the HZ