Nathan Kaib
(University of Oklahoma)
17/05/2016 10:15
The Oort cloud has previously been invoked to explain observations of centaurs with very high inclinations and/or very large semimajor axes since such orbits are difficult to generate from the scattered disk. However, the known sample of centaurs has been detected with a combination of surveys with different observational biases, some more well-characterized than others. Consequently, it is...
Prof.
Vacheslav Emel'yanenko
(Institute of Astronomy, RAS)
17/05/2016 11:00
We discuss how many comets come to short-period orbits from different sources in the outer solar system. The observed distribution of Centaurs, as a transition population, plays a pivotal role in constraining our models. We show that the Oort cloud and the scattered disc produce similar numbers of Jupiter-family comets.
Dr
Piotr A. Dybczyński
(Astronomical Observatory Institute, faculty of physics, A.Mickiewicz Univ., Poznań, Poland)
17/05/2016 14:00
Galactic and stellar perturbations are important factors when studying the
past and future motion of the observed Oort spike comets. Since our
knowledge on the Solar System Galactic environment is continuously
increasing it is necessary to upgrade our methods and computer codes for
taking into account these perturbations in a proper way. I will report our
preparations to incorporate new...
Małgorzata Królikowska
(SRC PAS)
17/05/2016 14:45
Currently, this Catalogue includes orbits of about 160 Oort spike comets defined as objects with original 1/a less than 0.000100 au$^{-1}$. Orbits were determined or redetermined in a completely homogeneous way and constitute more than 85% of the Oort spike comets discovered before 2010. In the publicly available Catalogue, we offer observed (i.e. osculating orbit at the epoch close to the...
Dr
Brasser Ramon
(Institute for Astronomy and Astrophysics, Taiwan)
17/05/2016 16:00
I discuss how the proposed instability of the giant planets that
sculpted the Kuiper Belt and Scattered Disc also formed the Oort comet
cloud. I show the results of numerical simulations of this problem and
discuss formation efficiency, number of comets in the cloud and the Oort
cloud to Scattered Disc population ratios. I compare these with
observations and give an updated estimate based...
Hans Rickman
(Uppsala University)
17/05/2016 16:45
Solar type stars typically form as members of embedded clusters, which dissolve on different time scales depending on their masses and densities. Most such clusters are small and short-lived, and Oort Cloud (OC) formation has often been modeled within such a scenario. But Lada & Lada (2003) showed that about equal numbers of stars are formed in clusters with populations of 10^2, 10^3 and 10^4...
Giovanni Valsecchi
(IAPS-INAF)
18/05/2016 10:00
Close encounters with the giant planets play an important role in the
evolution of the orbits of long period comets, and have been treated in
a number of papers. We revisit the subject in the framework of an
analytic theory of close encounters, that provides useful insight on the
properties of the strong perturbations caused by planetary encounters.
Prof.
Rudolf Dvorak
(Universite de Vienne, Autriche)
18/05/2016 11:15
We investigate whether there can exist comet families in the extrasolar planetary systems
Kepler 90 and HD 10180, systems which consist of six planets; the outermost is a giant.
This is done by extensive numerical integrations of millions of hypothetical comets entering the inner system on almost hyperbolic orbits. The goal is to find whether
families like the Halley comets or the Jupiter...
Dr
alessandro morbidelli
(OCA)
18/05/2016 12:00
Comets are often thought of as "pristine planetesimals". However, most cometary objects that we study are just a few km in size. Planetesimals this small are highly unlikely to be pristine planetesimals. In fact, the collisional environment in the trans-Neptunian planetesimal disk was very severe both before and during the giant planet instability phase that formed and sculpted the current...
Dr
Bjorn Davidsson
(Uppsala university)
18/05/2016 14:15
For decades, comet scientists have debated whether comet nuclei are primordial
rubble piles, formed at their current sizes through gentle accretion in the Solar Nebula,
or if they are collisional rubble piles formed in the aftermath of violent collisions
between larger parent bodies. The Rosetta mission to comet 67P/Churyumov-Gerasimenko and
the Stardust sample-return mission to comet...
Maria Antonietta Barucci
(LESIA - Paris Observatory)
18/05/2016 16:15
The study of the small bodies that orbit the Sun beyond Neptune, the transneptunian objects, has completely changed our view of the Solar System. The last decade, a huge quantity of data has been obtained by ground large telescopes and by space missions.
Various surface compounds have been detected, including ices of water, methane, nitrogen, methanol, ethane and ammonia. An overview for all...
Slawomira Szutowicz
(Space Research Centre)
18/05/2016 17:00
In comets the anisotropic gas emission from their nuclei have been discovered in gas jets, fans, close-up images of cometary nuclei provided by missions, asymmetric shapes of the cometary gas production curves with respect to perihelion, asymmetric non-gravitational forces perturbing the cometary orbits and finally in the spectral imaging of comets in the molecular lines. The evidence of...
Holger Sierks
(Max planck Institute, Gottingen, Germany)
19/05/2016 10:00
Comets with their coma and tail are a spectacular sight on the night sky; they are important objects to understand the origin of our solar system. Comets are pristine and thus carry information on how they initially formed 4.5 billion years ago. 67P/Churyumov-Gerasimenko is the first comet studied in detail with a spacecraft in its vicinity for more than two years along the orbit around the...
Prof.
Dominique Bockelée-Morvan
(LESIA)
19/05/2016 11:15
Cometary activity involves complex processes, which are related to the thermal history of the comet nucleus and evolutionary effects, and depend on the nature and properties of surface and subsuface material. Whereas ground-based observations provided insights on the volatiles responsible for cometary activity and showed evidence for non-uniform activity and seasonnal effects, a thorough...
Fabrizio Capaccioni
(IAPS-INAF)
19/05/2016 12:00
The paper will describe the major results obtained so far by the Visible, Infrared and Thermal Imaging Spectrometer (VIRTIS), the dual channel spectrometer onboard Rosetta, on the surface composition and physical properties of the nucleus of comet 67P/Churyumov-Gerasimenko and the implications on the origin and evolution of the nucleus.
These results were achieved studying the reflected and...
Dr
Cécile Engrand
(C.S.N.S.M.)
19/05/2016 14:15
The composition of cometary dust has been measured by in situ and remote sensing instruments in the last decades, each analysis adding pieces to the puzzle of how and where comets formed. Giotto analyses of comet 1P/Halley dust particles have shown the presence of CHON and mixed particles. Astronomical observations showed that olivine and pyroxene are present in comets. Laboratory analyses of...
Hans Rickman
(PAS Space Research Center, Warszawa, Poland)
19/05/2016 17:00
We have simulated the orbital evolution of icy planetesimals ("comets") in the inner solar system upon dispersal of the primordial planetesimal disk by giant planet migration as prescribed by the Nice Model. Using both the assumption of non-evolving comets and models including erosion by sublimation and splitting, we have estimated the impact rate and crater formation due to these comets on...
