scholarly journals Comets and Constraints on Solar System Formation

1992 ◽  
Vol 9 ◽  
pp. 347-354 ◽  
Author(s):  
A.Chantal Levasseur-Regourd
Keyword(s):  
Solar System ◽  
Oort Cloud ◽  
Dust Particles ◽  
Solar System Formation ◽  
Cometary Dust ◽  
System Formation ◽  
Deuterium Enrichment ◽  
Dust Complex ◽  
Comet Halley

AbstractNew and important data have been obtained during the 1985-1986 return of comet Halley, including in situ observations of the nucleus and the coma. Since the interpretation of the observations is not straightforward, the results are presented in a rather conservative manner. Some clues to the solar system formation are suggested, e.g. the shape of the nucleus, its low density, the estimated mass of the Oort cloud, the elemental abundances in comet Halley. Constraints related to isotopie abundances (deuterium enrichment, possible anomalies in carbon isotopes) and to cometary dust (complex organic compounds, submicron sized dust particles) are extensively discussed.

scholarly journals Dust in the Solar System

1989 ◽  
Vol 44 (10) ◽  
pp. 877-882 ◽  
Author(s):  
H. Fechtig
Keyword(s):  
Solar Irradiation ◽  
Dust Particles ◽  
Normal Density ◽  
Dust Grains ◽  
Cometary Dust ◽  
In Situ Experiments ◽  
Asteroidal Belt ◽  
Comet Halley ◽  
Cometary Origin

Abstract Properties of cometary dust particles are better known since the space missions to Comet Halley. Their properties (densities, atomic composition) are compared with relevant observations from lunar microcraters and in-situ experiments. At 1 AU in the eliptic, 2/3 of the dust grains are normal density particles, presumably of asteroidal origin and irregularly shaped, while the remaining 1/3 are low density particles, presumably of cometary origin, but due to solar irradiation in a processed state (corresponding to “Brownlee”-particles). Beyond the asteroidal belt only black cometary dust grains are observed which have recently been released from comet nuclei orbiting on highly eccentric trajectories.

scholarly journals Galactic environment and cometary flux from the Oort cloud

2009 ◽  
Vol 5 (S263) ◽  
pp. 57-66 ◽  
Author(s):  
Marc Fouchard
Keyword(s):  
Solar System ◽  
Oort Cloud ◽  
The Sun ◽  
Gravitational Attraction ◽  
Solar System Formation ◽  
Gravitational Effects ◽  
Long Period ◽  
System Formation ◽  
The Galaxy ◽  
The Difference

AbstractThe Oort cloud, which corresponds to the furthest boundary of our Solar System, is considered as the main reservoir of long period comets. This cloud is likely a residual of the Solar System formation due to the gravitational effects of the young planets on the remaining planetesimals. Given that the cloud extends to large distances from the Sun (several times 10 000 AU), the bodies in this region have their trajectories affected by the Galactic environment of the Solar System. This environment is responsible for the re-injection of the Oort cloud comets into the planetary region of the Solar System. Such comets, also called “new comets”, are the best candidates to become Halley type or “old” long period comets under the influence of the planetary gravitational attractions. Consequently, the flux of new comets represents the first stage of the long trip from the Oort cloud to the observable populations of comets. This is why so many studies are still devoted to this flux.The different perturbers related to the Galactic environment of the Solar System, which have to be taken into account to explain the flux are reviewed. Special attention will be paid to the gravitational effects of stars passing close to the Sun and to the Galactic tides resulting from the difference of the gravitational attraction of the Galaxy on the Sun and on a comet. The synergy which takes place between these two perturbers is also described.

Comets : A Key to Solar System Formation

1989 ◽  
Vol 44 (10) ◽  
pp. 867-876
Author(s):  
Horst Uwe Keller
Keyword(s):  
Solar System ◽  
Heliocentric Distance ◽  
Planetary System ◽  
Cometary Nucleus ◽  
Interplanetary Dust ◽  
Dust Particles ◽  
Interplanetary Dust Particles ◽  
The Earth ◽  
Comet Halley

Abstract Four lines of information on comets are discussed: their orbits, their relation to other bodies of the planetary system, their physical state and chemical composition, and implications of recent observations of the nucleus of comet Halley. The in situ measurements during the flybys of comet Halley strongly support the assumption that comets are members of the solar system and were created during its formation. The region (heliocentric distance) of their formation is, however, still difficult to assess. The size, shape, and topography of the cometary nucleus suggest that it was formed from relatively large subnuclei in a region of the primordial solar nebula where relative velocities were sufficiently small. There are indications that some of the interplanetary dust particles in the Earth atmosphre may originate from comets.

First measurement of decimeter-sized rocky material in the Oort cloud

2021 ◽  
Author(s):  
Denis Vida ◽  
Peter Brown ◽  
Hadrien Devillepoix ◽  
Paul Wiegert ◽  
Danielle Moser ◽  
...  
Keyword(s):  
Solar System ◽  
Planet Formation ◽  
Giant Planet ◽  
Oort Cloud ◽  
Asteroid Belt ◽  
Solar System Formation ◽  
System Formation ◽  
Cometary Material ◽  
High Fraction ◽  
Global Strength

Abstract The Oort cloud is thought to be a reservoir of icy planetesimals and a source of long-period comets (LPCs) implanted from the outer Solar System during the time of giant planet formation. The presence of rocky ice-free bodies is much harder to explain. The rocky fraction in the Oort cloud is a key diagnostic of Solar System formation models as this ratio can distinguish between "massive" and "depleted" proto-asteroid belt scenarios and thus disentangle competing planet formation models. Objects of asteroidal appearance have been telescopically observed on LPC orbits, but from reflectance spectra alone it is uncertain whether they are asteroids or extinct comets. Here we report a first direct observation of a decimeter-sized rocky meteoroid on a retrograde LPC orbit (e ≈ 1.0, i = 121°). The ~2 kg object entered the atmosphere at 62 km/s. The associated fireball terminated at 46.5 km, 40 km deeper than cometary objects of similar mass and speed. During its flight, it experienced dynamic pressures of several MPa, comparable to meteorite-dropping fireballs. In contrast, cometary material measured by Rosetta have compressive strengths of ~1 kPa. The earliest fragmentation of this fireball occurred at >100 kPa, indicating it had a minimum global strength well in excess of cometary. A numerical ablation model produces bulk density and ablation properties consistent with asteroidal meteoroids. We estimate the flux of rocky objects impacting Earth from the Oort cloud to be ~0.7 × 106 km2 per year to a mass limit of 10 g. This is ~6% of the total flux of fireballs on LPC-orbits to these masses. Our results suggests there is a high fraction of asteroidal material in the Oort cloud at small sizes and gives support to migration-based dynamical models of the formation of the Solar System which predict that significant rocky material is implanted in the Oort cloud, a result not explained by traditional Solar System formation models.

scholarly journals New Results on the Composition of the Outer Planets and Titan

2005 ◽  
Vol 13 ◽  
pp. 891-893
Author(s):  
Thierry Fouchet
Keyword(s):  
Solar System ◽  
Atmospheric Chemistry ◽  
Recent Progress ◽  
Giant Planets ◽  
Atmospheric Composition ◽  
Solar System Formation ◽  
Outer Planets ◽  
System Formation ◽  
The Impact

AbstractIn this brief summary, I present recent progress on our knowledge of the Giant Planets and Titan atmospheric composition, as well as the impact of this progress on our understanding of Solar System formation, and atmospheric chemistry.

Solar System Formation and Early Evolution: the First 100 Million Years

2007 ◽  
pp. 39-95 ◽  
Author(s):  
Thierry Montmerle ◽  
Jean-Charles Augereau ◽  
Marc Chaussidon ◽  
Matthieu Gounelle ◽  
Bernard Marty ◽  
...  
Keyword(s):  
Solar System ◽  
Early Evolution ◽  
Solar System Formation ◽  
System Formation
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