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Stéphane Ferron - One of the best experts on this subject based on the ideXlab platform.
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A survey of water production in 61 Comets from SOHO/SWAN observations of hydrogen Lyman-alpha: Twenty-one years 1996–2016
Icarus, 2019Co-Authors: Michael Combi, Terhi T. Mäkinen, Jean-loup Bertaux, Eric Quémerais, Stéphane FerronAbstract:The Solar Wind Anisotropies (SWAN) instrument on the SOlar and Heliospheric Observatory (SOHO) satellite has observed 44 long Period and new Oort cloud Comets and 36 apparitions of 17 Short Period Comets since its launch in December 1995. Water production rates have been determined from the over 3700 images producing a consistent set of activity variations over large parts of each comet's orbit. This has enabled the calculation of exponential power-law variations with heliocentric distance of these Comets both before and after perihelion, as well as the absolute values of the water production rates. These various measures of overall water activity including pre- and post-perihelion exponents, absolute water production rates at 1 AU, active surface areas and their variations have been compared with a number of dynamical quantities for each comet including dynamical class, original semi-major axis, nucleus radius (when available), and compositional taxonomic class. Evidence for evolution of cometary nuclei is seen in both long-Period and Short-Period Comets.
J A Fernandez - One of the best experts on this subject based on the ideXlab platform.
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ON DYNAMICAL SCATTERING OF KUIPER BELT OBJECTS IN 2:3 RESONANCE WITH NEPTUNE INTO Short-Period Comets
Astronomy and Astrophysics, 1997Co-Authors: J A FernandezAbstract:A large number of trans-Neptunian Comets might have been detected by the Hubble Space Telescope. If a signi- cant fraction of these Halley-sized objects are stored in the 2:3 orbitalresonancewithNeptune,randomgravitationalscattering bytheKuiperbeltobjects(KBOs)withdiametersinthehundred km range is found to be of potential importance in destabilizing the resonant orbits and hence acts as an injection mechanism of Short-Period Comets. The relevant feeding rate of Short-Period Cometsfromthe2:3resonantpopulationisestimatedtobecom- parable to the injection rate as a result of dynamical sculpting by long-term planetary perturbations. Similar dynamical inter- actioncouldalsoleadtotheinjectionofKBOsofafewhundred km diameter from the 2:3 resonant zone into the region inside the orbits of Neptune and Uranus. The comet-like object, 2060 Chiron might be such an example. The number of similar ob- jects is estimated to be 5{10, while the total number of KBOs of 100km size or larger leaking across the orbit or Neptune, e.g. Centaurs, may be on the order of 50.
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steady state injection of Short Period Comets from the trans neptunian cometary belt
Icarus, 1991Co-Authors: J A FernandezAbstract:Abstract To examine the scenario of the existence of a trans-Neptunian comet belt as an important source region of the Short-Period Comets, the dynamical perturbation on a system of such icy planetesimals by a few Mars- to Earth-sized planetoids in highly eccentric orbits is considered. In the context of our planetoid-scattering model with three or four large planetoids orbiting in highly eccentric orbits, the total mass of the trans-Neptunian comet belt between the orbit of Neptune and 200 AU could be on the order of 0.002 M ⊕ , at the present time, and the total number of the trans-Neptunian belt objects should be on the order of 1–3 × 10 8 with about 10 6 of them orbiting between Saturn and Uranus. Because of the strong gravitational scattering by the hypothetical planetoids, the number of the trans-Neptunian belt Comets so derived should be regarded as a lower limit. It is quite possible that in the absence of such large planetoids, a much larger population (i.e., a factor of 100) of the trans-Neptunian belt Comets might exist.
Michael Combi - One of the best experts on this subject based on the ideXlab platform.
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A survey of water production in 61 Comets from SOHO/SWAN observations of hydrogen Lyman-alpha: Twenty-one years 1996–2016
Icarus, 2019Co-Authors: Michael Combi, Terhi T. Mäkinen, Jean-loup Bertaux, Eric Quémerais, Stéphane FerronAbstract:The Solar Wind Anisotropies (SWAN) instrument on the SOlar and Heliospheric Observatory (SOHO) satellite has observed 44 long Period and new Oort cloud Comets and 36 apparitions of 17 Short Period Comets since its launch in December 1995. Water production rates have been determined from the over 3700 images producing a consistent set of activity variations over large parts of each comet's orbit. This has enabled the calculation of exponential power-law variations with heliocentric distance of these Comets both before and after perihelion, as well as the absolute values of the water production rates. These various measures of overall water activity including pre- and post-perihelion exponents, absolute water production rates at 1 AU, active surface areas and their variations have been compared with a number of dynamical quantities for each comet including dynamical class, original semi-major axis, nucleus radius (when available), and compositional taxonomic class. Evidence for evolution of cometary nuclei is seen in both long-Period and Short-Period Comets.
Luke Dones - One of the best experts on this subject based on the ideXlab platform.
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Origin and Evolution of Short-Period Comets
The Astrophysical Journal, 2017Co-Authors: David Nesvorný, Harold F. Levison, David Vokrouhlický, Luke Dones, Nathan A. Kaib, Alessandro MorbidelliAbstract:Comets are icy objects that orbitally evolve from the trans-Neptunian region (the Kuiper belt and beyond) into the inner Solar System, where they are heated by solar radiation and become active due to sublimation of water ice. Here we perform end-to-end simulations in which cometary reservoirs are formed in the early Solar System and evolved over 4.5 Gyr. The gravitational effects of Planet 9 (P9), hypothesized to circle the Sun on a wide orbit, are included in some of our simulations. Different models are considered for Comets to be active, including a simple assumption that Comets remain active for Np(q) perihelion passages with perihelion distance q 1000 is required to obtain a steady-state population of large active HTCs that is consistent with observations. To fit the ratio of the returning-to-new OCCs, by contrast, our model implies that Np(2.5)
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origin and evolution of Short Period Comets
The Astrophysical Journal, 2017Co-Authors: David Nesvorný, Harold F. Levison, David Vokrouhlický, Luke Dones, Nathan A. Kaib, Alessandro MorbidelliAbstract:Comets are icy objects that orbitally evolve from the trans-Neptunian region (the Kuiper belt and beyond) into the inner Solar System, where they are heated by solar radiation and become active due to sublimation of water ice. Here we perform end-to-end simulations in which cometary reservoirs are formed in the early Solar System and evolved over 4.5 Gyr. The gravitational effects of Planet 9 (P9), hypothesized to circle the Sun on a wide orbit, are included in some of our simulations. Different models are considered for Comets to be active, including a simple assumption that Comets remain active for Np(q) perihelion passages with perihelion distance q 1000 is required to obtain a steady-state population of large active HTCs that is consistent with observations. To fit the ratio of the returning-to-new OCCs, by contrast, our model implies that Np(2.5)<10, possibly because the detected long-Period Comets are smaller and much easier to disrupt than observed HTCs.
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capture statistics of Short Period Comets implications for comet d shoemaker levy 9
Icarus, 1996Co-Authors: David M Kary, Luke DonesAbstract:Abstract Comet D/Shoemaker–Levy 9 orbited Jupiter for decades (P. W. Chodas and D. K. Yeomans 1995, Bull. Am. Astron. Soc. 27, 1111–1112; L. A. M. Benner and W. B. McKinnon 1995, Icarus 118, 155–168) and was tidally disrupted during the orbit before impact. To estimate the rate of such events and to infer the implications for the comet's previous orbit, we have performed numerical integrations of test particles with orbits similar to those of Jupiter-family Comets. We follow the dynamical evolution of 49,000 synthetic Comets for ∼10 5 years and find 10,089 captures in which a comet completed more than one full orbit around Jupiter. Of these Jupiter-orbiting Comets (“orbiters”), one in 112 undergoes a long capture, an event in which the comet orbits Jupiter for over 50 years. Captured bodies with mean orbital Periods >3.5 years generally have jovicentric inclinations >120° and large perijove distances, while bodies with Shorter orbital Periods have smaller inclinations and are more likely to approach Jupiter closely. Long captures are more likely to include very close approaches to Jupiter. For example, long captures make up roughly one event in 15 in which an orbiter passes within 2.4 R J (Jupiter radii) of Jupiter's center (without immediately impacting the planet). Thus, if passage within ∼2.4 R J makes a comet observable by causing mass loss, the bias in favor of long capture events is a factor of eight over the general population of Jupiter-orbiting Comets. About 15% of the Comets that hit Jupiter are orbiting the planet at impact; approximately 1% impact after orbiting for more than 50 years. We infer that a 1-km comet impacts Jupiter once every 30–500 years, with a most probable interval of 240 years. Comets in orbit about Jupiter impact once every (0.2–3.5) × 10 3 years; orbiting Comets impact one orbit after tidal disruption once every (0.1–2) × 10 5 years.
Suk Minn Kwon - One of the best experts on this subject based on the ideXlab platform.
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dark red debris from three Short Period Comets 2p encke 22p kopff and 65p gunn
Icarus, 2007Co-Authors: M. Ishiguro, Yuki Sarugaku, Munetaka Ueno, Naoya Miura, Fumihiko Usui, Moo-young Chun, Suk Minn KwonAbstract:Abstract We present observations of the extended dust structures near the orbits of three Short-Period Comets: 2P/Encke, 22P/Kopff, and 65P/Gunn. The dust trails were originally discovered by the Infrared Astronomical Satellite (IRAS). Our observations were made using wide-field optical CCD cameras on the University of Hawaii 2.24-m telescope, the Canada–France–Hawaii 3.6-m telescope, and the Kiso 1.05-m Schmidt telescope. We compared the observed images with models and found that the extended structures seen around 2P/Encke and 22P/Kopff before perihelion passage were most likely “dust trails,” whereas images taken after perihelion passage show a high contamination by recently released particles (i.e., particles in Neck-Line structures are visible). We could not confirm the existence of a dust trail from 65P/Gunn within the field of view of the camera used. The effective sizes of the particles responsible for the scattered light were estimated at 1–100 mm (2P/Encke), 1–10 mm (22P/Kopff), and 100 μm–1 mm (65P/Gunn), respectively, which is consistent with previous studies of dust trails made with infrared space telescopes and optical telescopes. We evaluated the mass loss rates of these Comets, averaged over their orbits, as reaching 48 ± 20 kg s −1 (2P/Encke), 17 ± 3 kg s −1 (22P/Kopff), and 27 ± 9 kg s −1 (65P/Gunn). These values are consistent with previous work. Therefore, the total amount of material ejected from these three Comets is 10 2 kg s −1 , which would contribute a considerable fraction of the 10 4 kg s −1 lost within 1 AU that needs to be replaced if the zodiacal cloud is to be maintained in a steady state. We also found that the particles in the dust structures are significantly redder than the Sun and the zodiacal light, and might be redder than the average Short-Period comet nuclei. Specifically, the reflectivity gradients of 2P/Encke, 22P/Kopff, and 65P/Gunn are 13 ± 7 (% 10 3 A −1 ), 20 ± 5 (% 10 3 A −1 ), and 15 ± 4 (% 10 3 A −1 ), respectively. We examined the change in color with distance from the nucleus. No clear correlation was detected for 2P/Encke or 22P/Kopff to an accuracy of 3–11%, while the 65P/Gunn tail did show color variation, becoming redder with increasing distance from the nucleus. This dark red material, consisting of particles of sand–cobble size, has marginally escaped from the nuclei and will evolve into finer-grained interplanetary dust particles after subsequent collisions.
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Dark red debris from three Short-Period Comets: 2P/Encke, 22P/Kopff, and 65P/Gunn
Icarus, 2007Co-Authors: M. Ishiguro, Yuki Sarugaku, Munetaka Ueno, Naoya Miura, Fumihiko Usui, Moo-young Chun, Suk Minn KwonAbstract:Abstract We present observations of the extended dust structures near the orbits of three Short-Period Comets: 2P/Encke, 22P/Kopff, and 65P/Gunn. The dust trails were originally discovered by the Infrared Astronomical Satellite (IRAS). Our observations were made using wide-field optical CCD cameras on the University of Hawaii 2.24-m telescope, the Canada–France–Hawaii 3.6-m telescope, and the Kiso 1.05-m Schmidt telescope. We compared the observed images with models and found that the extended structures seen around 2P/Encke and 22P/Kopff before perihelion passage were most likely “dust trails,” whereas images taken after perihelion passage show a high contamination by recently released particles (i.e., particles in Neck-Line structures are visible). We could not confirm the existence of a dust trail from 65P/Gunn within the field of view of the camera used. The effective sizes of the particles responsible for the scattered light were estimated at 1–100 mm (2P/Encke), 1–10 mm (22P/Kopff), and 100 μm–1 mm (65P/Gunn), respectively, which is consistent with previous studies of dust trails made with infrared space telescopes and optical telescopes. We evaluated the mass loss rates of these Comets, averaged over their orbits, as reaching 48 ± 20 kg s −1 (2P/Encke), 17 ± 3 kg s −1 (22P/Kopff), and 27 ± 9 kg s −1 (65P/Gunn). These values are consistent with previous work. Therefore, the total amount of material ejected from these three Comets is 10 2 kg s −1 , which would contribute a considerable fraction of the 10 4 kg s −1 lost within 1 AU that needs to be replaced if the zodiacal cloud is to be maintained in a steady state. We also found that the particles in the dust structures are significantly redder than the Sun and the zodiacal light, and might be redder than the average Short-Period comet nuclei. Specifically, the reflectivity gradients of 2P/Encke, 22P/Kopff, and 65P/Gunn are 13 ± 7 (% 10 3 A −1 ), 20 ± 5 (% 10 3 A −1 ), and 15 ± 4 (% 10 3 A −1 ), respectively. We examined the change in color with distance from the nucleus. No clear correlation was detected for 2P/Encke or 22P/Kopff to an accuracy of 3–11%, while the 65P/Gunn tail did show color variation, becoming redder with increasing distance from the nucleus. This dark red material, consisting of particles of sand–cobble size, has marginally escaped from the nuclei and will evolve into finer-grained interplanetary dust particles after subsequent collisions.