|
|
| Line 1: |
Line 1: |
| [[File:Neptunian rings scheme 2.svg|300px|thumb|The scheme of Neptune's ring-moon system. Solid lines denote rings; dashed lines denote orbits of moons.]]
| | The name of the writer is Numbers. Bookkeeping is my occupation. What I adore performing is to gather badges but I've been using on new issues lately. North Dakota is our beginning place.<br><br>my weblog ... [http://www.rachat-points.com/node/5948373 rachat-points.com] |
| The '''rings of Neptune''' consist primarily of five principal [[Planetary ring|rings]] and were first discovered (as "arcs") in 1984 in Chile by Patrice Bouchet, Reinhold Häfner and Jean Manfroid at [[La Silla Observatory]] (ESO) during an observing program proposed by André Brahic and Bruno Sicardy from Paris-Meudon Observatory, and at Cerro Tololo Interamerican Observatory by F. Vilas and L.-R. Elicer for a program led by Williams Hubbard.<ref name ="Hubbard1985" /><ref name ="Manfroid1986" /> They were eventually imaged in 1989 by the ''[[Voyager 2]]'' spacecraft.<ref name="Miner2007" /> At their densest, they are comparable to the less dense portions of [[Rings of Saturn|Saturn's main rings]] such as the C ring and the Cassini Division, but much of Neptune's ring system is quite tenuous, faint and [[Cosmic dust|dusty]], more closely resembling the [[rings of Jupiter]]. [[Neptune]]'s rings are named after astronomers who contributed important work on the planet:<ref name="Miner2007" /> [[Johann Gottfried Galle|Galle]], [[Urbain Le Verrier]], [[William Lassell|Lassell]], [[François Arago|Arago]], and [[John Couch Adams|Adams]].<ref>Listed in increasing distance from the planet</ref><ref name="Miner2007b" /> Neptune also has a faint unnamed ring coincident with the orbit of the moon [[Galatea (moon)|Galatea]]. Three other moons orbit between the rings: [[Naiad (moon)|Naiad]], [[Thalassa (moon)|Thalassa]] and [[Despina (moon)|Despina]].<ref name="Miner2007b" />
| |
| | |
| The rings of Neptune are made of extremely dark material, likely [[Organic compound|organic]] compounds processed by [[radiation]], similar to that found in the [[rings of Uranus]].<ref name="SmithSoderblom1989" /> The proportion of dust in the rings (between 20% and 70%) is high,<ref name="SmithSoderblom1989" /> while their [[optical depth]] is low to moderate, at less than 0.1.<ref name="Horn1990" /> Uniquely, the Adams ring includes five distinct arcs, named Fraternité, Égalité 1 and 2, Liberté, and Courage. The arcs occupy a narrow range of [[Longitude of the periapsis|orbital longitude]]s and are remarkably stable, having changed only slightly since their initial detection in 1980.<ref name="SmithSoderblom1989" /> How the arcs are stabilized is still under debate. However, their stability is probably related to the [[Orbital resonance|resonant]] interaction between the Adams ring and its inner [[shepherd moon]], Galatea.<ref name="Burns2001" /> | |
| | |
| == Discovery and observations ==
| |
| [[File:PIA02202 Neptune's full rings.jpg|thumb|320px|A pair of ''Voyager 2'' images of Neptune's ring system]]
| |
| The first mention of rings around Neptune dates back to 1846 when [[William Lassell]], the discoverer of Neptune's largest moon [[Triton (moon)|Triton]], thought he had seen a ring around the planet.<ref name="Miner2007" /> However, his claim was never confirmed and it is likely that it was an [[Artifact (observational)|observational artifact]]. The first reliable detection of a ring was made in 1968 by stellar [[occultation]], although that result would go unnoticed until 1977 when the [[rings of Uranus]] were discovered.<ref name="Miner2007" /> Soon after the Uranus discovery, a team from [[Villanova University]] led by [[Harold J. Reitsema]] began searching for rings around Neptune. On 24 May 1981, they detected a dip in a star's brightness during one occultation; however, the manner in which the star dimmed did not suggest a ring. Later, after the Voyager fly-by, it was found that the occultation was due to the small Neptunian moon [[Larissa (moon)|Larissa]], a highly unusual event.<ref name="Miner2007" />
| |
| | |
| In the 1980s, significant occultations were much rarer for Neptune than for Uranus, which lay near the [[Milky Way]] at the time and was thus moving against a denser field of stars. Neptune's next occultation, on 12 September 1983, resulted in a possible detection of a ring.<ref name="Miner2007" /> However, ground-based results were inconclusive. Over the next six years, approximately 50 other occultations were observed with only about one-third of them yielding positive results.<ref name="Sicardy1991" /> Something (probably incomplete arcs) definitely existed around Neptune, but the features of the ring system remained a mystery.<ref name="Miner2007" /> The ''[[Voyager 2]]'' spacecraft made the definitive discovery of the Neptunian rings during its fly-by of Neptune in 1989, passing by as close as {{convert|4950|km|mi|abbr=on}} above the planet's atmosphere on 25 August. It confirmed that occasional occultation events observed before were indeed caused by the arcs within the Adams ring (see below).<ref name="Nicholson1990" /> After the Voyager fly-by the previous terrestrial occultation observations were reanalyzed yielding features of the ring's arcs as they were in 1980s, which matched those found by Voyager almost perfectly.<ref name="SmithSoderblom1989" />
| |
| | |
| Since Voyager's fly-by, the brightest rings (Adams and Le Verrier) have been imaged with the [[Hubble Space Telescope]] and Earth-based telescopes, owing to advances in resolution and light-gathering power<!--not to mention that the astronomers now know what they're looking for-->.<ref name="Dumas1999" /> They are visible, slightly above [[Cosmic microwave background|background noise]] levels, at [[methane]]-absorbing [[wavelength]]s in which the glare from Neptune is significantly reduced. The fainter rings are still far below the visibility threshold.<ref name="dePater2005" />
| |
| | |
| == General properties ==
| |
| [[File:PIA02224 Neptune's rings.jpg|thumb|200px|A ''Voyager'' ring image shown at increased brightness to bring out fainter features]]
| |
| Neptune possesses five distinct rings<ref name="SmithSoderblom1989" /> named, in order of increasing distance from the planet, Galle, Le Verrier, Lassell, Arago and Adams.<ref name="Miner2007b" /> In addition to these well-defined rings, Neptune may also possess an extremely faint sheet of material stretching inward from the Le Verrier to the Galle ring, and possibly farther in toward the planet.<ref name="SmithSoderblom1989" /><ref name="Burns2001" /> Three of the Neptunian rings are narrow, with widths of about 100 km or less;<ref name="Horn1990" /> in contrast, the Galle and Lassell rings are broad—their widths are between 2,000 and 5,000 km.<ref name="SmithSoderblom1989" /> The Adams ring consists of five bright arcs embedded in a fainter continuous ring.<ref name="SmithSoderblom1989" /> Proceeding counterclockwise, the arcs are: Fraternité, Égalité 1 and 2, Liberté, and Courage.<ref name="Burns2001" /><ref name="Porco1991" /> The first three names come from "[[Liberté, égalité, fraternité|liberty, equality, fraternity]]", the motto of the [[French Revolution]] and [[French Republic|Republic]]. The terminology was suggested by their original discoverers, who had found them during stellar occultations in 1984 and 1985.<ref name="Sicardy1991" /> Four small Neptunian moons have orbits inside the ring system: [[Naiad (moon)|Naiad]] and [[Thalassa (moon)|Thalassa]] orbit in the gap between the Galle and Le Verrier rings; [[Despina (moon)|Despina]] is just inward of the Le Verrier ring; and [[Galatea (moon)|Galatea]] lies slightly inward of the Adams ring,<ref name="Miner2007b" /> embedded in an unnamed faint, narrow ringlet.<ref name="Burns2001" />
| |
| | |
| The Neptunian rings contain a large quantity of [[Micrometre|micrometer]]-sized [[Cosmic dust|dust]]: the dust fraction by cross-section area is between 20% and 70%.<ref name="Burns2001" /> In this respect they are similar to the [[rings of Jupiter]], in which the dust fraction is 50%–100%, and are very different from the [[rings of Saturn]] and [[Rings of Uranus|Uranus]], which contain little dust (less than 0.1%).<ref name="Miner2007b" /><ref name="Burns2001" /> The particles<!--isn't dust made up of particles, too?--> in Neptune's rings are made from a dark material; probably a mixture of ice with [[radiation]]-processed [[organic compound|organics]].<ref name="Miner2007b" /><ref name="SmithSoderblom1989" /> The rings are reddish in color, and their geometrical (0.05) and [[Bond albedo|Bond]] (0.01–0.02) [[albedo]]s are similar to those of the Uranian rings' particles and the inner [[Moons of Neptune|Neptunian moons]].<ref name="SmithSoderblom1989" /> The rings are generally optically thin (transparent); their normal [[optical depth]]s do not exceed 0.1.<ref name="SmithSoderblom1989" /> As a whole, the Neptunian rings resemble those of Jupiter; both systems consist of faint, narrow, dusty ringlets and even fainter broad dusty rings.<ref name="Burns2001" />
| |
| | |
| The rings of Neptune, like those of Uranus, are thought to be relatively young; their age is probably significantly less than that of the [[Solar System]].<ref name="SmithSoderblom1989" /> Also, like those of Uranus, Neptune's rings probably resulted from the collisional fragmentation of onetime inner moons.<ref name="Burns2001" /> Such events create [[Rings of Saturn#Moonlets|moonlet]] belts, which act as the sources of dust for the rings. In this respect the rings of Neptune are similar to faint dusty bands observed by ''Voyager 2'' between the main rings of Uranus.<ref name="SmithSoderblom1989" />
| |
| | |
| == Inner rings ==
| |
| The innermost ring of Neptune is called the ''Galle ring'' after [[Johann Gottfried Galle]], the first person to see Neptune through a telescope (1846).<ref name="Galle" /> It is about 2,000 km wide and orbits 41,000–43,000 km from the planet.<ref name="Miner2007b" /> It is a faint ring with an average normal optical depth of around 10<sup>−4</sup>,{{refn|The normal optical depth τ of a ring is the ratio of the total geometrical [[Cross section (geometry)|cross-section]] of the ring's particles to the area of the ring. It assumes values from zero to infinity. A light beam passing normally through a ring will be attenuated by the factor e<sup>–τ</sup>.<ref name="Ockert1987" />|name=footnoteA|group=lower-alpha}} and with an equivalent depth of 0.15 km.{{refn|The equivalent depth ED of a ring is defined as an integral of the normal optical depth across the ring. In other words <nowiki>ED = ∫τdr</nowiki>, where r is radius.<ref name="Holberg1987" />|name=footnoteB|group=lower-alpha}}<ref name="SmithSoderblom1989" /> The fraction of dust in this ring is estimated from 40% to 70%.<ref name="SmithSoderblom1989" /><ref name="Colwell1990" />
| |
| | |
| The next ring is named the ''Le Verrier ring'' after [[Urbain Le Verrier]], who predicted Neptune's position in 1846.<ref name="LeVerrier" /> With an orbital radius of about 53,200 km,<ref name="Miner2007b" /> it is narrow, with a width of about 113 km.<ref name="Horn1990" /> Its normal optical depth is 0.0062 ± 0.0015, which corresponds to an equivalent depth of 0.7 ± 0.2 km.<ref name="Horn1990" /> The dust fraction in the Le Verrier ring ranges from 40% to 70%.<ref name="Burns2001" /><ref name="Colwell1990" /> The small moon [[Despina (moon)|Despina]], which orbits just inside of it at 52,526 km, may play a role in the ring's confinement by acting as a [[shepherd moon|shepherd]].<ref name="Miner2007b" />
| |
| | |
| The ''Lassell ring'', also known as the ''plateau'', is the broadest ring in the Neptunian system.<ref name="Burns2001" /> It is the namesake of [[William Lassell]], the English astronomer who discovered Neptune's largest moon, [[Triton (moon)|Triton]].<ref name="Lassell" /> This ring is a faint sheet of material occupying the space between the Le Verrier ring at about 53,200 km and the Arago ring at 57,200 km.<ref name="Miner2007b" /> Its average normal optical depth is around 10<sup>−4</sup>, which corresponds to an equivalent depth of 0.4 km.<ref name="SmithSoderblom1989" /> The ring's dust fraction is in the range from 20% to 40%.<ref name="Colwell1990" />
| |
| | |
| There is a small peak of brightness near the outer edge of the Lassell ring, located at 57,200 km from Neptune and less than 100 km wide,<ref name="Miner2007b" /> which some planetary scientists call the ''Arago ring'' after [[François Arago]], a French mathematician, physicist, astronomer and politician.<ref name="Arago" /> However, many publications do not mention the Arago ring at all.<ref name="Burns2001" />
| |
| | |
| == Adams ring ==
| |
| [[File:Neptune ring arcs.jpg|thumb|left|280px|Arcs in the Adams ring (left to right: Fraternité, Égalité, Liberté), plus the Le Verrier ring on the inside]]
| |
| The outer Adams ring, with an orbital radius of about 63,930 km,<ref name="Miner2007b" /> is the best studied of Neptune's rings.<ref name="Miner2007b" /> It is named after [[John Couch Adams]], who predicted the position of Neptune independently of Le Verrier.<ref name="Adams" /> This ring is narrow, slightly eccentric and inclined, with total width of about 35 km (15–50 km),<ref name="Horn1990" /> and its normal optical depth is around 0.011 ± 0.003 outside the arcs, which corresponds to the equivalent depth of about 0.4 km.<ref name="Horn1990" /> The fraction of dust in this ring is from 20% to 40%—lower than in other narrow rings.<ref name="Colwell1990" /> Neptune's small moon [[Galatea (moon)|Galatea]], which orbits just inside of the Adams ring at 61,953 km, acts like a shepherd, keeping ring particles inside a narrow range of orbital radii through a 42:43 outer [[Orbital resonance|Lindblad resonance]].<ref name="Porco1991" /> Galatea's gravitational influence creates 42 radial wiggles in the Adams ring with an amplitude of about 30 km, which have been used to infer Galatea's [[mass]].<ref name="Porco1991" />
| |
| | |
| === Arcs ===
| |
| The brightest parts of the Adams ring, the ring arcs, were the first elements of Neptune's ring system to be discovered.<ref name="Miner2007" /> The arcs are discrete regions within the ring in which the particles that comprise it are mysteriously clustered together. The Adams ring is known to comprise five short arcs, which occupy a relatively narrow range of [[longitude]]s from 247° to 294°.{{refn|The longitude system is fixed as of 18 August 1989. The zero point corresponds to the zero meridian on Neptune.<ref name="Miner2007b" />|group=lower-alpha}} In 1986 they were located between longitudes of:
| |
| * 247–257° (Fraternité),
| |
| * 261–264° (Égalité 1),
| |
| * 265–266° (Égalité 2),
| |
| * 276–280° (Liberté),
| |
| * 284.5–285.5° (Courage).<ref name="Miner2007b" /><ref name="Porco1991" />
| |
| The brightest and longest arc was Fraternité; the faintest was Courage. The normal optical depths of the arcs are estimated to lie in the range 0.03–0.09<ref name="SmithSoderblom1989" /> (0.034 ± 0.005 for the leading edge of Liberté arc as measured by stellar occultation);<ref name="Horn1990" /> the radial widths are approximately the same as those of the continuous ring—about 30 km.<ref name="SmithSoderblom1989" /> The equivalent depths of arcs vary in the range 1.25–2.15 km (0.77 ± 0.13 km for the leading edge of Liberté arc).<ref name="Horn1990" /> The fraction of dust in the arcs is from 40% to 70%.<ref name="Colwell1990" /> The arcs in the Adams ring are somewhat similar to the arc in [[Rings of Saturn#G Ring|Saturn's G ring]].<ref name="Hedman2007" />
| |
| | |
| The highest resolution ''Voyager 2'' images revealed a pronounced clumpiness in the arcs, with a typical separation between visible clumps of 0.1° to 0.2°, which corresponds to 100–200 km along the ring. Because the clumps were not resolved, they may or may not include larger bodies, but are certainly associated with concentrations of microscopic dust as evidenced by their enhanced brightness when backlit by the Sun.<ref name="SmithSoderblom1989" />
| |
| | |
| The arcs are quite stable structures. They were detected by ground based stellar occultations in the 1980s, by ''Voyager 2'' in 1989 and by Hubble Space Telescope and ground based telescopes in 1997–2005 and remained at approximately the same orbital longitudes.<ref name="SmithSoderblom1989" /><ref name="dePater2005" /> However some changes have been noticed. The overall brightness of arcs decreased since 1986.<ref name="dePater2005" /> The Courage arc jumped forward by 8° to 294° (it probably jumped over to the next stable co-rotation resonance position) while the Liberté arc had almost disappeared by 2003.<ref name="Showalter2005" /> The Fraternité and Égalité (1 and 2) arcs have demonstrated irregular variations in their relative brightness. Their observed dynamics is probably related to the exchange of dust between them.<ref name="dePater2005" /> Courage, a very faint arc found during the Voyager flyby, was seen to flare in brightness in 1998, while more recently it was back to its usual dimness. Visible light observations show that the total amount of material in the arcs has remained approximately constant, but they are dimmer in the [[infrared]] light wavelengths where previous observations were taken.<ref name="Showalter2005" />
| |
| | |
| === Confinement ===
| |
| The arcs in the Adams ring remain unexplained.<ref name="Miner2007b" /> Their existence is a puzzle because basic orbital dynamics imply that they should spread out into a uniform ring over a matter of years. Several theories about the arcs' confinement have been suggested, the most widely publicized of which holds that Galatea confines the arcs via its 42:43 co-rotational inclination resonance (CIR).{{refn|The corotation inclination resonance (CIR) of the order ''m'' between a moon on inclined orbit and a ring occurs if the pattern speed of the perturbing potential <math>\Omega</math> (from a moon) equals the [[mean motion]] of the ring particles <math>n_p</math>. In other words the following condition should be met <math>m\Omega=n_pm=(m-1)n_s+\dot\Omega_s</math>, where <math>\dot\Omega_s</math> and <math>n_s</math> are the [[orbital node|nodal]] [[precession]] rate and mean motion of the moon, respectively.<ref name="Porco1991" /> CIR supports ''2m'' stable sites along the ring.|group=lower-alpha}}<ref name="Porco1991" /> The resonance creates 84 stable sites along the ring's orbit, each 4° long, with arcs residing in the adjacent sites.<ref name="Porco1991" /> However measurements of the rings' mean motion with Hubble and [[W. M. Keck Observatory|Keck]] telescopes in 1998 led to the conclusion that the rings are not in CIR with Galatea.<ref name="Dumas1999" /><ref name="Sicardy1999" />
| |
| | |
| A later model suggested that confinement resulted from a co-rotational eccentricity resonance (CER).{{refn|The corotation eccentricity resonance (CER) of the order ''m'' between a moon on eccentric orbit and a ring occurs if the pattern speed of the perturbing potential <math>\Omega</math> (from a moon) equals the [[mean motion]] of the ring particles <math>n_p</math>. In other words the following condition should be met <math>m\Omega=n_pm=(m-1)n_s+\dot\omega_s</math>, where <math>\dot\omega_s</math> and <math>n_s</math> are the [[apsides|apsidal]] [[precession]] rate and mean motion of the moon, respectively.<ref name="Namouni2002" /> CER supports ''m'' stable sites along the ring.|group=lower-alpha}}<ref name="Namouni2002" /> The model takes into account the finite mass of the Adams ring, which is necessary to move the resonance closer to the ring. A byproduct of this theory is a mass estimate for the Adams ring—about 0.002 of the mass of Galatea.<ref name="Namouni2002" /> A third theory proposed in 1986 requires an additional moon orbiting inside the ring; the arcs in this case are trapped in its stable [[Lagrangian point]]s. However ''Voyager 2'''s observations placed strict constraints on the size and mass of any undiscovered moons, making such a theory unlikely.<ref name="SmithSoderblom1989" /> Some other more complicated theories hold that a number of moonlets are trapped in co-rotational resonances with Galatea, providing confinement of the arcs and simultaneously serving as sources of the dust.<ref name="Salo1998" />
| |
| | |
| == Exploration ==
| |
| The rings were investigated in detail during the ''Voyager 2'' spacecraft's flyby of Neptune in August 1989.<ref name="SmithSoderblom1989" /> They were studied with optical imaging, and through observations of occultations in ultraviolet and visible light.<ref name="Horn1990" /> ''Voyager 2'' observed the rings in different geometries relative to the Sun, producing images of [[backscatter|back-scattered]], [[forward scatter|forward-scattered]] and side-scattered light.<ref group=lower-alpha>Forward-scattered light is light scattered at a small angle relative to solar light. Back-scattered light is light scattered at an angle close to 180° (backwards) relative to solar light. The scattering angle is close to 90° for side-scattered light.</ref><ref name="SmithSoderblom1989" /> Analysis of these images allowed derivation of the phase function (dependence of the ring's reflectivity on the angle between the observer and Sun), and geometrical and [[Bond albedo]] of ring particles.<ref name="SmithSoderblom1989" /> Analysis of Voyager's images also led to discovery of six inner [[moons of Neptune]], including the Adams ring shepherd [[Galatea (moon)|Galatea]].<ref name="SmithSoderblom1989" />
| |
| | |
| == Properties ==
| |
| {| class="wikitable plainrowheaders" style="text-align: center;"
| |
| |-
| |
| ! scope="col" style="width: 8em;" | Ring name
| |
| ! scope="col" | Radius (km)<ref name="Miner2007b" />
| |
| ! scope="col" | Width (km)
| |
| ! scope="col" | Eq. depth (km)<ref group=lower-alpha name=footnoteB /><ref group=lower-alpha>The equivalent depth of Galle and Lassell rings is a product of their width and the normal optical depth.</ref>
| |
| ! scope="col" | N. Opt. depth<ref group=lower-alpha name=footnoteA />
| |
| ! scope="col" | Dust fraction,%<ref name="Colwell1990" />
| |
| ! scope="col" | Ecc.
| |
| ! scope="col" | Incl.(°)
| |
| ! scope="col" | Notes
| |
| |-
| |
| ! scope="row" | Galle (N42)
| |
| | 40,900–42,900
| |
| | 2,000
| |
| | 0.15<ref name="SmithSoderblom1989" />
| |
| | ~ 10<sup>−4</sup><ref name="SmithSoderblom1989" />
| |
| | 40–70
| |
| | ?
| |
| | ?
| |
| | style="text-align: left;" | Broad faint ring
| |
| |-
| |
| ! scope="row" | Le Verrier (N53)
| |
| | 53,200 ± 20
| |
| | 113<ref name="Horn1990" />
| |
| | 0.7 ± 0.2<ref name="Horn1990" />
| |
| | 6.2 ± 1.5{{Esp|–3}}<ref name="Horn1990" />
| |
| | 40–70
| |
| | ?
| |
| | ?
| |
| | style="text-align: left;" | Narrow ring
| |
| |-
| |
| ! scope="row" | Lassell
| |
| | 53,200–57,200
| |
| | 4,000
| |
| | 0.4<ref name="SmithSoderblom1989" />
| |
| | ~ 10<sup>−4</sup><ref name="SmithSoderblom1989" />
| |
| | 20–40
| |
| | ?
| |
| | ?
| |
| | style="text-align: left;" rowspan="2" | Lassell ring is a faint sheet of material stretching from Le Verrier to Arago
| |
| |-
| |
| ! scope="row" | Arago
| |
| | 57,200
| |
| | <100<ref name="SmithSoderblom1989" />
| |
| | ?
| |
| | ?
| |
| | ?
| |
| | ?
| |
| | ?
| |
| |-
| |
| ! scope="row" | Adams (N63)
| |
| | 62,932 ± 2
| |
| | 15–50<ref name="Horn1990" />
| |
| | 0.4<ref name="SmithSoderblom1989" /><p>1.25–2.15<ref name="Horn1990" /> (in arcs)
| |
| | 0.011 ± 0.003<ref name="Horn1990" /><p>0.03–0.09<ref name="SmithSoderblom1989" /> (in arcs)
| |
| | 20–40<p> 40–70 (in arcs)
| |
| | 4.7 ± 0.2{{Esp|–4}}<ref name="Porco1991" />
| |
| | 0.0617 ± 0.0043<ref name="Porco1991" />
| |
| | style="text-align: left;" | Five bright arcs
| |
| |}
| |
| | |
| ''*A question mark means that the parameter is not known.''
| |
| | |
| == Notes ==
| |
| {{reflist|group=lower-alpha}}
| |
| | |
| == References ==
| |
| {{reflist
| |
| | colwidth = 30em
| |
| | refs =
| |
| <ref name="Hubbard1985">{{cite journal |first=W.B.|last=Hubbard|coauthors=Brahic, A.; Bouchet, P.; Elicer, L.-R.; Haefner, R.; Manfroid, J.; Roques, F.; Sicardy, B.; Vilas, F.|title=Occultation Detection of a Neptune Ring Segment|year=1985|journal=Press Abstracts from the Sixteenth Lunar and Planetary Science Conference, held March 11–15, 1985, in Houston, TX. LPI Contribution 559, published by the Lunar and Planetary Institute, 3303 Nasa Road 1, Houston, TX 77058, 1985, p.35| bibcode=1985LPICo.559...35H}}</ref>
| |
| <ref name="Manfroid1986">{{cite journal |first=J. |last=Manfroid|coauthors= Haefner, R.; Bouchet, P.|title=New evidence for a ring around Neptune|journal= Astronomy and Astrophysics|year=1986|volume=157|issue=1|page=L3 |bibcode=1986A&A...157L...3M}}</ref>
| |
| <ref name="Miner2007">{{cite book|title=Planetary Ring Systems|year=2007|author= Miner, Ellis D., Wessen, Randii R., Cuzzi, Jeffrey N. |publisher= Springer Praxis Books |chapter=The discovery of the Neptune ring system| isbn=978-0-387-34177-4}}</ref>
| |
| <ref name="Nicholson1990">{{cite journal |first= P.D.|last=Nicholson|title= Five Stellar Occultations by Neptune: Further Observations of Ring Arcs| journal= Icarus| year= 1990| volume= 87 |issue= 1| page= 1| bibcode= 1990Icar...87....1N|doi= 10.1016/0019-1035(90)90020-A |author2= Cooke, Maren L. |last3= Matthews |first3= Keith |display-authors= 2 |last4= Elias |first4= Jonathan H. |last5= Gilmore |first5= Gerard}}</ref>
| |
| <ref name="dePater2005">{{cite journal|last=dePater|first=Imke|title= The Dynamic Neptunian Ring Arcs: Evidence for a Gradual Disappearance of Liberté and Resonant Jump of Courage|year=2005|journal=Icarus|volume=174|issue=1|pages=263–272| doi=10.1016/j.icarus.2004.10.020|url=http://astro.berkeley.edu/~echiang/ppp/nepring.pdf|format=pdf|bibcode=2005Icar..174..263D|author2=Gibbard, Seren|last3=Chiang|first3=Eugene|display-authors=2|last4=Hammel|first4=Heidi B.|last5=MacIntosh|first5=Bruce|last6=Marchis|first6=Franck|last7=Martin|first7=Shuleen C.|last8=Roe|first8=Henry G.|last9=Showalter|first9=Mark}}</ref>
| |
| <ref name="SmithSoderblom1989">
| |
| {{cite doi|10.1126/science.246.4936.1422}}
| |
| </ref>
| |
| <ref name="Dumas1999">{{cite journal|last=Dumas|first=Cristophe|title=Stability of Neptune's ring arcs in question|year=1999|journal=Nature|volume=400|issue=6746|pages=733–735|doi=10.1038/23414| url=http://nicmosis.as.arizona.edu:8000/PUBLICATIONS/NEPTUNE_RING.pdf|format=pdf|bibcode = 1999Natur.400..733D|author2=Terrile, Richard J.|last3=Smith|first3=Bradford A.|display-authors=2|last4=Schneider|first4=Glenn|last5=Becklin|first5=E. E. }}</ref>
| |
| <ref name="Sicardy1991">{{cite journal |first=B.|last=Sicardy|coauthors=Roques, F.; Brahic, A.|title= ''Neptune's Rings, 1983–1989 Ground-Based Stellar Occultation Observations''| journal= Icarus| year= 1991| volume= 89 |issue=2| page= 220|bibcode= 1991Icar...89..220S|doi= 10.1016/0019-1035(91)90175-S}}</ref>
| |
| <ref name="Burns2001">{{cite encyclopedia|last=Burns|first=J.A.|coauthors=Hamilton, D.P.; Showalter, M.R.|title=Dusty Rings and Circumplanetary Dust: Observations and Simple Physics |encyclopedia=Interplanetary Dust|year=2001 |publisher=Springer |place=Berlin |editor=Grun, E.; Gustafson, B. A. S.; Dermott, S. T.; Fechtig H. |pages=641–725|url=http://www.astro.umd.edu/~hamilton/research/preprints/BurHamSho01.pdf|format=pdf}}</ref>
| |
| <ref name="Miner2007b">{{cite book|title=Planetary Ring System|year=2007|author= Miner, Ellis D., Wessen, Randii R., Cuzzi, Jeffrey N. |publisher= Springer Praxis Books |chapter=Present knowledge of the Neptune ring system| isbn=978-0-387-34177-4}}</ref>
| |
| <ref name="Horn1990">{{cite journal|last=Horn|first=Linda J.|coauthors=Hui, John; Lane, Arthur L.|title=Observations of Neptunian rings by Voyager photopolarimeter experiment|year=1990|journal=Geophysics Research Letters|volume=17|issue=10|pages=1745–1748|doi=10.1029/GL017i010p01745|bibcode=1990GeoRL..17.1745H}}</ref>
| |
| <ref name="Colwell1990">{{cite journal|last=Colwell|first=Joshua E.|coauthors=Esposito, Larry W.|title=A model of dust production in the Neptunian ring system|year=1990|journal=Geophysics Research Letters|volume=17|issue=10|pages=1741–1744|doi=10.1029/GL017i010p01741|bibcode=1990GeoRL..17.1741C}}</ref>
| |
| <ref name="Porco1991">{{cite journal |first=C.C.|last=Porco|title= An Explanation for Neptune's Ring Arcs| journal= Science| year= 1991| volume= 253| pages= 995–1001| bibcode= 1991Sci...253..995P| doi= 10.1126/science.253.5023.995|pmid= 17775342 |issue=5023}}</ref>
| |
| <ref name="Hedman2007">{{cite journal|title=The Source of Saturn's G Ring|last=Hedman|first= M. M.| journal=Science|volume=317|pages=653–656|year=2007|doi=10.1126/science.1143964|pmid=17673659| url=http://ciclops.org/media/sp/2007/3882_9284_0.pdf|format=pdf|issue=5838|bibcode = 2007Sci...317..653H|author-separator=,|author2=Burns|author3=J. A.|author4=Tiscareno|author5=M. S.|display-authors=4|last6=Roussos|first6=E.|last7=Krupp|first7=N.|last8=Paranicas|first8=C.|last9=Kempf|first9=S. }}</ref>
| |
| <ref name="Showalter2005">{{cite journal|first=M.R.|last=Showalter|coauthors=et al.| title= Updates on the dusty rings of Jupiter, Uranus and Neptune| journal= Dust in Planetary Systems, Proceedings of the conference held September 26–28, 2005 in Kaua'i, Hawaii| year= 2005|volume=1280| page= 130| bibcode= 2005LPICo1280..130S|last2=Burns|last3=De Pater|last4=Hamilton|last5=Lissauer|last6=Verbanac}}</ref>
| |
| <ref name="Sicardy1999">{{cite journal |first=B.|last=Sicardy| title= Images of Neptune's ring arcs obtained by a ground-based telescope|journal=Nature|year=1999|volume=400 |issue=6746|pages=731–733|doi= 10.1038/23410|bibcode=1999Natur.400..731S |author2=Roddier, F. |last3=Roddier |first3=C. |display-authors=2 |last4=Perozzi |first4=E. |last5=Graves |first5=J. E. |last6=Guyon |first6=O. |last7=Northcott |first7=M. J.}}</ref>
| |
| <ref name="Salo1998">{{cite journal|last=Salo|first=Heikki|coauthors=Hanninen, Jyrki |title=Neptune's Partial Rings: Action of Galatea on Self-Gravitating Arc Particles|year=1998| journal=Science|volume=282|pages=1102–1104| doi=10.1126/science.282.5391.1102|bibcode=1998Sci...282.1102S|pmid=9804544|issue=5391}}</ref>
| |
| <ref name="Namouni2002">{{cite journal|last= Namouni|first=Fathi|coauthors=Porco, Carolyn |title= The confinement of Neptune's ring arcs by the moon Galatea|year=2002|journal=Nature |volume=417|pages=45–47|doi=10.1038/417045a|url=|pmid= 11986660|issue= 6884|bibcode = 2002Natur.417...45N }}</ref>
| |
| <ref name="Ockert1987">{{cite journal
| |
| | last = Ockert
| |
| | first = M.E.
| |
| | coauthors = Cuzzin, J.N.; Porco, C.C.; and Johnson, T.V.
| |
| | title = Uranian ring photometry: Results from Voyager 2
| |
| | journal = Journal of Geophysical Research
| |
| | year = 1987
| |
| | volume = 92
| |
| | issue = A13
| |
| | pages = 14,969–78
| |
| | bibcode = 1987JGR....9214969O
| |
| | doi = 10.1029/JA092iA13p14969
| |
| }}</ref>
| |
| <ref name="Holberg1987">{{cite journal
| |
| | last = Holberg
| |
| | first = J.B.
| |
| | coauthors = Nicholson, P. D.; French, R.G.; Elliot, J.L.
| |
| | title = Stellar occultation probes of the Uranian rings at 0.1 and 2.2 μm – A comparison of Voyager UVS and earth-based results
| |
| | journal = The Astronomical Journal
| |
| | year = 1987
| |
| | volume = 94
| |
| | pages = 178–188
| |
| | bibcode = 1987AJ.....94..178H
| |
| | doi = 10.1086/114462
| |
| }}</ref>
| |
| <ref name="Galle">{{cite journal|title=Obituaries: G. V. Schiaparelli, J. G. Galle, J. B. N. Hennessey J. Coles, J. E. Gore|journal=The Observatory|volume=33|pages=311–318|year=1910|url=http://adsabs.harvard.edu/abs/1910Obs....33..311|bibcode = 1910Obs....33..311.|author=Editorial }}</ref>
| |
| <ref name="LeVerrier">{{cite journal|last=Adams|first=John|title=Prof. Adams on Leverrier's Planetary Theories|journal=Nature|volume=16|issue=413|pages=462–464|year=1877|url=http://adsabs.harvard.edu/abs/1877Natur..16..462|doi=10.1038/016462a0|bibcode = 1877Natur..16..462. }}</ref>
| |
| <ref name="Lassell">{{cite journal|title=Fellows deceased, list of Lassell, W|journal=Monthly Notices of the Royal Astronomical Society|volume=41|pages=188–191|year=1881|bibcode=1881MNRAS..41..188.|author1=<Please add first missing authors to populate metadata.>}}</ref>
| |
| <ref name="Arago">{{cite journal|title=Extract of a Letter respecting the Lunar Tables (Obituary of M. Arago)|journal=Monthly Notices of the Royal Astronomical Society|volume=14|pages=102–107|year=1854|bibcode=1853MNRAS..14....1H|author1=Hansen|first1=P. A.}}</ref>
| |
| <ref name="Adams">{{cite journal|title= OBITUARY: List of Fellows and Associates deceased during the year: John Couch Adams|journal=Monthly Notices of the Royal Astronomical Society|volume=53|pages=184–209|year=1893|bibcode=1893MNRAS..53..184.|author1= <Please add first missing authors to populate metadata.>}}</ref>
| |
| }}
| |
| | |
| == External links ==
| |
| {{Commons category}}
| |
| * [http://solarsystem.nasa.gov/planets/profile.cfm?Object=Neptune&Display=Rings Neptune's Rings] by [http://solarsystem.nasa.gov NASA's Solar System Exploration]
| |
| * [http://planetarynames.wr.usgs.gov/append8.html Gazetteer of Planetary Nomenclature – Ring and Ring Gap Nomenclature (Neptune), USGS]
| |
| | |
| {{Planetary rings}}
| |
| {{Neptune}}
| |
| {{Moons of Neptune}}
| |
| {{Voyager program}}
| |
| | |
| {{Featured article}}
| |
| | |
| [[Category:Neptune]]
| |
| [[Category:Planetary rings|Neptune]]
| |
| [[Category:Astronomical objects discovered in 1989]]
| |
| | |
| {{Link FA|es}}
| |
| {{Link FA|ca}}
| |
| {{Link GA|ja}}
| |
| [[nl:Neptunus (planeet)#Manen en ringen rondom Neptunus]]
| |