Polydeuces (moon)

Last updated

Polydeuces
Polydeuces PIA08209.png
Polydeuces imaged approximately 73,000 km (45,000 mi) away from the Cassini spacecraft on 22 May 2006
Discovery [1] [2]
Discovered by Cassini Imaging Science Team [lower-alpha 1]
Discovery date21 October 2004
(date of discovery images) [4] : 223 
Designations
Designation
Saturn XXXIV
Pronunciation /ˌpɒlɪˈdjuːsiːz/ [5]
Named after
 Πολυδεύκης Polydeykēs
S/2004 S 5
Adjectives Polydeucean /ˌpɒlɪdjuːˈsiːən/ [6]
Polydeucian /ˌpɒlɪˈdjuːsiən/ [7]
Orbital characteristics  [8] [9] : 9 
Epoch 1 January 2000 12:00 UT
(JD 2451545.0)
Earliest precovery date2 April 2004 [10] : 695, 702  [11] : 261 
377600 km
Eccentricity 0.019
2.736916  d [8]
Average orbital speed
10.03 km/s [12] : 2 
Inclination 0.2° [lower-alpha 2]
Satellite of Saturn
Group L5 Dione trojan
Physical characteristics
Dimensions3.50 × 3.10 × 2.62 km
(± 0.40 × 0.40 × 0.40 km) [13] : 7 
Mean diameter
3.06±0.40 km [13] : 7 
Volume 15 km3 [lower-alpha 3]
Mass ≈ 8×1012 kg (assumed; unmeasured) [lower-alpha 4]
Mean density
≈ 0.5 g/cm3 (assumed; unmeasured) [14] [15] : 3  [12] : 2 
≈ 0.0002 m/s2 at longest axis
to ≈ 0.0003 m/s2 at poles [lower-alpha 5]
≈ 0.0008 km/s at longest axis
to ≈ 0.0009 km/s at poles [lower-alpha 6]
assumed synchronous [12] : 4 

    Polydeuces /ˌpɒlɪˈdjuːsiːz/ , also designated Saturn XXXIV, is a small trojan moon of Saturn occupying the trailing L5 Lagrange point of Dione. It was discovered by the Cassini Imaging Science Team in images taken by the Cassini space probe on 21 October 2004. With a mean diameter of about 3 km (1.9 mi), Polydeuces is thought to have a smooth surface coated with fine, icy particles accumulated from the cryovolcanic plumes of Enceladus. In its orbit around Saturn, Polydeuces periodically drifts away from Dione's Lagrange point due to gravitational perturbations by other nearby moons of Saturn. Of the four known trojan moons of Saturn, Polydeuces exhibits the largest displacement from its Lagrange point.

    Contents

    Discovery

    Cassini discovery images of Polydeuces on 21 October 2004 Polydeuces discovery images annotated.gif
    Cassini discovery images of Polydeuces on 21 October 2004

    Polydeuces was discovered by the Cassini Imaging Science Team [lower-alpha 1] on 24 October 2004 while routinely investigating images taken by the Cassini space probe earlier on 21 October 2004. [4] : 223  The images were visually inspected through the blink comparison technique, which revealed any potential moons that moved relative to the background stars. The discovery images consisted of four frames taken with Cassini's wide-angle camera over less than six minutes, which showed Polydeuces moving 3–6 pixels per frame. [lower-alpha 7] [4] : 223  The observed motion of Polydeuces immediately suggested that it could be orbiting Saturn at the distance of one of the large moons, Dione, possibly sharing its orbit in a co-orbital configuration. [4] : 223 

    By 4 November 2004, the Cassini Imaging Science Team obtained more Cassini images of Polydeuces, including two frames taken on 2 November 2004 and another two predating the discovery images by three hours. [4] : 223–226  Preliminary orbit determinations using these images confirmed that Polydeuces was a co-orbital trojan moon residing around Dione's L5 Lagrange point. [4] : 226  With the aid of ephemeris predictions from Polydeuces's newly determined orbit, the Cassini Imaging Science Team was able to identify 52 pre-discovery detections of Polydeuces in Cassini's narrow-angle camera images taken between 9 April 2004 and 9 May 2004. [4] : 226  The International Astronomical Union (IAU) announced the discovery of Polydeuces on 8 November 2004. [16] Besides Polydeuces, Cassini has discovered five other objects orbiting Saturn in 2004: Methone, Pallene, S/2004 S 3, S/2004 S 4, and S/2004 S 6. [17] : 1226–1227 

    After the discovery announcement, Cassini was retasked to begin targeted observations of Polydeuces in January 2005 to better determine its orbit. [4] : 226  In 2006, researchers found even earlier Cassini pre-discovery images of Polydeuces taken on 2 April 2004. [10] : 695, 702 

    Name

    The name Polydeuces was approved and announced by the IAU Working Group on Planetary System Nomenclature on 21 January 2005. [18] In Greek mythology, Polydeuces is another name for Pollux, who is the twin brother of Castor and the son of Zeus and Leda. [2] Polydeuces is also known by its official Roman numeral designation Saturn XXXIV (34th moon of Saturn discovered) and was previously known by its provisional designation S/2004 S 5, which was given by the IAU when it announced the moon's discovery. [16] [18]

    Orbit

    The trojan points are located on the L4 and L5 Lagrange points, on the orbital path of the secondary object Dione (blue), around the primary object Saturn (yellow). All of the Lagrange points are highlighted in red. Lagrange very massive.svg
    The trojan points are located on the L4 and L5 Lagrange points, on the orbital path of the secondary object Dione (blue), around the primary object Saturn (yellow). All of the Lagrange points are highlighted in red.
    Animation of Polydeuces's librating tadpole orbit in a rotating reference frame with respect to Dione .mw-parser-output .legend{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .legend-color{display:inline-block;min-width:1.25em;height:1.25em;line-height:1.25;margin:1px 0;text-align:center;border:1px solid black;background-color:transparent;color:black}.mw-parser-output .legend-text{} Polydeuces * Helene * Dione * Saturn Animation of Polydeuces's orbit relative to Saturn and Dione.gif
    Animation of Polydeuces's librating tadpole orbit in a rotating reference frame with respect to Dione
      Polydeuces  ·  Helene ·  Dione ·  Saturn

    Polydeuces is an inner moon of Saturn in a co-orbital configuration with Dione, meaning they share the same orbit. [11] : 261  [19] : 2  Together with Dione and its other co-orbital companion Helene, Polydeuces orbits Saturn in 2.74 days at an average distance of 377,600 km (234,600 mi) from the planet's center, between the orbits of Tethys and Rhea. [8] Due to gravitational perturbations by other nearby moons of Saturn, Polydeuces's orbital radius can vary by ±7,660 km (4,760 mi) over time. [4] : 232  Its orbit is closely aligned with Saturn's equatorial plane with a low orbital inclination of 0.2°. [lower-alpha 2]

    Polydeuces has a slightly elliptical orbit with an eccentricity of 0.019, which is unusually higher than Dione's eccentricity of 0.002. While Dione's eccentricity is known to result from its 1:2 mean-motion orbital resonance with Enceladus, the effects of this resonance are too weak to explain Polydeuces's relatively high eccentricity. [4] : 233  One possible explanation is that Polydeuces always had an eccentric orbit since its formation because its orbit did not change much over billions of years. [4] : 233 

    Polydeuces resides around Dione's L5 Lagrange point trailing 60° behind Dione in its orbit, which makes Polydeuces a trojan moon of Dione. The Lagrange points are locations where the gravitational pulls of Dione and Saturn balance out, allowing for stable co-orbital configurations in Dione's trojans. [20] Dione's other co-orbital moon, Helene, is a trojan residing around the L4 Lagrange point leading 60° ahead of Dione. Trojan moons are not unique to Dione; another large moon of Saturn, Tethys, also has two trojans, named Telesto and Calypso, which reside in its L4 and L5 Lagrange points, respectively. [4]

    Because of perturbations by other moons of Saturn, Polydeuces does not stay exactly 60° behind Dione; its angular distance from Dione oscillates or librates over time. [4] : 231  Of Saturn's four known trojan moons, Polydeuces librates the farthest from its Lagrange point: its angular distance behind Dione oscillates from 33.9° to 91.4° with a period of 790.931 days (2.17 years). [10] : 702  [lower-alpha 8] In a rotating reference frame with respect to Dione's orbit, Polydeuces appears to travel in a looping path around Dione's L5 point due to its varying relative speed and radial distance from Saturn in its perturbed eccentric orbit. [4] : 231–232  Polydeuces's apparent looping motion combined with its librating angular distance from Dione forms a tadpole orbit about Dione's L5 point. [4] : 231 

    Origin

    Polydeuces is thought to have formed by accreting out of leftover debris trapped in Dione's L5 Lagrange point, in a similar process experienced by Saturn's other trojan moons. This process likely took place at an intermediate stage of the formation of Saturn's moons, when Tethys and Dione have not finished forming and gases have become depleted in Saturn's circumplanetary disk. [21] : 2133  [12] : 4  Mean-motion orbital resonances by other nearby moons did not appear to play a significant role in the formation of the trojan moons. [21] : 2139 

    Dynamical modeling of the trojan moons' formation suggests that Tethys's and Dione's L4 and L5 Lagrange points should have started with similar amounts of material for trojan moons to form with roughly similar sizes. [21] : 2136  However, this is not the case for Dione's trojans, Helene and Polydeuces, whose masses significantly differ by more than an order of magnitude. As of yet, this mass asymmetry in Dione's L4 and L5 trojans remains unexplained. [21] : 2139 

    Physical characteristics

    As of 2020, the most recent estimate for Polydeuces's dimensions is 3.50 km × 3.10 km × 2.62 km (2.17 mi × 1.93 mi × 1.63 mi), based on resolved Cassini imagery of the moon from 2015. [13] : 7, 30  These dimensions correspond to a volume-equivalent mean diameter of 3.06 km (1.90 mi) for Polydeuces. [13] : 7 Cassini's highest-resolution images of Polydeuces from 2015 show that it has an elongated shape, with a relatively smooth limb deviating from a simple ellipsoid. [13] : 30  Polydeuces presumably rotates synchronously with its orbital period, similar to the rest of Saturn's trojan moons. [12] : 4 

    Little is known about Polydeuces's other physical properties because it was never approached up close by Cassini or any other space mission to Saturn. [19] : 3  Because of its very small size, Polydeuces's gravitational perturbations on the trajectory of Cassini spacecraft and other Saturnian moons are negligible, which prevents the measurement of the moon's mass and density. [9] : 5  In spite of this, researchers assume that Polydeuces has a density similar to those of Saturn's small inner moons, whose average density is 0.5 g/cm3, [14] [15] : 3  [12] : 2  [19] : 2 

    Cassini images of Polydeuces
    Polydeuces N1809910848.png
    Distance approx. 44,800 km (27,800 mi), 9 May 2015
    Polydeuces N1813127275 enhanced.png
    Distance approx. 34,800 km (21,600 mi), 16 June 2015. Polydeuces is illuminated by both Saturn and the Sun.

    Polydeuces's small size makes it prone to disruption by impact events. Depending on the size-frequency of impactors in the Saturnian system, Polydeuces is predicted to have suffered at least one disruptive impact in the last one billion years. [12] : 11  This implies that Polydeuces is either very young with an age of less than one billion years, or it is a primordial moon that has consistently reaccreted from each disruptive impact over the Saturnian system's 4.5 billion-year lifespan. [12] : 13 

    Polydeuces has a bright and likely smooth surface due to the accumulation of fine water ice particles from the surrounding E Ring, which is generated by the cryovolcanic plumes of Enceladus. [22] [12] : 11  Because of its small size, any craters on Polydeuces would be completely buried in E Ring material, giving it a craterless appearance resembling Methone or Pallene. [22] [12] : 11  Its geometric albedo is unknown since it has never been observed at low phase angles. [13] : 10, 30 Cassini imagery shows that Polydeuces has a uniform surface brightness across its leading and trailing hemispheres. [13] : 23  Its surface is about as bright as Dione's but darker than Helene's. [13] : 23  The trojan moons of Tethys exhibit a similar difference in surface brightness, where Calypso is brighter than Telesto and Tethys. [13] : 23  The reason for these brightness asymmetries in the trojan moons of Dione and Tethys remains unknown; possible explanations include an asymmetric distribution of E Ring particles or recent impacts that brightened Helene and Calypso. [13] : 27–28 

    Exploration

    Cassini is the only space mission to Saturn that has made targeted observations of Polydeuces. [4] Over the 13-year span of Cassini's mission in orbit around Saturn, the spacecraft has made 22 close approaches within 130,000 km (81,000 mi) of Polydeuces. [23] Cassini's closest encounter with Polydeuces took place on 17 February 2005, when it passed 6,446.7 km (4,005.8 mi) from Polydeuces while moving outbound from periapse. [23] However, Cassini did not take any images of Polydeuces on that date. [24] The only encounters where Cassini has taken resolved images of Polydeuces were on 22 May 2006, 10 May 2015, and 16 June 2015, at closest approach distances of 64,089.9 km (39,823.6 mi), 33,997.8 km (21,125.3 mi), and 34,794.3 km (21,620.2 mi), respectively. [23] [13] : 31  [lower-alpha 9] Cassini's two close encounters in 2015 provided the first images where Polydeuces was larger than 10 pixels across. [13] : 30 

    See also

    Notes

    1. 1 2 Members of the Cassini Imaging Science Team include (in alphabetical surname order): Andre Brahic, Joe Burns, Tony DelGenio, Luke Dones, Andy Ingersoll, Torrence Johnson, Alfred McEwen, Carl D. Murray, Gerhard Neukum, Carolyn Porco, Steve Squyres, Peter Thomas, Joe Veverka, and Bob West. [3]
    2. 1 2 The mean orbital inclination is given with respect to the Polydeuces's local Laplace plane. [8] [9] : 9  Conincidentally, the Laplace plane inclination value is close to the mean orbital inclination with respect to Saturn's equator, given as 0.1774° in Spitale et al. (2006), Table 6. [10] : 695, 698 
    3. ↑ Volume calculated from Polydeuces's volume-equivalent sphere radius of 1.53±0.20 km given by Hedman et al. (2020). [13] : 7 
    4. ↑ Mass calculated by multiplying Polydeuces's volume with its assumed density of 500 kg/m3 according to the formula .
    5. ↑ Surface gravity g is calculated from the formula , where G is the gravitational constant, M is the body's mass, and r is the body's radius (or semi-axis if nonspherical). For Polydeuces, its mass is approximately 8×1012 kg for an assumed density of 500 kg/m3. For Polydeuces's longest semi-axis of 1.75 km, [13] : 7  the surface gravity would be about 0.0002 m/s2, while for Polydeuces's shortest (polar) semi-axis of 1.31 km, the surface gravity would be about 0.0003 m/s2.
    6. ↑ Escape velocity ve is calculated from the formula , where G is the gravitational constant, M is the body's mass, and r is the body's radius (or semi-axis if nonspherical). For Polydeuces, its mass is approximately 8×1012 kg for an assumed density of 500 kg/m3. For Polydeuces's longest semi-axis of 1.75 km, [13] : 7  the escape velocity would be about 0.0008 km/s, while for Polydeuces's shortest (polar) semi-axis of 1.31 km, the escape velocity would be about 0.0009 km/s.
    7. ↑ The discovery announcement of Polydeuces in IAUC 8432 mistakenly reports that it was discovered in narrow-angle Cassini images on 21 October 2004. [16] All Cassini images containing Polydeuces on 21 October 2004 were taken with the wide-angle camera, as reported in Murray et al. (2005), Table 1 [4] : 224–225  and shown in NASA's Outer Planets Unified Search tool for archived Cassini data.
    8. ↑ The angular distance minimum and maximum are calculated by adding –60° (negative because L5 is behind Dione) to Polydeuces's libration amplitudes of –31.41° and +26.06° given by Spitale et al. (2006) [10] : 702 
    9. ↑ Hedman et al. (2020) list all resolved Cassini observations of Polydeuces in Table 7, but they only give the image IDs of these observations. [13] : 31  Inputting these image IDs into NASA's Outer Planets Unified Search query form shows the date on which these images were taken.

    Related Research Articles

    <span class="mw-page-title-main">Lagrange point</span> Equilibrium points near two orbiting bodies

    In celestial mechanics, the Lagrange points are points of equilibrium for small-mass objects under the gravitational influence of two massive orbiting bodies. Mathematically, this involves the solution of the restricted three-body problem.

    <span class="mw-page-title-main">Telesto (moon)</span> Trojan moon of Saturn

    Telesto is a moon of Saturn. It was discovered by Smith, Reitsema, Larson and Fountain in 1980 from ground-based observations, and was provisionally designated S/1980 S 13. In the following months, several other apparitions were observed: S/1980 S 24, S/1980 S 33, and S/1981 S 1.

    <span class="mw-page-title-main">Atlas (moon)</span> Moon of Saturn

    Atlas is an inner satellite of Saturn which was discovered by Richard Terrile in 1980 from Voyager photos and was designated S/1980 S 28. In 1983 it was officially named after Atlas of Greek mythology, because it "holds the rings on its shoulders" like the Titan Atlas held the sky up above the Earth. It is also designated Saturn XV.

    <span class="mw-page-title-main">Rhea (moon)</span> Moon of Saturn

    Rhea is the second-largest moon of Saturn and the ninth-largest moon in the Solar System, with a surface area that is comparable to the area of Australia. It is the smallest body in the Solar System for which precise measurements have confirmed a shape consistent with hydrostatic equilibrium. It was discovered in 1672 by Giovanni Domenico Cassini.

    <span class="mw-page-title-main">Helene (moon)</span> Trojan moon of Saturn

    Helene is a moon of Saturn. It was discovered by Pierre Laques and Jean Lecacheux in 1980 from ground-based observations at Pic du Midi Observatory, and was designated S/1980 S 6. In 1988 it was officially named after Helen of Troy, who was the granddaughter of Cronus (Saturn) in Greek mythology. Helene is also designated Saturn XII (12), which it was given in 1982, and Dione B, because it is co-orbital with Dione and located in its leading Lagrangian point (L4). It is one of four known trojan moons.

    <span class="mw-page-title-main">Tethys (moon)</span> Moon of Saturn

    Tethys, or Saturn III, is a fifth largest moon of Saturn about 1,060 km (660 mi) across. It was discovered by G. D. Cassini in 1684 and is named after the titan Tethys of Greek mythology.

    <span class="mw-page-title-main">Iapetus (moon)</span> Moon of Saturn

    Iapetus is a moon of Saturn. With an estimated diameter of 1,469 km, it is the third-largest moon of Saturn and the eleventh-largest in the Solar System. Named after the Titan Iapetus, the moon was discovered in 1671 by Giovanni Domenico Cassini.

    <span class="mw-page-title-main">Janus (moon)</span> Moon of Saturn

    Janus is an inner satellite of Saturn. It is also known as Saturn X. It is named after the mythological Janus.

    <span class="mw-page-title-main">Epimetheus (moon)</span> Moon of Saturn

    Epimetheus is an inner satellite of Saturn. It is also known as Saturn XI. It is named after the mythological Epimetheus, brother of Prometheus.

    <span class="mw-page-title-main">Pandora (moon)</span> Moon of Saturn

    Pandora is an inner satellite of Saturn. It was discovered in 1980 from photos taken by the Voyager 1 probe and was provisionally designated S/1980 S 26. In late 1985, it was officially named after Pandora from Greek mythology. It is also designated as Saturn XVII.

    <span class="mw-page-title-main">Calypso (moon)</span> Trojan moon of Saturn

    Calypso is a moon of Saturn. It was discovered in 1980, from ground-based observations, by Dan Pascu, P. Kenneth Seidelmann, William A. Baum, and Douglas G. Currie, and was provisionally designated S/1980 S 25. Several other apparitions of it were recorded in the following months: S/1980 S 29, S/1980 S 30, S/1980 S 32, and S/1981 S 2. In 1983 it was officially named after Calypso of Greek mythology. It is also designated Saturn XIV or Tethys C.

    <span class="mw-page-title-main">Dione (moon)</span> Moon of Saturn

    Dione, also designated Saturn IV, is the fourth-largest moon of Saturn. Its trailing hemisphere is marked by large ice cliffs called chasmata and is also darkened compared to the leading hemisphere. Based on its density, Dione’s interior is likely a combination of silicate rock and water ice in nearly equal parts by mass. The moon was discovered by Italian astronomer Giovanni Domenico Cassini in 1684 and is named after the Titaness Dione in Greek mythology.

    <span class="mw-page-title-main">Prometheus (moon)</span> Moon of Saturn

    Prometheus is an inner satellite of Saturn. It was discovered in 1980 from photos taken by the Voyager 1 probe, and was provisionally designated S/1980 S 27.

    <span class="mw-page-title-main">Moons of Saturn</span> Natural satellites of the planet Saturn

    The moons of Saturn are numerous and diverse, ranging from tiny moonlets only tens of meters across to the enormous Titan, which is larger than the planet Mercury. There are 146 moons with confirmed orbits, the most of any planet in the solar system. This number does not include the many thousands of moonlets embedded within Saturn's dense rings, nor hundreds of possible kilometer-sized distant moons that were seen through telescopes but not recaptured. Seven Saturnian moons are large enough to have collapsed into a relaxed, ellipsoidal shape, though only one or two of those, Titan and possibly Rhea, are currently in hydrostatic equilibrium. Three moons are particularly notable. Titan is the second-largest moon in the Solar System, with a nitrogen-rich Earth-like atmosphere and a landscape featuring river networks and hydrocarbon lakes. Enceladus emits jets of ice from its south-polar region and is covered in a deep layer of snow. Iapetus has contrasting black and white hemispheres as well as an extensive ridge of equatorial mountains among the tallest in the solar system.

    <span class="mw-page-title-main">Methone (moon)</span> Moon of Saturn

    Methone is a small, egg-shaped moon of Saturn that orbits out past Saturn's ring system, between the orbits of Mimas and Enceladus. It was discovered in 2004, though it wasn't until 2012 that it was imaged in detail by the Cassini spacecraft.

    <span class="mw-page-title-main">Pallene (moon)</span> Moon of Saturn

    Pallene is a very small natural satellite of Saturn. It is one of three small moons known as the Alkyonides that lie between the orbits of the larger Mimas and Enceladus. It is also designated Saturn XXXIII.

    <span class="mw-page-title-main">S/2004 S 3</span> Unconfirmed object orbiting Saturn

    S/2004 S 3 is the provisional designation of an object seen orbiting Saturn just beyond the outer strand of the F ring on June 21, 2004. It was discovered by the Cassini Imaging Science Team in images taken by the Cassini–Huygens probe on June 21, 2004 and announced on September 9, 2004.

    <span class="mw-page-title-main">Trojan (celestial body)</span> Objects sharing the orbit of a larger one

    In astronomy, a trojan is a small celestial body (mostly asteroids) that shares the orbit of a larger body, remaining in a stable orbit approximately 60° ahead of or behind the main body near one of its Lagrangian points L4 and L5. Trojans can share the orbits of planets or of large moons.

    In astronomy, a co-orbital configuration is a configuration of two or more astronomical objects orbiting at the same, or very similar, distance from their primary; i.e., they are in a 1:1 mean-motion resonance..

    <span class="mw-page-title-main">S/2009 S 1</span> Small moonlet in Saturns B ring

    S/2009 S 1 is a moonlet embedded in the outer part of Saturn's B Ring, orbiting 117,000 km (73,000 mi) away from the planet. The moonlet was discovered by the Cassini Imaging Team during the Saturnian equinox event on 26 July 2009, when the Cassini spacecraft imaged the moonlet casting a 36 km (22 mi)-long shadow onto the B Ring. With a diameter of 300 m (1,000 ft), it is most likely a long-lived solid body, which would count it as the smallest and innermost known moon of Saturn.

    References

    1. ↑ "Planetary Satellite Discovery Circumstances". Jet Propulsion Laboratory. 23 May 2023. Archived from the original on 27 September 2021. Retrieved 5 June 2023.
    2. 1 2 "Planet and Satellite Names and Discoverers". Gazetteer of Planetary Nomenclature. USGS Astrogeology Science Center. Archived from the original on 21 August 2014. Retrieved 5 June 2023.
    3. ↑ "Cassini Imaging Science Team". Cassini Imaging Central Laboratory for Operations. NASA. Archived from the original on 5 July 2022. Retrieved 13 June 2023.
    4. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Murray, C. D.; Cooper, N. J.; Evans, M. W.; Beurle, K. (December 2005). "S/2004 S 5: A new co-orbital companion for Dione". Icarus. 179 (1): 222–234. Bibcode:2005Icar..179..222M. doi:10.1016/j.icarus.2005.06.009. S2CID   120102820.
    5. ↑ "Polydeuces". Lexico UK English Dictionary. Oxford University Press. Archived from the original on 24 October 2021.
    6. ↑ Lundström (1997) Eranos, v. 95
    7. ↑ Levin (1971) Apollonius' Argonautica, v. 1, p. 139
    8. 1 2 3 4 "Planetary Satellite Mean Orbital Parameters". Jet Propulsion Laboratory. Archived from the original on 6 October 2021. Retrieved 5 June 2023.
    9. 1 2 3 Jacobson, Robert A. (November 2022). "The Orbits of the Main Saturnian Satellites, the Saturnian System Gravity Field, and the Orientation of Saturn's Pole". The Astronomical Journal. 164 (5): 19. Bibcode:2022AJ....164..199J. doi: 10.3847/1538-3881/ac90c9 . S2CID   252992162. 199.
    10. 1 2 3 4 5 Spitale, J. N.; Jacobson, R. A.; Porco, C. C.; Owen, W. M. Jr. (August 2006). "The orbits of Saturn's small satellites derived from combined historic and Cassini imaging observations". The Astronomical Journal. 132 (2): 692–710. Bibcode:2006AJ....132..692S. doi: 10.1086/505206 . S2CID   26603974.
    11. 1 2 Jacobson, R. A.; Spitale, J.; Porco, C. C.; Beurle, K.; Cooper, N. J.; Evans, M. W.; Murray, C. D. (January 2008). "Revised Orbits of Saturn's Small Inner Satellites". The Astronomical Journal. 135 (1): 261–263. Bibcode:2008AJ....135..261J. doi: 10.1088/0004-6256/135/1/261 . S2CID   26603974.
    12. 1 2 3 4 5 6 7 8 9 10 Rossignoli, N. L.; Di Sisto, R. P.; Zanardi, M.; Dugaro, A. (July 2019). "Cratering and age of the small Saturnian satellites". Astronomy & Astrophysics. 627: 14. arXiv: 1904.13011 . Bibcode:2019A&A...627A..12R. doi: 10.1051/0004-6361/201834660 . S2CID   198473514. A12.
    13. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Hedman, M. M.; Helfenstein, P.; Chancia, R. O.; Thomas, P.; Roussos, E.; Paranicas, C.; et al. (April 2020). "Photometric Analyses of Saturn's Small Moons: Aegaeon, Methone, and Pallene Are Dark; Helene and Calypso Are Bright". The Astronomical Journal. 159 (4): 48. arXiv: 1912.09192 . Bibcode:2020AJ....159..129H. doi: 10.3847/1538-3881/ab659d . S2CID   209414585. 129.
    14. 1 2 "Polydeuces By the Numbers". Solar System Exploration. NASA. Archived from the original on 14 June 2023. Retrieved 13 June 2023.
    15. 1 2 Ćuk, Matija; Dones, Luke; Nesvorný, David (April 2016). "Dynamical Evidence for a Late Formation of Saturn's Moons". The Astrophysical Journal. 820 (2): 16. arXiv: 1603.07071 . Bibcode:2016ApJ...820...97C. doi: 10.3847/0004-637X/820/2/97 . S2CID   118604203.
    16. 1 2 3 Green, Daniel W. E. (8 November 2004). "IAUC 8432: Sats, RINGS OF SATURN; 2004fc". International Astronomical Union Circular. Central Bureau for Astronomical Telegrams (8432): 1. Bibcode:2004IAUC.8432....1P. Archived from the original on 29 May 2012. Retrieved 31 December 2011.
    17. ↑ Porco, C. C.; Baker, E.; Barbara, J.; Beurle, K.; Brahic, A.; Burns, J. A.; et al. (February 2005). "Cassini Imaging Science: Initial Results on Saturn's Rings and Small Satellites" (PDF). Science. 307 (5713): 1226–1236. Bibcode:2005Sci...307.1226P. doi:10.1126/science.1108056. PMID   15731439. S2CID   1058405. Archived from the original (PDF) on 13 February 2012.
    18. 1 2 Green, Daniel W. E. (21 January 2005). "IAUC 8471: 2005O; C/2004 T8, Y5, Y6, Y7, Y8; Sats OF SATURN". International Astronomical Union Circular. Central Bureau for Astronomical Telegrams (8471): 6. Bibcode:2005IAUC.8471....6G. Archived from the original on 25 June 2013. Retrieved 31 December 2011.
    19. 1 2 3 Thomas, P. C.; Helfenstein, P. (July 2020). "The small inner satellites of Saturn: Shapes, structures and some implications". Icarus. 344: 20. Bibcode:2020Icar..34413355T. doi:10.1016/j.icarus.2019.06.016. S2CID   197474587. 113355.
    20. ↑ "Polydeuces In Depth". Solar System Exploration. NASA. 19 December 2019. Archived from the original on 6 June 2023. Retrieved 11 June 2023.
    21. 1 2 3 4 Izidoro, A.; Winter, O. C.; Tsuchida, M. (July 2010). "Co-orbital satellites of Saturn: congenital formation". Monthly Notices of the Royal Astronomical Society. 405 (4): 2132–2140. arXiv: 1002.4617 . Bibcode:2010MNRAS.405.2132I. doi: 10.1111/j.1365-2966.2010.16655.x . S2CID   119119468.
    22. 1 2 Hirata, Naoyuki; Miyamoto, Hideaki; Showman, Adam P. (June 2014). "Particle deposition on the saturnian satellites from ephemeral cryovolcanism on Enceladus". Geophysical Research Letters. 41 (12): 4135–4141. arXiv: 2205.11265 . Bibcode:2014GeoRL..41.4135H. doi: 10.1002/2014GL060470 . S2CID   140539103.
    23. 1 2 3 "Cassini Tour Event Summary: Planned Observations of Small Satellites". PDS Atmospheres Node. NASA. Archived from the original on 6 June 2023. Retrieved 6 June 2023.
    24. ↑ Spitale, J. N.; Jacobson, R. A.; Porco, C. C.; Owen, W. M. Jr. (August 2006). "The orbits of Saturn's small satellites derived from combined historic and Cassini imaging observations – Table 3". The Astronomical Journal (Saturian satellite image measurements). 132 (2): 695. Bibcode:2006AJ....132..692S. doi: 10.1086/505206 . S2CID   26603974.
    This page is based on this Wikipedia article
    Text is available under the CC BY-SA 4.0 license; additional terms may apply.
    Images, videos and audio are available under their respective licenses.