(136472) 2005 FY9
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- The correct title of this article is (136472) 2005 FY9. It features superscript or subscript characters that are substituted or omitted because of technical limitations.
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| Artist's conception of 2005 FY9 |
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| Discovery A | |
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| Discoverer | Michael E. Brown, Chad Trujillo, David Rabinowitz |
| Discovery date | March 31, 2005 |
| Alternate designations B |
none |
| Category | Trans-Neptunian object |
| Orbital elements C | |
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| Eccentricity (e) | 0.159 |
| Semi-major axis (a) | 6850.2 Gm (45.791 AU) |
| Perihelion (q) | 5760.7 Gm (38.508 AU) |
| Aphelion (Q) | 7939.7 Gm (53.0736 AU) |
| Orbital period (P) | 113179 d (309.868 a) |
| Mean orbital speed | 4.419 km/s |
| Inclination (i) | 28.963° |
| Longitude of the ascending node (Ω) |
79.3816° |
| Argument of perihelion (ω) |
298.407° |
| Mean anomaly (M) | 85.14653° |
| Physical characteristics D | |
| Dimensions | 1600 – 2000? km |
| Mass | ?×10? kg |
| Density | ? g/cm³ |
| Surface gravity | ? m/s² |
| Escape velocity | ? km/s |
| Rotation period | ? d |
| Spectral class | ? |
| Absolute magnitude | -0.4 |
| Albedo (geometric) | 0.8 ± 0.2 |
| Mean surface temperature |
~? K |
(136472) 2005 FY9 (also written (136472) 2005 FY9) is a very large Kuiper belt object discovered on March 31, 2005 by the team led by Michael Brown. Its discovery was announced on July 29, 2005 on the same day as two other very large trans-Neptunian objects, 2003 EL61 and Eris.
The designation 2005 FY9 was given to the object when the discovery was made public. Before that, the discovery team used the codename "Easterbunny" for the object because of the discovery time shortly after Easter. The designation is only provisional; according to the current naming rules of the International Astronomical Union, it will receive a permanent name after a creation or underworld deity.
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[edit] Physical characteristics
[edit] Size
The albedo of 2005 FY9 remains unknown leading to a significant uncertainty in the object’s size. The detection in infrared by the Spitzer space telescope, combined with the similarities of spectrum with Pluto yield a conservative estimate of 1500 km. This is similar to the size of 2003 EL61 making 2005 FY9 the largest known Kuiper belt object after Eris and Pluto. However, should the albedo prove to be closer to that of Quaoar for example, the size of the object diameter could reach 3000 km. 2005 FY9 is currently visually the second brightest Kuiper belt object after Pluto having the apparent magnitude of nearly 17. Therefore it is visible to high-end amateur telescopes.
[edit] Spectra
In a recent paper, Licandro et al. showed that the surface of 2005 FY9 resembles that of Pluto by measuring its visible and near infrared spectrum using the William Herschel Telescope and Telescopio Nazionale Galileo.
The object appears red in the visible spectrum (see colour comparison for TNOs).
The infrared spectrum is marked by the presence of methane (CH4) as observed on both Pluto and Eris. However, Eris presents neutral (and not red) spectrum. In addition Eris is a scattered disk object, implying much wider seasonal changes than for the classical objects.
The presence of methane, even more prominent that on Pluto, leads to a possibility that 2005 FY9 could have a similar transient atmosphere as Pluto near perihelion.
[edit] Satellites
No satellites have been detected so far, distinguishing 2005 FY9 from the other largest known trans-Neptunian objects: Eris (1 satellite), 2003 EL61 (2) and Pluto (3). 10% to 20% of all trans-Neptunian objects are expected to have one or more satellites.
[edit] Discovery circumstances
Despite its relative brightness, 2005 FY9 was not discovered until fairly recently, well after many much fainter Kuiper belt objects. This is probably due to its relatively high orbital inclination, and the fact that its angular distance from the ecliptic was near maximum at the time of its discovery (in the northern constellation of Coma Berenices). Most searches for minor planets are conducted relatively close to the ecliptic, due to the greater probability of finding objects there.
However, at the time of Clyde Tombaugh's discovery of Pluto, 2005 FY9 was only a few degrees from the ecliptic, near the border of Taurus and Auriga. Unfortunately, this position was also very near the galactic equator, making it almost impossible to find such an object within the dense concentration of background stars of the Milky Way. Tombaugh continued searching for some years after the discovery of Pluto, but he failed to find 2005 FY9 or any other trans-Neptunian objects.
[edit] Orbit
2005 FY9 is classified a classical Kuiper belt object and follows an orbit very similar to that of 2003 EL61: highly inclined (29°) and moderately eccentric (e~0.16). 2005 FY9 is slightly farther from the Sun (both the semi major axis and perihelion). Unlike Pluto and plutinos approaching the Sun closer than Neptune thanks to the resonance, the classical objects have perihelia further from the Sun, free from Neptune’s perturbation.
The diagram shows the similar orbits of the two cubewanos contrasted with the orbit of Pluto. The perihelia (q) and the aphelia (Q) are marked with the dates of passage. The present positions (as of April 2006) are marked with the spheres illustrating relative sizes and differences in albedo and colour. Both cubewanos are currently far from (above) the ecliptic (illustrated as Neptune orbit in grey). 2005 FY9 approaches its aphelion while 2003 EL61 passed its own in 1991.
[edit] External links
- MPEC listing for 2005 FY9
- AstDys orbital elements
- Orbital simulation from JPL (Java)
- Press release from WHT and TNG on 2005 FY9 's similarity to Pluto.
- 2005 FY9 chart and Orbit Viewer
[edit] References
- Licandro, J.; Pinilla-Alonso, N.; Pedani, M.; Oliva, E.; Tozzi, G. P.; Grundy, W. M. The methane ice rich surface of large TNO 2005 FY_9: a Pluto-twin in the trans-neptunian belt? , Astronomy and Astrophysics, 445 (2006), pp.L35-L38 Abstract.
- S.C. Tegler, W. Grundy, W. Romanishin, G. Consolmagno, K. Mogren, F. Vilas: Optical Spectroscopy of the Large Kuiper Belt Objects 136472 (2005 FY9) and 136108 (2003 EL61). Preprint
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| Kuiper belt: Orcus | Pluto (Charon) | Ixion | 2002 UX25 | Varuna | 2002 TX300 | 2003 EL61 | Quaoar | 2005 FY9 | 2002 AW197 |
| Scattered disc: 2002 TC302 | Eris | 2004 XR190 | Sedna |
| See also Triton, astronomical objects and the solar system's list of objects, sorted by radius or mass. For pronunciation, see: Centaur and TNO pronunciation. |
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| Vulcanoids | Near-Earth asteroids | Main belt | Jupiter Trojans | Centaurs | Damocloids | Comets | Trans-Neptunians (Kuiper belt · Scattered disc · Oort cloud) |
| For other objects and regions, see: asteroid groups and families, binary asteroids, asteroid moons and the Solar system For a complete listing, see: List of asteroids. See also Pronunciation of asteroid names and Meanings of asteroid names. |
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| Plutinos : Pluto* | 1993 RO | 1993 RP | 1993 SB | 1993 SC | 1994 TB | 1995 QZ9 | 1996 SZ4 | 1996 TP66 | 38083 Rhadamanthus | 38628 Huya | 28978 Ixion | 2003 VS2 | 90482 Orcus | Unnumbered: 2003 AZ84
Cubewanos: 1992 QB1 | 1994 GV9 | 1994 JQ1 | 1994 VK8 | 1996 TO66 | 58534 Logos| 1998 WW31 | 19521 Chaos | 53311 Deucalion | 20000 Varuna | 2002 AW197 | 50000 Quaoar | 2002 MS4 | 2002 TX300 | 2002 UX25 | 2003 EL61 | 2004 GV9| 2005 FY9 | Unnumbered: | 2003 QW90 | 2005 RN43 Twotinos: 2002 WC19 | 1996 TR66 | Unnumbered: 1998 SM165 | 1997 SZ10 | 1999 RB216 | 2000 JG81 Scattered disc objects: Eris* | 1995 TL8 | 1996 GQ21 | 1996 TL66 | 2000 OO67 | 2000 OM67 | 2001 KC77 | 2001 UR163 | 2002 CY224 | 2002 GX32 | 2002 TC302 | 90377 Sedna** Unnumbered: 2004 XR190 Unclassified Objects : 1994 JS | 1994 JR1 | 1995 DA2 | 1995 SM55 | 1996 TQ66 | 1997 CR29 | 1997 CS29 | 1997 CU29 | 1997 QJ4 | 1998 HJ151 | 1998 HK151 | 1998 HP151 | 1998 HM151 | 1998 KR65 | 1998 SM165 | 1998 SN1651998 US43 | 1998 VG44 | 1998 WW24 | 1998 WA31 | 1998 WU31 | 1998 WA25 | 1999 CP133 | 1999 CL158 | 1999 CC158 | 1999 DF9 | 1999 HT11 | 1999 HB12 | 1999 HC12 | 1999 KR16 | 1999 OY3 Natural satellites : Charon (Pluto) | Hydra (Pluto) | Nix (Pluto) | Dysnomia (Eris) | S/2000 (1998 WW31) 1 | S/2005 (2003 EL61) 1 | S/2005 (2003 EL61) 2 | (58534) Logos I Zoe |
| * - Also classified as a dwarf planet ** - Currently classified as an SDO, though may be part of the Inner Oort Cloud |
| Minor planets | ||
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