(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.
Artist's conception of 2005 FY9
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Discovery
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| Discovered by | Michael E. Brown, Chad Trujillo, David Rabinowitz |
| Discovery date | March 31, 2005 |
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Designations
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| MPC designation | (136472) 2005 FY9 |
| Alternative names | Easterbunny |
| Minor planet category |
TNO |
| Epoch January 28, 1955 (JD 2435135.5) | |
| Aphelion | 7,939.7 Gm (53.0736 AU) |
| Perihelion | 5,760.7 Gm (38.508 AU) |
| Semi-major axis | 6,850.2 Gm (45.791 AU) |
| Eccentricity | 0.159 |
| Orbital period | 113,179 d (309.868 a) |
| Average orbital speed | 4.419 km/s |
| Mean anomaly | 85.14653° |
| Inclination | 28.963° |
| Longitude of ascending node | 79.3816° |
| Argument of perihelion | 298.407° |
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Physical characteristics
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| Dimensions | 1,300 – 1,900 km |
| Mean radius | 750+200-100 km[1] |
| Surface area | ~ 7,000,000 km² |
| Volume | ~ 1.8×109 km³ |
| Mass | ~ 4×1021 kg |
| Mean density | ~2 g/cm³ |
| Equatorial surface gravity | ~ 0.5 m/s² |
| Escape velocity | ~ 0.8 km/s |
| Albedo | 0.8 ± 0.2 |
| Temperature | ~30 K |
| Absolute magnitude | -0.4 |
(136472) 2005 FY9 (also written (136472) 2005 FY9) is a very large Kuiper belt object, and one of the two largest among the population in the classical KBO orbits. It was discovered on March 31, 2005 by the team led by Michael Brown. Prior to making it public, the discovery team referred to it by the codename "Easterbunny". The designation 2005 FY9 is only provisional, and it will eventually receive a permanent name after a creation deity from the International Astronomical Union.
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[edit] Physical characteristics
[edit] Size and brightness
(136472) 2005 FY9 is currently visually the second brightest Kuiper belt object after Pluto having the apparent magnitude of nearly 17, bright enough to be visible using a high-end amateur telescope. The size of 2005 FY9 is not currently known, but the detection in infrared by the Spitzer space telescope, combined with the similarities of spectrum with Pluto yielded an estimate of a 1,500+400-200 km diameter [1]. This is slightly larger than the size of 2003 EL61 making 2005 FY9 the third largest known Trans-Neptunian object after Eris and Pluto. Currently 2005 FY9 is the best candidate to be designated the fourth dwarf planet in the Solar System.[2] [3]
[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. It appears red in the visible spectrum, as opposed to e.g. Eris which has a neutral spectrum (see colour comparison for TNOs). The infrared spectrum is marked by the presence of methane (CH4), as also observed on Pluto and Eris. Its presence, more prominent even than on Pluto, suggests that 2005 FY9 could have a transient atmosphere similar to Pluto's near perihelion.
[edit] Satellites
No satellites have been detected, a situation different from the other largest known trans-Neptunian objects: Eris (1 satellite), 2003 EL61 (2 satellites) and Pluto (3 satellites). From 10% to 20% of all trans-Neptunian objects are expected to have one or more satellites.
[edit] Discovery circumstances
2005 FY9 was 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 deity.
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 (in terms of both the semi major axis and perihelion). Unlike Pluto and the other plutinos, which can cross Neptune's orbit due to their resonance, the classical objects have perihelia further from the Sun, free from Neptune’s perturbation. Its orbital period is nearly 310 Earth years, more than Pluto.
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 above the ecliptic (illustrated as Neptune's orbit in grey). 2005 FY9 is approaching 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
- ^ a b Stansberry, J.; Grundy, W.; Brown, M.; et.al. (2007). "Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer Space Telescope" (abstract).
- ^ Tegler, S.C.; Grundy, W.M.; Romanishin, W.; et.al. (2007). "Optical Spectroscopy of the Large Kuiper Belt Objects 136472 (2005 FY9) and 136108 (2003 EL61)" 133: 526–530. doi:.
- ^ Dwarf planet. Retrieved on 2007-05-31.
- 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.
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