(386723) 2009 YE7


(386723) 2009 YE7
Haumea family orbits.png
(386723) 2009 YE7 among other Haumea family objects
Discovered byDavid Rabinowitz
Discovery date17 December 2009
2009 YE7
Haumea family[3][4]
Orbital characteristics[6]
Epoch 13 January 2016 (JD 2457400.5)
Uncertainty parameter 4
Observation arc2273 days (6.22 yr)
Aphelion50.694 AU (7.5837 Tm)
Perihelion37.893 AU (5.6687 Tm)
44.293 AU (6.6261 Tm)
294.79 yr (107672 d)
0° 0m 12.037s / day (n)
≈ 5 May 2164[5]
±15 days
Physical characteristics
Mean diameter
200[7]–560[8] km[6][9]
assume 0.7 to 0.09
Temperature< 44 K
≈21.7(JPL Horizons)

(386723) 2009 YE7, provisional designation 2009 YE7, is a trans-Neptunian object (TNO) discovered by David Rabinowitz on December 17, 2009 at the La Silla Observatory in Chile.


The orbit of 2009 YE7 compared to Pluto and Neptune


2009 YE7 is a classical Kuiper belt object: Its orbit is not controlled by an orbital resonance with Neptune, similar to 15760 Albion, but with a much greater orbital eccentricity and inclination. It completes one orbit around the Sun in just over 247 Earth years, at an average distance of about 44 AU. It came to perihelion around 1868,[6] and to aphelion in 2015. It is currently about 50.7 AU from the Sun, and will again return to perihelion around 2163.


2009 YE7 has been observed 70 times, with precovery images dating back to 2006, and has an orbital quality code of 4.

Physical characteristics

Absolute magnitude

Different albedos correspond to different sizes

The size of an object can be ascertained once its absolute magnitude (H) and its albedo (the proportion of light it reflects) are known. When 2009 YE7 was first discovered, it was believed to have an absolute magnitude (H) of 2.8, which would have made it the first bright KBO found from the southern hemisphere.[10] 2009 YE7 has an absolute magnitude (H) of 4.5.[6] Since 2009 YE7 has an absolute magnitude dimmer than (H=1), it will not be overseen by two naming committees and will not automatically be listed as a dwarf planet by the International Astronomical Union (IAU).[11] This value would've made it the eighth-intrinsically-brightest known trans-Neptunian object, but it was later found to be much dimmer. It has an absolute magnitude (H) of 4.5,[6] which would make it a good dwarf-planet candidate when using an albedo of 0.09. However, it is probably much smaller than previously thought, since it is also suspected of being a highly reflective icy member of the Haumea family.[3][4]

2009 YE7 has been found to be a member of the Haumea family fragment due to its Haumea-like orbit and the detection of water ice on its surface.[3] This means 2009 YE7 could have an albedo of up to 0.7, resulting in a small size close to 200 kilometres (120 mi). However, its actual albedo is unknown; if its albedo turns out to be lower, it would result in a larger size estimate.

Any icy body with a diameter equal to or greater than 400 kilometres (250 mi) is expected to be spherical.[12] Many small icy low-density moons, such as Mimas and Miranda are known to be spherical.

See also


  1. ^ "List of Transneptunian Objects". IAU Minor Planet Center. 2009-12-28. Retrieved 2009-12-28.
  2. ^ "2009 YE7 Orbit". IAU Minor Planet Center. Retrieved 2014-04-02.
  3. ^ a b c Trujillo; Sheppard & Schaller (14 February 2011). "A Photometric System for Detection of Water and Methane Ices on Kuiper Belt Objects". The Astrophysical Journal. 730 (2): 105. arXiv:1102.1971. Bibcode:2011ApJ...730..105T. doi:10.1088/0004-637X/730/2/105. S2CID 53942260.
  4. ^ a b Mike Brown (2009-12-29). "A ghost of Christmas past". Mike Brown's Planets (blog). Archived from the original on 2 January 2010. Retrieved 2009-12-29.
  5. ^ JPL Horizons Observer Location: @sun (Perihelion occurs when deldot changes from negative to positive. Uncertainty in time of perihelion is 3-sigma.)
  6. ^ a b c d e f "JPL Small-Body Database Browser: 386723 (2009 YE7)" (last observation: 2010-09-12). Archived from the original on 25 September 2019. Retrieved 12 April 2016.
  7. ^ Assuming a Haumea-like albedo of 0.7
  8. ^ Assuming an unlikely albedo of 0.09
  9. ^ Dan Bruton. "Conversion of Absolute Magnitude to Diameter for Minor Planets". Department of Physics & Astronomy (Stephen F. Austin State University). Archived from the original on 18 December 2008. Retrieved 2009-01-07.
  10. ^ "JPL Small-Body Database Search Engine (H<=4)". 2009-12-27. Retrieved 2009-12-27.[permanent dead link]
  11. ^ "Plutoid chosen as name for Solar System objects like Pluto" (Press release). Archived from the original on 2 July 2011. Retrieved 28 December 2009.
  12. ^ Mike Brown. "The Dwarf Planets". Archived from the original on 9 January 2010. Retrieved 2009-12-28.

External links

  • (386723) 2009 YE7 at the JPL Small-Body Database
    • Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters