2009 YE7

2009 YE7
Discovery[1]
Discovered by David Rabinowitz
Discovery date December 17, 2009
Designations
MPC designation 2009 YE7
Minor planet
category		 TNO
Cubewano[2]
Haumea family[3][4]
Epoch July 23, 2010 (2455400.5)
Aphelion 50.7 AU (Q)
Perihelion 38.3 AU (q)
Semi-major axis 44.5 AU (a)
Eccentricity 0.14
Orbital period 297 yr
Average orbital speed 4.47
Mean anomaly 177° (M)
Inclination 29.1°
Longitude of ascending node 141°
Argument of perihelion 97.3°
Satellites ?
Physical characteristics
Dimensions 200[5]–560[6] km[2][7]
Albedo assume 0.7 to 0.09
Apparent magnitude ~21.7(JPL Horizons)
Absolute magnitude (H) 4.5[2]

2009 YE7 is a trans-Neptunian object with an absolute magnitude (H) of 4.5.[2] However, it only qualifies as a weak dwarf-planet candidate since it is also suspected of being a highly reflective icy member of the Haumea family.[3][4] It was discovered by David Rabinowitz on December 17, 2009 at the La Silla Observatory in Chile. 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.[8]

Contents

Orbit

The preliminary orbit suggests it came to perihelion around 1864.[2] It is currently 50 AU from the Sun and will come to aphelion (furthest distance from the Sun) in 2012.

The orbit is preliminary as it has only been observed over an observation-arc of 98 days since December 13, 2009.[2]

Physical characteristics

Absolute magnitude

The size of an object can be ascertained once its absolute magnitude (H) and its albedo (the proportion of light it reflects) are known. 2009 YE7 has an absolute magnitude (H) of 4.5.[2] 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).[9]

Assuming 2009 YE7 has a trans-Neptunian albedo of about 0.25, which is somewhat common with KBOs around a size of ~1000 km, it would only be around 340 km in diameter.[7] But since the true albedo is unknown, it could easily be from about 200 to an unlikely 560 km in diameter.

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 smaller size closer to the 200 km estimate.

Any icy body with a diameter greater than 400 km is likely spherical.[10] Many small icy low-density moons are known to be spherical.

See also

References

  1. ^ "List of Transneptunian Objects". IAU Minor Planet Center. 2009-12-28. http://www.minorplanetcenter.org/iau/lists/TNOs.html. Retrieved 2009-12-28. 
  2. ^ a b c d e f g h "JPL Small-Body Database Browser: (2009 YE7)". 2010-09-12 last obs. http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2009YE7. Retrieved 2010-09-13. 
  3. ^ a b c Trujillo, Sheppard and Schaller (14 February 2011). "A Photometric System for Detection of Water and Methane Ices on Kuiper Belt Objects". The Astrophysical Journal. arXiv:1102.1971. 
  4. ^ a b Mike Brown (2009-12-29). "A ghost of Christmas past". Mike Brown's Planets (blog). http://www.mikebrownsplanets.com/2009/12/ghost-of-christmas-past.html. Retrieved 2009-12-29. 
  5. ^ Assuming a Haumea-like albedo of 0.7
  6. ^ Assuming an unlikely albedo of 0.09
  7. ^ a b Dan Bruton. "Conversion of Absolute Magnitude to Diameter for Minor Planets". Department of Physics & Astronomy (Stephen F. Austin State University). http://www.physics.sfasu.edu/astro/asteroids/sizemagnitude.html. Retrieved 2009-01-07. 
  8. ^ "JPL Small-Body Database Search Engine (H<=4)". 2009-12-27. http://home.comcast.net/~kpheider/JPL-Small-Body-2009.gif. Retrieved 2009-12-27. 
  9. ^ "Plutoid chosen as name for Solar System objects like Pluto" (Press release). http://www.iau.org/public_press/news/release/iau0804/. 
  10. ^ Mike Brown. "The Dwarf Planets". http://web.gps.caltech.edu/~mbrown/dwarfplanets/. Retrieved 2009-12-28. 

External links