Large Size and Slow Rotation of the Trans-Neptunian Object (225088) 2007 OR10 Discovered from Herschel and K2 Observations
Abstract
We present the first comprehensive thermal and rotational analysis of the second most distant trans-Neptunian object (TNOs) (225088) 2007 OR10. We combined optical light curves provided by the Kepler Space Telescope-K2 extended mission and thermal infrared data provided by the Herschel Space Observatory. We found that (225088) 2007 OR10 is likely to be larger and darker than derived by earlier studies: we obtained a diameter of d={1535}-225+75 {{km}} which places (225088) 2007 OR10 in the biggest top three TNOs. The corresponding visual geometric albedo is {p}V={0.089}-0.009+0.031. The light-curve analysis revealed a slow rotation rate of Prot = 44.81 ± 0.37 hr, superseded by very few objects. The most likely light-curve solution is double-peaked with a slight asymmetry; however, we cannot safely rule out the possibility of having a rotation period of Prot = 22.40 ± 0.18 hr, which corresponds to a single-peaked solution. Due to the size and slow rotation, the shape of the object should be a MacLaurin ellipsoid, so the light variation should be caused by surface inhomogeneities. Its newly derived larger diameter also implies larger surface gravity and a more likely retention of volatiles—CH4, CO, and N2—on the surface.
- Publication:
-
The Astronomical Journal
- Pub Date:
- May 2016
- DOI:
- 10.3847/0004-6256/151/5/117
- arXiv:
- arXiv:1603.03090
- Bibcode:
- 2016AJ....151..117P
- Keywords:
-
- Kuiper belt objects: individual: (225088 OR10;
- methods: observational;
- minor planets;
- asteroids: general;
- radiation mechanisms: thermal;
- techniques: photometric;
- Astrophysics - Earth and Planetary Astrophysics
- E-Print:
- Accepted for publication in AJ, 8 pages in emulateapj style