LARGE SIZE AND SLOW ROTATION OF THE TRANS-NEPTUNIAN OBJECT (225088) 2007 OR{sub 10} DISCOVERED FROM HERSCHEL AND K2 OBSERVATIONS

• Published in: The Astronomical journal Vol. 151; no. 5
• Main Authors: Pál, András, Kiss, Csaba, Molnár, László, Szabó, Róbert, Szabó, Gyula M., Sárneczky, Krisztián, Kiss, László L., Müller, Thomas G.
• Format: Journal Article
• Language: English
• Published: United States 01.05.2016
• Subjects: ALBEDO; ASTEROIDS; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASYMMETRY; CARBON MONOXIDE; GRAVITATION; METHANE; PHOTOMETRY; RETENTION; ROTATION; SPACE; SURFACES; TELESCOPES
• ISSN: 1538-3881; 1538-3881

We present the first comprehensive thermal and rotational analysis of the second most distant trans-Neptunian object (TNOs) (225088) 2007 OR{sub 10}. 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 OR{sub 10} is likely to be larger and darker than derived by earlier studies: we obtained a diameter of d=1535{sub −225}{sup +75} km which places (225088) 2007 OR{sub 10} in the biggest top three TNOs. The corresponding visual geometric albedo is p{sub V}=0.089{sub −0.009}{sup +0.031}. The light-curve analysis revealed a slow rotation rate of P{sub rot} = 44.81 ± 0.37 hr, superseded by very few objects.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 P{sub rot} = 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—CH{sub 4}, CO, and N{sub 2}—on the surface.