![]() Hubble Space Telescope image of 55637 Uni and its moon Tinia at 10 o'clock. | |
Discovery | |
---|---|
Discovered by | Brown et al. |
Discovery date | 2007 |
Designations | |
Designation | (55637) Uni I |
Named after | Tinia |
Orbital characteristics | |
4750±40 km [1] | |
Eccentricity | 0.18±0.02 [1] |
8.3095 d (prograde) [1] | |
Inclination | 63.1° [1] |
Satellite of | 55637 Uni |
Physical characteristics | |
105±15 km [2] | |
Uni + 2.5 | |
Tinia is the only known natural satellite of the trans-Neptunian planetoid 55637 Uni.
Tinia was discovered in August 2005, by observations with the Hubble Space Telescope, and announced on February 22, 2007. [3] It was named together with Uni on 1 September 2025 after Tinia, the Etruscan sky god and husband of the Etruscan goddess of love and fertility Uni. [4]
Tinia was discovered at 0.16 arcseconds from Uni with a difference in apparent magnitude of 2.5 [5] Its diameter is estimated at 210±30 km. Assuming an albedo similar to its primary, Tinia should have a diameter of approximately 190 km; [6] assuming an albedo of 0.05, typical of cool classical KBOs of similar size, it should have a diameter of approximately 260 km. [7]
Tinia completes one complete orbit around Uni every 8.309±0.0002 days, at a distance of 4770±40 km, indicating a total system mass of (1.25±0.03)×1020 kg. [7] [6] Its orbital eccentricity is 0.17±0.03. [6]