 Hubble Space Telescope image of55637 Uni and its moon Tinia at 10 o'clock. | |
| Discovery | |
|---|---|
| Discovered by | Brown et al. |
| Discovery date | August 2005 |
| Designations | |
Designation | (55637) Uni I |
Named after | Tinia |
| Orbital characteristics | |
| 4750±40 km[1] | |
| Eccentricity | 0.17±0.03[2] |
| 8.3095 d (prograde)[1] | |
| Inclination | 63.1°[1] |
| Satellite of | 55637 Uni |
| Physical characteristics | |
| 105±15 km[3] | |
| Uni + 2.5 | |
Tinia is the only knownnatural satellite of thetrans-Neptunian object55637 Uni.
Tinia was discovered in August 2005, by observations with theHubble Space Telescope, and announced on 22 February 2007.[4]It was named together with Uni on 1 September 2025 afterTinia, theEtruscan sky god and husband of the Etruscan goddess of love and fertilityUni.[5]
Tinia was discovered at 0.16arcseconds from Uni with a difference inapparent magnitude of 2.5[6] Its diameter is estimated at210±30 km. Assuming analbedo similar to its primary, Tinia should have a diameter of approximately 190 km;[2] 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 every8.309±0.0002 days, at a distance of4770±40 km, indicating a total system mass of(1.25±0.03)×1020 kg.[7][2] Its orbital eccentricity is0.17±0.03.[2]