 | |
| Discovery | |
|---|---|
| Discovered by | Mark R. Showalter andJack J. Lissauer |
| Discovery date | August 25, 2003 |
| Designations | |
Designation | Uranus XXVI |
| Pronunciation | /ˈmæb/[1] |
| Adjectives | Mabian[2] |
| Orbital characteristics[3] | |
| Epoch 2008 September 1 | |
| 97 735.966 km | |
| Eccentricity | 0.00347 |
| 0.923d (calculated) | |
Averageorbital speed | 7.70 km/s (calculated) |
| Inclination | 0.12217° (to Uranus's equator) |
| Satellite of | Uranus |
| Physical characteristics | |
| 6 km/12.4±0.5 km[4] | |
Meandensity | 0.5–1.2 g/cm3[5] |
| synchronous | |
| 0 | |
| Albedo | ~0.46/0.1 (assumed)[4] |
| 26[6] | |
Mab, orUranus XXVI,[7] is aninner satellite ofUranus. It was discovered byMark R. Showalter andJack J. Lissauer in 2003 using theHubble Space Telescope.[8] It was named afterQueen Mab, a fairy queen from English folklore who is mentioned inWilliam Shakespeare's playRomeo and Juliet.[7]
Because the moon is small and dark, it was not seen in the heavily scrutinized images taken byVoyager 2 during its Uranus flyby in 1986. However, it is brighter than another moon,Perdita, which was discovered from Voyager's photos in 1997. This led scientists to re-examine the old photos again, and the satellite was finally found in the images.[4] Following its discovery, Mab was given the temporary designationS/2003 U 1.[8]
The size of Mab is not precisely known and has not been measured, so it is inferred by assuming the albedo to be similar to that of one of Mab's neighbouring moons, those beingPuck andMiranda. If it is as dark as Puck, it would be about 24.8 ± 1.0 km (15.4 ± 0.6 mi) in diameter.[10] On the other hand, if it has a relatively bright surface like the neighbouring moon Miranda, it would be smaller thanCupid and comparable to the smallest outer satellites.[4] Infrared observations published in 2023 suggest that Mab is probably a 12 km (7.5 mi) diameter body with a brighter, Miranda-like surface that is rich in water ice; though not leaving out the possibility of it being a 24 km (15 mi) diameter body with a dark, Puck-like surface.[11]
Mab is heavilyperturbed. The actual source for perturbation is still unclear, but is presumed to be one or more of the nearby orbiting moons.[4]
Mab orbits at the same distance from Uranus as theμ ring (formerly known as R/2003 U 1), a dustyring discovered around the same time as Mab. The moon is nearly the optimal size for dust production, since larger moons can recollect the escaping dust and smaller moons have too small surface areas for supplying the ring via ring particle ormeteoroid collisions.[12] No rings associated with Perdita and Cupid have been found, probably becauseBelinda limits the lifetimes of dust they generate.[4]
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