Actaea (moon)
 Salacia and its moon Actaea, imaged by the Keck telescope on 3 August 2010. Actaea is the fainter object to the left of Salacia. | |
| Discovery | |
|---|---|
| Discovered by | Keith S. Noll, Harold F. Levison, Denise C. Stephen, William M. Grundy |
| Discovery date | 21 July 2006 |
| Designations | |
Designation | Salacia I |
| Pronunciation | /ækˈtiːə/ |
| S/2006 (120347) 1 | |
| Adjectives | Actaean /ækˈtiːən/ |
| Orbital characteristics[1] | |
| 5724±27 km | |
| Eccentricity | 0.0098±0.0038 |
| 5.493882±0.000023 days | |
| Inclination | 23.59±0.36° |
| 45.2±1.6° | |
| 134±23° | |
| Satellite of | Salacia |
| Physical characteristics | |
| Dimensions | 284±10 km[1] |
| Mass | ≈ 20×1018 kg |
| Albedo | ≈ 0.035 +0.010/−0.007[citation needed] |
Spectral type | V–I = 0.89±0.02 (Actaea) |
| 1.9 mag[citation needed] | |
Actaea, officially (120347) Salacia I Actaea, is a
Discovery and name
It was discovered on 21 July 2006 by Keith S. Noll,
Orbit
Actaea orbits its primary every 5.493 d at a distance of 5619±87 km and with an eccentricity of 0.0084±0.0076.[6] The ratio of its semi-major axis to its primary's Hill radius is 0.0023, the tightest trans-Neptunian binary with a known orbit.[7]
Physical characteristics
The mass of the system is (4.92±0.07)×1020 kg, with perhaps 4% of this being in Actaea.[1] Actaea is 2.372±0.060 magnitudes fainter than Salacia, implying a diameter ratio of 2.98 for equal albedos.[7] Hence, assuming equal albedos, it has a diameter of 284±10 km.[1] Actaea has the same color as Salacia (V−I = 0.89±0.02 and 0.87±0.01, respectively), supporting the assumption of equal albedos.[7] It has been calculated that the Salacia system should have undergone enough tidal evolution to circularize their orbits, which is consistent with the low measured eccentricity, but that the primary need not be tidally locked.[7] Salacia and Actaea will next occult each other in 2067.[7]
References
- ^ S2CID 133585837. Retrieved 2019-10-26.
- S2CID 119343798.
- S2CID 119099266.
- S2CID 44546400.
- ^ "IAUC 8751: (120347) 2004 SB_60; 2006gi, 2006gj; V733 Cep". Cbat.eps.harvard.edu. Archived from the original on 2013-12-03. Retrieved 2014-06-14.
- ^ Johnston Archive: (120347) Salacia and Actaea
- ^ a b c d e Stansberry, J.A.; Grundy, W.M.; Mueller, M.; et al. (2012). "Physical Properties of Trans-Neptunian Binaries (120347) Salacia–Actaea and (42355) Typhon–Echidna". Icarus. 219 (2): 676–688. .