341520 Mors–Somnus
Binary trans-Neptunian object
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341520 MorsâSomnus (/ËmÉËrs ËsÉmnÉs/; provisional designation 2007 TY430) is a binary system of plutinos. It consists of two components less than 60 kilometers in diameter, orbiting at an average distance of 21000 km.
MorsâSomnus photographed by the Hubble Space Telescope on 20 September 2008 | |
| Discovery[1] | |
|---|---|
| Discovered by | S. S. Sheppard C. Trujillo |
| Discovery site | Mauna Kea Obs. |
| Discovery date | 14 October 2007 |
| Designations | |
| (341520) Mors-Somnus | |
Named after | Mors and Somnus (Roman mythology)[2] |
| 2007 TY430 | |
| TNO[1] · Plutino[3] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 3 | |
| Observation arc | 6.12 yr (2,235 days) |
| Aphelion | 49.184 AU |
| Perihelion | 28.839 AU |
| 39.012 AU | |
| Eccentricity | 0.2607 |
| 243.67 yr (89,000 days) | |
| 0.4680° | |
| 0° 0m 14.4s / day | |
| Inclination | 11.304° |
| 196.75° | |
| 205.32° | |
| Known satellites | 1[4] |
| Physical characteristics | |
| Dimensions | 102 km (derived)[4] 175.20 km (calculated)[5] <60 km (each component)[3] |
| Mass | (7.90±0.21)Ã1017 kg[3] |
Mean density | >0.5 g/cm3[3] |
| 9.28±0.05 h[6] | |
| 0.10 (assumed)[5] 0.23[3] | |
| BâV = 1.290±0.014[3] VâR = 0.740±0.010[3] VâI = 1.370±0.014[3] C[5] | |
| 6.9[1][5] 6.94±0.02[3] | |
MorsâSomnus was discovered on 14 October 2007, by American astronomers Scott Sheppard and Chad Trujillo with the Subaru Telescope at Mauna Kea Observatories in Hawaii, United States. It was later named after the twins Mors and Somnus from Roman mythology.[2]
Orbit and binarity
MorsâSomnus is a small double plutino occupying the 3:2 mean motion resonance with Neptune.[3] The object is a wide optically resolved binary with the following orbital parameters:
| Semi-major axis, km | Eccentricity | Period, d | Inclination, degree |
| 21000 ± 160 | 0.1529 ± 0.0028 | 961.2 ± 4.6 | 15.68 ± 0.22 |
The components have almost equal size.
Physical characteristics
The total mass of the system is 7.90 ± 0.21Ã1017 kg. For a realistic minimal density of 0.5 g/cm3 the albedo is >0.17 and the size of the components is <60 km.[3] The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.1 and calculates a diameter of 175.20 kilometers based on an absolute magnitude of 6.9.[5]
MorsâSomnus has an ultra-red spectrum in the visible and near-infrared parts of the spectrum. The colors of two components are indistinguishable from each other.[3] It demonstrates a double-peaked light curve with the period of about 9.28 hours and amplitude of 0.24. This indicates that either primary or secondary has an elongated shape and rotates non-synchronuosly.[6]
Evolution
The MorsâSomnus system is likely to be an escaped cold classical Kuiper belt object.[3]
Naming
The minor planet was named after the mythological twin Roman gods of death (Mors) and sleep (Somnus).[2] The approved naming citation was published by the Minor Planet Center on 2 June 2015 (M.P.C. 94392).[7]
