341520 Mors–Somnus

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341520 Mors–Somnus
Discovery [1]
Discovered byS. S. Sheppard
C. Trujillo
Discovery siteMauna Kea Obs.
Discovery date14 October 2007
MPC designation(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 arc6.12 yr (2,235 days)
Aphelion49.184 AU
Perihelion28.839 AU
39.012 AU
243.67 yr (89,000 days)
0° 0m 14.4s / day
Known satellites1 [4]
Physical characteristics
Dimensions102 km (derived)[4]
175.20 km (calculated)[5]
<60 km (each component)[3]
Mean density
>0.5 g/cm3[3]
9.28±0.05 h[6]
0.10 (assumed)[5]
B–V = 1.290±0.014[3]
V–R = 0.740±0.010[3]
V–I = 1.370±0.014[3]

341520 Mors–Somnus /ˌmɔːrsˈsɒmnəs/, provisional designation 2007 TY430, is a trans-Neptunian object and binary system that resides in the Kuiper belt. It is classified as a plutino and measures approximately 100 kilometers in diameter.

It 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[edit]

Mors–Somnus 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:

Orbital parameters of the Mors–Somnus system[3]
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 has almost equal size.

Physical properties[edit]

The total mass of the system is 7.90 ± 0.21×1017 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]

Mors–Somnus 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 of secondary has an elongated shape and rotates non-synchronuosly.[6]


The Mors–Somnus system is likely to be an escaped cold classical Kuiper Belt object.[3]


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]


  1. ^ a b c d "JPL Small-Body Database Browser: 341520 Mors-Somnus (2007 TY430)" (2013-11-26 last obs.). Jet Propulsion Laboratory. Retrieved 5 July 2017.
  2. ^ a b c "341520 Mors-Somnus (2007 TY430)". Minor Planet Center. Retrieved 5 July 2017.
  3. ^ a b c d e f g h i j k l m Sheppard, Scott S.; Ragozzine, Darin; Trujillo, Chadwick (March 2012). "2007 TY430: A Cold Classical Kuiper Belt Type Binary in the Plutino Population" (PDF). The Astronomical Journal. 143 (3): 13. arXiv:1112.2708. Bibcode:2012AJ....143...58S. doi:10.1088/0004-6256/143/3/58. Retrieved 5 July 2017.
  4. ^ a b Wm. Robert Johnston (6 June 2015). "(341520) Mors-Somnus". Asteroids with Satellites Database—Johnston's Archive. Retrieved 5 July 2017.
  5. ^ a b c d e "LCDB Data for (341520) Mors–Somnus". Asteroid Lightcurve Database (LCDB). Retrieved 5 July 2017.
  6. ^ a b Thirouin, A.; Noll, K. S.; Ortiz, J. L.; Morales, N. (September 2014). "Rotational properties of the binary and non-binary populations in the trans-Neptunian belt". Astronomy and Astrophysics. 569: 20. arXiv:1407.1214. Bibcode:2014A&A...569A...3T. doi:10.1051/0004-6361/201423567. Retrieved 5 July 2017.
  7. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 5 July 2017.

External links[edit]