120347 Salacia

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120347 Salacia
Sidereal rotation period
6.09 h[1]
0.044±0.004[6]
0.042±0.004[7]
BB[9]
B−V=0.66±0.06[9]
V−R=0.40±0.04[9]
V−I=0.83±0.04[9]
20.7
4.360±0.011 (system)[8]
4.476±0.013 (Salacia)[8]
6.850±0.053 (Actaea)[8]
3.9[1]

Salacia (

Salacia and has a single known moon, Actaea
.

Brown estimated that Salacia is nearly certainly a dwarf planet.[10] However, William Grundy et al. argue that objects in the size range of 400–1,000 km, with densities of ≈ 1.2 g/cm3 or less and albedos less than ≈ 0.2, have likely never compressed into fully solid bodies or been resurfaced, let alone differentiated or collapsed into hydrostatic equilibrium, and so are highly unlikely to be dwarf planets.[11] Salacia is at the upper end of this size range and has a very low albedo, though Grundy et al. later found it to have the relatively high density of 1.5±0.1 g/cm3.[5]

Orbit

longitude of ascending node
. Its current position is near its most northern position above the ecliptic.

Salacia is a non-resonant object with a moderate eccentricity (0.11) and large inclination (23.9°), making it a scattered–extended object in the classification of the Deep Ecliptic Survey and a hot classical Kuiper belt object in the classification system of Gladman et al.,[12] which may be the same thing if they are part of a single population that formed during the outward migration of Neptune.[8] Salacia's orbit is within the parameter space of the Haumea collisional family, but Salacia is not part of it, as evidenced by its lack of the strong water-ice absorption bands.[8]

Physical characteristics

As of 2019, the total mass of the Salacia–Actaea system is estimated at (4.922±0.071)×1020 kg, with an average system density of 1.51 g/cm3; Salacia itself is estimated to be around 846 km in diameter.[5] Salacia has the lowest albedo of any known large trans-Neptunian object.[8] According to the estimate from 2017 based on an improved thermophysical modelling, the size of Salacia is slightly larger at 866 km and its density therefore slightly lower (calculated at 1.26 g/cm3 with the old mass estimate discussed below).[7]

Salacia was previously believed to have a mass of around (4.38±0.16)×1020 kg, in which case it would also have had the lowest density (around 1.29 g/cm3) of any known large TNO;

Near-infrared spectroscopy by the James Webb Space Telescope (JWST) in 2022 revealed the presence of water ice in Salacia's surface.[14] No signs of volatile ices such as methane were detected in JWST's spectrum of Salacia.[14] Its light-curve amplitude is only 3%.[8]

Satellite

Main article: Actaea (moon)

Salacia has one known

Harold Levison, Denise Stephens and William Grundy with the Hubble Space Telescope.[15]

Actaea is 2.372±0.060 magnitudes fainter than Salacia,[6] implying a diameter ratio of 2.98 for equal albedos.[8] Hence, assuming equal albedos, it has a diameter of 286±24 km[6] According to the estimate from 2017 based on an improved modelling, the size of Actaea is slightly larger at 290±21 km.[7]

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.[8]

It has been calculated that the Salacia system should have undergone enough

Hill radius is 0.0023, the tightest trans-Neptunian binary with a known orbit.[8] Salacia and Actaea will next occult each other in 2067.[8]

Name

This minor planet was named after

M.P.C. 73984).[16]

The moon's name,

nereid
or sea nymph.

hippocamp (, formerly ) as the symbol for Salacia;[17]
this symbol is not widely used.

See also

Notes

  1. ^ approximation if Salacia and Actaea were both spherical and had the same albedo

References

EarthMoonCharonCharonNixNixKerberosKerberosStyxStyxHydraHydraPlutoPlutoDysnomiaDysnomiaErisErisNamakaNamakaHi'iakaHi'iakaHaumeaHaumeaMakemakeMakemakeMK2MK2XiangliuXiangliuGonggongGonggongWeywotWeywotQuaoarQuaoarSednaSednaVanthVanthOrcusOrcusActaeaActaeaSalaciaSalacia2002 MS42002 MS4File:10 Largest Trans-Neptunian objects (TNOS).png
Artistic comparison of Pluto, Eris, Makemake, Haumea, Gonggong (2007 OR10), Sedna, Quaoar, Orcus, 2002 MS4, and Salacia.
  1. ^ a b c d e "JPL Small-Body Database Browser: 120347 Salacia (2004 SB60)" (2019-09-21 last obs.). Jet Propulsion Laboratory. 7 November 2019. Archived from the original on 3 April 2017. Retrieved 20 February 2020.
  2. ^ a b c "120347 Salacia (2004 SB60)". Minor Planet Center. Archived from the original on 3 April 2017. Retrieved 22 July 2018.
  3. IAU Minor Planet Center. 2009-09-04. Archived
    from the original on 2018-10-02. Retrieved 2011-07-05.
  4. Buie, Marc W. "Orbit Fit and Astrometric record for 120347" (2007-08-12 using 62 of 73 observations). SwRI (Space Science Department). Archived
    from the original on 2012-03-09. Retrieved 2009-10-04.
  5. ^
    S2CID 133585837. Archived from the original
    (PDF) on 2020-01-15. Retrieved 2019-10-26.
  6. ^ a b c d e f g h Fornasier, S.; Lellouch, E.; Müller, P., T.; et al. (2013). "TNOs are Cool: A survey of the trans-Neptunian region. VIII. Combined Herschel PACS and SPIRE observations of 9 bright targets at 70–500 μm". Astronomy & Astrophysics. 555: A92.
    S2CID 119261700
    .
  7. ^
    doi:10.3847/1538-3881/aa6346
    .
  8. ^ a b c d e f g h i j k l m 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.
    doi:10.1016/j.icarus.2012.03.029
    .
  9. ^
    doi:10.1016/j.icarus.2014.12.004
    .
  10. ^ Brown, Michael E. "How many dwarf planets are there in the outer solar system? (updates daily)". California Institute of Technology. Archived from the original on 2022-07-19. Retrieved 2016-11-29.
  11. ^ a b W.M. Grundy, K.S. Noll, M.W. Buie, S.D. Benecchi, D. Ragozzine & H.G. Roe, 'The Mutual Orbit, Mass, and Density of Transneptunian Binary Gǃkúnǁʼhòmdímà ((229762) 2007 UK126)', Icarus (forthcoming, available online 30 March 2019) Archived 7 April 2019 at the Wayback Machine DOI: 10.1016/j.icarus.2018.12.037,
  12. ^ Gladman, B.; Marsden, B. G.; VanLaerhoven, C. (2008). "Nomenclature in the Outer Solar System" (PDF). The Solar System Beyond Neptune. p. 43. Archived (PDF) from the original on 2012-11-02. Retrieved 2016-05-01.
  13. ^ Schaller, E. L.; Brown, M. E. (2008). "Detection of Additional Members of the 2003 EL61 Collisional Family via Near-Infrared Spectroscopy".
    S2CID 118487075
    .
  14. ^ a b Cook, J. C.; Brunetto, R.; De Souza Feliciano, A. C.; Emery, J.; Holler, B.; Parker, A. H.; et al. (June 2023). Hapke Modeling of Several KBOs from JWST Observations (PDF). Asteroids, Comets, Meteors Conference 2023. Lunar and Planetary Institute. Archived (PDF) from the original on 2023-05-24. Retrieved 2023-05-24.
  15. ^ "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.
  16. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Archived from the original on 11 September 2019. Retrieved 3 April 2017.
  17. ^ Miller, Kirk (26 October 2021). "Unicode request for dwarf-planet symbols" (PDF). unicode.org. Archived (PDF) from the original on 23 March 2022. Retrieved 18 October 2022.

External links

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