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.jpg) Makemake and its moon S/2015 (136472) 1 (arrow) | |
| Discovery | |
|---|---|
| Discovered by |
|
| Discovery date | April 2015 |
| Designations | |
| Alternative names | MK2 (unofficial) |
| Orbital characteristics | |
| Semi-major axis | >21000 km |
| Eccentricity | unknown |
| Orbital period (sidereal) | >12.4 days |
| Satellite of | Makemake |
| Physical characteristics | |
| Mean radius | ~ 87.5 km (for an assumed albedo of 4%) |
| Albedo | 0.04 |
| Apparent magnitude | 25.0 |
| Absolute magnitude (H) | 7.89±0.04 |
S/2015 (136472) 1, unofficially nicknamed MK2 by the discovery team, is the only known moon of the trans-Neptunian dwarf planet Makemake. It is estimated to be 175 km (110 mi) in diameter (for an assumed albedo of 4%) and has a semi-major axis of at least 21,000 km (13,000 mi) from Makemake. Its orbital period is at least 12 days if it has a circular orbit. Observations leading to its discovery occurred in April 2015, using the Hubble Space Telescope's Wide Field Camera 3, and its discovery was announced on 26 April 2016.
Physical characteristics
S/2015 (136472) 1 is extremely faint, with an apparent magnitude of 25 in visible light. The satellite is 1,300 times fainter than Makemake, which corresponds to a magnitude difference of 7.80 between it and Makemake.
Prior to the discovery S/2015 (136472) 1, measurements of Makemake's far-infrared thermal emission by the Spitzer and Herschel space telescopes suggested that the dwarf planet was emitting more thermal radiation than expected for its size and brightness in visible light, which led astronomers to suspect that Makemake may have extra dark surface area contributing to this excess thermal emission. However, Makemake does not exhibit significant variations in brightness as it rotates, which indicates that this dark surface area does not lie on Makemake's surface. Instead, this dark surface area most likely resides on S/2015 (136472) 1, which would mean it is a very dark satellite. Assuming S/2015 (136472) 1 has a uniformly dark surface and contributes to all of Makemake's excess thermal emission, the satellite has a geometric albedo or visible light reflectivity of 2–4%, which makes it as dark as charcoal. The satellite is exceptionally dark compared to Makemake's geometric albedo of 82%; this may be because the satellite's gravity is too weak to hold on to bright, volatile ices as they sublimate off the satellite's surface into space.
Orbit
Alex Parker, the leader of the team that performed the analysis of the discovery images at the Southwest Research Institute, said that from the discovery images, MK2's orbit appears to be aligned edge-on to Earth-based observatories. This would make it difficult to detect because it would be lost in Makemake's glare much of the time, which, along with its dark surface, would contribute to previous surveys failing to observe it. Observations taken in 2018 and 2019 may be enough to determine whether the orbit is close to circular, which would suggest that MK2 was formed by an ancient impact event, or if it is significantly eccentric, which would suggest that it was captured.
Name
See also: Makemake (deity)As of 2024, the satellite has no official name. The designation S/2015 (136472) 1 is the satellite's provisional designation, with S/ indicating "satellite", 2015 being the satellite's year of discovery, and 1 being the satellite's order of discovery in that year. (136472) is Makemake's minor-planet number.
The nickname 'MK2' simply means object 2 in the Makemake system. A permanent name may be chosen from an associated figure in the mythology of Easter Island.
Notes
References
- ^ Parker, A. H.; Buie, M. W.; Grundy, W. M.; Noll, K. S. (25 April 2016). "Discovery of a Makemakean Moon". The Astrophysical Journal. 825 (1): L9. arXiv:1604.07461. Bibcode:2016ApJ...825L...9P. doi:10.3847/2041-8205/825/1/L9. S2CID 119270442.
- ^ "HubbleSite – NewsCenter – Hubble Discovers Moon Orbiting the Dwarf Planet Makemake (04/26/2016) – The Full Story". hubblesite.org. Retrieved 14 July 2022.
- ^ William M. Grundy (13 February 2020). "Makemake (136472 2005 FY9)". Lowell Observatory. Retrieved 20 February 2020.
- Parker et al. (2018) The Mass, Density, and Figure of the Kuiper Belt Dwarf Planet Makemake
- Chang, Kenneth (26 April 2016). "Makemake, the Moonless Dwarf Planet, Has a Moon, After All". The New York Times. Retrieved 26 April 2016.
- ^ Parker, A. (2 May 2016). "A Moon for Makemake". Planetary Society blogs. Planetary Society. Retrieved 2 May 2016.
- ^ Green, Daniel W. E. (26 April 2016). "S/2015 (136472) 1". Central Bureau Electronic Telegram (4275). Central Bureau for Astronomical Telegrams. Bibcode:2016CBET.4275....1P.
{{cite journal}}:|access-date=requires|url=(help) - Cite error: The named reference
Spacecom-20160426was invoked but never defined (see the help page). - ^ Mike Wall (26 April 2016). "Distant Dwarf Planet Makemake Has Its Own Moon". Space.com. Retrieved 26 April 2016.
- "JPL Small-Body Database Browser: 136472 Makemake (2005 FY9)". NASA Jet Propulsion Laboratory (2019-05-12 last obs). Archived from the original on 16 June 2019. Retrieved 20 February 2020.
- "Naming of Astronomical Objects". International Astronomical Union. Retrieved 8 July 2017.
- International Astronomical Union (19 July 2008). "Fourth dwarf planet named Makemake" (Press release). International Astronomical Union (News Release – IAU0806). Archived from the original on 23 July 2008. Retrieved 20 July 2008.
External links
- MPEC 2016-H46 : S/2015 (136472) 1, Minor Planet Center, 26 April 2016
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