S / 2015 (136472) 1
| S / 2015 (136472) 1 | |
|---|---|
|
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| The dwarf planet Makemake and its moon S / 2015 (136472) 1 (see arrow) taken by Hubble on April 27, 2015 | |
| Provisional or systematic name | S / 2015 (136472) 1 |
| Central body | Makemake |
| Properties of the orbit | |
| Major semi-axis | ≈ 20,900 - 300,000 km |
| Periapsis | unknown |
| Apoapsis | unknown |
| Orbital time | 12.4 - 660 d |
| Physical Properties | |
| Albedo | ≈ 0.04 |
| Medium diameter | ≈ 175 ± 75 km |
| Acceleration of gravity on the surface | ≈ 0 m / s 2 |
| Escape speed | ≈ 0 m / s |
| discovery | |
| Explorer |
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| Date of discovery | April 27, 2015 |
| Remarks | dark surface |
S / 2015 (136472) 1 is a moon of the trans-Neptunian dwarf planet ( Plutoid ) Makemake , which is classified as Cubewano in terms of orbital dynamics .
Discovery and naming
S / 2015 (136472) 1 was recorded on April 27, 2015 by Alex H. Parker, Marc W. Buie ( Lowell Observatory , Flagstaff , Arizona , USA ), Will M. Grundy and Keith S. Noll on recordings of Makemake with the Hubble Space Telescope Wide Field Camera 3 from the Hubble Space Telescope , conducted in April 2015. Both components of the system could be recognized as clearly separated by the recordings. The discovery was announced almost exactly one year later on April 25, 2016, the moon was given the provisional designation S / 2015 (136472) 1 and the nickname MK 2 .
Track properties
S / 2015 (136472) 1 was found on an orbit at a distance of 20,900 km from Makemake's center (around 15 Makemake radii) and orbited the dwarf planet within at least 12.4 days, which corresponds to about 38.3 turns of Makemake. However, this period of at least 12 days requires a circular orbit, otherwise it could be much higher. The orbit of the moon seems to be strongly inclined towards the ecliptic as well as towards the orbit plane of Makemake. A double-bound rotation can be ruled out due to the long orbit of the moon.
Physical Properties
The diameter of S / 2015 (136472) 1 is estimated to be around 160-175 km, based on an estimated albedo of 4%. The discovery of the moon does not seem to have any significant influence on the determination of the size of the dwarf planet, which according to current estimates is still 1430 km in size. So S / 2015 (136472) 1 should be around 12% of the diameter of Makemake. The observations are not yet sufficient to determine the mass of the two bodies.
The moon had previously escaped discovery, as the surface of the dwarf planet is extremely bright due to the suspected surface of frozen methane and has therefore outshone S / 2015 (136472) 1. The surface of the moon, on the other hand, is described as dark like coal and is therefore about 1300 times fainter than the dwarf planet. According to estimates by the team of astronomers at the Southwest Research Institute , the Lowell Observatory and the Goddard Space Flight Center , there are two possible explanations for this: On the one hand, it is stated that S / 2015 (136472) 1 was caused by a collision of Makemake with another Kuiper belt object and therefore would have to be composed of a similar material - similar to the earth's moon - but that the gravity of the moon could be too small to hold reflective ice, so that this sublimated into space and left behind today's extremely dark surface. On the other hand, it would of course also be possible that the moon had a completely different place of origin in the Kuiper Belt and was captured by Makemake.
exploration
After Makemake's discovery, no moon could be seen at first. Finally, S / 2015 (136472) 1 was discovered on photos of the Hubble Space Telescope from April 2015. To determine more precise orbit data, in particular to determine the shape of the orbit and the physical structure, further Hubble observations are necessary.
See also
Web links
- NASA - Hubble Discovers Moon Orbiting the Dwarf Planet Makemake (April 26, 2016)