Minorplanet: | yes |
Background: |
|
113 Amalthea | |
Discovered: | 12 March 1871 |
Mpc Name: | (113) Amalthea |
Alt Names: | A871 EA; ; 1951 CY |
Epoch: | 31 July 2016 (JD 2457600.5) |
Observation Arc: | 144.90 yr (52926 d) |
Uncertainty: | 0 |
Semimajor: | 2.37598AU |
Perihelion: | 2.1701AU |
Aphelion: | 2.5819abbr=onNaNabbr=on |
Eccentricity: | 0.086651 |
Period: | 3.66 yr (1337.7 d) |
Inclination: | 5.0422° |
Asc Node: | 123.486° |
Arg Peri: | 79.118° |
Mean Motion: | / day |
Rotation: | 9.95abbr=onNaNabbr=on |
Abs Magnitude: | 8.74 |
113 Amalthea is a stony Florian asteroid from the inner regions of the asteroid belt, approximately 50abbr=offNaNabbr=off in diameter. It was discovered on 12 March 1871, by German astronomer Robert Luther at the Bilk Observatory in Düsseldorf, Germany. The elongated S-type asteroid has a rotation period of 9.95 hours. It was named after Amalthea from Greek mythology. A purported satellite of Amalthea was announced in July 2017, but was later found to be a software error in July 2021.
Amalthea is thought to be a fragment from the mantle of a Vesta-sized, 300–600 km diameter parent body that broke up around one billion years ago, with the other major remnant being 9 Metis. The spectrum of Amalthea reveals the presence of the mineral olivine, a relative rarity in the asteroid belt.
Based on observations made during a stellar occultation by Amalthea of a 10th-magnitude star on 14 March 2017, it was announced in July 2017 that the asteroid has a small, 5-kilometer-sized satellite, provisionally designated S/2017 (113) 1. However, the satellite was later retracted as a software-reduction coding error on 17 July 2021.[1] The occultation also indicated that Amalthea has a distinctly elongated shape.[2]
One of Jupiter's inner small satellites, unrelated to 113 Amalthea, is also called Amalthea, as is a (apparently fictional) small Arjuna asteroid in Neal Stephenson's 2015 novel Seveneves.