核心概念
Three new outer satellites have been discovered around Uranus and Neptune through ultra-deep pencil beam surveys, revealing dynamical groupings of these distant irregular moons.
要約
The authors conducted extremely deep pencil beam observations around Uranus and Neptune using the Subaru and Magellan telescopes, reaching magnitudes as faint as 26.9 and 27.2 in the r-band, respectively. This allowed them to discover one new moon of Uranus, S/2023 U1, and two new moons of Neptune, S/2021 N1 and S/2002 N5.
S/2023 U1 is a 26.6 mag, 7 km diameter retrograde moon of Uranus, with an orbit similar to the previously known moons Caliban and Stephano. This suggests S/2023 U1 is a fragment from a once larger parent satellite.
S/2021 N1 is a 26.9 mag, 14 km diameter retrograde moon of Neptune, with an orbit similar to Neso and Psamathe, indicating they are a dynamical family. The authors find S/2021 N1 is in a Kozai-Lidov orbital resonance.
S/2002 N5 is a 25.9 mag, 23 km diameter prograde moon of Neptune, making a family with the moons Sao and Laomedeia.
These new discoveries nearly complete the outer satellite populations of Uranus and Neptune down to about 8 km and 14 km in diameter, respectively. The size distributions of the satellite dynamical families show a strong steepening in the power law for satellites smaller than 5 km, suggesting these smaller moons are collisional fragments of once larger parent satellites.
統計
S/2023 U1 is about 7 km in diameter.
S/2021 N1 is about 14 km in diameter.
S/2002 N5 is about 23 km in diameter.
引用
"S/2023 U1 was 26.6 mags, is about 7 km in diameter and has a distant, eccentric and inclined retrograde orbit similar to Caliban and Stephano, implying these satellites are fragments from a once larger parent satellite."
"S/2021 N1 was 26.9 mags, about 14 km in size and has a retrograde orbit similar to Neso and Psamathe, indicating they are a dynamical family."
"S/2002 N5 was 25.9 mags, is about 23 km in size and it makes a family of distant prograde satellites with Sao and Laomedeia."