Albiorix (moon)

Albiorix /ˌælbiˈɒrɪks/ is a prograde irregular satellite of Saturn. It was discovered by Holman and colleagues in 2000, and given the temporary designation S/2000 S 11.^[7][8][9]

Albiorix

Composite image of Albiorix from 2010 observations by the Wide-field Infrared Survey Explorer (WISE) spacecraft
Discovery[1]
Discovered by	M. J. Holman et al.
Discovery date	19 December 2000
Designations
Designation	Saturn XXVI
Pronunciation	/ˌælbiˈɒrɪks/
Named after	Mars Albiorix
Alternative names	S/2000 S 11
Adjectives	Albiorigian /ˌælbiəˈrɪdʒiən/[2]
Orbital characteristics[3]
Epoch 2000 January 1.5
Semi-major axis	16329100 km
Eccentricity	0.470
Orbital period (sidereal)	783.5 d (2.15 yr)
Inclination	38.9°
Satellite of	Saturn
Group	Gallic group
Physical characteristics
Mean diameter	28.6±5.4 km[4]
Synodic rotation period	13.33±0.03 h[5]
Albedo	0.062±0.028[4]
Spectral type	light red (varying) B−V=0.89, R−V=0.50[6]
Apparent magnitude	20.5[5]
Absolute magnitude (H)	11.35±0.05[4]

Albiorix is the largest member of the Gallic group of irregular satellites.

Name

It was named in August 2003^[10] for Albiorix, "a Gallic giant who was considered to be the king of the world."^[11] The name is known from an inscription found near the French town of Sablet which connects him with the Roman god Mars.^[12] It is still unclear if Albiorix was just an honorific suffix (lit. "Mars, king of the world") or a Celtic deity interpretatio with Mars.^[13]

Orbit

Irregular prograde groups of satellites of Saturn: Gallic (red) and Inuit (blue)

Albiorix orbits Saturn at a distance of about 16 million kilometers. The rotation period was measured by the ISS camera of the Cassini spacecraft to 13 hours and 19 minutes.^[14]

The diagram illustrates the Albiorigian orbit in relation to other prograde irregular satellites of Saturn. The eccentricity of the orbits is represented by the yellow segments extending from the pericentre to the apocentre.

Given the similarity of the orbital elements and the homogeneity of the physical characteristics with other members of the Gallic group, it was suggested that these satellites could have a common origin in the break-up of a larger moon.^[6][9]

Physical characteristics

Albiorix observed by WISE in 2010

The James Webb Space Telescope took the spectrum of Albiorix with NIRSpec, detecting a 3.0 micron absorption feature associated with hydrated minerals, though water ice was not found to be present in substantial quantities. Additionally, carbon dioxide formed by irradiation of organic compounds was detected on Albiorix's surface. Albiorix appears nearly identical in its composition to Siarnaq, another Saturnian irregular satellite observed by James Webb Space Telescope.^[15]

Measurements from NEOWISE constrain the albedo of Albiorix at 0.062±0.028, in which case its diameter is a rather large 28.6±5.4 km.^[5] Albiorix is red in color, but some parts of its surface are less red than others. Varying colours suggest a possibility of a large crater, leading to an alternative hypothesis that Erriapus and Tarvos could be fragments of Albiorix following a near-break-up collision with another body.^[16] It has a rotation period of 13.33±0.03 h, and while one light curve measured by Cassini–Huygens found two minima with a moderate perturbation in one of them, a different angle showed a sharp minimum and two shallower ones.