Camilla ( minor planet designation: 107 Camilla) is one of the largest asteroids from the outermost edge of the

asteroid belt The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies, of many sizes, but much smaller than planets, c ...

, approximately in diameter. It is a member of the Sylvia family and located within the

Cybele group The Cybele asteroids (also known as the "Cybeles") are a dynamical group of asteroids, named after the asteroid 65 Cybele. Considered by some as the last outpost of an extended asteroid belt, the group consists of just over 2000 members an ...

. It was discovered on 17 November 1868, by English astronomer Norman Pogson at

Madras Observatory The Madras Observatory was an astronomical observatory which had its origins in a private observatory set up by William Petrie in 1786 and later moved and managed by the British East India Company from 1792 in Madras (now known as Chennai). The ...

, India, and named after Camilla, Queen of the

Volsci The Volsci (, , ) were an Italic tribe, well known in the history of the first century of the Roman Republic. At the time they inhabited the partly hilly, partly marshy district of the south of Latium, bounded by the Aurunci and Samnites on the ...

Roman mythology Roman mythology is the body of myths of ancient Rome as represented in the literature and visual arts of the Romans. One of a wide variety of genres of Roman folklore, ''Roman mythology'' may also refer to the modern study of these representa ...

. The

X-type asteroid The X-group of asteroids collects together several types with similar spectra, but probably quite different compositions. Tholen classification In the Tholen classification the X-group consists of the following types: * E-type – with high al ...

is a rare

trinary asteroid A minor-planet moon is an astronomical object that orbits a minor planet as its natural satellite. , there are 457 minor planets known or suspected to have moons. Discoveries of minor-planet moons (and binary objects, in general) are important ...

with two

minor-planet moon A minor-planet moon is an astronomical object that orbits a minor planet as its natural satellite. , there are 457 minor planets known or suspected to have moons. Discoveries of minor-planet moons (and binary objects, in general) are importan ...

s discovered in 2001 and 2016, respectively. It is elongated in shape and has a short rotation period of 4.8 hours.

Physical characteristics

Camilla has a very dark surface and primitive

carbonaceous Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon makes up ...

composition. A large number of rotational

lightcurve In astronomy, a light curve is a graph of light intensity of a celestial object or region as a function of time, typically with the magnitude of light received on the y axis and with time on the x axis. The light is usually in a particular freq ...

s of have been obtained from photometric observations since the 1980s. Best rated results gave a short rotation period of 4.844 hours with a brightness amplitude between 0.32 and 0.53 magnitude. Lightcurve analysis indicates that Camilla's pole most likely points towards

ecliptic coordinates The ecliptic coordinate system is a celestial coordinate system commonly used for representing the apparent positions, orbits, and pole orientations of Solar System objects. Because most planets (except Mercury) and many small Solar System bodi ...

(β, λ) = (+51°, 72°) with a 10° uncertainty, which gives it an

axial tilt In astronomy, axial tilt, also known as obliquity, is the angle between an object's rotational axis and its orbital axis, which is the line perpendicular to its orbital plane; equivalently, it is the angle between its equatorial plane and orb ...

of 29°. Follow-up modeling of photometric data gave similar results.

Diameter and albedo

10 μ radiometric data collected from

Kitt Peak Kitt Peak ( ood, Ioligam) is a mountain in the U.S. state of Arizona, and at is the highest point in the Quinlan Mountains. It is the location of the Kitt Peak National Observatory. The radio telescope at the observatory is one of ten dishes co ...

in 1975 gave a first diameter estimate of 209 km. According to the space-based surveys carried out by the Japanese Akari satellite, the Infrared Astronomical Satellite

IRAS The Infrared Astronomical Satellite (Dutch: ''Infrarood Astronomische Satelliet'') (IRAS) was the first space telescope to perform a survey of the entire night sky at infrared wavelengths. Launched on 25 January 1983, its mission lasted ten mo ...

and the

NEOWISE Wide-field Infrared Survey Explorer (WISE, observatory code C51, Explorer 92 and SMEX-6) is a NASA infrared astronomy space telescope in the Explorers Program. It was launched in December 2009, and placed in hibernation mode in February 201 ...

mission of NASA's

Wide-field Infrared Survey Explorer Wide-field Infrared Survey Explorer (WISE, observatory code C51, Explorer 92 and SMEX-6) is a NASA infrared astronomy space telescope in the Explorers Program. It was launched in December 2009, and placed in hibernation mode in February 201 ...

, as well as observations by the

Keck Observatory The W. M. Keck Observatory is an astronomical observatory with two telescopes at an elevation of 4,145 meters (13,600 ft) near the summit of Mauna Kea in the U.S. state of Hawaii. Both telescopes have aperture primary mirrors, and when co ...

and photometric modeling, Camilla measures between 185 and 247 kilometers in diameter and its surface has an

albedo Albedo (; ) is the measure of the diffuse reflection of solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body that refl ...

between 0.160 and 0.294.

Satellites

Camilla is the 6th

that has been discovered in the

, after 87 Sylvia, 45 Eugenia,

216 Kleopatra 216 Kleopatra is a large M-type asteroid with a mean diameter of and is noted for its elongate bone or dumbbell shape. It was discovered on 10 April 1880 by Austrian astronomer Johann Palisa at the Austrian Naval Pola Observatory, in what is no ...

93 Minerva Minerva (minor planet designation: 93 Minerva) is a large trinary main-belt asteroid. It is a C-type asteroid, meaning that it has a dark surface and possibly a primitive carbonaceous composition. It was discovered by J. C. Watson on 24 August ...

and

130 Elektra Elektra ( minor planet designation: 130 Elektra) is a large outer main-belt asteroid and quadruple system with three minor-planet moons. It was discovered on 17 February 1873, by astronomer Christian Peters at Litchfield Observatory, New York, ...

(a quaternary).

S1

On 1 March 2001, a

of Camilla was found by A. Storrs, F. Vilas, R. Landis, E. Wells, C. Woods, B. Zellner, and M. Gaffey using the

Hubble Space Telescope The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most vers ...

. It has been designated but has not yet received an official name. Later observations in September 2005 with the

Very Large Telescope The Very Large Telescope (VLT) is a telescope facility operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of northern Chile. It consists of four individual telescopes, each with a primary mirror 8.2 m acro ...

(VLT) allowed the determination of an orbit. Apart from data in infobox, the inclination was found to be 3 ± 1° with respect to an axis pointing towards (β, λ) = (+55°, 75°). Given the ~10° uncertainty in the actual rotational axis of Camilla, one can say that the orbit's inclination is less than 10°. The satellite is estimated to measure about 11 km in diameter. Assuming a similar density to the primary, this would give it an approximate mass of ~1.5 kg. It has a similar colour to the primary.

S2

In 2016, the discovery of a second satellite of Camilla was reported by astronomers at Cerro Paranal's Very Large Telescope in Chile. It has the provisional designation . Observations were taken between 29 May 2015 and 30 July 2016, using the

VLT-SPHERE Spectro-Polarimetric High-contrast Exoplanet REsearch (VLT-SPHERE) is an adaptive optics system and coronagraphic facility at the Very Large Telescope (VLT). It provides direct imaging as well as spectroscopic and polarimetric characterization o ...

, the principal instrument attached to the 8-meter "Melipal" (UT3) unit of the VLT. On 3 out of 5 observation sessions, the new satellite could be detected. The body's orbit has a semi-major axis of 340 kilometers.

Notes

References

External links

IAU Circulars – 2016: S/2016 (107) 1

johnstonsarchive.net

(SpaceDaily.com, 21-03-2001), includes discovery image.

orbit data website maintained by F. Marchis. Includes orbit diagrams. * * {{DEFAULTSORT:Camilla 000107 000107 Discoveries by N. R. Pogson Named minor planets 000107 000107 000107 18681117