704 Interamnia is a large

F-type asteroid F-type asteroids are a relatively uncommon type of carbonaceous asteroid, falling into the wider C-group. Characteristics F-type asteroids have spectra generally similar to those of the B-type asteroids, but lack the "water" absorption feature ar ...

. With a mean diameter of around 330 kilometres, it is the fifth-largest asteroid, after Ceres, Vesta,

Pallas Pallas may refer to: Astronomy * 2 Pallas asteroid ** Pallas family, a group of asteroids that includes 2 Pallas * Pallas (crater), a crater on Earth's moon Mythology * Pallas (Giant), a son of Uranus and Gaia, killed and flayed by Athena * Pa ...

and Hygiea. Its mean distance from the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

is 3.067 ( AU). It was discovered on 2 October 1910 by

Vincenzo Cerulli Vincenzo Cerulli (20 April 1859 – 30 May 1927) was an Italian astronomer and founder of the Collurania-Teramo Observatory in Teramo, central Italy, where he was born. He earned a degree in physics from the Sapienza University of Rome in 1881 ...

, and named after the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

name for Teramo,

Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical ...

, where Cerulli worked. Its

mass Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different eleme ...

is probably between fifth and tenth highest in the asteroid belt, with a mass estimated to be 1.2% of the mass of the entire asteroid belt. Observations by 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 ...

SPHERE A sphere () is a geometrical object that is a three-dimensional analogue to a two-dimensional circle. A sphere is the set of points that are all at the same distance from a given point in three-dimensional space.. That given point is th ...

imager in 2017–2019, combined with occultation results, indicate that the shape of Interamnia may be consistent with

hydrostatic equilibrium In fluid mechanics, hydrostatic equilibrium (hydrostatic balance, hydrostasy) is the condition of a fluid or plastic solid at rest, which occurs when external forces, such as gravity, are balanced by a pressure-gradient force. In the planetary ...

for a body of its density with a rotational period of 7.6 hours. (Its current period is 8.7 hours.) This suggests that Interamnia may have formed as an equilibrium body, and that impacts changed its rotational period after it fully solidified.

Characteristics

Although Interamnia is the largest asteroid after the "big four", it is a very little-studied body. It is easily the largest of the

s, but until 2017-2019 there existed very few details of its internal composition or shape, and no

light curve 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 frequ ...

analysis has yet been done to determine the ecliptic coordinates of Interamnia's poles (and hence its

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 ...

). Studies by the Very Large Telescope give an average diameter of about 332 km and found an ellipsoidal shape for Interamnia, similar to 4 Vesta; the resulting density calculation (1.98 ± 0.68 g·cm⁻³) is not precise enough to definitely infer Interamnia's composition, but the presence of hydrated materials at the surface and its overall spectral similarities to Ceres suggest that it is likely an icy body. The absence of an affiliated asteroid family implies that Interamnia has not suffered a giant impact within the past 3 billion years, in contrast to 4 Vesta and 10 Hygeia. Its very dark surface and relatively large distance from the Sun means Interamnia can never be seen with 10x50 binoculars. At most oppositions its

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

is around +11.0, which is less than the ''minimum'' brightness of Vesta, Ceres or Pallas. Even at a perihelic opposition its magnitude is only +9.9, which is over four magnitudes lower than Vesta.

Surface

There are no deep basins visible in the VLT images. Any large craters must have flat floors, consistent with an icy C/F-type composition.

Mass

In 2001, Michalak estimated Interamnia to have a mass of . Michalak's estimate depends on the masses of 19 Fortuna,

29 Amphitrite Amphitrite ( minor planet designation: 29 Amphitrite) is one of the largest S-type asteroids, approximately in diameter, and probably fifth largest after Eunomia, Juno, Iris and Herculina. Discovery Amphitrite was discovered by Albert Mart ...

, and 16 Psyche; thus this mass was obtained assuming an incomplete dynamical model. In 2011, Baer calculated Interamnia had a mass of . Goffin's 2014 astrometric reanalysis gives an even lower mass of . In 2019, Hanuš et al. consolidated 21 selected prior mass estimates, dating from 1992 to 2017, with a metastatistical result of (that is, to within 1 sigma uncertainty. File:SPHERE image of Interamnia.jpg,

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 ...

image of Interamnia File:Animation of 704 Interamnia orbit 2000-2020.gif, Animation of 704 Interamnia orbit 2000-2020
File:TESS observation of Interamnia.gif, The Transiting Exoplanet Survey Satellite (TESS) observed 704 Interamnia passing close to a target star, TIC 14802783, on 18/01/19.

References

External links

Animation of Asteroid Interamnia
taken on 1 & 2 April 2003

Occultation of GSC 23450183
by on 17 December 1996

by on 23 March 2003
(704) Interamnia: A transition object between a dwarf planet and a typical irregular-shaped minor body
* * {{DEFAULTSORT:000704 Background asteroids Interamnia Interamnia F-type asteroids (Tholen) B-type asteroids (SMASS) 19101002 19101002 Objects observed by stellar occultation Possible dwarf planets

Characteristics

Surface

Mass

See also

References

External links