|Discovered by||Vincenzo Cerulli|
|Discovery date||October 2, 1910|
|Alternative names||1910 KU; 1952 MW|
|Minor planet category||Main belt|
|Epoch November 30, 2008 (JD 2454800.5)|
|Aphelion||3.522 AU (526.883 Gm)|
|Perihelion||2.601 AU (389.104 Gm)|
|Semi-major axis||3.062 AU (458.068 Gm)|
|Orbital period||5.36 a (1957.49 d)|
|Average orbital speed||16.92 km/s|
|Longitude of ascending node||280.38°|
|Argument of perihelion||95.76°|
326 km (mean)
317 km IRAS
|Mean density||2.22 ± 0.17 g/cm³|
|Equatorial surface gravity||0.186 m/s²|
|Escape velocity||242.9 m/s|
|Rotation period||0.364 d 2
|Apparent magnitude||9.9 to 13.0|
|Absolute magnitude (H)||5.94|
704 Interamnia is a very large asteroid, with an estimated diameter of 350 kilometres. Its mean distance from the Sun is 3.067 (AU). It was discovered on October 2, 1910 by Vincenzo Cerulli, and named after the Latin name for Teramo, Italy, where Cerulli worked. It is probably the fifth-most-massive asteroid after Ceres, Vesta, Pallas, and Hygiea, with a mass estimated to be 1.2% of the mass of the entire asteroid belt.
Although Interamnia is the largest asteroid after the "big four", it is a very little-studied body. It is easily the largest of the F-type asteroids, but there exist very few details of its internal composition or shape, and no lightcurve analysis has yet been done to determine the ecliptic coordinates of Interamnia's poles (and hence its axial tilt). Its apparently high bulk density (though subject to much error) suggests an extremely solid body entirely without internal porosity or traces of water. This also strongly suggests that Interamnia is large enough to have fully withstood all the collisions that have occurred in the asteroid belt since the Solar System was formed.
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 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.
Its orbit is slightly more eccentric that that of Hygiea (15% versus 12%) but differs from Hygiea's in its much greater inclination and slightly shorter period. Another difference is that Interamnia's perihelion is located on the opposite side from the perihelia of the "big four", so that Interamnia at perihelion is actually closer to the Sun than Ceres and Pallas are at the same longitude. It is unlikely to collide with Pallas because their nodes are located too far apart, whilst although its nodes are located on the opposite side from those of Ceres, it is generally clear of Ceres when both cross the same orbital plane and a collision is again unlikely.
In 2001, Michalak estimated Interamnia to have a mass of 6.9×1019 kg. Michalak's estimate depends on the masses of 19 Fortuna, 29 Amphitrite, and 16 Psyche; thus this mass was obtained assuming an incomplete dynamical model.
In 2007, Baer and Chesley estimated Interamnia to have a mass of (7.12±0.84)×1019 kg. As of 2010[update], Baer suggests Interamnia has a mass of only (3.90±0.18)×1019 kg. This makes it more massive than 511 Davida, though the error bars overlap.
- "JPL Small-Body Database Browser: 704 Interamnia (1910 KU)". 2008-04-14 last obs. Retrieved 2008-11-04.
- Nugent, Richard (2003-03-23). "704 Interamnia 2003 Mar 23". Richard's Astronomy Pages. Archived from the original on 27 December 2008. Retrieved 2008-12-03.
- Baer, James (2010). "Recent Asteroid Mass Determinations". Personal Website. Retrieved 2011-02-13.
- "Bright Minor Planets 2007". Minor Planet Center. Retrieved 2008-05-21.
- "Mass of 704 Interamnia" 0.186 / "Mass of Mbelt" 15 = 0.0124
- Michalak, G. (2001). "Determination of asteroid masses". Astronomy & Astrophysics 374 (2): 703–711. Bibcode:2001A&A...374..703M. doi:10.1051/0004-6361:20010731. Retrieved 2008-11-04.
- Baer, Jim; Steven R. Chesley (2008). "Astrometric masses of 21 asteroids, and an integrated asteroid ephemeris" (PDF). Celestial Mechanics and Dynamical Astronomy (Springer Science+Business Media B.V. 2007) 100 (2008): 27–42. Bibcode:2008CeMDA.100...27B. doi:10.1007/s10569-007-9103-8. Retrieved 2008-11-21.
- Orbital simulation from JPL (Java) / Ephemeris
- Animation of Asteroid Interamnia taken on April 1 & 2, 2003
- Occultation of GSC 23450183 by (704) Interamnia on 1996 December 17 (dia: 329 km; rotation period of 8.70 +/- 0.06 hours)
- Interamnia Occultations Observed before 2003
- Occultation of HIP36189 by (704) Interamnia on 2003 March 23 (dia: 350.4×303.7 km) recorded by Isao Ootsuki (graze) and Hideo Takashima and Fujio Ohbain Japan, analysis by Tsutomu Hayamizu