704 Interamnia

Infobox Planet | discovery=yes | physical_characteristics = yes | bgcolour=#FFFFC0
name=704 Interamnia
discoverer=Vincenzo Cerulli
discovered=October 2, 1910
alt_names=1910 KU; 1952 MW
mp_category=Main belt
epoch=October 22, 2004 (JD 2453300.5)
semimajor=458.187 Gm (3.063 AU)
perihelion=389.910 Gm (2.606 AU)
aphelion=526.464 Gm (3.519 AU)
eccentricity=0.149
period=1957.827 d (5.36 a)
inclination=17.285°
asc_node=280.422°
arg_peri=95.654°
mean_anomaly=204.093°
avg_speed=16.92 km/s
dimensions=350.4×303.7 km ^{[http://uchukan.satsumasendai.jp/data/occult/0303intera.html 1]}
mass=5.7×10¹⁹ kg
density=3.6 g/cm³
surface_grav=0.186 m/s²
escape_velocity=242.9 m/s
rotation=0.364 d ^{[http://obswww.unige.ch/~behrend/page2cou.html 2]}
spectral_type=F
magnitude = 9.9 to 13.0
abs_magnitude=5.94
albedo=0.075
single_temperature=~160 K

704 Interamnia (pronEng|ˌɪntərˈæmniə "in'-tər-am'-nee-ə," from Latin "Interamnium)" 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 the fifth most massive asteroid after Ceres, Vesta, Pallas and Hygiea with a mass estimated to be 2.0% of the mass of the entire asteroid belt.

Characteristics

Although the largest asteroid apart from the "big four", Interamnia 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 determining 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 form 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,cite web
title=Bright Minor Planets 2007
publisher=Minor Planet Center
url=http://www.cfa.harvard.edu/iau/Ephemerides/Bright/2007
accessdate=2008-05-21] 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 slighly shorter period. Another difference is that Interamnia's perihelion is located on the opposite side from the perihelia of the "big four", so that at 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.

References

External links

* [http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=704;orb=1 Orbital simulation] from JPL (Java) / [http://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=sb&sstr=704 Ephemeris]
*G. Michalak [http://www.aanda.org/index.php?option=com_base_ora&access=standard&Itemid=39&url=articles/aa/pdf/2001/29/aa10228.pdf Determination of asteroid masses] Astronomy & Astrophysics, Vol. 374, 703 (2001)
* [http://physics.bgsu.edu/~layden/Anim/Asteroids/interamnia.htm Animation of Asteroid Interamnia] taken on April 1st & 2nd, 2003
* [http://adsabs.harvard.edu/abs/1997DPS....29.0710B Occultation] of GSC 23450183 by (704) Interamnia on 1996 December 17 (dia: 329km; rotation period of 8.70 +/- 0.06 hours)
* [http://iota.jhuapl.edu/mp704d17.htm Interamnia Occultations Observed before 2003]
* [http://uchukan.satsumasendai.jp/data/occult/limovie/0303intera-study.html 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