22 Kalliope

Infobox Planet | discovery=yes | physical_characteristics = yes | bgcolour=#FFFFC0
name=22 Kalliope
discoverer=John Russell Hind
discovered=November 16, 1852
alt_names="none"
mp_category=Main belt
epoch=November 12, 2005 (JD 2453686.5)
semimajor=435.182 Gm (2.909 AU)
perihelion=390.433 Gm (2.610 AU)
aphelion=479.931 Gm (3.208 AU)
eccentricity=0.103
period=1812.245 d (4.96 a)
inclination=13.710°
asc_node=66.240°
arg_peri=356.172°
mean_anomaly=303.545°
avg_speed=17.42 km/s
dimensions=215×180×150 km [http://www.psi.edu/pds/archive/astdata04/simps04/diamalb.tab Supplemental IRAS Minor Planet Survey] ] cite journal | author= M. Kaasalainen et al| title= "Models of Twenty Asteroids from Photometric Data"| journal= Icarus| year= 2002| volume= 159| pages= 369| url= http://www.rni.helsinki.fi/~mjk/IcarPIII.pdf | doi= 10.1006/icar.2002.6907]
mass=6.3 ± 0.5 e|18 kg cite journal | author= F. Marchis et al| title= "A three-dimensional solution for the orbit of the asteroidal satellite of 22 Kalliope"| journal= Icarus| year= 2003| volume= 165| pages= 112| url=http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2003Icar..165..112M&db_key=AST&data_type=HTML&format=&high=444b66a47d11635 | doi= 10.1016/S0019-1035(03)00195-7] cite journal | author= J.L. Margot & M.E. Brown| title= "A Low-Density M-type Asteroid in the Main Belt"| journal= Science| year= 2003| volume= 300| pages= 1939| url= http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2003Sci...300.1939M&db_key=AST&data_type=HTML&format=&high=444b66a47d06635 | doi= 10.1126/science.1085844| pmid= 12817147]
density=2.03 ± 0.16 g/cm³
surface_grav=0.038 m/s²
escape_velocity=0.09 km/s
rotation=0.1728 d (4.148 h) [http://www.psi.edu/pds/archive/lc.html PDS lightcurve data] ]
spectral_type=M [http://www.psi.edu//pds/resource/taxonomy.html PDS spectral class data] ]
abs_magnitude=6.45
albedo=0.142
single_temperature=~161 K
"max:" 240 K (-32 °C)

22 Kalliope (pronEng|kəˈlaɪəpi, _gr. "Καλλιόπη)" is a large main belt asteroid of the M-type, discovered by J. R. Hind on November 16, 1852. It is named after Calliope, the Greek Muse of epic poetry.

Characteristics

Kalliope is somewhat elongated, approximately 180 km in diameter, and slightly asymmetric, as evidenced by resolved images taken with the VLT at the European Southern Observatory [http://astro.berkeley.edu/~fmarchis/Science/Asteroids/Kalliope.html synthesis of several observations] including recent ones with the VLT 8 m telescope.] .

While its spectrum is an M-type, Kalliope does not appear to be metallic, similarly to other M-types such as 21 Lutetia, for example. Firstly, its density, which is known with confidence from its satellite's orbit, is far too low to agree with any plausible metallic substance, even a rubble pile. It would have to be 70% porous, which is inconsistent with packing considerations. Furthermore, spectroscopic studies have shown evidence of hydrated minerals cite journal | author= A.S. Rivkin et al| title= "The nature of M-class asteroids from 3-micron observations"| journal= Icarus| year= 2000| volume= 145| pages= 351| url= http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2000Icar..145..351R&db_key=AST&data_type=HTML&format=&high=444b66a47d32455 | doi= 10.1006/icar.2000.6354] and silicates cite journal | author= D.F. Lupishko et al| title= "UBV photometry of the M-type asteroids 16 Psyche and 22 Kalliope"| journal= Solar System Research| year= 1982| volume= 16| pages= 75] , which indicate rather a stony surface composition. Kalliope also has a low radar albedo , which is again inconsistent with a metallic surface.

Lightcurve analysis indicates that Kalliope's pole most likely points towards ecliptic coordinates (β, λ) = (-23°, 20°) with a 10° uncertainty cite journal | author= M. Kaasalainen et al| title= "Models of Twenty Asteroids from Photometric Data"| journal= Icarus| year= 2002| volume= 159| pages= 369| url= http://www.rni.helsinki.fi/~mjk/IcarPIII.pdf | doi= 10.1006/icar.2002.6907] , which gives Kalliope an axial tilt of 103°. Kalliope's rotation is then slightly retrograde.

atellite

Kalliope has one known natural satellite, Linus, or (22) Kalliope I Linus. It is quite large being 30-40 km in diameter, and would be a sizeable asteroid by itself. It orbits about 1065 km from Kalliope, equivalent to about 12 Kalliope radii. Linus was discovered on August 29, 2001 by Jean-Luc Margot and Michael E. Brown, while another team lead by William Merline also independently detected the moon 3 days later.

First Stellar Occultation

On November 7 2006, the first stellar occultation by the satellite of an asteroid (Linus) was successfully observed by a group of Japanese observers cite journal | author=M. Soma et al| title='Occulation by Kalliope and Linus"| journal=CBET|year=2006| volume = 732| url = http://adsabs.harvard.edu/abs/2006CBET..732....1S] according to a prediction that was made just one day before by Berthier et al. cite journal | author=J. Berthier et al.| title='Prediction of stellar occultations by satellite of asteroids"| journal=DPS-AAS|year=2004| volume = 32.23| url = http://adsabs.harvard.edu/abs/2004DPS....36.3223B] based on more than 5 years of regular observations of Kalliope binary system using adaptive optics systems on ground-based telescopes. The observed chords of Linus give a unique opportunity to estimate the size of the moonlet which was estimated to 20-28 km.

References

External links

* [http://astron.berkeley.edu/~fmarchis/Science/Asteroids/Kalliope.html Kalliope and Linus] very well resolved with the 8 m VLT at ESO. Also includes a Kalliope shape model.
* [http://www.rni.helsinki.fi/~mjk/IcarPIII.pdf shape model deduced from lightcurve]
* [http://www.eso.org/outreach/press-rel/pr-2004/pr-21-04.html#phot-24j-04 orbit diagram for Linus]
* [http://occsec.wellington.net.nz/planet/2004/updates/040708_22_1819_u.htm A different VLT image of Kalliope and Linus]
* [http://www.johnstonsarchive.net/astro/astmoons/am-00022.html Data sheet at Johnston's Archive] , includes some other parameters.
* [http://www.imcce.fr/page.php?nav=en/ephemerides/phenomenes/occult/stellarocc.php?query=predoc] , Prediction and Reduction of Stellar Occultations of Binary Asteroids.