PROFILPELAJAR.COM

22 Kalliope
	Kalliope and satellite Linus as seen by the W.M. Keck II telescope in 2010
Discovery
Discovered by	John Russell Hind
Discovery date	16 November 1852
Designations
MPC designation	(22) Kalliope
Pronunciation	/kəˈlaɪ.əpi/ kə-LY-ə-pee
Named after	Καλλιόπη Kalliopē
Minor planet category	Main belt
Adjectives	Kalliopean /kəˌlaɪ.əˈpiːən/ kə-LY-ə-PEE-ən
Orbital characteristics
	Epoch 23 July 2010 (JD 2455400.5)
Aphelion	479.98 Gm (3.2085 AU)
Perihelion	391.03 Gm (2.6139 AU)
Semi-major axis	435.09 Gm (2.9112 AU)
Eccentricity	0.10213
Orbital period (sidereal)	1814.3 d (4.97 yr)
Mean anomaly	282.54°
Inclination	13.703°
Longitude of ascending node	66.17°
Argument of perihelion	355.03°
Known satellites	Linus
Physical characteristics
Dimensions	235 km × 144 km × 124 km; 190 km × 125 km
Mean diameter	150±5 km; 166.2±2.8 km; 167.536±3.053 km; 181.0±4.6 km (IRAS);
Flattening	0.41
Mass	(7.7±0.4)×1018 kg; (8.16±0.26)×1018 kg; 7.36×1018 kg; (6.30±0.50)×1018 kg
Mean density	4.36±0.50 g/cm3; 3.35±0.33 g/cm3; 2.37±0.40 g/cm3; 2.03±0.16 g/cm3;
Synodic rotation period	0.17285 days (4.1483 h)
Geometric albedo	0.198; 0.17; 0.166 ± 0.005
Spectral type	M (Tholen); X (SMASS); X (Bus-DeMeo) ;
Absolute magnitude (H)	6.81

22 Kalliope (/kəˈlaɪ.əpi/; kə-LY-ə-pee) is a large M-type asteroid from the asteroid belt discovered by J. R. Hind on 16 November 1852. It is named after Calliope, the Greek Muse of epic poetry. It is orbited by a small moon named Linus.

Characteristics

Kalliope is somewhat elongated, approximately 166 km in diameter,^[3] and slightly asymmetric, as evidenced by resolved images taken with the VLT at the European Southern Observatory. This new diameter, which was measured by observing mutual eclipses of Kalliope and Linus, is 8% smaller than that calculated from IRAS observations.^[3]

The spectrum of Kalliope is an M-type, indicating that its surface may be partially composed of iron–nickel metal. The asteroid's density is about 3.4 g/cm³.^[3] Since the asteroid is likely to be a rubble pile, accounting for a possible porosity of 20–40% leads to the material density of 4.2–5.8 g/cm³, which means that Kalliope is probably made of a mixture of metal with silicates.^[3] Spectroscopic studies have shown, however, evidence of hydrated minerals^[9] and silicates,^[10] which indicate rather a stony surface composition. Kalliope also has a low radar albedo,^[6] which is inconsistent with a purely metallic surface.

Lightcurve analysis indicates that Kalliope's pole most likely points towards ecliptic coordinates (β, λ) = (−23°, 20°) with a 10° uncertainty,^[11]^[7] which gives Kalliope an axial tilt of 103°. Kalliope's rotation is then slightly retrograde.

Between 2004 and 2021, 22 Kalliope has been observed to occult fifteen stars.

In 2022, it was discovered that 22 Kalliope is part of an asteroid family that formed about 900 million years ago. Its moon, Linus, may have been formed at the same time.^[12]

Satellite

Kalliope has one known natural satellite, called Linus or (22) Kalliope I Linus. It is quite large – about 28 km in diameter – and would be a sizeable asteroid by itself. It orbits about 1100 km from the center of Kalliope, equivalent to about 13.2 Kalliope radii.^[3] Linus was discovered on 29 August 2001 by Jean-Luc Margot and Michael E. Brown, while another team led by William Merline also independently detected the moon 3 days later.^[6]^[7]

First stellar occultation

On 7 November 2006, the first stellar occultation by the satellite of an asteroid (Linus) was successfully observed by a group of Japanese observers^[4] according to a prediction that was made just one day before by Berthier et al.^[13] 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.

Notes

^ Flattening derived from the maximum aspect ratio (c/a): $f=1-{\frac {c}{a}}$ , where (c/a) = 0.59±0.02.^[5]

References

^ "calliope". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
^ ^a ^b ^c ^d ^e ^f ^g "JPL Small-Body Database Browser: 22 Kalliope" (2010-06-02 last obs). Retrieved 22 July 2010.
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j Descamps, P.; Marchis, F.; et al. (2008). "New determination of the size and bulk density of the binary asteroid 22 Kalliope from observations of mutual eclipses". Icarus. 196 (2): 578–600. arXiv:0710.1471. Bibcode:2008Icar..196..578D. doi:10.1016/j.icarus.2008.03.014. S2CID 118437111.
^ ^a ^b M. Sôma, et al. (2006). "'Occultation by Kalliope (22) and its satellite Linus". Central Bureau Electronic Telegrams. 732: 1. Bibcode:2006CBET..732....1S.
^ ^a ^b ^c ^d ^e Vernazza, P.; et al. (October 2021). "VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis". Astronomy & Astrophysics. 654: A56. Bibcode:2021A&A...654A..56V. doi:10.1051/0004-6361/202141781. hdl:10261/263281. S2CID 239104699.
^ ^a ^b ^c ^d ^e J.L. Margot & M.E. Brown (2003). "A Low-Density M-type Asteroid in the Main Belt". Science. 300 (5627): 1939–1942. Bibcode:2003Sci...300.1939M. doi:10.1126/science.1085844. PMID 12817147. S2CID 5479442.
^ ^a ^b ^c ^d ^e F. Marchis (2003). "A three-dimensional solution for the orbit of the asteroidal satellite of 22 Kalliope". Icarus. 165 (1): 112–120. Bibcode:2003Icar..165..112M. doi:10.1016/S0019-1035(03)00195-7.
^ "EAR-A-5-DDR-TAXONOMY-V6.0". Planetary Data System. Archived from the original on 17 December 2015. Retrieved 16 April 2018.
^ A.S. Rivkin (2000). "The nature of M-class asteroids from 3-micron observations". Icarus. 145 (2): 351–368. Bibcode:2000Icar..145..351R. doi:10.1006/icar.2000.6354.
^ D.F. Lupishko (1982). "UBV photometry of the M-type asteroids 16 Psyche and 22 Kalliope". Solar System Research. 16: 75. Bibcode:1982AVest..16..101L.
^ M. Kaasalainen (2002). "Models of Twenty Asteroids from Photometric Data" (PDF). Icarus. 159 (2): 369–395. Bibcode:2002Icar..159..369K. doi:10.1006/icar.2002.6907.
^ Brož, M.; Ferrais, M.; Vernazza, P.; Ševeček, P.; Jutzi, M. (2022). "Discovery of an asteroid family linked to (22) Kalliope and its moon Linus". Astronomy & Astrophysics. 664: A69. arXiv:2205.15736. Bibcode:2022A&A...664A..69B. doi:10.1051/0004-6361/202243628.
^ J. Berthier, et al. (2004). "'Prediction of stellar occultations by satellite of asteroids". AAS/Division for Planetary Sciences Meeting Abstracts #36. 32 (23): 1142. Bibcode:2004DPS....36.3223B.