107 Camilla

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107 Camilla (pronounced /kəˈmɪlə/ kə-mil'-ə) is one of the largest main belt asteroids. It orbits within the Cybele Group, beyond most of the main belt asteroids. It has a very dark surface and primitive carbonaceous composition. It was discovered by N. R. Pogson on November 17, 1868 and named after Camilla, Queen of the Volsci in Roman mythology. Lightcurve analysis indicates that Camilla's pole most likely points towards ecliptic coordinates (β, λ) = (+51°, 72°) with a 10° uncertainty [1], which gives it an axial tilt of 29°. [edit] Satellite (S/2001 (107) I) On 1 March 2001, a satellite of Camilla was found by A. Storrs, F. Vilas, R. Landis, E. Wells, C. Woods, B. Zellner, and M. Gaffey using the Hubble Space Telescope [2]. It has been designated S/2001 (107) 1 but has not yet received an official name. Later observations in September 2005 with the VLT allowed the determination of an orbit [3]. Apart from data in infobox, the inclination was found to be 3 ± 1° with respect to an axis pointing towards (β, λ) = (+55°, 75°) [3]. Given the ~10° uncertainty in the actual rotational axis of Camilla, one can say that the orbit's inclination is less than 10°. The satellite is estimated to measure about 11 km in diameter [4]. Assuming a similar density to the primary, this would give it an approximate mass of ~1.5×1015 kg. It has a similar colour to the primary [2]. S/2001 (107) 1 Discovery[2] and designation Discovered by A. Storrs, F. Vilas, R. Landis, E. Wells, C. Woods, B. Zellner, and M. Gaffey Discovery date 1 March 2001 Designations Minor planet category Main belt (Cybele) Orbital characteristics[3] Semi-major axis 1235 ± 16 km Eccentricity 0.006 ± 0.002 Orbital period 3.710 ± 0.001 d Average orbital speed 24.2 m/s Inclination < 10° Satellite of 107 Camilla Physical characteristics Dimensions ~ 11 ± 2 km[4] Mass ~1.5×1015 kg [5] Equatorial escape velocity ~ 6 m/s Absolute magnitude 13.18[4]

107 Camilla Discovery Discovered by Norman Robert Pogson Discovery date November 17, 1868 Designations Alternative names A893 QA; 1938 OG; 1949 HD1 Minor planet category Main belt (Cybele) Orbital characteristics Epoch December 31, 2006 (JD 2454100.5) Aphelion 560.937 Gm (3.750 AU) Perihelion 479.343 Gm (3.204 AU) Semi-major axis 520.140 Gm (3.477 AU) Eccentricity 0.078 Orbital period 2368.050 d (6.48 a) Average orbital speed 15.95 km/s Mean anomaly 1.746° Inclination 10.048° Longitude of ascending node 173.132° Argument of perihelion 309.877° Physical characteristics Dimensions 285×205×170 ± 20 km [6][1][4][7] Mass 1.09±0.04×1019 kg [3][8] Mean density ~1.9 g/cm³ [3] Equatorial surface gravity ~0.036 m/s² Escape velocity 0.10 km/s Rotation period 0.2018 d (4.84393 h) [1] Albedo 0.0525 [6] Temperature ~151 K max: 223 K (-52°C) Spectral type C [9] Absolute magnitude 7.08 [6]

[edit] External links

• Data on (87) Sylvia from Johnston's archive (maintained by W. R. Johnston)
• Hubble Finds New Asteroid Moon (SpaceDaily.com, 21-03-2001), includes discovery image.
• 107 Camilla and S/2001 (107) 1, orbit data website maintained by F. Marchis. Includes orbit diagrams.

[edit] References

1. ^ ^{a b c} J. Torppa et al (2003). "Shapes and rotational properties of thirty asteroids from photometric data". Icarus 164: 346. doi:10.1016/S0019-1035(03)00146-5. 
2. ^ ^{a b c} IAUC 7599
3. ^ ^{a b c d e} 107 Camilla and S/2001 (107) 1, F. Marchis
4. ^ ^{a b c d} F. Marchis et al (2006). "Shape, size and multiplicity of main-belt asteroids I. Keck Adaptive Optics survey". Icarus 185: 39. doi:10.1016/j.icarus.2006.06.001. 
5. ^ Assuming a similar density to the primary.
6. ^ ^{a b c} Supplemental IRAS Minor Planet Survey
7. ^ Axis ratios (rounded to nearest 5 km) based on lightcurve analysis of Torppa et al (2003), however taking IRAS mean diameter is inconsistent with the maximum value of the short axis obtained in Marchis et al (2006). Hence, presumably IRAS measurements were taken of a large face. Therefore, anchoring absolute size by requiring the shortest axis to be no larger than the maximum allowed by Marchis et al (2006).
8. ^ Error estimate derived from consideration of and given errors in a and P. See propagation of uncertainty.
9. ^ PDS spectral class data

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