41 Daphne

41 Daphne
Daphne and satellite as seen by the W.M. Keck II telescope in 2008
Discovery[1]
Discovered by H. Goldschmidt
Discovery date May 22, 1856
Designations
MPC designation (41) Daphne
Pronunciation /ˈdæfni/
Named after
 Daphnē
1949 TG
Main belt
Adjectives Daphnean /ˈdæfniən/
Orbital characteristics[1]
Epoch 31 December 2006 (JD 2454100.5)
Aphelion 3.517 AU (526.144 Gm)
Perihelion 2.014 AU (301.220 Gm)
2.765 AU (413.682 Gm)
Eccentricity 0.272
4.60 a (1,679.618 d)
247.500°
Inclination 15.765°
178.159°
46.239°
Known satellites S/2008 (41) 1
Physical characteristics
Dimensions 174.0 ± 11.2 km[1]
189 km[2]
213×160 km[3]
239x183x153 km[4]
Mass ~6.8×1018 kg[5]
Mean density
 ~1.95 g/cm³[4]
5.9 hr[1]
0.083[1]
C [1]
7.12[1]

    41 Daphne is a large asteroid from the asteroid belt.[1] It is a dark-surfaced body 174 km in diameter is probably composed of primitive carbonaceous chondrites. The spectra of the asteroid displays evidence of aqueous alteration.[6] It was discovered by H. Goldschmidt on May 22, 1856, and named after Daphne, the nymph in Greek mythology who was turned into a laurel tree. Incorrect orbital calculations initially resulted in 56 Melete being mistaken for a second sighting of Daphne. Daphne was not sighted again until August 31, 1862.[7]

    The orbit of 41 Daphne places it in a 9:22 mean motion resonance with the planet Mars. The computed Lyapunov time for this asteroid is 14,000 years, indicating that it occupies a chaotic orbit that will change randomly over time because of gravitational perturbations of the planets.[8]

    In 1999, Daphne occulted three stars, and on July 2, 1999, produced eleven chords indicating an ellipsoid of 213×160 km.[3] Daphnean lightcurves also suggest that the asteroid is irregular in shape. Daphne was observed by Arecibo radar in April 2008.[9][10] Based upon radar data, the near surface solid density of the asteroid is 2.4+0.7
    −0.5     g cm−3.[11]

    Satellite

    41 Daphne has at least one satellite, designated S/2008 (41) 1.[12] It was identified on March 28, 2008, and has a projected separation of 443 km, an orbital period of approximately 1.1 days,[4] and an estimated diameter of less than 2 km. If these preliminary observations hold up, this binary system has the most extreme size ratio known.[13]

    References

    1. 1 2 3 4 5 6 7 8 Yeomans, Donald K., "41 Daphne", JPL Small-Body Database Browser, NASA Jet Propulsion Laboratory, retrieved 2013-04-07.
    2. ↑ Matter, Alexis; Marco Delbo; Sebastiano Ligori; Nicolas Crouzet; Paolo Tanga (2011). "Determination of physical properties of the asteroid (41) Daphne from interferometric observations in the thermal infrared". Icarus. 215 (1): 47–56. arXiv:1108.2616. Bibcode:2011Icar..215...47M. doi:10.1016/j.icarus.2011.07.012.
    3. 1 2 "1999 European Asteroidal Occultation Results". euraster.net (a website for Asteroidal Occultation Observers in Europe). 2009-02-09. Retrieved 2008-12-01. (1999-Jul-02 Chords)
    4. 1 2 3 Conrad, Al; Carry, B.; Drummond, J. D.; Merline, W. J.; Dumas, C.; Owen, W. M.; et al. (2008). "Shape and Size of Asteroid (41) Daphne from AO Imaging" (PDF). American Astronomical Society. 40 (28.12): 438. Bibcode:2008DPS....40.2812C. Archived from the original (PDF) on 2009-09-18.
    5. ↑ Using the volume of an ellipsoid of 239x183x153km * a density of 1.95 g/cm³ yields a mass (m=d*v) of 6.8E+18 kg
    6. ↑ Fornasier, S.; et al. (February 1999), "Spectroscopic comparison of aqueous altered asteroids with CM2 carbonaceous chondrite meteorites", Astronomy and Astrophysics Supplement, 135: 65−73, Bibcode:1999A&AS..135...65F, doi:10.1051/aas:1999161.
    7. ↑ Appletons' annual cyclopaedia and register of important events of the year: 1862. New York: D. Appleton & Company. 1863. p. 173.
    8. ↑ Šidlichovský, M. (1999), Svoren, J.; Pittich, E. M.; Rickman, H., eds., "Resonances and chaos in the asteroid belt", Evolution and source regions of asteroids and comets : proceedings of the 173rd colloquium of the International Astronomical Union, held in Tatranska Lomnica, Slovak Republic, August 24–28, 1998, pp. 297–308, Bibcode:1999esra.conf..297S.
    9. ↑ Mike Nolan (2012-01-18). "Scheduled Arecibo Radar Asteroid Observations". Planetary Radar at Arecibo Observatory. Retrieved 2012-01-23.
    10. ↑ "Radar-Detected Asteroids and Comets". NASA/JPL Asteroid Radar Research. Retrieved 2012-01-23.
    11. ↑ Magri, C.; et al. (December 2001), "Radar constraints on asteroid regolith compositions using 433 Eros as ground truth", Meteoritics & Planetary Science, 36 (12), pp. 1697–1709, Bibcode:2001M&PS...36.1697M, doi:10.1111/j.1945-5100.2001.tb01857.x.
    12. ↑ "IAUC 8930: COMET P/2006 B7 (ODAS); S/2008 (41) 1; 196P; STEREO SPACECRAFT". IAU Central Bureau for Astronomical Telegrams. 2008-03-31. Retrieved 2008-03-31.
    13. ↑ "Discovery of an Extreme Mass-Ratio Satellite of (41) Daphne in a Close Orbit" (PDF). Lunar and Planetary Institute. 2008. Retrieved 2011-10-13.
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