32 Pomona

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32 Pomona
32Pomona (Lightcurve Inversion).png
A three-dimensional model of 32 Pomona based on its light curve.
Discovery
Discovered by H. Goldschmidt
Discovery date October 26, 1854
Designations
Pronunciation /pəˈmnə/
Named after
Pōmōna
A899 QA; A911 KF;
1945 RB; 1949 SH;
1950 YD
Minor planet category Main belt
Orbital characteristics[1]
Epoch December 31, 2006 (JD 2454100.5)
Aphelion 419.316 Gm (2.803 AU)
Perihelion 354.967 Gm (2.373 AU)
387.142 Gm (2.588 AU)
Eccentricity 0.083
1520.602 d (4.16 a)
18.48 km/s
46.086°
Inclination 5.530°
220.574°
339.680°
Physical characteristics
Dimensions 80.8 ± 1.6 km[1] (IRAS)
0.3937 d (9.448 h)[1]
Albedo 0.2564[1]
Spectral type
S[1]
7.56[1]

32 Pomona is a stony main-belt asteroid that is 81 km across. It was discovered by German-French astronomer Hermann Mayer Salomon Goldschmidt on October 26, 1854,[2] and is named after Pōmōna, the Roman goddess of fruit trees.

Photometric observations of this asteroid gave a light curve with a synodic rotation period of 9.448 hours. The data was used to construct a model for the asteroid, revealing it to be an angular object that is spinning about a pole with ecliptic coordinates (β, λ) = (+58°, 267°). The ratio of the major to minor axes' lengths is roughly equal to 1.3.[3]

The spectrum of 32 Pomona matches an S-type in the Tholen classification system, and is similar to primitive achondrite meteorites.[4] Measurements of the thermal inertia of 32 Pomona give a value of around 20–120 m–2 K–1 s–1/2, compared to 50 for lunar regolith and 400 for coarse sand in an atmosphere.[5]

Observations[edit]

Australian amateur astronomer Jonathan Bradshaw recorded an unusual asteroid occultation by 32 Pomona on 16 August 2008. The expected maximum duration of the occultation was 7.1 secs; however, the video recording shows two separate occultations of equal depth each lasting 1.2 seconds, separated by 0.8 secs. Those durations convert to chord lengths at the asteroid of 15 km, 10 km, and 15 km – for a total length of 40 km.[6] The IRAS diameter for Pomona is 80.8 ± 1.6 km.[1] The most likely explanation for this observation is that the asteroid is either binary (including a contact binary), or is a unitary asteroid with a significant concave region on its surface.[6][7] The video of this occultation can be viewed on YouTube.

References[edit]

  1. ^ a b c d e f g Yeomans, Donald K., "32 Pomona", JPL Small-Body Database Browser (NASA Jet Propulsion Laboratory), retrieved 2013-04-10. 
  2. ^ "Numbered Minor Planets 1–5000", Discovery Circumstances (IAU Minor Planet center), retrieved 2013-04-07. 
  3. ^ Kaasalainen, M. et al. (October 2002), "Models of Twenty Asteroids from Photometric Data", Icarus 159 (2): 369–395, Bibcode:2002Icar..159..369K, doi:10.1006/icar.2002.6907. 
  4. ^ Hiroi, T. et al. (March 1993), "Modeling of S-type asteroid spectra using primitive achondrites and iron meteorites", Icarus 102 (1): 107–116, Bibcode:1993Icar..102..107H, doi:10.1006/icar.1993.1036. 
  5. ^ Delbo', Marco; Tanga, Paolo (February 2009), "Thermal inertia of main belt asteroids smaller than 100 km from IRAS data", Planetary and Space Science 57 (2): 259–265, arXiv:0808.0869, Bibcode:2009P&SS...57..259D, doi:10.1016/j.pss.2008.06.015. 
  6. ^ a b David O'Driscoll (19 September 2009). "Jonathan Wooes the Goddess of Fruit Trees!". Astronomical Association of Queensland (AAQ). Retrieved 2012-01-28. 
  7. ^ "Occultation of UCAC2 38196247 by 32 Pomona 2008 August 16". Royal Astronomical Society of New Zealand. Retrieved 2012-01-28.  (concave region)

External links[edit]