324 Bamberga

324 Bamberga
VLT image of Bamberga
Discovery
Discovered byJohann Palisa
Discovery date25 February 1892
Designations
(324) Bamberga
Pronunciation/bæmˈbɜːrɡə/
Named after
Bamberg
Main belt
AdjectivesBambergian /bæmˈbɜːrdʒiən, -ɡiən/
Orbital characteristics[1]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc124.08 yr (45321 d)
Aphelion3.59442 AU (537.718 Gm)
Perihelion1.77023 AU (264.823 Gm)
2.68232 AU (401.269 Gm)
Eccentricity0.34004
4.39 yr (1604.6 d)
225.419°
0° 13m 27.682s / day
Inclination11.1011°
327.883°
44.2409°
Physical characteristics
Dimensionsc/a = 0.96±0.05[2]
227±3 km[2]
234.67 ± 7.80 km[3]
229.4 ± 7.4 km (IRAS)[4]
Mass(10.2±0.9)×1018 kg[2]
11×1018 kg[5]
(10.3±1.0)×1018 kg[3]
Mean density
1.67±0.16 g/cm3[2]
1.52±0.20 g/cm3[3]
1.226 d[6]
29.43 h (1.226 d)[1]
0.060 (calculated)[2]
0.0628±0.004[4]
C-type asteroid[7]
6.82[1][4]

324 Bamberga is one of the largest asteroids in the asteroid belt. It was discovered by Johann Palisa on 25 February 1892 in Vienna. It is one of the top-20 largest asteroids in the asteroid belt. Apart from the near-Earth asteroid Eros, it was the last asteroid which is ever easily visible with binoculars to be discovered.

Overall Bamberga is the tenth-brightest main-belt asteroid after, in order, Vesta, Pallas, Ceres, Iris, Hebe, Juno, Melpomene, Eunomia and Flora. Its high eccentricity (for comparison 36% higher than that of Pluto), though, means that at most oppositions other asteroids reach higher magnitudes.

Observation

Bamberga's orbit

Although its very high orbital eccentricity means its opposition magnitude varies greatly, at a rare opposition near perihelion Bamberga can reach a magnitude of +8.0,[8] which is as bright as Saturn's moon Titan. Such near-perihelion oppositions occur on a regular cycle every twenty-two years, with the last occurring in 2013 and the next in 2035, when attaining magnitude 8.1 on 13 September. Its brightness at these rare near-perihelion oppositions makes Bamberga the brightest C-type asteroid, roughly one magnitude brighter than 10 Hygiea's maximum brightness of around +9.1. At such an opposition Bamberga can in fact be closer to Earth than any main-belt asteroid with magnitude above +9.5, getting as close as 0.78 AU. For comparison, 7 Iris never comes closer than 0.85 AU and 4 Vesta never closer than 1.13 AU (when it becomes visible to the naked eye in a light pollution-free sky).

Characteristics

The 29-hour rotation period is unusually long for an asteroid more than 150 km in diameter.[9] Its spectral class is intermediate between the C-type and P-type asteroids.[7]

10μ radiometric data collected from Kitt Peak in 1975 gave a diameter estimate of 255 km.[10] An occultation of Bamberga was observed on 8 December 1987, and gave a diameter of about 228 km, in agreement with IRAS results. In 1988 a search for satellites or dust orbiting this asteroid was performed using the UH88 telescope at the Mauna Kea Observatories, but the effort came up empty.[11]

References

  1. ^ a b c "JPL Small-Body Database Browser: 324 Bamberga". 2008-07-26 last obs. Retrieved 11 May 2016.
  2. ^ a b c d e P. Vernazza et al. (2021) VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis. Astronomy & Astrophysics 54, A56
  3. ^ a b c Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science, vol. 73, pp. 98–118, arXiv:1203.4336, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009. See Table 1.
  4. ^ a b c Tedesco, E.F.; Noah, P.V.; Noah, M.; Price, S.D. (2004). "IRAS Minor Planet Survey. IRAS-A-FPA-3-RDR-IMPS-V6.0". NASA Planetary Data System. Archived from the original on 19 January 2007. Retrieved 15 March 2007.
  5. ^ Pitjeva, E. V. (2005). "High-Precision Ephemerides of Planets—EPM and Determination of Some Astronomical Constants" (PDF). Solar System Research. 39 (3): 176. Bibcode:2005SoSyR..39..176P. doi:10.1007/s11208-005-0033-2. Archived from the original (PDF) on 31 October 2008.
  6. ^ Harris, A. W.; Warner, B.D.; Pravec, P., eds. (2006). "Asteroid Lightcurve Derived Data. EAR-A-5-DDR-DERIVED-LIGHTCURVE-V8.0". NASA Planetary Data System. Archived from the original on 28 January 2007. Retrieved 15 March 2007.
  7. ^ a b Neese, C., ed. (2005). "Asteroid Taxonomy.EAR-A-5-DDR-TAXONOMY-V5.0". NASA Planetary Data System. Archived from the original on 10 March 2007. Retrieved 15 March 2007.
  8. ^ Donald H. Menzel & Jay M. Pasachoff (1983). A Field Guide to the Stars and Planets (2nd ed.). Boston, MA: Houghton Mifflin. p. 391. ISBN 0-395-34835-8.
  9. ^ "JPL Small-Body Database Search Engine: diameter > 150 (km) and rot_per > 24 (h)". JPL Solar System Dynamics. Retrieved 6 June 2015.
  10. ^ Morrison, D.; Chapman, C. R. (March 1976), "Radiometric diameters for an additional 22 asteroids", Astrophysical Journal, vol. 204, pp. 934–939, Bibcode:2008mgm..conf.2594S, doi:10.1142/9789812834300_0469.
  11. ^ Gradie, J.; Flynn, L. (March 1988), "A Search for Satellites and Dust Belts Around Asteroids: Negative Results", Abstracts of the Lunar and Planetary Science Conference, vol. 19, pp. 405–406, Bibcode:1988LPI....19..405G.