324 Bamberga

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324 Bamberga
Discovery and designation
Discovered by Johann Palisa
Discovery date February 25, 1892
Reference date 30 January, 2005 (JD 2453400.5)
Longest distance from the Sun 537.241 Gm (3.591 AU)
Shortest distance from the Sun 265.576 Gm (1.775 AU)
Longest distance from the center of its orbital path
("semi-major axis")
401.409 Gm (2.683 AU)
How long it takes to complete an orbit 1605.397 d (4.4 a)
Mean anomaly 4.564°
Angle above the reference plane
Size and other qualities
Measurements 229 km[1]
Mass 1.1×1019 kg[2]
Average density 1.8 g/cm³
Escape velocity 0.23 km/s
Rotation period 1.226 d[3]
How much light it reflects 0.0628[1]
Avg. surface temp. ~172 K
Spectral type C-type asteroid[4]
True brightness
("absolute magnitude")

324 Bamberga is the 16th biggest asteroid in the Main asteroid belt. It was found by Johann Palisa on February 25, 1892 in Vienna, making it one of the last big (diameter over 200 km) asteroids found. Apart from the near-earth asteroid Eros, it was the last asteroid which is ever easily visible with binoculars to be found.

Although its very high orbital eccentricity means its opposition magnitude varies a lot, at a rare opposition near perihelion Bamberga can reach a magnitude of +8.0,[5] which is as bright as Saturn's moon Titan. Such near-perihelion oppositions happen on a regular cycle every twenty-two years, with the last happening in 1991 and the next in 2013. Its brightness at these rare near-perihelion oppositions makes Bamberga the brightest C-type asteroid, about 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 pollution-free sky.

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.

It has an unusually long rotation period among the big asteroids. Its spectral class is between the C-type and P-type asteroids.[4]

An occultation of Bamberga was seen on 8 December, 1987, and gave a diameter of about 228 km, in agreement with IRAS results.

References[change | change source]

  1. 1.0 1.1 1.2 Tedesco, E.F. (2004). "IRAS Minor Planet Survey. IRAS-A-FPA-3-RDR-IMPS-V6.0". NASA Planetary Data System. Retrieved 2007-03-15.  Unknown parameter |coauthors= ignored (|author= suggested) (help)
  2. Pitjeva, E. V. (2005). "High-Precision Ephemerides of Planets — EPM and Determination of Some Astronomical Constants" (PDF). Solar System Research 39 (3): 176. doi:10.1007/s11208-005-0033-2. http://iau-comm4.jpl.nasa.gov/EPM2004.pdf.
  3. Harris, A. W. (2006). "Asteroid Lightcurve Derived Data. EAR-A-5-DDR-DERIVED-LIGHTCURVE-V8.0". NASA Planetary Data System. Retrieved 2007-03-15.  Unknown parameter |coauthors= ignored (|author= suggested) (help)
  4. 4.0 4.1 Neese, C. (2005). "Asteroid Taxonomy.EAR-A-5-DDR-TAXONOMY-V5.0". NASA Planetary Data System. Retrieved 2007-03-15.  Unknown parameter |coauthors= ignored (|author= suggested) (help)
  5. Donald H. Menzel and Jay M. Pasachoff (1983). A Field Guide to the Stars and Planets (2nd edition ed.). Boston, MA: Houghton Mifflin. pp. p. 391. ISBN 0-395-34835-8.