Damocloid

Damocloids are a class of minor planets such as 5335 Damocles and 1996 PW that have Halley-type or long-period highly eccentric orbits typical of periodic comets such as Halley's Comet, but without showing a cometary coma or tail. David Jewitt defines a damocloid as an object with a Jupiter Tisserand invariant (TJ) of 2 or less,[1][a] while Akimasa Nakamura defines this group with the following orbital elements:[2]

  • q < 5.2 AU, a > 8.0 AU, and e > 0.75,
  • or alternatively, i > 90°

However, this definition that does not focus on Jupiter excludes objects such as (127546) 2002 XU93, 2003 WG166, and (661238) 2004 DA62.[3]

Using the Tisserand's parameter with respect to Jupiter of 2 or less, there are currently 220 damocloid candidates as of January 2022.[4] Of these objects, 189 have orbital observation arcs greater than 30 days providing reasonably decent orbits.[1][5] Their average radius is eight kilometers assuming an albedo of 0.04. The albedos of four damocloids have been measured, and they are among the darkest objects known in the Solar System.[citation needed] Damocloids are reddish in color, but not as red as many Kuiper-belt objects or centaurs. Other damocloids include: 2013 BL76, (668643) 2012 DR30, (528219) 2008 KV42, (65407) 2002 RP120, and 20461 Dioretsa.

Retrograde objects such as Halley's Comet and damocloid 343158 Marsyas can have relative velocities to Earth of 81 km/s (290,000 km/h).[6]

  1. ^ a b Cite error: The named reference Jewitt-2013 was invoked but never defined (see the help page).
  2. ^ Cite error: The named reference Nakamura-Damocloid-list was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference Jewitt-2005 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference jpl-search was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference jpl-30day was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference velocity was invoked but never defined (see the help page).


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