Properties of JFC Jupiter-MOID

This is a scatter plot showing the Tisserand invariants TJ and MOIDs with Jupiter MJ for the Jupiter-family comets (JFCs) listed on my other page.

As the plot shows, most JFCs (the black squares) have MOIDs with Jupiter than are less than 1 au. Relatively few have MOIDs as high as 1.5 au, and even fewer above 2.0 au. There are no known JFCs with MOID above 2.4 au (dark grey rectangle).

The plot also shows objects known as Activated Asteroids (AAs; also known sometimes as Main Belt Comets, MBCs). The AAs (open circles) reside in the upper-right part of the plot with un-comet like Tisserands and relatively high Jupiter-MOIDs.

It is interesting to note that there are no JFCs in a triangular region (smaller grey triangle) between Tisserands ~2.4 and 3.0 and MOIDs ~1 to 2.4 au. This triangle has been placed completely by eye. It’s not a fit! The diagonal bound of the triangle is defined by MJ = -2TJ + 7.15.

Scatter plot showing orbital properties of 714 JFCs and 48 AAs, with Tisserand parameter (Tj) on x-axis and perihelion-MOID (y-axis); shaded regions highlight specific parameter ranges.

Notes about some oddball objects:

  • The two AAs within that grey triangle are both high-inclination objects, and they have large MOIDs that suggest they aren’t JFCs:
  • The JFC with both high TJ (above 3) and high MJ (near 2.4 au) is a high-inclination (30º), modest-eccentricity (0.39) object:
  • The JFC with very high TJ (above 3.2) all by itself has a very short period, Earth-crossing orbit:
  • There are 4 other JFCs with high TJ (above 3.05) that are within the cluster of AAs. Three of these are possibly actually AAs, but they have eccentricities just higher than my cutoff of 0.35.

Those 6 JFCs within the light grey trapezoid (whose lower boundary is defined by MJ = -2TJ + 6.85) are: 199P/Shoemaker 4, 219P/LINEAR, 347P/PANSTARRS, 451P/Christensen, P/2009 Y2, and P/2018 A5.

Comments are welcome!