A Chiron-type comet (CTC) is a member of a small family of

comet A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or Coma (cometary), coma surrounding ...

s defined as having a

semi-major axis In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the longe ...

larger than that of

Jupiter Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a Jupiter mass, mass more than 2.5 times that of all the other planets in the Solar System combined a ...

(5.2 AU) and a

Tisserand's parameter Tisserand's parameter (or Tisserand's invariant) is a number calculated from several orbital elements (semi-major axis, orbital eccentricity, and inclination) of a relatively small object and a larger " perturbing body". It is used to distinguish d ...

with respect to Jupiter (T_Jupiter) of more than 3. The family is named after its largest and most prominent member

2060 Chiron 2060 Chiron is a ringed small Solar System body in the outer Solar System, orbiting the Sun between Saturn and Uranus. Discovered in 1977 by Charles Kowal, it was the first-identified member of a new class of objects now known as centaurs— ...

, officially designated as both a comet ( 95P/Chiron) and a minor planet of the

centaur A centaur ( ; ; ), occasionally hippocentaur, also called Ixionidae (), is a creature from Greek mythology with the upper body of a human and the lower body and legs of a horse that was said to live in the mountains of Thessaly. In one version o ...

-class, which blurs the line between the two groups. There are four numbered comets considered to be classical members of this family:

39P/Oterma 39P/Oterma is a currently inactive List of periodic comets, periodic comet with an orbital period of nearly 20 years that stays outside the orbit of Jupiter. The comet nucleus, nucleus has a diameter around 4–5 km. It was last observed in ...

, 165P/LINEAR, 166P/NEAT, and 167P/CINEOS. CTCs are distinct from the Encke-type comets (ETC) and Jupiter-family comets (JFC). Contrary to the Chiron-type comets, JFCs have a T_Jupiter of less than 3 (typically with a period of less than 20 years), while the ETCs have a

smaller than that of Jupiter. Another group, the

Halley-type comet A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or Coma (cometary), coma surrounding ...

s (HTC), only have a classical definition, that is a period between 20 and 200 years. Members of the CTC family have a dynamical lifetime of 6.5 million years, much longer than the 50,000 years attributed to the Jupiter-family comets.

References

External links

95P/Chiron - 2060 Chiron (1977 UB), Cometary behavior
Comet Countdown {{Comets, nonobject=yes *