What is Known about Comet Wirtanen?

Studies of comet Wirtanen over the past few apparitions have revealed some of the characteristics of the nucleus, though much is still unknown. Best estimates of some properties are listed here.

Nucleus Physical Properties

Property Value Reference
Effective Radius 0.56 km Boehnhardt et al (2002) A&A 387, 1107-1113
Axial Ratio (prolate ellipsoid) >1.4 Boehnhardt et al (2002) A&A 387, 1107-1113
Rotation Period 7.6 hr
6.0 hr
Meech et al (1997) A&A 326, 1268-1276
Lamy et al. (1998) A&A 335, L25-29
Spin Axis Unknown
Peak Water Production 1.3×1028 molec/s
1.7×1028 molec/s
Groussin & Lamy (2003) A&A 412, 879-891
Kobayashi & Kawakita (2010) Pub. Ast. Soc. Japan 62, 1025-1033
Peak Afρ 150 cm Average of many measurements
Active Fraction 100% Groussin & Lamy (2003) A&A 412, 879-891

Other Phenomena

  • Earliest solid detection of coma is at 3.3 AU inbound
  • Possible outbursts were seen in 2002 and 2008.
  • Samarasinha et al. (Planet Space Sci 44, 275-281, 1996) suggest that the nucleus is likely in non-principal axis rotation.