The Lightcurve and Colors of Unusual Minor Planet 1998 WU24

✍ Scribed by John K. Davies; David J. Tholen; Robert J. Whiteley; Simon F. Green; Jon K. Hillier; Michael J. Foster; Neil McBride; Tom.H Kerr; Erica Muzzerall

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 93 KB
• Volume: 150
• Category: Article
• ISSN: 0019-1035
• DOI: 10.1006/icar.2000.6554

✦ Synopsis

Minor planet 1998 WU 24 is unusual in having the orbital characteristics of a Halley family comet but showing no sign of cometary activity. We present optical data that reveal a double-peaked lightcurve with a period of 7.283 ± 0.003 h and a peak-to-peak amplitude of ∼0.54 mag. Infrared spectroscopy and quasi-simultaneous BVRIJHK photometry reveal a featureless K-band spectrum and colors typical of D-type asteroids, and suspected "bare" comet nuclei (B-V = 0.78 ± 0.034, V-R = 0.53 ± 0.037, V-I = 0.99 ± 0.035, V-J = 1.67 ± 0.043, V-H = 2.10 ± 0.076 and V-K = 2.34 ± 0.102). Image profiles from co-added frames in the R band indicate no apparent cometary activity, with an implied upper limit to the dust production rate of 150 g s -1 . Assuming a D-type albedo of 0.04 we derive a spherical equivalent diameter of 5.28 ± 0.07 km although the lightcurve amplitude implies an irregular body with an axial ratio of 1.64 : 1. We conclude that 1998 WU 24 is probably an inactive comet nucleus.