2006 Fragmentation of Comet 73P/Schwassmann-Wachmann 3B observed with Subaru/Suprime-Cam

Abstract

a b s t r a c tThe fragmentation of the split Comet 73P/Schwassmann-Wachmann 3 B was observed with the primefocus camera Suprime-Cam attached to the Subaru 8.2-m telescope. The fragmentation revealed dozens of miniature comets [Fuse, T., Yamamoto, N., Kinoshita, D., Furusawa, H., Watanabe, J., 2007. Publ. Astron. Soc. Jpn. 59 (2), 381-386]. We analyzed the Subaru/Suprime-Cam images, detecting no fewer than 154 mini-comets, mostly extending to the southwest. Three were close to the projected orbit of fragment B. We applied synchrone-syndyne analysis, modified for rocket effect analysis, to the mini-fragment spatial distribution. We found that most of these mini-comets were ejected from fragment B by an outburst occurring around 1 April 2006, and three fragments on the leading side of nucleus B could have been released sunward on the previous return. Several fragments might have been released by successive outbursts around 24 April and 2 May 2006. The ratio of the rocket force to solar gravity was 7-23 times larger than that exerted on fragment B. No significant color variation was found. The mean color index, V-R = 0.50 ± 0.07, was slightly redder than that of the Sun and similar to that of the largest fragment, C, which suggests that these mini-fragments were detected mainly through sunlight reflected by dust particles and materials on the nuclei. We examined the surface brightness profiles of all detected fragments and estimated the sizes of 154 fragments. We found that the radius of these mini-fragments was in the 5-to 108-m range (equivalent size of Tunguska impactor). The power-law index of the differential size distribution was q = À3.34 ± 0.05. Based on this size distribution, we found that about 1-10% of the mass of fragment B was lost in the April 2006 outbursts. Modeling the cometary fragment dynamics [Desvoivres, E.] revealed that it is likely that mini-fragments smaller than $10-20 m could be depleted in water ice and become inactive, implying that decameter-sized comet fragments could survive against melting and remain as near-Earth objects. We attempted to detect the dust trail, which was clearly found in infrared wavelengths by Spitzer. No brightness enhancement brighter than 30.0 mag arcsec À2 (3r) was detected in the orbit of fragment B.

Physical Properties of Asteroids in Comet-Like Orbits in Infrared Asteroid Survey Catalogs

“…A good example event was observed at 73P/Schwassmann-Wachamann 3, in which the comet nucleus was ground into 10-100 m bodies. The power exponents of the cumulative size distribution of the fragments was ∼−2.3 (Ishiguro et al 2009;Fuse et al 2007). If the splitting is a principal mechanism in determining the size distribution of comet nuclei, the size distribution of PDCs might be steeper than the value we derived for PDCs.…”

2007 Outburst of 17p/Holmes: The Albedo and the Temperature of the Dust Grains

“…We considered the energy balance on the surface of the icy body given by (Desvoivres et al 1999(Desvoivres et al , 2000Ishiguro et al 2009)…”

“…As a result of these studies, we found that the power index of the size distribution of almost all comets would be in the range of −4 and −3 (Fulle 2004). We would like to emphasize that the power indices for the debris associated with comet outbursts are also in this range, that is, −3.7 < q < −3.3 for 29P/Schwassmann-Wachmann 1 (Moreno 2009) and −3.4 < q < −3.3 for 73P/Schwassmann-Wachmann 3B (Ishiguro et al 2009). Therefore, we will adopt an assumption of −4 < q < −3.…”

Size-frequency distribution of boulders ≥10 m on comet 103P/Hartley 2

“…By switching to differential size-frequency distributions of −1.84 on 73P small fragments and −2.56 on 73P large fragments, Reach et al (2009) compare 73P results with fragments of comet C/1999 S4 LINEAR (−2.72, as from Mäkinen et al 2001), as well as with fragments derived from the Kreutz group of cometary Sungrazers (−2.7 to −3.0, as from Sekanina 2003), indicating how 73P fragments presents the shallowest power-index slope. Nevertheless, Ishiguro et al (2009) used Subaru/Suprime-Cam data to derive a power-law index of the differential size distribution for 73P of −3.34, which is particularly higher with respect to Reach et al (2009) measurements. This difference may be explained by the fact that the power index of these split fragments has large uncertainties associated with contaminations of dust grains surrounding these objects.…”