60 research outputs found
2006 Fragmentation of Comet 73P/Schwassmann-Wachmann 3B Observed with Subaru/Suprime-Cam
We analyzed the Subaru/Suprime-Cam images of 73P/Schwassmann-Wachmann 3B and
detected no fewer than 154 mini-comets. 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. The ratio of the rocket force to solar
gravity was 7 to 23 times larger than that exerted on fragment B. No
significant color variation was found. 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 = -3.34 +/- 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 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^-2 (3sigma) was detected
in the orbit of fragment B.Comment: Total pages: 46 Figures: 12 Tables: 1 To appear ICARU
Location of upper borders of cavities containing dust and gas under pressure in comets
The distance between the pre-impact surface of Comet 9P/Tempel 1 and the
upper border of the largest cavity excavated during ejection of material after
the collision of the impact module of the Deep Impact spacecraft with the comet
is estimated to be about 5-6 metres if the diameter of the DI transient crater
was about 150-200 m. The estimated distance was 4 m at the diameter was 100 m.
This result suggests that cavities containing dust and gas under pressure
located a few metres below surfaces of comets can be frequent.Comment: Monthly Notices of Royal Astronomical Society, 2012, in press, 7
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Dust from Comet 209P/LINEAR during its 2014 Return: Parent Body of a New Meteor Shower, the May Camelopardalids
We report a new observation of the Jupiter-family comet 209P/LINEAR during
its 2014 return. The comet is recognized as a dust source of a new meteor
shower, the May Camelopardalids. 209P/LINEAR was apparently inactive at a
heliocentric distance rh = 1.6 au and showed weak activity at rh < 1.4 au. We
found an active region of <0.001% of the entire nuclear surface during the
comet's dormant phase. An edge-on image suggests that particles up to 1 cm in
size (with an uncertainty of factor 3-5) were ejected following a differential
power-law size distribution with index q=-3.25+-0.10. We derived a mass loss
rate of 2-10 kg/s during the active phase and a total mass of ~5x10^7 kg during
the 2014 return. The ejection terminal velocity of millimeter- to
centimeter-sized particles was 1-4 m/s, which is comparable to the escape
velocity from the nucleus (1.4 m/s). These results imply that such large
meteoric particles marginally escaped from the highly dormant comet nucleus via
the gas drag force only within a few months of the perihelion passage.Comment: 18 pages, 4 figures, accepted on 2014 December 11 for publication in
the Astrophysical Journal Letter
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