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KISO/KWFC Observation of the Dust Ejecta Associated with the 2007 Outburst of 17P/Holmes
Masateru Ishiguro,Yuki Sarugaku,Daisuke Kuroda,Hidekazu Hanayama,Yoonyoung Kim,Yuna Kwon,Hiroyuki Maehara,Jun Takahashi,Tsuyoshi Terai,Fumihiko Usui,Jeremie J.Vaubaillon,Tomoki Morokuma,Naoto Kobayash 한국천문학회 2015 天文學會報 Vol.40 No.2
Ishiguro, Masateru,Kuroda, Daisuke,Hanayama, Hidekazu,Takahashi, Jun,Hasegawa, Sunao,Sarugaku, Yuki,Watanabe, Makoto,Imai, Masataka,Goda, Shuhei,Akitaya, Hiroshi,Takagi, Yuhei,Morihana, Kumiko,Honda, IOP Publishing 2015 ASTROPHYSICAL JOURNAL LETTERS - Vol.798 No.2
<P>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 r(h) = 1.6AU and showed weak activity at r(h) <= 1.4AU. 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(-1) during the active phase and a total mass of approximate to 5 x 10(7) kg during the 2014 return. The ejection terminal velocity of millimeter- to centimeter-sized particles was 1-4ms(-1), which is comparable to the escape velocity from the nucleus (1.4ms(-1)). 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.</P>
COMET 17P/HOLMES: CONTRAST IN ACTIVITY BETWEEN BEFORE AND AFTER THE 2007 OUTBURST
Ishiguro, Masateru,Kim, Yoonyoung,Kim, Junhan,Usui, Fumihiko,Vaubaillon, Jeremie J.,Ishihara, Daisuke,Hanayama, Hidekazu,Sarugaku, Yuki,Hasegawa, Sunao,Kasuga, Toshihiro,Warjurkar, Dhanraj S.,Ham, Ji- IOP Publishing 2013 The Astrophysical journal Vol.778 No.1
<P>A Jupiter-family comet, 17P/Holmes, underwent outbursts in 1892 and 2007. In particular, the 2007 outburst is known as the greatest outburst over the past century. However, little is known about the activity before the outburst because it was unpredicted. In addition, the time evolution of the nuclear physical status has not been systematically studied. Here, we study the activity of 17P/Holmes before and after the 2007 outburst through optical and mid-infrared observations. We found that the nucleus was highly depleted in its near-surface icy component before the outburst but that it became activated after the 2007 outburst. Assuming a conventional 1 mu m sized grain model, we derived a surface fractional active area of 0.58% +/- 0.14% before the outburst whereas the area was enlarged by a factor of similar to 50 after the 2007 outburst. We also found that large (>= 1 mm) particles could be dominant in the dust tail observed around aphelion. Based on the size of the particles, the dust production rate was >= 170 kg s(-1) at a heliocentric distance of r(h) = 4.1 AU, suggesting that the nucleus was still active around the aphelion passage. The nucleus color was similar to that of the dust particles and average for a Jupiter-family comet but different from that of most Kuiper Belt objects, implying that color may be inherent to icy bodies in the solar system. On the basis of these results, we concluded that more than 76 m of surface material was blown off by the 2007 outburst.</P>