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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
DETECTION OF REMNANT DUST CLOUD ASSOCIATED WITH THE 2007 OUTBURST OF 17P/HOLMES
Ishiguro, Masateru,Sarugaku, Yuki,Kuroda, Daisuke,Hanayama, Hidekazu,Kim, Yoonyoung,Kwon, Yuna G.,Maehara, Hiroyuki,Takahashi, Jun,Terai, Tsuyoshi,Usui, Fumihiko,Vaubaillon, Jeremie J.,Morokuma, Tomok American Astronomical Society 2016 The Astrophysical journal Vol.817 No.1
<P>This article reports a new optical observation of 17P/Holmes one orbital period after the historical outburst event in 2007. We detected not only a common dust tail near the nucleus. but also a long narrow structure that extended along the position angle 274 degrees.6 +/- 0 degrees.1 beyond the field of view (FOV) of the Kiso Wide Field Camera, i.e., >0 degrees.2 eastward and >2 degrees.0 westward from the nuclear position. The width of the structure decreased westward with increasing distance from the nucleus. We obtained the total cross section of the long extended structure in the FOV, C-FOV = (2.3 +/- 0.5) x 10(10) m(2). From the position angle, morphology, and mass, we concluded that the long. narrow structure consists of materials ejected during the 2007 outburst. On the basis of the dynamical behavior of dust grains in the solar radiation field, we estimated that the long. narrow structure would be composed of 1 mm(-1) cm grains having an ejection velocity of >50 m s(-1). The velocity was more than one order of magnitude faster than that of millimeter-centimeter grains from typical comets around a heliocentric distance r(h) of 2.5 AU. We considered that sudden sublimation of a large amount of water-ice (approximate to 10(30) mol s(-1)) would be responsible for the high ejection velocity. We finally estimated a total mass of M-TOT = (4-8) x 10(11) kg and a total kinetic energy of E-TOT = (1-6) x 10(15) J for the 2007 outburst ejecta, which are consistent with those of previous studies that were conducted soon after the outburst.</P>
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>
Ishiguro, Masateru,Kuroda, Daisuke,Hasegawa, Sunao,Kim, Myung-Jin,Choi, Young-Jun,Moskovitz, Nicholas,Abe, Shinsuke,Pan, Kang-Sian,Takahashi, Jun,Takagi, Yuhei,Arai, Akira,Tokimasa, Noritaka,Hsieh, He IOP Publishing 2014 The Astrophysical journal Vol.792 No.1
<P>We investigated the magnitude-phase relation of (162173) 1999 JU3, a target asteroid for the JAXA Hayabusa 2 sample return mission. We initially employed the International Astronomical Union's H-G formalism but found that it fits less well using a single set of parameters. To improve the inadequate fit, we employed two photometric functions: the Shevchenko and Hapke functions. With the Shevchenko function, we found that the magnitude-phase relation exhibits linear behavior in a wide phase angle range (alpha = 5 degrees-75 degrees) and shows weak nonlinear opposition brightening at alpha < 5 degrees, providing a more reliable absolute magnitude of H-V = 19.25 +/- 0.03. The phase slope (0.039 +/- 0.001 mag deg(-1)) and opposition effect amplitude (parameterized by the ratio of intensity at alpha = 0 degrees.3 to that at alpha = 5 degrees, I(0 degrees.3)/I(5 degrees) = 1.31 +/- 0.05) are consistent with those of typical C-type asteroids. We also attempted to determine the parameters for the Hapke model, which are applicable for constructing the surface reflectance map with the Hayabusa 2 onboard cameras. Although we could not constrain the full set of Hapke parameters, we obtained possible values, w = 0.041, g = -0.38, B-0 = 1.43, and h = 0.050, assuming a surface roughness parameter <(theta)over bar> = 20 degrees. By combining our photometric study with a thermal model of the asteroid, we obtained a geometric albedo of p(v) = 0.047 +/- 0.003, phase integral q = 0.32 +/- 0.03, and Bond albedo A(B) = 0.014 +/- 0.002, which are commensurate with the values for common C-type asteroids.</P>
Polarimetric Observation of (3200) Phaethon, in Preparation for the Upcoming DESTINY+ Space Mission
Jooyeon Geem,Masateru Ishiguro,Jun Takahashi,Hiroshi Akitaya,Koji S. Kawabata,Tatsuya Nakaoka,Ryo Imazawa,Fumiki Mori,Daisuke Kuroda,Sunao Hasegawa,Fumi Yoshida,Ko Ishibashi,Tomoko Arai,Tomohiko Sekig 한국천문학회 2022 天文學會報 Vol.47 No.1
OPTICAL AND NEAR-INFRARED POLARIMETRY FOR A HIGHLY DORMANT COMET 209P/LINEAR
Kuroda, Daisuke,Ishiguro, Masateru,Watanabe, Makoto,Akitaya, Hiroshi,Takahashi, Jun,Hasegawa, Sunao,Ui, Takahiro,Kanda, Yuka,Takaki, Katsutoshi,Itoh, Ryosuke,Moritani, Yuki,Imai, Masataka,Goda, Shuhei IOP Publishing 2015 The Astrophysical journal Vol.814 No.2
<P>We conducted an optical and near-infrared polarimetric observation of the highly dormant Jupiter-Family Comet, 209P/LINEAR. Because of its low activity, we were able to determine the linear polarization degrees of the coma dust particles and nucleus independently, that is P-n = 30.3(-0.9)(+1.3)% at alpha = 92 degrees.2 and P-n = 31.0(-0.7)(+1.0)% at alpha = 99 degrees.5 for the nucleus, and P-c = 28.8(-0.4)(+0.4)% at alpha = 92 degrees.2 and 29.6(-0.3)(+0.3)% at alpha = 99 degrees.5 for the coma. We detected no significant variation in P at the phase angle coverage of 92 degrees.2-99 degrees.5, which may imply that the obtained polarization degrees are nearly at maximum in the phase-polarization curves. By fitting with an empirical function, we obtained the maximum values of linear polarization degrees P-max = 30.8% for the nucleus and P-max = 29.6% for the dust coma. The P-max of the dust coma is consistent with those of dust-rich comets. The low geometric albedo of P-v. =. 0.05 was derived from the slope-albedo relationship and was associated with high P-max. We examined P-max-albedo relations between asteroids and 209P, and found that the so-called Umov law seems to be applicable on this cometary surface.</P>
MONITORING OBSERVATIONS OF THE JUPITER-FAMILY COMET 17P/HOLMES DURING ITS 2014 PERIHELION PASSAGE
Kwon, Yuna Grace,Ishiguro, Masateru,Hanayama, Hidekazu,Kuroda, Daisuke,Honda, Satoshi,Takahashi, Jun,Kim, Yoonyoung,Lee, Myung Gyoon,Choi, Young-Jun,Kim, Myung-Jin,Vaubaillon, Jeremie J.,Miyaji, Takes American Astronomical Society 2016 The Astrophysical journal Vol.818 No.1
<P>We performed a monitoring observation of a Jupiter-family comet, 17P/Holmes, during its 2014 perihelion passage to investigate its secular change in activity. The comet has drawn the attention of astronomers since its historic outburst in 2007, and this occasion was its first perihelion passage since then. We analyzed the obtained data using an aperture photometry package and derived the Af rho parameter, a proxy for the dust-production rate. We found that Af rho showed asymmetric properties with respect to the perihelion passage: it increased moderately from 100 cm at the heliocentric distance of r(h) = 2.6-3.1 AU to a maximal value of 185 cm at r(h) = 2.2 AU (near the perihelion) during the inbound orbit, while dropping rapidly to 35 cm at r(h) = 3.2 AU during the outbound orbit. We applied a model for characterizing dust-production rates as a function of r(h) and found that the fractional active area of the cometary nucleus had dropped from 20%-40% in 2008-2011 (around the aphelion) to 0.1%-0.3% in 2014-2015 (around the perihelion). This result suggests that a dust mantle would have developed rapidly in only one orbital revolution around the Sun. Although a minor eruption was observed on UT 2015 January 26 at r(h) = 3.0 AU, the areas excavated by the 2007 outburst would be covered with a layer of dust (less than or similar to 10 cm depth) which would be enough to insulate the subsurface ice and to keep the nucleus in a state of low activity.</P>