Near-Infrared Photometric And Polarimetric Observations Of Comet Hale-Bopp |
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| Authors: | Hitoshi Hasegawa Takashi Ichikawa Shinsuke Abe Shiomo Hamamura Koji Ohnishi Jun-Ich Watanabe |
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| Institution: | (1) ASTEC, Inc., Koishikawa Bunkyo-Ku, 1-3-11, 112-0002 Tokyo, Japan;(2) University of Tohoku, Sendai, Miyagi, Japan;(3) The Graduate University for Advanced Studies, Mitaka, Tokyo, Japan;(4) Suginami Science Education Center, Suginami, Tokyo, Japan;(5) Nagano National College of Technology, Nagano, Nagano, Japan;(6) National Astronomical Observatory, Mitaka, Tokyo, Japan |
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| Abstract: | Near-infrared photometric and polarimetric observations of comet Hale-Bopp (1995 O1) using KONIC (Kiso Observatory Near-Infrared
Camera) are reported. Observations were carried out on March 18 UT and April 26 UT 1997, when the heliocentric distances of
the comet were 0.94 and 1.02 AU, and the phase angles were 48.5 deg and 32.9 deg, respectively. In the J, H, and K′ bands,
we obtained linear polarization of the near-nucleus region of 16.4 ± 1.2, 18.8 ± 1.3, and 15.1 ± 0.9 percent on March 18UT
and 7.1 ± 1.1, 8.9 ± 1.0, and 6.9 ± 0.6 percent on April 26, respectively. These values were higher than those observed for
1P/Halley. The maximum polarization was found at H band on both dates. Polarization maps showed higher polarization regions
toward the anti-solar direction in the J and H bands. No distinct correlation was found between high polarization regions
and bright regions. The projected expansion velocity of the arc structure of the dust jet was 375 ± 35.7 m/s on 17–19 March.
The periodicity was found to be 11.1 ± 2.8 hours.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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| Keywords: | Comet polarization dust jet infrared |
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