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Hasegawa, Hitoshi; Ichikawa, Takashi; Abe, Shinsuke; Hamamura, Shiomi; Ohnishi, Koji; Watanabe, J.

doi:10.1023/a:1006298327163

Cited by 15 publications

(9 citation statements)

References 5 publications

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“…• , in the near infrared domain (2000 nm), are just below the fit obtained for the red domain and 5% smaller than the values obtained by Hasegawa et al (1997). This discrepancy could be due to the fact that they used different apertures (respectively 18.4 arcmin and 20 arcsec), and that the arcs region was thus not completely included in the Jones et al observations.…”

Section: Wavelength Dependencementioning

confidence: 66%

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Dust evolution of comet C/1995 O1 (Hale-Bopp) by imaging polarimetric observations

Hadamcik

Levasseur-Regourd

2003

A&A

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Abstract. Comet C/1995 O1 (Hale-Bopp) has been observed over a large range of phase angles (7• -47 • ) by the imaging polarimetric method from June 1996 to April 1997. Polarization maps were obtained and long-term evolution (month) of the coma structures followed. Short-term evolution (20 min) during the April 1997 observations has allowed us to measure the period of rotation of the central arc on the polarization maps. The comparison between the polarization maps and the intensity structures confirms a greater polarization in the jets. Phase curves are obtained for different regions of the coma and compared to those obtained for the whole coma. For the region around the nucleus, the phase curve is always underneath the phase curve corresponding to the whole coma, and the polarization at phase angles smaller than 25• is negative (P min = −5%). In the jets, the phase curve is always above the whole coma phase curve, and the polarization is always positive. Whole coma phase curves are obtained with all the available data sets in different wavelengths. A comparison with other diagnostics and laboratory experiments leads us to suggest that small grains build up fluffy aggregates of high porosity; the light scattered by such aggregates is highly polarized, as observed in this active comet.

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Section: Wavelength Dependencementioning

confidence: 66%

“…All the phase curves have a similar behavior. Figure 9 presents the available data set (data from Hasegawa 1997, andJones et al 2000 for the infrared domain). The Jones et al (2000) values at α 40…”

Section: Wavelength Dependencementioning

confidence: 99%

Dust evolution of comet C/1995 O1 (Hale-Bopp) by imaging polarimetric observations

Hadamcik

Levasseur-Regourd

2003

A&A

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“…For HaleBopp there are enough observations for us to interpolate the observations from a large range in wavelength to 40 phase angle. The results are shown in Figure 4, which include near-IR observations from Hasegawa et al (1999). The observations span almost a factor of 10 in wavelength, with only a modest wavelength dependence to the polarization.…”

Section: Polarization Versus Phasementioning

confidence: 95%

“…Spatial variations in polarization were found in several comets at optical wavelengths (Eaton, Scarrott, & Draper 1988; and in comet Hale-Bopp at IR wavelengths (Jones & Gehrz 2000;Hasegawa et al 1999). Many comets (but not all) tend to show weaker polarization at the nucleus than in the immediate surrounding coma (for references, see the review by Kolokolova et al 2004).…”

Section: Spatial Distributionmentioning

confidence: 99%

“…This feature, known as the ''primary jet,'' does not point directly at the Sun and must correspond to a specific location on the nucleus. With the reasonable assumption that the primary jet is aligned with the axis of rotation, Farnham & Cochran (2002) argued that this jet is pointing to an (R.A., (Hadamcik & LevasseurRegourd 2003;Harris et al 1997;Hasegawa et al 1999;Jones & Gehrz 2000;Kiselev & Velichko 1999). Note the weak wavelength dependence of the polarization and the nearly flat polarization longward of 0.7 m.…”

Section: Spatial Distributionmentioning

confidence: 99%

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Near-Infrared Polarimetry and Photometry of Recent Comets

et al. 2004

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We present near-infrared (2.2 m) imaging polarimetry and near-infrared photometry for recent comets. The 2.2 m polarization as a function of phase angle is 1%-2% higher than typical comet visual narrowband red polarization. This implies a general, but weak, trend to higher polarization at wavelengths longer than 0.7 m. As found with visual narrowband red polarimetry, comets appear to divide into a high-and a low-polarization class at 2.2 m as well. The high-polarization class is characterized by moderate to strong mid-infrared silicate emission, while the low-polarization class is characterized by weak to absent silicate emission. In contrast to C/1995 O1 (HaleBopp) and some other dusty comets, no significant grain population radial gradient is seen in any of the polarization maps for the six comets in our sample with near-infrared imaging polarimetry. Our analysis of previously published Hale-Bopp data shows that the polarization at 40 phase angle varies by only about a factor of 1.6 from 0.3 to 2.2 m and is nearly flat from 0.7 to 2.2 m. Any model of comet dust must reproduce this weak wavelength dependence.

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Analysis of Coma Dust Optical Properties in Comet C/1995 O1 (Hale–Bopp) II. Effects of Polarization

Kerola

Larson

2001

Icarus

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Cited by 15 publications

References 5 publications

Dust evolution of comet C/1995 O1 (Hale-Bopp) by imaging polarimetric observations

Dust evolution of comet C/1995 O1 (Hale-Bopp) by imaging polarimetric observations

Near-Infrared Polarimetry and Photometry of Recent Comets

Analysis of Coma Dust Optical Properties in Comet C/1995 O1 (Hale–Bopp) II. Effects of Polarization

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