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arXiv · 1311.4896

Hubble Space Telescope Pre-Perihelion ACS/WFC Imaging Polarimetry of Comet ISON (C/2012 S1) at 3.81 AU

Dean C. Hines·Gorden Videen·Evgenij Zubko·Karri Muinonen·Yuriy Shkuratov·Vadim G. Kaydash·Matthew M. Knight·Michael L. Sitko·Carey M. Lisse·Max Mutchler·Derek Hammer·Padmavati A. Yanamandra-Fisher
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Abstract

We present polarization images of Comet ISON (C/2012 S1) taken with the Hubble Space Telescope (HST) on UTC 2013 May 8 (rh = 3.81 AU, Delta = 4.34 AU), when the phase angle was alpha = 12.16 degrees. This phase angle is approximately centered in the negative polarization branch for cometary dust. The region beyond 1000 km from the nucleus shows a negative polarization amplitude of p% -1.6%. Within 1000 km of the nucleus, the polarization position angle rotates to be approximately perpendicular to the scattering plane, with an amplitude p% +2.5%. Such positive polarization has been observed previously as a characteristic feature of cometary jets, and we show that Comet ISON does indeed harbor a jet-like feature. These HST observations of Comet ISON represent the first visible light, imaging polarimetry with sub-arcsecond spatial resolution of a Nearly Isotropic Comet (NIC) beyond 3.8 AU from the Sun at a small phase angle. The observations provide an early glimpse of the properties of the cometary dust preserved in this Oort-cloud comet.

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Dean C. Hines, Gorden Videen, Evgenij Zubko, Karri Muinonen, Yuriy Shkuratov, Vadim G. Kaydash, Matthew M. Knight, Michael L. Sitko, Carey M. Lisse, Max Mutchler, Derek Hammer, Padmavati A. Yanamandra-Fisher. 2013-11-19. Hubble Space Telescope Pre-Perihelion ACS/WFC Imaging Polarimetry of Comet ISON (C/2012 S1) at 3.81 AU. https://doi.org/10.1088/2041-8205/780/2/l32

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