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| Titel |
Polarimetry of Comet 9P/Tempel 1 around the epoch of the Deep Impact Event |
| VerfasserIn |
G. P. Tozzi, S. Bagnulo, H. Boehnhardt, L. Kolokolova |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250069235
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| Zusammenfassung |
| We present imaging and spectro-polarimetric observations of comet
9P/Tempel 1 obtained before and after the epoch of the Deep Impact
event using the FORS1 and SoFI instruments of the
ESO La Silla-Paranal Observatory.
We obtained narrow-band linear polarisation in imaging mode and low
resolution linear and circular spectro-polarimetry in the visible
wavelength range, and broadband linear polarisation in imaging mode in
the near-IR. Due to the adverse temporal phasing of our post-impact
observations, we found only marginal indications for DI-induced
effects in the polarimetric data. Namely, we found slightly negative
spectral slope in linear spectro-polarimetry, and, comparing imaging
polarimetry taken before and after impact, we found a moderate change
of the overall spatial gradient in the canonical coma
sectors. Otherwise, our polarimetric results characterise the
persisting coma activity. We measured a global 7.3% linear
polarisation, which is typical for dusty comets. The
linear polarization in the coma decreases with distance from the
nucleus, which might be related to changing grain properties. A small
fraction (0.2%) of circular polarisation was detected, which can be
entirely interpreted in terms of cross-talk from linear
polarisation. Therefore the actual circular polarisation of Comet
9P/Tempel 1 appears consistent with zero. |
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