Linear polarization measurements of Comet C/2011 W3 (Lovejoy) from STEREO

Thompson, W. T.

doi:10.1016/j.icarus.2015.08.018

Cited by 6 publications

(17 citation statements)

References 52 publications

(61 reference statements)

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“…Secondly, the 0 • polariser of the C3 coronagraph has been out of commission for most of the SOHO mission lifetime, though workarounds using the clear glass image may be used to compensate for that (e.g. Grynko et al 2004;Thompson 2015). Thirdly, SOHO mission is in part a more prolific comet discoverer than STEREO due to the wider bandpasses on the coronagraphs which include the NaI doublet (Biesecker et al 2002).…”

Section: Observationsmentioning

confidence: 99%

“…The inclusion of strong gas signatures, however, contaminates polarimetric signal from the cometary dust. Thompson (2015) has shown that these drawbacks make SOHO data much less useful for discussion of polarimetric properties. Comet C/2010 E6 furthermore passed very near the support for the occulter disk for the C3 coronagraph, making photometric data less reliable as well.…”

Section: Observationsmentioning

confidence: 99%

“…It is a semi-automated series of routines fine-tuned for use with STEREO/SECCHI/COR2 polarised image triplet data. It was inspired by similar work on STEREO observations of comet C/2011 W3 (Lovejoy) (Thompson 2015) and, more recently, comet C/2012 S1 (ISON) (Thompson 2020). Firstly, the image triplets undergo standard pre-processing using the SECCHI_PREP routine from the SolarSoft library for IDL -a handful of other useful SolarSoft routines is utilised within composite as well (Eichstedt et al 2008;Freeland & Handy 1998).…”

Section: Data Reductionmentioning

confidence: 99%

“…Each presented comet trace along the tail extends up to 2 𝑅 (red) from the comet photocentre (purple and dark blue, referred to as 'comet nucleus' in the plot) via cyan, green, and yellow, depending on the quality of the imagery. The plotting procedure was inspired by Thompson (2015).…”

Section: Phase Angle Curvesmentioning

confidence: 99%

“…A new method for data analysis is introduced, inspired by Thompson (2015)'s analysis of pre-perihelion STEREO and SOHO spacecraft observations of comet C/2011 W3 (Lovejoy), and his later work on comet C/2012 S1 (ISON) (Thompson 2020). The major difference between the approach by those observations of those two comets and this work is that the spatial position of the comet is here determined from its orbital parameters, whereas (Thompson 2015) uses simultaneous observations by both STEREO-A and B spacecraft (described in Sec.…”

Section: Introductionmentioning

confidence: 99%

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Polarimetric analysis of STEREO observations of sungrazing Kreutz comet C/2010 E6 (STEREO)

Nežič,

Bagnulo,

Jones

et al. 2020

Preprint

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Twin STEREO spacecraft pre-perihelion photometric and polarimetric observations of the sungrazing Kreutz comet C/2010 E6 (STEREO) in March 2010 at heliocentric distances 3 − 28 𝑅 were investigated using a newly-created set of analysis routines. The comet fully disintegrated during its perihelion passage. Prior to that, a broadening and an increase of the intensity peak with decreasing heliocentric distance was accompanied by a drop to zero polarisation at high phase angles (∼105 − 135 • , STEREO-B) and the emergence of negative polarisation at low phase angles (∼25 − 35 • , STEREO-A). Outside the near-comet region, the tail exhibited a steep slope of increasing polarisation with increasing cometocentric distance, with the slope showing a marked decrease with decreasing heliocentric distance. The steep slope is attributed to sublimation of refractory organic matrix and the accompanied processing of the fluffy aggregate dust grains, exposing silicates. The decrease in slope is likely caused by the gradual sublimation of all refractory material closer to the Sun, with resulting gases suppressing polarisation signal of the dust. Near-zero polarisation closer to the comet head may be explained by the same mechanism, stronger there due to the large amounts of material being ejected and sublimated from the presumably disintegrating core, which correlates with intensity data. Negative polarisation at small phase angles may be explained by the presence of freshly ejected large silicate-rich aggregates. Despite both zero and negative polarisation being observed simultaneously, the two hypotheses on their causes are not easily reconciled. The need for further studies of such comets, both observational and theoretical, is highlighted.

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Section: Observationsmentioning

confidence: 99%

Section: Observationsmentioning

confidence: 99%