Imaging polarimetry and photometry of comet 21P/Giacobini-Zinner

• Published in: Icarus (New York, N.Y. 1962) N.Y. 1962), 2020-02, Vol.337, p.113471, Article 113471
• Main Authors: Chornaya, Ekaterina, Zubko, Evgenij, Luk'yanyk, Igor, Kochergin, Anton, Zheltobryukhov, Maxim, Ivanova, Oleksandra V., Kornienko, Gennady, Matkin, Alexey, Baransky, Alexander, Molotov, Igor E., Sharoshchenko, Vladimir S., Videen, Gorden
• Format: Article
• Language: English
• Subjects: Agglomerated debris particles; Color slope; Comet 21P/Giacobini-Zinner; Modeling; Polarization
• ISSN: 0019-1035; 1090-2643
• DOI: 10.1016/j.icarus.2019.113471

We report results of polarimetric observations of comet 21P/Giacobini-Zinner made at phase angles, α ≈ 76–78°, between 10 and 17 of September 2018, and compare them with previous measurements. We find significant variations in the polarimetric signals that appear consistent with those reported previously. These variations and subsequent modeling suggest that the particles in the coma are replenished within a period of approximately one day. This period is significantly shorter for highly absorbing carbonaceous particles than for non-absorbing Mg-rich silicate particles. Such a difference in the relative abundances of these components can lead to variations in the polarization response of the coma. The strong positive polarization in the subsolar direction suggests a large relative abundance of carbonaceous material, which may be an indicator of jet-type activity. •We observe the degree of linear polarization and color in comet 21P/Giacobini-Zinner.•Comet 21P reveals noticeable spatial and temporal variations of polarization.•Observations can be fitted using a two-component composition of coma.•The modeling suggests that the main components may consist of Mg-rich silicate and amorphous-carbon particles.•Relative abundance of these two components is inferred on different epochs.