A comprehensive study of comet 67P/Churyumov-Gerasimenko in the 2021/2022 apparition. II. Colorimetry, polarimetry, modeling
arXiv:2607.20038 · doi:10.1016/j.icarus.2025.116799
Abstract
This paper presents the second part of our multi-technique observational study of comet 67P during its 2021-2022 apparition. While the first paper focused on photometry and spectroscopy, here we investigate the dust color and linear polarization of the coma. Imaging in the g-sdss and r-sdss filters was obtained with the 6-m BTA SAO Telescope, and aperture polarimetry was performed with the 2.6-m Shajn Telescope (CrAO) and the 2-m RCC Telescope. Observations at phase angles of 47.9 deg (6 October 2021) and 10.5 deg (6 February 2022) show negative polarization of about 0.5-2.5% at 10.5 deg and positive polarization of about 11% at 47.9 deg. The dust color was red, reaching about 0.8 mag near the nucleus and in the tail, and decreasing to about 0.2 mag in the coma and jet within 20,000 km of the nucleus. Spatial maps reveal a gradual decrease in color index and a corresponding increase in polarization with distance from the nucleus. Numerical modeling using ballistic particle-cluster aggregates composed of equal fractions of silicates and organics indicates that the coma is dominated by particles larger than 10 micrometers, while local polarization enhancements are consistent with regions containing smaller (1-10 micrometer) grains. Combining our aperture measurements with published data from four previous apparitions confirms that comet 67P belongs to the high-polarization class. The unusually high positive polarization observed during the 2021/22 apparition, together with the relatively isotropic coma morphology, suggests that the dust properties may have changed after the 2015/16 apparition.
arXiv comment15 pages, 11 figures
References in corpus (24)
- Astrometry.net: Blind astrometric calibration of arbitrary astronomical images
- The Absolute Magnitude of the Sun in Several Filters
- SCORPIO at the 6-m telescope: current state and perspectivies for spectroscopy of galactic and extragalactic objects
- The Dust Trail of Comet 67P/Churyumov-Gerasimenko between 2004 and 2006
- Technique of Polarimetric Observations of Faint Objects at the 6-m BTA Telescope
- Cometary Dust Trail Associated with Rosetta Mission Target: 67P/Churyumov-Gerasimenko
- Comet 22P/Kopff: Dust environment and grain ejection anisotropy from visible and infrared observations
- The Dust Trail of Comet 67P/Churyumov-Gerasimenko
- Spitzer Observations of Comet 67P/Churyumov-Gerasimenko at 5.5-4.3 AU From the Sun
- The 67P/Churyumov-Gerasimenko observation campaign in support of the Rosetta mission
- The highly active Anhur-Bes regions in the 67P/Churyumov - Gerasimenko comet: results from OSIRIS/ROSETTA observations
- Mt. Wendelstein Imaging of the Post-Perihelion Dust Coma of 67P/Churyumov-Gerasimenko in 2015/2016
- Rotation of Comet Hartley 2 from Structures in the Coma
- Linking surface morphology, composition, and activity on the nucleus of 67P/Churyumov-Gerasimenko
- Dust observations of Comet 9P/Tempel 1 at the time of the Deep Impact
- Photometry, spectroscopy, and polarimetry of distant comet C/2014 A4 (SONEAR)
- Polarimetry, photometry, and spectroscopy of comet C/2009 P1(Garradd)
- First in-situ detection of the CN radical in comets and evidence for a distributed source
- Comet 2P/Encke in apparitions of 2013 and 2017: I. Imaging photometry and long-slit spectroscopy
- SCORPIO-2 Guiding and Calibration System in the Prime Focus of the 6-m Telescope
- Rotation-stimulated structures in the CN and C3 comae of comet 103P/Hartley 2 around the EPOXI encounter
- Diurnal variation of dust and gas production in comet 67P/Churyumov-Gerasimenko at the inbound equinox as seen by OSIRIS and VIRTIS-M on board Rosetta
- The optical characteristics of the dust of sungrazing comet C/2012 S1 (ISON) observed at large heliocentric distances
- Searching for Outbursts in the Ground-Based Photometry of 67P/Churyumov-Gerasimenko