New Polarimetric Data for the Galilean Satellites: Io and Ganymede Observations and Modeling
New high-precision disk-integrated measurements of the polarization of Io and Ganymede in the UBVRI bands are presented. The observations were obtained using polarimeters mounted on the Crimean Astrophysical Observatory and the Peak Terskol Observatory in 2019–2023. For Io, the negative polarization...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2024-01-01
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| Series: | The Planetary Science Journal |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/PSJ/ad0bf9 |
| _version_ | 1797352130468642816 |
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| author | Nikolai Kiselev Vera Rosenbush Ari Leppälä Karri Muinonen Ludmilla Kolokolova Aleksandr Savushkin Nikolai Karpov |
| author_facet | Nikolai Kiselev Vera Rosenbush Ari Leppälä Karri Muinonen Ludmilla Kolokolova Aleksandr Savushkin Nikolai Karpov |
| author_sort | Nikolai Kiselev |
| collection | DOAJ |
| description | New high-precision disk-integrated measurements of the polarization of Io and Ganymede in the UBVRI bands are presented. The observations were obtained using polarimeters mounted on the Crimean Astrophysical Observatory and the Peak Terskol Observatory in 2019–2023. For Io, the negative polarization branch (NPB) reaches a minimum of P _min ≈ −0.25 ± 0.02% in the V band at a phase angle of α _min = 2.°1 ± 0.°5. The inversion angle is α _inv = 26° ± 6° in the V and R bands. The NPB for Ganymede is an asymmetric curve, with P _min = −0.34 ± 0.01% at α _min = 0.°52 ± 0.°06 and α _inv = 8.°5 ± 0.°2 in the V band. Although Io and Europa have similar geometric albedos (0.63 and 0.67, respectively), their NPB shapes differ. The NPB of Ganymede (albedo of 0.43) is morphologically similar to that of Europa, although it is described by different parameter values ( P _min , α _min , and α _inv ). This discrepancy is likely due to the compositions of their surfaces: Europa’s with H _2 O ice, Io’s with sulfuric/silicate composition, and Ganymede’s with H _2 O ice and silicates. Numerical computations using the radiative transfer coherent backscattering method demonstrated a match to the polarimetric observations and to the geometric albedos for Ganymede with the single-scattering albedo ≈ 0.943 and mean free path length kl = 2 πl / λ _eff ≈ 150, where λ _eff is the wavelength. For Io’s regolith, the single-scattering albedo was found to be ≈ 0.979 and kl ≈ 40. |
| first_indexed | 2024-03-08T13:10:51Z |
| format | Article |
| id | doaj.art-f88e0e7bcb024c218bb0f7f0bc139de2 |
| institution | Directory Open Access Journal |
| issn | 2632-3338 |
| language | English |
| last_indexed | 2024-03-08T13:10:51Z |
| publishDate | 2024-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Planetary Science Journal |
| spelling | doaj.art-f88e0e7bcb024c218bb0f7f0bc139de22024-01-18T13:31:25ZengIOP PublishingThe Planetary Science Journal2632-33382024-01-01511010.3847/PSJ/ad0bf9New Polarimetric Data for the Galilean Satellites: Io and Ganymede Observations and ModelingNikolai Kiselev0https://orcid.org/0000-0002-2451-4079Vera Rosenbush1https://orcid.org/0000-0002-2353-2451Ari Leppälä2https://orcid.org/0009-0008-7221-1671Karri Muinonen3https://orcid.org/0000-0001-8058-2642Ludmilla Kolokolova4https://orcid.org/0000-0002-9321-3202Aleksandr Savushkin5Nikolai Karpov6Crimean Astrophysical Observatory, Nauchnij, 298409, CrimeaTaras Shevchenko National University of Kyiv , Astronomical Observatory, 04053 Kyiv, Ukraine; Main Astronomical Observatory of National Academy of Sciences of Ukraine, 03143 Kyiv, UkraineUniversity of Helsinki , Department of Physics, Helsinki, Finland ; ari.leppala@helsinki.fiUniversity of Helsinki , Department of Physics, Helsinki, Finland ; ari.leppala@helsinki.fiUniversity of Maryland , College Park, MD 20742, USACrimean Astrophysical Observatory, Nauchnij, 298409, CrimeaInternational Center for Astronomical, Medical and Ecological Research, Peak Terskol Observatory, UkraineNew high-precision disk-integrated measurements of the polarization of Io and Ganymede in the UBVRI bands are presented. The observations were obtained using polarimeters mounted on the Crimean Astrophysical Observatory and the Peak Terskol Observatory in 2019–2023. For Io, the negative polarization branch (NPB) reaches a minimum of P _min ≈ −0.25 ± 0.02% in the V band at a phase angle of α _min = 2.°1 ± 0.°5. The inversion angle is α _inv = 26° ± 6° in the V and R bands. The NPB for Ganymede is an asymmetric curve, with P _min = −0.34 ± 0.01% at α _min = 0.°52 ± 0.°06 and α _inv = 8.°5 ± 0.°2 in the V band. Although Io and Europa have similar geometric albedos (0.63 and 0.67, respectively), their NPB shapes differ. The NPB of Ganymede (albedo of 0.43) is morphologically similar to that of Europa, although it is described by different parameter values ( P _min , α _min , and α _inv ). This discrepancy is likely due to the compositions of their surfaces: Europa’s with H _2 O ice, Io’s with sulfuric/silicate composition, and Ganymede’s with H _2 O ice and silicates. Numerical computations using the radiative transfer coherent backscattering method demonstrated a match to the polarimetric observations and to the geometric albedos for Ganymede with the single-scattering albedo ≈ 0.943 and mean free path length kl = 2 πl / λ _eff ≈ 150, where λ _eff is the wavelength. For Io’s regolith, the single-scattering albedo was found to be ≈ 0.979 and kl ≈ 40.https://doi.org/10.3847/PSJ/ad0bf9Planetary scienceSolar system astronomy |
| spellingShingle | Nikolai Kiselev Vera Rosenbush Ari Leppälä Karri Muinonen Ludmilla Kolokolova Aleksandr Savushkin Nikolai Karpov New Polarimetric Data for the Galilean Satellites: Io and Ganymede Observations and Modeling The Planetary Science Journal Planetary science Solar system astronomy |
| title | New Polarimetric Data for the Galilean Satellites: Io and Ganymede Observations and Modeling |
| title_full | New Polarimetric Data for the Galilean Satellites: Io and Ganymede Observations and Modeling |
| title_fullStr | New Polarimetric Data for the Galilean Satellites: Io and Ganymede Observations and Modeling |
| title_full_unstemmed | New Polarimetric Data for the Galilean Satellites: Io and Ganymede Observations and Modeling |
| title_short | New Polarimetric Data for the Galilean Satellites: Io and Ganymede Observations and Modeling |
| title_sort | new polarimetric data for the galilean satellites io and ganymede observations and modeling |
| topic | Planetary science Solar system astronomy |
| url | https://doi.org/10.3847/PSJ/ad0bf9 |
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