5:15 PM - 6:45 PM
[PPS01-P11] Estimation of Atmospheric Transportation on Uranus with the Ground Based Telescope
Keywords:Uranus, Outer Planet, Ground Based Telescope, Spectroscopic Observation
Uranus is a planet that orbits at an inclination of 98 degrees to its orbital plane. As of February 2024, the only close observations of Uranus were made during the flyby observation by Voyager-2 in 1986. Apart from that, ground based observations have been ongoing using telescopes. In 2007, Uranus passed through the vernal equinox, and since 2014, a polar cap resulting from methane condensation has been observed in the northern polar region[Toledo et al., 2018]. Also, in observations conducted at the Hband (1.6 μm), bright localized cloud regions have been identified on Uranus, which appear brighterthan other areas[Sromovsky et al., 2015]. Furthermore, the highest speeds of the absorption bands, estimated to be approximately 250 m/s each near the north and south poles, were tracked using the Hubble Space Telescope (HST) cloud-top patterns [Soyuer et al., 2021].
In this study, continuous observations of Uranus were conducted using the imaging device MSI [Watanabe et al., 2012]mounted on the Cassegrain focus of the 1.6 m Pirika Telescope owned by Hokkaido University. The estimation of the transport speeds of the zonal winds at various altitudes was based on the absorption levels of methane and ammonia, both components of the Uranian atmosphere. From December 2021 to December 2022, spectral imaging in the wavelength range of 530 - 760 nm was performed using MSI. The absorption changes at the ammonia absorption wavelength of 552 nm and methane absorption wavelength of 619 nm were utilized to estimate transport speeds based on the periodicity of Uranus. The results showed that, while similar speeds to those reported in [Soyuer et al., 2021] were estimated for the methane absorption wavelength, faster speeds were calculated for the ammonia absorption wavelength.
Uranus are estimated from the observed brightness variations. Parallel observations using MSI and the spectrometer UVS, which is installed on Cassegrain focus, were conducted from August 2023 to January 2024. The local cloud positions were estimated based on the brightness changes within a 1 month observation span. This presentation focuses on the photometric results of images captured by MSI in the polar cap region and the overall region, along with the spectroscopic results from UVS. Discussions and future works will be presented comparing these results with a simple simulation of brightness changes due to the movement of bright clouds.
In this study, continuous observations of Uranus were conducted using the imaging device MSI [Watanabe et al., 2012]mounted on the Cassegrain focus of the 1.6 m Pirika Telescope owned by Hokkaido University. The estimation of the transport speeds of the zonal winds at various altitudes was based on the absorption levels of methane and ammonia, both components of the Uranian atmosphere. From December 2021 to December 2022, spectral imaging in the wavelength range of 530 - 760 nm was performed using MSI. The absorption changes at the ammonia absorption wavelength of 552 nm and methane absorption wavelength of 619 nm were utilized to estimate transport speeds based on the periodicity of Uranus. The results showed that, while similar speeds to those reported in [Soyuer et al., 2021] were estimated for the methane absorption wavelength, faster speeds were calculated for the ammonia absorption wavelength.
Uranus are estimated from the observed brightness variations. Parallel observations using MSI and the spectrometer UVS, which is installed on Cassegrain focus, were conducted from August 2023 to January 2024. The local cloud positions were estimated based on the brightness changes within a 1 month observation span. This presentation focuses on the photometric results of images captured by MSI in the polar cap region and the overall region, along with the spectroscopic results from UVS. Discussions and future works will be presented comparing these results with a simple simulation of brightness changes due to the movement of bright clouds.