Continuum Study on Uranus at the Millimeter/Submillimeter Wavelength with ALMA Data

Abstract

AbstractUranus is a unique solar system body with its extreme rotational axis, low luminosity, asymmetrical internal magnetic field and magnetosphere, and questionable internal structure. Yet unlike the other Solar System planets, Uranus is the least understood and least visited planet that was only be attained once by Voyager 2 flyby mission in 1986. However, with the development of observation techniques and instruments both in space and ground, some advanced telescopes presently observe Uranus routinely. Moreover, most of the exoplanets detected so far have similarities with the ice giant type. Atacama Large Millimeter/submillimeter Array (ALMA) is one high-end radio interferometer that frequently observes Uranus since it is often chosen as a calibrator. With the abundance of ALMA data, this study is aimed to reconstruct the Uranus images and build the Uranus continuum model from the distribution of flux density over several frequencies on ALMA wide-range bands. Common Astronomy Software Application (CASA) data processing tool with a Python interface is used to achieve these goals. The ALMA data used in this research was Uranus observational data from 2012 to 2018 at bands 3, 4, 6, 7, and 8. After careful data selection and calibration, we obtained 110 observational data points. Due to the high angular resolution that can be achieved by ALMA, some well-resolved radio continuum images of Uranus were also obtained. Furthermore, the deconvolution result of the combined 78-point continuum data is sufficiently representative to build the continuum model, showing the higher the frequency the higher the flux density.KeywordsUranus continuumMillimeter/submillimeter wavelengthALMA dataFlux densityBrightness temperature