HST and ground-based observations of bright storms on Uranus during 2014-2015.

Abstract:

We report the temporal evolution of bright, long-lived cloud features on Uranus. We observed and tracked the features between August 2014 and January 2015 with the Hubble Space Telescope, the Keck 2 10-m telescope, VLT, Gran Telescopio Canarias, Gemini, William Herschel Telescope, Robo-AO, Pic du Midi 1-m telescope, and multiple smaller telescopes operated by amateur astronomers. Surprisingly bright features were first revealed in the Keck adaptive-optics images in August; this initial set of observations motivated follow-up observations around the world. One of the storms (identified as “Feature F” in Sromovsky et al. 2015, and Feature 2 in de Pater et al. 2015), which was the deepest in that dataset, was bright enough that it was detected by multiple amateur observers, permitting us to trigger a Hubble Target of Opportunity (ToO) observation on October 14^th, 2014. A complex of features at this latitude was also observed by Hubble as part of the Outer Planet Atmospheres Legacy (OPAL) program on November 8-9, 2014. We will present the temporal evolution of the cloud activities from August 2014 through January 2015, and analyze the vertical structure of the cloud features in the Hubble datasets.

The Hubble images used in our study were collected with support of HST grants GO13712 to KMS and GO13937 to AAS.

Sromovsky et al. 2015, “High S/N Keck and Gemini AO imaging of Uranus during 2012–2014: New cloud patterns, increasing activity, and improved wind measurements.” Icarus 258, 192-223.

de Pater et al. 2014, “Record-breaking storm activity on Uranus in 2014.” Icarus 252, 121-128