Scientific rationale for Uranus and Neptune in situ explorations

As new large-scale astronomical surveys greatly increase the number of objects targeted and discoveries made, the requirement for efficient follow-up observations is crucial. Adaptive optics imaging, which compensates for the image-blurring effects of Earth's turbulent atmosphere, is essential for these surveys, but the scarcity, complexity and high demand of current systems limits their availability for following up large numbers of targets. To address this need, we have engineered and implemented Robo-AO, a fully autonomous laser adaptive optics and imaging system that routinely images over 200 objects per night with an acuity 10 times sharper at visible wavelengths than typically possible from the ground. By greatly improving the angular resolution, sensitivity, and efficiency of 1-3 m class telescopes, we have eliminated a major obstacle in the follow-up of the discoveries from current and future large astronomical surveys.

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High-efficiency Autonomous Laser Adaptive Optics

The Planetary Virtual Observatory and Laboratory (PVOL) and its integration into the Virtual European Solar and Planetary Access (VESPA)

An outburst of cloud activity on Neptune in 2015 led to speculation about whether the clouds were convective in nature, a wave phenomenon, or bright companions to an unseen dark vortex (similar to the Great Dark Spot studied in detail by Voyager 2). The Hubble Space Telescope (HST) finally answered this question by discovering a new dark vortex at 45 degrees south planetographic latitude, named SDS-2015 for “southern dark spot discovered in 2015.” SDS-2015 is only the fifth dark vortex ever seen on Neptune. In this paper, we report on imaging of SDS2015 using HST’s Wide Field Camera 3 across four epochs: 2015 September, 2016 May, 2016 October, and 2017 October. We find that the size of SDS-2015 did not exceed 20 degrees of longitude, more than a factor of two smaller than the Voyager dark spots, but only slightly smaller than previous northern-hemisphere dark spots. A slow (1.7–2.5 deg/year) poleward drift was observed for the vortex. Properties of SDS-2015 and its surroundings suggest that the meridional wind shear may be twice as strong at the deep level of the vortex as it is at the level of cloud-tracked winds. Over the 2015–2017 period, the dark spot’s contrast weakened from about -7% to about -3%, while companion clouds shifted from offset to centered, a similar evolution to some historical dark spots. The properties and evolution of SDS-2015 highlight the diversity of Neptune’s dark spots and the need for faster cadence dark spot observations in the future.

https://iopscience.iop.org/article/10.3847/1538-3881/aaa6d6/pdf

A New Dark Vortex on Neptune

Neptune Long-Lived Atmospheric Features in 2013 - 2015 from Small (28-cm) to Large (10-m) Telescopes

Bright features on Neptune in 2015

In the past 10 years, we have studied the atmospheres of Uranus and Neptune using telescopes with apertures ranging from 28 to 50 cm. Our focus was on the detection of bright features on these planets. In 2015, we have imaged a long-living bright storm on Neptune, which existed for at least 5 months. This storm showed a westward drift of 24.0o/day, which fitted quite well with the know local wind speeds. Other spots were also detected. In 2016 a bright spot was detected on Uranus. In general, the occurrence of bright features on Uranus seems to be rarer than on Neptune. This study illustrates the potentials of amateurs to contribute to studies of the distant ice giants.

J. Sussenbach

Papers

Neptune Long-Lived Atmospheric Features in 2013 - 2015 from Small (28-cm) to Large (10-m) Telescopes

Bright features on Neptune in 2015

Bright features on Uranus and Neptune