Title of programme: How Cloudy is the Neptune Desert?
Abstract: We aim to continue to use the unique capabilities afforded by CHEOPS to measure optical secondary eclipses from planets around the Neptune Desert. We have selected two new planet-hosting stars that are bright enough to gain the required ~30 ppm precision to detect their expected eclipse depths. With these observations we aim to determine the planetary atmospheric albedos, providing the first benchmark ensemble measurements of the characteristics of any clouds or hazes in hot Neptunes. Indeed, the question if Neptunes are simply scaled-down gas giants can be tested directly by these observations, by helping to determine if they are cloud dominated planets or not. The presence, or lack thereof, of clouds also helps to understand the global abundance mixing ratios of planets. For example, we may expect metal-rich planets to exhibit more dense cloud formation, but on the other hand metal-richness may also mean that there is a lack of dayside clouds due to condensates being sequestered at deeper layers in the atmosphere. The long-term goal of the project is to combine these results with measurements from other optical and near-infrared bands to understand in detail the properties of aerosols and other condensates in these low-mass planets. Finally, we shall include the observations we have already attained with CHEOPS for the ultrahot Neptune LTT 9779b, allowing a robust test of the nature of absorbers in the upper atmospheres of irradiated Neptunes.
Temporal Coverage
2021-04-30T16:31:00Z / 2021-05-01T00:45:00Z
Version
3.0
Mission Description
CHEOPS (Benz et al., https://doi.org/10.1007/s10686-020-09679-4) is a European Space Agency (ESA) mission in partnership with Switzerland with important contributions to the payload and the ground segment from Austria, Belgium, France, Germany, Hungary, Italy, Portugal, Spain, Sweden and the United Kingdom.
The satellite has a single payload comprising an ultra-high precision photometer covering the 330 - 1100 nm wavelength range in a single photometric band. Observations are made as part of the Guaranteed Time Observing Programme that is formulated by the CHEOPS Science Team, and the Guest Observers Programme through which the Community at large can apply for CHEOPS time.
