2385801

Target RA (J2000): 181.632462 and deg Target Dec (J2000): -31.64567 and deg Gaia GMag: 10.24 Programme ID: CH_PR240022 PI of observing programme: Jenkins Title of programme: Constraining the Prevalence of Metallic Clouds within the Neptune Desert Abstract: With the recent stunning discovery of a very high albedo for the extreme Neptune Desert planet LTT9779b a result that is likely due to the presence of high-altitude metallic clouds in the atmosphere scattering the incoming starlight we are finally beginning to understand the chemical structure and evolution of these desert worlds. However given their rarity one may wonder whether such cloud structures are normal for these types of planets and if so what are the physical processes driving this. In order to respond to this question we request observations using CHEOPS to observe two other planets that have recently been confirmed to reside in the Neptune Desert and who orbit stars bright enough to significantly detect their secondary eclipses in the optical. We shall measure the eclipses of the planets TOI-1997b and TOI-2352b allowing us to place strong constraints on their albedos and therefore model their atmospheric structures. This work will provide evidence for or against the presence of highly reflective silicate and titanium clouds in these planets and allow us to begin to build a global picture of the atmospheric constituents of some of the most extreme Neptune planets currently known. [truncated! Please see actual data for full text]