Title of programme: Readying a warm sub-Neptune orbiting around the bright, Sun-like star TOI-4320, for future atmospheric characterisation
Abstract: Sub-Neptune sized planets are amongst the most common types of exoplanets in our Galaxy, however, their formation and composition are still widely debated. Through transit spectroscopy we can probe their atmospheric composition and thus help constrain theories of how these systems form and evolve. We propose to refine the ephemerides and radius of a sub-Neptune sized planet orbiting around a bright, Sun-like star, that was identified in the TESS data by citizen scientists taking part in the Planet Hunters TESS project. The refined orbital period that we can determine with just one additional transit observation with CHEOPS will ensure that the mid-transit time of this target will be sufficiently constrained for future atmospheric characterisation with JWST or Ariel. Furthermore, the refined planet radius, combined with our ongoing radial velocity campaign to determine the mass of this planet, will allow us to constrain the bulk composition and thus infer the internal structure of the planet. Even though sub-Neptune sized planets are common, this one stands out due to its long orbital period (~25 days) compared to the majority of TESS planets, and due to the brightness of the host star (Vmag = 9.17). To date, less than 3% of all known sub-Neptune size planets transit stars with a Vmag brighter than10, highlighting the unique opportunity presented by this system.
Temporal Coverage
2023-10-22T17:58:00Z / 2023-10-23T08:51:00Z
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.
