English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Occultations are windows of opportunity to indirectly peek into the daysideatmosphere of exoplanets. High-precision transit events provide information onthe spin-orbit alignment of exoplanets around fast-rotating hosts. We aim toprecisely measure the planetary radius and geometric albedo of the ultra-hotJupiter (UHJ) KELT-20 b as well as the system's spin-orbit alignment. Weobtained optical high-precision transits and occultations of KELT-20 b usingCHEOPS observations in conjunction with the simultaneous TESS observations. Weinterpreted the occultation measurements together with archival infraredobservations to measure the planetary geometric albedo and daysidetemperatures. We further used the host star's gravity-darkened nature tomeasure the system's obliquity. We present a time-averaged precise occultationdepth of 82(6) ppm measured with seven CHEOPS visits and 131(+8/-7) ppm fromthe analysis of all available TESS photometry. Using these measurements, weprecisely constrain the geometric albedo of KELT-20 b to 0.26(0.04) and thebrightness temperature of the dayside hemisphere to 2566(+77/-80) K. AssumingLambertian scattering law, we constrain the Bond albedo to 0.36(+0.04/-0.05)along with a minimal heat transfer to the night side. Furthermore, using fivetransit observations we provide stricter constraints of 3.9(1.1) degrees on thesky-projected obliquity of the system. The aligned orbit of KELT-20 b is incontrast to previous CHEOPS studies that have found strongly inclined orbitsfor planets orbiting other A-type stars. The comparably high planetarygeometric albedo of KELT-20 b corroborates a known trend of strongly irradiatedplanets being more reflective. Finally, we tentatively detect signs of temporalvariability in the occultation depths, which might indicate variable cloudcover advecting onto the planetary day side.

CHEOPS observations of KELT-20 b/MASCARA-2 b: An aligned orbit and signs of variability from a reflective dayside