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 Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Ultra-hot Jupiters are emerging as a new class of exoplanets. Studying theirchemical compositions and temperature structures will improve the understandingof their mass loss rate as well as their formation and evolution. We presentthe detection of ionized calcium in the two hottest giant exoplanets - KELT-9band WASP-33b. By utilizing transit datasets from CARMENES and HARPS-Nobservations, we achieved high confidence level detections of Ca II using thecross-correlation method. We further obtain the transmission spectra around theindividual lines of the Ca II H&K doublet and the near-infrared triplet, andmeasure their line profiles. The Ca II H&K lines have an average line depth of2.02 $\pm$ 0.17 % (effective radius of 1.56 Rp) for WASP-33b and an averageline depth of 0.78 $\pm$ 0.04 % (effective radius of 1.47 Rp) for KELT-9b,which indicates that the absorptions are from very high upper atmosphere layersclose to the planetary Roche lobes. The observed Ca II lines are significantlydeeper than the predicted values from the hydrostatic models. Such adiscrepancy is probably a result of hydrodynamic outflow that transports asignificant amount of Ca II into the upper atmosphere. The prominent Ca IIdetection with the lack of significant Ca I detection implies that calcium ismostly ionized in the upper atmospheres of the two planets.

Ionized calcium in the atmospheres of two ultra-hot exoplanets WASP-33b and KELT-9b