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

The K2-33 planetary system hosts one transiting ~5 R_E planet orbiting theyoung M-type host star. The planet's mass is still unknown, with an estimatedupper limit of 5.4 M_J. The extreme youth of the system (<20 Myr) gives theunprecedented opportunity to study the earliest phases of planetary evolution,at a stage when the planet is exposed to an extremely high level of high-energyradiation emitted by the host star. We perform a series of 1D hydrodynamicsimulations of the planet's upper atmosphere considering a range of possibleplanetary masses, from 2 to 40 M_E, and equilibrium temperatures, from 850 to1300 K, to account for internal heating as a result of contraction. We obtaintemperature profiles mostly controlled by the planet's mass, while theequilibrium temperature has a secondary effect. For planetary masses below 7-10M_E, the atmosphere is subject to extremely high escape rates, driven by theplanet's weak gravity and high thermal energy, which increase with decreasingmass and/or increasing temperature. For higher masses, the escape is insteaddriven by the absorption of the high-energy stellar radiation. A roughcomparison of the timescales for complete atmospheric escape and age of thesystem indicates that the planet is more massive than 10 M_E.

Young planets under extreme UV irradiation. I. Upper atmosphere modelling of the young exoplanet K2-33b