K2-198d Archives

Future radii of planets b, c, d at an age of 5 Gyr. The current radii of planets c, d and b are shown as dashed lines, together with the current and final radii for a range of planetary masses for the outer two planets d and b; the core is represented by a black circle, while the envelope is shown as a colored circle around the core. The core size increases with increasing mass. Note that the size scaling of the envelope compared to the core is arbitrary. It is chosen such that one can easily compare present and final planetary radii and immediately see, which configuration can hold on to some fraction of the envelope and remain above the gap. While the outermost planet b will retain enough envelope to remain well above the radius gap around 1.8 R⊕ for all masses considered, we find that for planet d there is an intermediate mass range between ∼7 to 18 M⊕, for which planets can retain an envelope and survive above the gap. Lower mass planets will experience enough mass loss to completely lose their envelope, while higher mass planets only have very thin envelopes at present age to match the observed radius due to their larger core size, that their thin envelope is easily lost, in spite of their large mass. Planet c is assumed to be rocky at present and will not change its size significantly. The current radius of planet c matches well with the radii predicted for Earth-like rocky cores in the mass regime of 3-5 M⊕. -- astro-ph.HE

Three Young Planets Around The K-dwarf K2-198: High-energy Environment, Evaporation History And Expected Future

by Keith CowingNovember 15, 2023November 15, 2023

Planets orbiting young stars are thought to experience atmospheric evaporation as a result of the host stars’ high magnetic activity. We study the evaporation history and expected future of the […]

K2-198d

Three Young Planets Around The K-dwarf K2-198: High-energy Environment, Evaporation History And Expected Future

White Paper On Phototrophic Biosignatures: Research Priorities For The Search For Life On Other Worlds

Autonomous AI-Cosmoindustry and the Quiet Expansion Filter: A Threshold-Based Resolution of the Fermi Paradox

A Scalable Path to Astrometric Exomoon Discoveries with the Nautilus Space Observatory

20 Years Later: The ALH 84001 Debate in Context with Viking’s Results. Lessons Learned and Portals Opened

Ocean Planet Research: 31 New Species Discovered in Two Weeks of Deep Sea Exploration