Transformational astrophysics and exoplanet science with Habitable Worlds Observatory's High Resolution Imager
White paper submitted to the UK Space Agency's initiative "UK Space Frontiers 2035
Abstract:
Habitable Worlds Observatory (HWO) will be NASA’s flagship space telescope of the 2040s, designed to search for life on other planets and to transform broad areas of astrophysics. NASA are
seeking international partners, and the UK is well-placed to lead the design and construction of its
imaging camera — which is likely to produce the mission’s most visible public impact. Early participation in the mission would return investment to UK industry, and bring generational leadership for
the UK in space science, space technology, and astrophysics.
seeking international partners, and the UK is well-placed to lead the design and construction of its
imaging camera — which is likely to produce the mission’s most visible public impact. Early participation in the mission would return investment to UK industry, and bring generational leadership for
the UK in space science, space technology, and astrophysics.
Magma Ocean Evolution at Arbitrary Redox State
Journal of Geophysical Research: Planets American Geophysical Union 129:12 (2024) e2024JE008576
Abstract:
Interactions between magma oceans and overlying atmospheres on young rocky planets leads to an evolving feedback of outgassing, greenhouse forcing, and mantle melt fraction. Previous studies have predominantly focused on the solidification of oxidized Earth‐similar planets, but the diversity in mean density and irradiation observed in the low‐mass exoplanet census motivate exploration of strongly varying geochemical scenarios. We aim to explore how variable redox properties alter the duration of magma ocean solidification, the equilibrium thermodynamic state, melt fraction of the mantle, and atmospheric composition. We develop a 1D coupled interior‐atmosphere model that can simulate the time‐evolution of lava planets. This is applied across a grid of fixed redox states, orbital separations, hydrogen endowments, and C/H ratios around a Sun‐like star. The composition of these atmospheres is highly variable before and during solidification. The evolutionary path of an Earth‐like planet at 1 AU ranges between permanent magma ocean states and solidification within 1 Myr. Recently solidified planets typically host H 2 O ${\mathrm{H}}_{2}\mathrm{O}$ ‐ or H 2 ${\mathrm{H}}_{2}$ ‐dominated atmospheres in the absence of escape. Orbital separation is the primary factor determining magma ocean evolution, followed by the total hydrogen endowment, mantle oxygen fugacity, and finally the planet's C/H ratio. Collisional absorption by H 2 ${\mathrm{H}}_{2}$ induces a greenhouse effect which can prevent or stall magma ocean solidification. Through this effect, as well as the outgassing of other volatiles, geochemical properties exert significant control over the fate of magma oceans on rocky planets.Volatile-rich Sub-Neptunes as Hydrothermal Worlds: The Case of K2-18 b
The Astrophysical Journal Letters American Astronomical Society 977:2 (2024) l51
Novel physics of escaping secondary atmospheres may shape the cosmic shoreline
(2024)
The Roasting Marshmallows Program with IGRINS on Gemini South. II. WASP-121 b has Superstellar C/O and Refractory-to-volatile Ratios
The Astronomical Journal American Astronomical Society 168:6 (2024) 293