BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//CERN//INDICO//EN
BEGIN:VEVENT
SUMMARY:Kevin Heng (Munich): The Geoastronomy of Sub-Neptunes
DTSTART:20261119T130000Z
DTEND:20261119T140000Z
DTSTAMP:20261030T095100Z
UID:indico-event-2189@indico.uu.se
DESCRIPTION:Title: The Geoastronomy of Sub-NeptunesSpeaker: Kevin HengAf
 filiation: Ludwig Maximilian University (LMU)Room: TBATime: 14:00-15:00
 Abstract:One of the biggest surprises of exoplanet science is the discover
 y of the small exoplanet population between the sizes of Earth and Neptune
 . Super Earths appear to be scaled-up versions of rocky planets. However\,
  it is less clear that sub-Neptunes are scaled-down versions of gas-giant 
 planets\, other than by analogy. The rocky cores and atmospheres of sub-Ne
 ptunes have comparable influence (and thus have comparable extents in radi
 us)\, but the cores dominate the mass budget if the atmospheres are hydrog
 en-dominated. If the cores are molten\, chemically active and dominate the
  masses\, then geochemical outgassing cannot be ignored. I will show that 
 the temperature-pressure conditions at the surfaces of these cores exert a
  zeroth-order control on the atmospheric chemistry. Less massive (and smal
 ler) sub-Neptunes have lower core surface pressures and temperatures\, whi
 ch leads to atmospheres with higher mean molecular weights. This naturally
  leads to a gradient in mean molecular weight across the radius valley of 
 small exoplanets. The strength of this gradient is controlled by the oxyge
 n fugacity of these cores and not by the elemental abundance of carbon. Th
 ese results imply a need to shift one’s mental framework away from the p
 lanet formation-driven approach of prioritising the carbon-to-oxygen ratio
  and “metallicity” and towards the more geoscience-oriented approach o
 f understanding the oxidation states of rocky mantles via the oxygen fugac
 ity.  This research is part of the European Research Council (ERC) Synerg
 y Grant awarded to Project Geoastronomy (PIs: Gaillard\, Heng & Mozjsis).
  \n\nhttps://indico.uu.se/event/2189/
URL:https://indico.uu.se/event/2189/
END:VEVENT
END:VCALENDAR