Photochemical hazes in sub-Neptunian atmospheres with focus on GJ 1214 b

Panayotis Lavvas, Tommi Koskinen, Maria Steinrueck, Antonio García Muñoz, Adam P. Showman

Research output: Contribution to journalArticlepeer-review

Abstract

We study the properties of photochemical hazes in super-Earths/mini-Neptunes atmospheres with particular focus on GJ1214b. We evaluate photochemical haze properties at different metallicities between solar and 10000×solar. Within the four orders of magnitude change in metallicity, we find that the haze precursor mass fluxes change only by a factor of ∼3. This small diversity occurs with a non-monotonic manner among the different metallicity cases, reflecting the interaction of the main atmospheric gases with the radiation field. Comparison with relative haze yields at different metallicities from laboratory experiments reveals a qualitative similarity with our theoretical calculations and highlights the contributions of different gas precursors. Our haze simulations demonstrate that higher metallicity results into smaller average particle sizes. Metallicities at and above 100×solar with haze formation yields of ∼10% provide enough haze opacity to satisfy transit observation at visible wavelengths and obscure sufficiently the H2O molecular absorption features between 1.1 µm and 1.7 µm. However, only the highest metallicity case considered (10000×solar) brings the simulated spectra into closer agreement with transit depths at 3.6 µm and 4.5 µm indicating a high contribution of CO/CO2 in GJ1214b’s atmosphere. We also evaluate the impact of aggregate growth in our simulations, in contrast to spherical growth, and find that the two growth modes provide similar transit signatures (for Df=2), but with different particle size distributions. Finally, we conclude that the simulated haze particles should have major implications for the atmospheric thermal structure and for the properties of condensation clouds.

Original languageEnglish (US)
JournalUnknown Journal
StatePublished - May 8 2019

Keywords

  • Exoplanets, hazes

ASJC Scopus subject areas

  • General

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