Date: Monday 18-Nov-2024
Time: 11:15 am - 12:15 pm
Location: ATL 1250 and Zoom (contact host Matt Nixon for link)
Speaker: Yoni Brande (University of Kansas)
Title: Aerosols and Sub-Neptune Diversity
Abstract: Recent analyses of exoplanetary atmospheres have shown that the presence of high-altitude atmospheric aerosols appears to be linked to physical planetary parameters such as equilibrium temperature. However, small sample sizes and limited spectral sensitivity (primarily from the water vapor feature visible with 1-1.8 micron G141 grism on Hubble's WFC3) make these identified trends uncertain. Previous work has, out of necessity, grouped dissimilar planets (massive Hot Jupiters as well as smaller, cooler gaseous planets) together in order to compile samples large enough to draw inferences from, but it is unclear that these planets exhibit all the same atmospheric physics which could affect their observed atmospheric spectra. I present a re-analysis of a smaller, yet more consistent sample of Neptune-size exoplanet atmospheric spectra, across a range of temperatures, confirming previously identified quadratic trends in absorption feature amplitude with temperature, as well as characterizing the intrinsic scatter of these measurements. While this scatter may be indicative of some stochasticity in the planet formation process, current sub-Neptune atmospheric models can only coarsely characterize these planets as a population. Initial JWST results show that sub-Neptunes can look very different in broader spectroscopy compared to HST's WFC3/G141 instrument, and can need much more sophisticated models to properly understand their atmospheric physics. To remedy this in the era of rich JWST atmospheric spectra, I introduce ExoHaze, a streamlined Python implementation of the CARMA aerosol microphysics code, and discuss some new results applied to JWST data.
If you have any questions, contact the PALS hosts: Benjamin Sharkey (small bodies) and Matt Nixon (exoplanets).
SPECIAL ACCOMMODATIONS:Special accommodations for individuals with disabilities can be made by calling (301) 405-3001. It would be appreciated if we are notified at least one week in advance.
ATL 1250 is a flat, carpeted conference room that can accommodate approximately 20-30 people at large tables. The closest wheelchair accessible entry to this room in the Atlantic building is the white stone entrance at 224 Stadium Drive.
