text:   Thermal Dissociation of Molecules",8,"[""As @V_Parmentier and @lkreidberg have been describing, ultra-hot Jupiters are weird and unique for several reasons, from dissociation of molecules to the presence of H- opacity. Here's just a couple of the things we found in my new paper: <LINK>"", ""Once the planet gets above a Teq of about 2500 K, TiO/VO become dissocated as well, so you might expect the atmosphere to becomes non-inverted. We find that that's not the case; something is doing the work of TiO/VO after those molecules have disappeared. https://t.co/6ojhfnzvry"", 'The short-wavelength radiation being pumped out by early-type host stars is absorbed by atomic metals, metal hydrides, SiO, and bound-free opacities. This, combined with a dearth of IR-active molecules to cool the atmosphere, causes the atmosphere heats up.', 'This plot is showing where the stellar flux is being absorbed: look at all that short wavelength flux being absorbed right where the temperature inversion is beginning, around 10 mbar! https://t.co/mdKZIWDBEh', ""We also show the first self-consistent model of the hottest known jovian planet, KELT-9b (Tdayside = 4600 K). Nearly all molecules are dissocated, even CO, and most atoms are ionized. But the spectrum doesn't look like a blackbody..."", 'H- is the main opacity source whose bound-free opacity varies smoothly with wavelength such that the brightness temperature of KELT-9b varies by about 1000 K across the JWST spectral range! https://t.co/d61L1YPqnv', ""There's much more in the paper, but, in short, ultra-hot/extremely irradiated hot Jupiters are fascinating and unique astrophysical objects, worthy of further characterization. This is good because their hot dayside atmosphere and their inflated radii make these great targets."", 'See also: \nMansfield+ https://t.co/5p3b7Mob1x\n@V_Parmentier+ https://t.co/ReHRrUXo8H\n@lkreidberg+ https://t.co/oc3ZyzrnDC']",18,05,1737