text:   and Gravity in Brown Dwarfs",10,"['I want to highlight our new paper, led by @exoEhsan, with @NatashaBatalha and @ChannonVisscher about Lithium in brown dwarfs: <LINK> <LINK>', ""In low mass stars and the most massive brown dwarfs Lithium is lost to fusion in the core. Li is a little bit easier to 'burn' than H but not as easy as deuterium. So while the minimum mass to steadily burn H is around 75 Jupiter masses, the limit for Li burning is around 65 M_J."", 'So brown dwarfs and stars older than around 250 Myr and more massive than 65 MJ do not have Li visible in their atmospheres. There is a strong Li line in the optical that makes Li detection feasible.', 'This led Rafael Rebolo in the 90s to suggest the ""Li test"" as a way of distinguishing brown dwarfs from stars. If you could detect Li you knew you had to have a brown dwarf on your hand since it would be below 65 MJ. For objects which were hot enough to be either this was helpful', ""If you have a cooler object, say one that has CH4, you KNOW you don't have a star on your hands, so the Li test seems less important. Also atomic Li goes into various other molecules and is removed, thus muddying the waters."", ""However there aren't many spectral gravity indicators for brown dwarfs and it would be nice to have some marker for the most massive objects, those between ~65 MJ and ~75 MJ. Missing Li would serve nicely, but you have the chemistry removing Li as well as the nuclear fires."", 'So the question becomes, can we detect the other Li molecules that show up at lower Teff? If so then we have a new lithium test for identifying the most massive brown dwarfs. But we need molecular opacities for species such as LiH, LiF, LiOH, and LiCl.', 'This is where Ehsan comes in. As part of his NPP postdoc at Ames Ehsan computed himself some of these opacities and compiled others so that we could investigate the detectability of the various Li species, allowing us to follow the lithium through the brown dwarf cooling sequence', 'You can read the paper for details, but some of these other Li species should be detectable in the mid-IR. Unfortunately the molecular signatures are more subtle than the atomic Li feature, but the 30m telescopes and perhaps JWST should be able to search for them.', ""I'm hopeful that someday Li could be used to resolve some puzzles, such as the mass of Gl 229 B. Special thanks to Channon for handling all of the Li-species chemistry for us. Our spectra were computed with PICASO.""]",21,06,2415