[{"id":187,"title":"Supercritical Exoplanetary Atmospheres as Potential Habitats for Extraterrestrial Aeroplankton","sha":"e464b97c0ead0438ccb94a7abe9dbc85","user_id":null,"state":"published","body":"An increasingly familiar class of exoplanets amongst those being continually discovered is the \"Super-Earth\" ([Valencia+2007](http://iopscience.iop.org/0004-637X/656/1/545/)), with a mass intermediate between Earth and Neptune. These have been found inside habitable zones ([Udry+2007](http://www.aanda.org/articles/aa/abs/2007/27/aa7612-07/aa7612-07.html)) and likely have dense atmospheres ([Lopez+2014](http://iopscience.iop.org/0004-637X/792/1/1), [Lammer+2012](http://mnras.oxfordjournals.org/content/430/2/1247)). With sufficient atmospheric pressure and temperature, these atmospheres are likely to enter a supercritical fluid phase with properties intermediate between gas and liquid. Supercritical fluid phases are typically considered for gas giant interiors ([Trachenko+2014](http://journals.aps.org/pre/abstract/10.1103/PhysRevE.89.032126)) or water oceans ([Elkins-Tanton+2008](http://iopscience.iop.org/0004-637X/685/2/1237)), though any gas or liquid can form such a phase. For example, an Earth-like atmospheric composition will enter a supercritical phase at T \u003e 132.6 K and p \u003e 37.21 atm. This pressure is significantly lower than the ≳300 atm ([Koschinsky+2008](http://geology.geoscienceworld.org/content/36/8/615)) experienced by life on the abyssal plain of Earth's oceans ([Rona+1986](http://www.nature.com/nature/journal/v321/n6065/abs/321033a0.html)). It is therefore possible for Earth-like life to tolerate the pressure-temperature conditions of a supercritical atmosphere. \r\n\r\nIn Earth's atmosphere, microbes have been found airborne as \"aeroplankton\" ([Sharma+2007](http://onlinelibrary.wiley.com/doi/10.1111/j.1529-8817.2007.00373.x/abstract)) and living microbes have been found at high altitudes ([Sattler+2002](http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=894204)), prompting planetary atmospheres to be considered as astrobiological targets ([Smith2013](http://online.liebertpub.com/doi/abs/10.1089/ast.2013.1074)). A denser atmosphere can support a greater number density of suspended particles, raising the possibility of aeroplankton ecologies in the dense supercritical atmospheres of Super-Earths.","created_at":"2015-07-07T08:44:34.680Z","updated_at":"2015-07-09T06:00:38.431Z","zenodo_id":35174,"doi":"http://dx.doi.org/10.5281/zenodo.19667","subject":null,"tags":["astrobiology","exoplanets","microbiology","fluid dynamics","astronomy"],"vote_count":0,"view_count":1,"score":0.1,"deleted":false,"muted":false,"tweeted":true,"attachment_file_name":null,"attachment_content_type":null,"attachment_file_size":null,"attachment_updated_at":null}]