Presentation #339.18 in the session “Stars, Brown Dwarfs, and Binaries”.
Brown dwarfs are stellar objects with masses too low to fuse hydrogen in their cores. The dividing line between low-mass hydrogen burning stars and brown dwarfs, called the hydrogen burning limit, is about 0.07 Msun. Under special circumstances, for instance collisions or binary interactions, it is possible for a brown dwarf to gain mass. If a brown dwarf gains enough mass to bring it above the hydrogen burning limit, does it become a low mass star, i.e. does fusion ignite in its core? We are using MESA to study what happens when a brown dwarf gains mass via an AGB wind. Our results show that it does not necessarily ignite a low-mass star but rather remains a brown dwarf more massive than hydrogen burning limit. We have successfully simulated a 5 Msun AGB star with a 0.07 Msun brown dwarf companion, which resulted in the creation of an over-massive brown dwarf with 0.07236 Msun. For reference the hydrogen burning limit for our specific parameter choices in MESA is at 0.0715 Msun. If such a system was to be observed at late times, it would be a white dwarf-brown dwarf binary system where the white dwarf is the remnant of the AGB star.