Nightmare on 'ELM' Street: The Search for Low log g Values

James Sullivan
2016 Proceedings of Frank N. Bash Symposium 2015 — PoS(BASH2015)   unpublished
Although the average mass of white dwarf (WD) stars is 0.6 ± 0.1M , recent surveys have found a number of extremely low mass (ELM) WDs, with masses less than 0.25 solar masses. Recently, we discovered large-amplitude pulsations in one such supposed ELM WD having effective temperature T eff ≈ 8000K and a surface gravity described by log(g) ≈ 4.6. While this log(g) value is nominally too high for it to be a main sequence star, it is also quite low to be an ELM WD. Using the open source stellar
more » ... lution code MESA, we examine a range of models produced with different final masses and mass loss rates, with the goal of finding the most likely evolutionary scenario that reproduces the parameters of this low -log(g) star. In addition, we calculate the low-order pulsation modes for these models and show how these change with the evolutionary state of the star. Further work with short-timescale pulsations will better constrain flashing ELM WD candidacy.
doi:10.22323/1.261.0021 fatcat:ootc2lxtbjcsve36hmgutikv3y