A New Merging Double Degenerate Binary in the Solar Neighborhood

摘要: Characterizing the local space density of double degenerate binary systems is a complementary approach to broad sky surveys degenerates determine expected rates white dwarf mergers, in particular those that may evolve into other observable phenomena such as extreme helium stars, Am CVn systems, and supernovae Ia. However, there have been few detected space. We report here discovery WD 1242$-$105, nearby bright WD, double-line spectroscopic consisting two DA dwarfs similar mass temperature, despite it previously having spectroscopically characterized single degenerate. Follow-up photometry, spectroscopy, trigonometric parallax obtained an effort fundamental parameters each component this system. The has ratio 0.7 25.5 mas, placing at distance 39 pc. system's total 0.95 M$_\odot$ orbital period 2.85 hours, making strongest known gravitational wave source ($\log h = -20.78$) mHz regime. Because its mass, 1242$-$105 predicted merge via radiation on timescale 740 Myr, which will most likely not result catastrophic explosion.