Position of J0809-2627 (red) in the Hertzsprung-Russell diagram compared to several evolutionary tracks. Pink lines show two double He-WD slow-merger tracks from Zhang & Jeffery (2012) for metallicity Z = 0.02. The final masses for both tracks are labelled. Black lines show the zero-age helium main sequence from Paczyński (1971), where black filled circles indicate masses of 0.5, 0.7, 1.0, and 1.5 M_⊙. The dashed-dotted grey lines indicate radii of 0.1 and 1 R_⊙.