Fig. 3.
Teff−log(g) diagram of the program stars. While known 3He sdBs from our sample are marked in black, the two 3He-enriched ESO SPY sdBs (HE 0929–0424, HE 1047–0436; see Sect. 5.3) are marked in red. The three blue dots at the cool end of the sequence represent PHL 25, PHL 382, and BD+48° 2721, highlighted with a solid circle (see Sect. 4.2 for details). The zero-age (ZAHB) and terminal-age horizontal branch (TAHB) as well as evolutionary tracks for different stellar masses but solar metallicity according to Dorman et al. (1993) are also shown with dashed and dotted lines, respectively.
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