... As well as RCB stars with F- and G-type spectra, the `extreme helium stars' (EHes) are low-gravity A- and B-type stars with weak or no Balmer lines, strong neutral helium and ionized carbon lines ([ Jeffery 2000 ]). ...
... Extreme Helium Stars. ... Apparently, some lose all of their hydrogen, revealing layers of helium and carbon. These are the hydrogen-deficient stars.. ...
... of a rapidly accreting helium white dwarf to become a low-luminosity helium star ... rapid accretion of matter, consisting mostly of helium, onto a helium white dwarf ... helium burning shell moves inwards with repeating shell flashes, the effective ...
... Helium white dwarf mergers as progeny for extreme helium stars. ... of helium onto a helium white dwarf is used to simulate the merger of two helium ... Helium-shell ignition occurs at the boundary between degenerate and non-degenerate ...
... Serendipitous Discovery of a Double Helium-rich Subdwarf. ... Amir Ahmad and Simon Jeffery have been studying some rare stars known, loosely, as helium-rich subdwarfs. ...
... Evolutionary models for double helium white dwarf mergers and the formation of helium-rich hot subdwarfs . ... dwarf masses, but are believed to include helium-rich subdwarfs, R CrB stars, extreme helium stars and also AM CVn systems and ...