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Chemical abundances in hot subdwarf B stars

Image Credit: Naslim Neelamkodan

Elemental abundances for hot subdwarf stars relative to solar values. Abundances for helium-rich subdwarfs and helium deficient normal subdwarfs are indicated by a mean (symbol) and range (line). The most heavy metal-rich stars in the Galaxy, HE 2359-2844 and HE 1256-2738 are shown in separate symbols.

The hot subdwarf stars which are found to be helium-main sequence or extended horizontal branch stars of approximately half a solar mass are the extreme chemically peculiar stars in our Galaxy. The figure summarizes the measured chemical abundances in hot subdwarf stars relative to solar values. Two helium-rich hot subdwarfs, HE 2359-2844 and HE 1256-2738 show absorption lines due to triply ionized lead which have never previously been detected in any star. Using these lines we measured the abundances of lead which is nearly 10000 times that measured in the Sun. These are the most lead rich stars known to science.