V391 Pegasi the ejection of the hydrogen envelope of a red giant star at or just before the onset of helium fusion. The ejection left only a tiny amount of hydrogen on the surface - less than 1/1000 of the total stellar mass. The future for the star is to eventually cool down to make a low mass white dwarf. Most stars retain more of their hydrogen after the first red giant phase, and eventually become asymptotic giant branch stars. The reason that some stars, like V391 Pegasi, lose so much mass is not well known. In 2007, a gas giant planet
S-type star difficult for a red giant to have other s-process elements in its atmosphere without technetium. S-type stars without technetium form by the transfer of technetium-rich matter, as well as other dredged-up elements, from an intrinsic S star in a binary system onto a smaller less-evolved companion. After a few hundred thousand years, the Tc will have decayed and a technetium-free star enriched with carbon and other s-process elements will remain. When this star is, or becomes, a G or K type red giant, it will be classified as a Barium star. When it evolves to temperatures cool enough for ZrO