Carbon-Deficient Red Giants: Discovery of a Stellar Merger Population

Watch an astronomy lecture exploring the mysterious carbon-deficient red giants (CDGs) and their potential formation through stellar mergers. Dive into groundbreaking research combining asteroseismology, spectroscopy, and astrometry that led to the discovery of 15 new CDGs in the Kepler field. Learn about the surprising findings that these stars are predominantly low-mass and in the red clump phase, contradicting previous theories about their intermediate mass classification. Examine the intriguing connection between CDGs and lithium-rich giants, with 50% of the studied CDGs showing high lithium content. Explore the observed bimodal luminosity distribution and the resulting classification of CDGs into three distinct groups. Follow the evidence supporting the theory that these stars likely formed through the merger of a helium white dwarf with a red giant branch star, potentially explaining both the overluminous CDGs and the formation of lithium-rich giants.