Spectacular Nucleosynthesis from Early Massive Stars
Bizyaev, Dmitry; Brownstein, Joel R.; Pan, Kaike; Conroy, Charlie; Cargile, Phillip A.; Kollmeier, Juna A.; Casey, Andrew R.; Stassun, Keivan G.; Laporte, Chervin F. P.; Rix, Hans-Walter; Price-Whelan, Adrian M.; Li, Haining; Horta, Danny; Cerny, William; Hawkins, Keith; Beaton, Rachael L.; Chiappini, Cristina; Holmbeck, Erika M.; Meynet, Georges; Ji, Alexander P.; Reggiani, Henrique; Stringfellow, Guy S.; Bergemann, Maria; Shah, Shivani P.; Tayar, Jamie; Schlaufman, Kevin C.; Usman, Sam A.; Chandra, Vedant; Johnson, Jennifer A.; Amarante, João A. S.; Pignatari, Marco; Loebman, Sarah; Morrison, Sean; Heger, Alexander; Gupta, Pramod; Ramirez, Solange V.; Sánchez-Gallego, José; Storm, Nicholas; Griffith, Emily J.; Thibodeaux, Pierre; Curtis, Sanjana; Fröhlich, Carla
United States, Germany, Australia, Hungary, United Kingdom, Spain, Canada, China, Switzerland, Russia
Abstract
Stars that formed with an initial mass of over 50 M ⊙ are very rare today, but they are thought to be more common in the early Universe. The fates of those early, metal-poor, massive stars are highly uncertain. Most are expected to directly collapse to black holes, while some may explode as a result of rotationally powered engines or the pair-creation instability. We present the chemical abundances of J0931+0038, a nearby low-mass star identified in early follow-up of the SDSS-V Milky Way Mapper, which preserves the signature of unusual nucleosynthesis from a massive star in the early Universe. J0931+0038 has a relatively high metallicity ([Fe/H] = ‑1.76 ± 0.13) but an extreme odd–even abundance pattern, with some of the lowest known abundance ratios of [N/Fe], [Na/Fe], [K/Fe], [Sc/Fe], and [Ba/Fe]. The implication is that a majority of its metals originated in a single extremely metal-poor nucleosynthetic source. An extensive search through nucleosynthesis predictions finds a clear preference for progenitors with initial mass >50 M ⊙, making J0931+0038 one of the first observational constraints on nucleosynthesis in this mass range. However, the full abundance pattern is not matched by any models in the literature. J0931+0038 thus presents a challenge for the next generation of nucleosynthesis models and motivates the study of high-mass progenitor stars impacted by convection, rotation, jets, and/or binary companions. Though rare, more examples of unusual early nucleosynthesis in metal-poor stars should be found in upcoming large spectroscopic surveys.