Science Highlights - An ALMA Detection of the Radioactive Molecule 26AlF in a Stellar Merger Remnant.




Although diffuse Galactic gamma-ray emission from the isotope of aluminum, 26Al, was first detected in the 1980s, the identification of the source of emission has been hard to pinpoint due to the poor spatial resolution of gamma-ray observations. In a recent Nature paper, a team led by Dr. Kaminski has made use of sensitive, high-resolution observations with ALMA and NOEMA to detect millimeter-wave emission from an isotopologue of aluminum monofluoride (26AlF) towards the stellar merger remnant CK Vul (aka Nova 1670; see Figure). These observations have provided information about the nature of one of the stars in the merger. I.e., in the case of CK Vul, the 26Al is likely produced within a star with an initial stellar mass in the range of 0.8-2.5 Msun that has already formed a condensed degenerate core. During the merger, the 26Al from the outer layers of the helium core are ejected. The authors propose that, unless there is significant amounts of 26Al in atomic phase, in molecules other than 26AlF, and in solids, there is unlikely to be a sufficient number of CK Vul-like merger events to account for the amount of Galactic gamma ray emission from 26Al.

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