Detection of Stellar-like Abundance Anomalies in the Slow Solar Wind

• Published in: Astrophysical journal. Letters Vol. 930; no. 1; p. L10
• Main Authors: Brooks, David H., Baker, Deborah, van Driel-Gesztelyi, Lidia, Warren, Harry P., Yardley, Stephanie L.
• Format: Journal Article
• Language: English
• Published: Austin The American Astronomical Society 01.05.2022; IOP Publishing; Bristol : IOP Publishing
• Subjects: Abundance; Anomalies; Astrophysics; Atmospheric models; Chemical composition; Chromosphere; Corona; Photosphere; Red dwarf stars; Sciences of the Universe; Slow solar wind; Solar abundances; Solar activity; Solar corona; Solar wind; Stellar abundances; Wind; Slow solar wind; Solar corona; Stellar abundances; Solar abundances
• ISSN: 2041-8205; 2041-8213
• DOI: 10.3847/2041-8213/ac6878

Abstract The elemental composition of the Sun’s hot atmosphere, the corona, shows a distinctive pattern that is different from the underlying surface or photosphere. Elements that are easy to ionize in the chromosphere are enhanced in abundance in the corona compared to their photospheric values. A similar pattern of behavior is often observed in the slow-speed (<500 km s −1 ) solar wind and in solar-like stellar coronae, while a reversed effect is seen in M dwarfs. Studies of the inverse effect have been hampered in the past because only unresolved (point-source) spectroscopic data were available for these stellar targets. Here we report the discovery of several inverse events observed in situ in the slow solar wind using particle-counting techniques. These very rare events all occur during periods of high solar activity that mimic conditions more widespread on M dwarfs. The detections allow a new way of connecting the slow wind to its solar source and are broadly consistent with theoretical models of abundance variations due to chromospheric fast-mode waves with amplitudes of 8–10 km s −1 , sufficient to accelerate the solar wind. The results imply that M-dwarf winds are dominated by plasma depleted in easily ionized elements and lend credence to previous spectroscopic measurements.