G. M. Mason, I. Roth, N. V. Nitta, R. Bučík, D. Lario, G. C. Ho, R. C. Allen, A. Kouloumvakos, R. F. Wimmer-Schweingruber, J. Rodriguez-Pacheco
{"title":"Heavy-ion Acceleration in <sup>3</sup>He-rich Solar Energetic Particle Events: New Insights from Solar Orbiter","authors":"G. M. Mason, I. Roth, N. V. Nitta, R. Bučík, D. Lario, G. C. Ho, R. C. Allen, A. Kouloumvakos, R. F. Wimmer-Schweingruber, J. Rodriguez-Pacheco","doi":"10.3847/1538-4357/acf31b","DOIUrl":null,"url":null,"abstract":"Abstract We present Solar Orbiter energetic particle observations of two 3 He-rich events with features more clearly observed than in prior studies. The event of 2022 November 9 observed from 0.59 au contained hundreds of ultraheavy (UH; mass >78 amu) ions whereas previous observations at 1 au have shown only an occasional count or two. The event of 2023 April 8 observed from 0.29 au fortuitously had very low ambient activity, making it possible to observe spectra from the 3 He acceleration mechanism without contamination, revealing extremely low H and 4 He intensities arriving simultaneously with other ions observed in typical 3 He-rich events. Taken together with previous studies, we believe these data show that 3 He-rich events have a single acceleration mechanism that is responsible for the unique abundance features of 3 He, heavy ions, and UH ions. Considering the acceleration model of Roth & Temerin that heats the ions over a broad range of gyrofrequencies away from those damped by H and 4 He, we calculate reasonable fits to the observed abundances O–Fe. A key result is that high values of, e.g., Fe/O typical of such events is not due to preferential Fe heating, but on the contrary is due mainly to the depletion of O, which at elevated temperatures has a charge-to-mass ratio in the region of the waves damped by 4 He. The model also naturally incorporates features of high-ionization states and neutron-rich isotope enhancements that have been long-standing puzzles in observations of this type of flare.","PeriodicalId":50735,"journal":{"name":"Astrophysical Journal","volume":null,"pages":null},"PeriodicalIF":4.8000,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Astrophysical Journal","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.3847/1538-4357/acf31b","RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ASTRONOMY & ASTROPHYSICS","Score":null,"Total":0}
引用次数: 0
Abstract
Abstract We present Solar Orbiter energetic particle observations of two 3 He-rich events with features more clearly observed than in prior studies. The event of 2022 November 9 observed from 0.59 au contained hundreds of ultraheavy (UH; mass >78 amu) ions whereas previous observations at 1 au have shown only an occasional count or two. The event of 2023 April 8 observed from 0.29 au fortuitously had very low ambient activity, making it possible to observe spectra from the 3 He acceleration mechanism without contamination, revealing extremely low H and 4 He intensities arriving simultaneously with other ions observed in typical 3 He-rich events. Taken together with previous studies, we believe these data show that 3 He-rich events have a single acceleration mechanism that is responsible for the unique abundance features of 3 He, heavy ions, and UH ions. Considering the acceleration model of Roth & Temerin that heats the ions over a broad range of gyrofrequencies away from those damped by H and 4 He, we calculate reasonable fits to the observed abundances O–Fe. A key result is that high values of, e.g., Fe/O typical of such events is not due to preferential Fe heating, but on the contrary is due mainly to the depletion of O, which at elevated temperatures has a charge-to-mass ratio in the region of the waves damped by 4 He. The model also naturally incorporates features of high-ionization states and neutron-rich isotope enhancements that have been long-standing puzzles in observations of this type of flare.
期刊介绍:
The Astrophysical Journal is the foremost research journal in the world devoted to recent developments, discoveries, and theories in astronomy and astrophysics.