J/ApJ/833/196ivo://CDS.VizieR/J/ApJ/833/196doi:10.26093/cds/vizier.18330196CDSMurphy R.J.Kozlovsky B.Share G.H.2017-06-21T07:41:22Z2017-05-29T07:43:39ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.fratomic-physicsgamma-ray-astronomyThe ^3^He abundance in impulsive solar energetic particle (SEP) events is enhanced up to several orders of magnitude compared to its photospheric value of [^3^He]/[^4^He] = 1-3 x 10^-4^. Interplanetary magnetic field and timing observations suggest that these events are related to solar flares. Observations of ^3^He in flare-accelerated ions would clarify the relationship between these two phenomena. Energetic ^3^He interactions in the solar atmosphere produce gamma-ray nuclear-deexcitation lines, both lines that are also produced by protons and {alpha} particles and lines that are essentially unique to ^3^He. Gamma-ray spectroscopy can, therefore, reveal enhanced levels of accelerated ^3^He. In this paper, we identify all significant deexcitation lines produced by ^3^He interactions in the solar atmosphere. We evaluate their production cross sections and incorporate them into our nuclear deexcitation-line code. We find that enhanced ^3^He can affect the entire gamma-ray spectrum. We identify gamma-ray line features for which the yield ratios depend dramatically on the ^3^He abundance. We determine the accelerated ^3^He/{alpha} ratio by comparing these ratios with flux ratios measured previously from the gamma-ray spectrum obtained by summing the 19 strongest flares observed with the Solar Maximum Mission Gamma-Ray Spectrometer. All six flux ratios investigated show enhanced ^3^He, confirming earlier suggestions. The ^3^He/{alpha} weighted mean of these new measurements ranges from 0.05 to 0.3 (depending on the assumed accelerated {alpha}/proton ratio) and has a <1 x 10^-3^ probability of being consistent with the photospheric value. With the improved code, we can now exploit the full potential of gamma-ray spectroscopy to establish the relationship between flare-accelerated ions and ^3^He-rich SEPs.2016ApJ...833..196Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/833/196CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/833/196https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/833/196http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/833/196https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/833/196https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/833/196http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/833/196GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapGamma-raydefaultJ/ApJ/833/196/table4Explicit line indexrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintLine[0.07/7] Line energyMeVphys.energy;phys.atmol.levelfloatTargetTarget namephys.atmol.ionStagecharNucExcited nucleus namephys.atmol.elementcharRxNameReaction namemeta.notecharJ/ApJ/833/196/table5Unresolved line indexRxNameReaction namemeta.notecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTargetTarget namephys.atmol.ionStagecharJ/ApJ/833/196/table6Particle energy and cross sectionsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameReaction namemeta.notecharNp[9/29] Number of cross sections in Namemeta.numberintEnergy[0.3/270] Particle energy in units of MeV/nucleonMeVphys.energy;phys.atmol.levelfloatCS[0/2482] Cross section at Energy in milliBarns (10^-31^m^2^; barn=10^-28^m^2^)mbarnphys.atmol.crossSectionfloat