The FIP and Inverse FIP Effects in Solar and Stellar Coronae

By J. Laming. 2015

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We review our state of knowledge of coronal element abundance anomalies in the Sun and stars. We concentrate on the first ionization potential (FIP) effect observed in the solar corona and slow-speed wind, and in the coronae of solar-like dwarf stars, and the “inverse FIP” effect seen in the corona of stars of later spectral type; specifically M dwarfs. These effects relate to the enhancement or depletion, respectively, in coronal abundance with respect to photospheric values of elements with FIP below about 10 eV. They are interpreted in terms of the ponderomotive force due to the propagation and/or reflection of magnetohydrodynamic waves in the chromosphere. This acts on chromospheric ions, but not neutrals, and so can lead to ion-neutral fractionation.A detailed description of the model applied to closed magnetic loops, and to open field regions is given, accounting for the observed difference in solar FIP fractionation between the slow and fast wind. It is shown that such a model can also account for the observed depletion of helium in the solar wind. The helium depletion is sensitive to the chromospheric altitude where ion-neutral separation occurs, and the behavior of the helium abundance in the closed magnetic loop strongly suggests that the waves have a coronal origin. This, and other similar inferences may be expected to have a strong bearing on theories of solar coronal heating.Chromospheric waves originating from below as acoustic waves mode convert, mainly to fast-mode waves, can also give rise to ion-neutral separation. Depending on the geometry of the magnetic field, this can result in FIP or Inverse FIP effects. We argue that such configurations are more likely to occur in later-type stars (known to have stronger field in any case), and that this explains the occurrence of the Inverse FIP effect in M dwarfs. We conclude with a discussion of possible directions for future work.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/cf52e86e783c6961a28f3e3870eaf57d40d0c5e6

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Citations in the corpus

Slow Solar Wind: Observations and Modeling (2016, unknown): “…than about 10 eV are photoionized by the solar Lyα radiation followed by certain ion-neutral fractionation process such as neutral atom diffusion (von Steiger and Geiss 1989; Peter 1998), wave heating of ions (Schwadron et al. 1999), or wave-induced pondermotive force (Laming 2004, 2009, 2015).”
The Solar Orbiter Solar Wind Analyser (SWA) suite (2020, background): “In addition, heavy ion elemental abundances are determined by processes in the chromosphere that can preferentially draw low ﬁrst ionisation potential (FIP) ions up into closed ﬁelds in the corona for later release into the solar wind (e.g. see Laming 2015).”
The Solar Orbiter mission (2020, background): “The low- FIP metallic ions are more abundant in the solar wind than midor high-FIP elements, in contrast to conditions in the photosphere (von Steiger et al. 1997; von Steiger & Zurbuchen 2015; Laming 2015).”