Solar Cycle Observations of the Neon Abundance in the Sun-as-a-star

Brooks, David H.; Baker, D.; Driel-Gesztelyi, L. van; Warren, Harry P.

doi:10.3847/1538-4357/aac6d8

Cited by 3 publications

(3 citation statements)

References 53 publications

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“…The FIP effect is reduced at lower temperatures (Laming et al 1995). Recent work of Brooks et al (2017Brooks et al ( , 2018 based on Sun-as-a-star spectra obtained by the Solar Dynamics Observatory (SDO) Extreme-Ultraviolet Variability Experiment (EVE) demonstrated that the variation of coronal composition is highly correlated with the solar cycle.…”

Section: Introductionmentioning

confidence: 99%

Transient Inverse-FIP Plasma Composition Evolution within a Solar Flare

Baker

Driel-Gesztelyi

Brooks

et al. 2019

ApJ

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Understanding elemental abundance variations in the solar corona provides an insight into how matter and energy flow from the chromosphere into the heliosphere. Observed variations depend on the first ionization potential (FIP) of the main elements of the Sun's atmosphere. High-FIP elements (>10 eV) maintain photospheric abundances in the corona, whereas low-FIP elements have enhanced abundances. Conversely, inverse FIP (IFIP) refers to the enhancement of high-FIP or depletion of low-FIP elements. We use spatially resolved spectroscopic observations, specifically the Ar XIV/Ca XIV intensity ratio, from Hinode's Extreme-ultraviolet Imaging Spectrometer to investigate the distribution and evolution of plasma composition within two confined flares in a newly emerging, highly sheared active region. During the decay phase of the first flare, patches above the flare ribbons evolve from the FIP to the IFIP effect, while the flaring loop tops show a stronger FIP effect. The patch and loop compositions then evolve toward the pre-flare basal state. We propose an explanation of how flaring in strands of highly sheared emerging magnetic fields can lead to flare-modulated IFIP plasma composition over coalescing umbrae which are crossed by flare ribbons. Subsurface reconnection between the coalescing umbrae leads to the depletion of low-FIP elements as a result of an increased wave flux from below. This material is evaporated when the flare ribbons cross the umbrae. Our results are consistent with the ponderomotive fractionation model (Laming 2015) for the creation of IFIP-biased plasma.

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Section: Introductionmentioning

confidence: 99%

Transient Inverse-FIP Plasma Composition Evolution within a Solar Flare

Baker

Driel-Gesztelyi

Brooks

et al. 2019

ApJ

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“…For the Sun, there is some evidence that the cyclic variation results from changes in the low FIP elements, since a similar cyclic variation is not seen directly in the high FIP element Ne (Schmelz et al 2005;Del Zanna & Andretta 2011). On the contrary, the Ne/O abundance ratio appears to vary with the solar cycle in the solar corona and solar wind (Shearer et al 2014;Landi & Testa 2015;Brooks et al 2018), which could in principle be due to changes in the Ne abundance. Solarlike stars of a similar spectral type to the Sun may show cyclic variations, but it may be more difficult to detect on later spectral type stars -where the inverse FIP effect is seen.…”

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confidence: 99%

A Diagnostic of Coronal Elemental Behavior during the Inverse FIP Effect in Solar Flares

Brooks

2018

ApJ

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The solar corona shows a distinctive pattern of elemental abundances that is different from that of the photosphere. Low first ionization potential (FIP) elements are enhanced by factors of several. A similar effect is seen in the atmospheres of some solar-like stars, while late type M stars show an inverse FIP effect. This inverse effect was recently detected on the Sun during solar flares, potentially allowing a very detailed look at the spatial and temporal behavior that is not possible from stellar observations. A key question for interpreting these measurements is whether both effects act solely on low FIP elements (a true inverse effect predicted by some models), or whether the inverse FIP effect arises because high FIP elements are enhanced. Here we develop a new diagnostic that can discriminate between the two scenarios, based on modeling of the radiated power loss, and applying the models to a numerical hydrodynamic simulation of coronal loop cooling. We show that when low/high FIP elements are depleted/enhanced, there is a significant difference in the cooling lifetime of loops that is greatest at lower temperatures. We apply this diagnostic to a post X1.8 flare loop arcade and inverse FIP region, and show that for this event, low FIP elements are depleted. We discuss the results in the context of stellar observations, and models of the FIP and inverse FIP effect. We also provide the radiated power loss functions for the two inverse FIP effect scenarios in machine readable form to facilitate further modeling.

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“…This result confirms the finding of McIntosh et al (2011), which found that the Fe/O ratio, another proxy for the FIP effect in the solar wind, also shows some degree of variability in the fast wind during the decay phase of the solar cycle from 2005 to 2009. Further remote sensing observations of the sun-as-a-star by Brooks et al (2017Brooks et al ( , 2018) also indicate that during the rising phase of the solar cycle (2010-2014) the FIP bias changes with time: their measurements mostly reflect the composition of the denser quiet Sun and active region plasmas where the reconnection-based slow wind likely comes from. Furthermore, despite the uncertainties in its measurement, the abundance of Ne seems to increase during solar minimum relative to all other elements, and the amount of increase seems to be lower at larger speeds.…”

Section: Relative Elemental Abundancesmentioning

confidence: 99%

ACE SWICS observations of solar cycle variations of the solar wind

Cardenas-O'Toole¹,

Landi²

2022

Preprint

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In the present work we utilize ACE/SWICS in-situ measurements of the properties of the solar wind outside ICMEs in order to determine whether, and to what extent are the solar wind properties affected by the solar cycle. We focus on proton temperatures and densities, ion temperatures and differential speeds, charge state distributions and both relative and absolute elemental abundances. We carry out this work dividing the wind in velocity bins to investigate how winds at different speeds react to the solar cycle. We also repeat this study, when possible, to the subset of SWICS measurements less affected by Coulomb collisions. We find that with the only exception of differential speeds (for which we do not have enough measurements) all wind properties change as a function of the solar cycle. Our results point towards a scenario where both the slow and fast solar wind are accelerated by waves, but originate from different sources (open/closed magnetic structures for the fast/slow wind, respectively) whose relative contribution changes along the solar cycle. We also find that the signatures of heating and acceleration on one side, and of the FIP effect on the other, indicate that wave-based plasma heating, acceleration and fractionation remain active throughout the solar cycle, but decrease their effectiveness in all winds, although the slow wind is much affected than the fast one.

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Solar Cycle Observations of the Neon Abundance in the Sun-as-a-star

Cited by 3 publications

References 53 publications

Transient Inverse-FIP Plasma Composition Evolution within a Solar Flare

Transient Inverse-FIP Plasma Composition Evolution within a Solar Flare

A Diagnostic of Coronal Elemental Behavior during the Inverse FIP Effect in Solar Flares

ACE SWICS observations of solar cycle variations of the solar wind

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