On 2008 May 2, Chandra observed the X-ray spectrum of Xi Boo (G8 V+K4 V), resolving the binary for the first time in X-rays and allowing the coronae of the two stars to be studied separately. With the contributions of Xi Boo A and B to the system's total X-ray emission now observationally established (88.5% and 11.5%, respectively), consideration of mass loss measurements for GK dwarfs of various activity levels (including one for Xi Boo) leads to the surprising conclusion that Xi Boo B may dominate the wind from the binary, with Xi Boo A's wind being very weak despite its active corona. Emission measure distributions and coronal abundances are computed for both stars and compared with Chandra measurements of other moderately active stars with G8-K5 spectral types, all of which exhibit a narrow peak in emission measure near log T=6.6, indicating that the coronal heating process in these stars has a strong preference for this temperature. As is the case for the Sun and many other stars, our sample of stars shows coronal abundance anomalies dependent on the first ionization potential (FIP) of the element. We see no dependence of the degree of "FIP effect" on activity, but there is a dependence on spectral type, a correlation that becomes more convincing when moderately active main sequence stars with a broader range of spectral types are considered. This clear dependence of coronal abundances on spectral type weakens if the stellar sample is allowed to be contaminated by evolved stars, interacting binaries, or extremely active stars with log L_X>29, explaining why this correlation has not been recognized in the past.
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…
Elemental abundances in the solar corona are known to be different from those observed in the solar photosphere. The ratio of coronal to photospheric abundance shows a dependence on the first ionisation potential (FIP) of the element. We estimate FIP bias from direct measurements of elemental abundances from soft X-ray spectra using data from multiple space missions covering a range of solar activity levels. This comprehensive analysis shows clear evidence for a decrease in FIP bias around maximum intensity of the X-ray flare with coronal abundances briefly tending to photospheric values and a…
The Inverse First Ionization Potential (FIP) Effect, the depletion in coronal abundance of elements like Fe, Mg, and Si that are ionized in the solar chromosphere relative to those that are neutral, has been identified in several solar flares. We give a more detailed discussion of the mechanism of fractionation by the ponderomotive force associated with magnetohydrodynamic waves, paying special attention to the conditions in which Inverse FIP fractionation arises in order to better understand its relation to the usual FIP Effect, i.e. the enhancement of coronal abundance of Fe, Mg, Si, etc. Th…
The element abundances in the solar corona and solar wind are often different from those of the solar photosphere, typically with a relative enrichment of elements with low first ionization potential (FIP effect). Here we study the spatial distribution and temporal evolution of the coronal chemical composition in an active region (AR) over about 10 days, using Hinode/EIS spectra, and we also analyze coordinated IRIS observations of the chromospheric and transition region emission to investigate any evidence of the footprints of the FIP effect in the lower atmosphere. To derive the coronal abun…
Dynamic modeling of coronal abundances during flares on M-dwarf stars
Computational Physics, Inc.（计算物理公司）；University College London, Mullard Space Science Laboratory（伦敦大学学院穆拉德空间科学实验室）；Institute for Astronomy, University of Hawai’i（夏威夷大学天文研究所）；ESTEC, European Space Agency（欧洲空间局欧洲空间研究与技术中心）；National Solar Observatory（国家太阳观测台）
The chemical composition of the solar corona is different from that of the solar photosphere, with the strongest variation being observed in active regions (ARs). Using data from the Extreme Ultraviolet (EUV) Imaging Spectrometer (EIS) on Hinode, we present a survey of coronal elemental composition as expressed in the first ionisation potential (FIP) bias in 28 ARs of different ages and magnetic flux content, which are at different stages in their evolution. We find no correlation between the FIP bias of an AR and its total unsigned magnetic flux or age. However, there is a weak dependence of …
Connecting in-situ measured solar-wind plasma properties with typical regions on the Sun can provide an effective constraint and test to various solar wind models. We examine the statistical characteristics of the solar wind with an origin in different types of source regions. We find that the speed distribution of coronal hole (CH) wind is bimodal with the slow wind peaking at ~400 km/s and a fast at ~600 km/s. An anti-correlation between the solar wind speeds and the O7+/O6+ ion ratio remains valid in all three types of solar wind as well during the three studied solar cycle activity phases,…
Sulfur fractionation in coronal plumes as observed by Solar Orbiter/SPICE
Université Paris-Saclay, CNRS, Institut d’Astrophysique Spatiale（巴黎萨克雷大学）；European Space Agency（欧洲空间局）；Mullard Space Science Laboratory, University College London（伦敦大学学院穆拉德太空科学实验室）；Dublin City University（都柏林城市大学）；Dublin Institute for Advanced Studies（都柏林高等研究院）
The chemical composition of solar and stellar atmospheres differs from that of their photospheres. Abundances of elements with low first ionization potential (FIP) are enhanced in the corona relative to high FIP elements with respect to the photosphere. This is known as the FIP effect and it is important for understanding the flow of mass and energy through solar and stellar atmospheres. We used spectroscopic observations from the Extreme-ultraviolet Imaging Spectrometer (EIS) onboard the Hinode observatory to investigate the spatial distribution and temporal evolution of coronal plasma compos…
Elemental Composition Evolution during the 2024 September 30 Solar Eruption: A Comparison of Hot and Cool Plasma Components with Solar Orbiter/SPICE, Hinode/EIS, and Chandrayaan-2/XSM
Southwest Research Institute（西南研究所）；Ann and H.J. Smead Aerospace Engineering Sciences, University of Colorado Boulder（科罗拉多大学博尔德分校安与H.J.斯梅德航空航天工程科学系）；Laboratory for Atmospheric and Space Physics, University of Colorado Boulder（科罗拉多大学博尔德分校大气与空间物理实验室）；University of Alabama in Huntsville（阿拉巴马大学亨茨维尔分校）；NASA Marshall Space Flight Center（美国国家航空航天局马歇尔太空飞行中心）
It is well established that elemental abundances vary in the solar atmosphere and that this variation is organized by first ionization potential (FIP). Previous studies have shown that in the solar corona low-FIP elements, such as Fe, Si, Mg, and Ca, are generally enriched relative to high-FIP elements, such as C, N, O, Ar, and Ne. In this paper we report on measurements of plasma composition made during impulsive heating events observed at transition region temperatures with the Extreme Ultraviolet Imaging Spectrometer (EIS) on Hinode. During these events the intensities of O IV, V, and VI em…
The relative abundances of chemical elements and isotopes have been our most effective tool in identifying and understanding energetic particles. The early surprise in solar energetic particles (SEPs) was 1000-fold enhancements in 3He/4He from resonant wave-particle interactions in the small "impulsive" SEP events that emit electron beams that produce type III radio bursts. Further studies found enhancements in Fe/O, then extreme enhancements in abundances that increase with mass-to-charge ratio A/Q by a factor of 1000 from He to Pb arising in magnetic reconnection on open field lines in solar…
We investigate in more detail the origin of chromospheric Alfven waves that give rise to the separation of ions and neutrals, the First Ionization Potential Effect (FIP), through the action of the ponderomotive force. In open field regions, we model the dependence of fractionation on the plasma upflow velocity through the chromosphere for both shear (or planar) and torsional Alfven waves of photospheric origin. These differ mainly through their parametric coupling to slow mode waves. Shear Alfven waves appear to reproduce observed fractionations for a wider range of model parameters, and prese…
Context. Elemental abundances in some coronal structures differ significantly from photospheric abundances, with a dependence on the first ionization potential (FIP) of the element. Measuring these FIP-dependent abundance biases is important for coronal and heliospheric physics. Aims. We aim to build a method for optimal determination of FIP biases in the corona from spectroscopic observations in a way that is in practice independent from Differential Emission Measure (DEM) inversions. Methods. We optimised linear combinations of spectroscopic lines of low-FIP and high-FIP elements so that the…
The enrichment of coronal loops and the slow solar wind with elements that have low First Ionisation Potential, known as the FIP effect, has often been interpreted as the tracer of a common origin. A current explanation for this FIP fractionation rests on the influence of ponderomotive forces and turbulent mixing acting at the top of the chromosphere. The implied wave transport and turbulence mechanisms are also key to wave-driven coronal heating and solar wind acceleration models. This work makes use of a shell turbulence model run on open and closed magnetic field lines of the solar corona t…
The different elemental abundances of the photosphere and the corona are striking features of not only the Sun, but other stars as well. This phenomenon is known as the FIP effect (FIP stands for first ionization potential), and its strength can be characterized by the FIP bias, the logarithmic abundance difference between low- and high-FIP elements in the corona, compared to the photosphere. The FIP bias was shown to depend on the surface temperature of the star. We compiled FIP bias and other parameters for 59 stars for which coronal composition is available, now including evolved stars. Usi…
We present evidences that anomalies in abundance of the chemical minor elements with the low first ionization potential (FIP) in the low corona of the late-type stars can be related with topology of the large-scale magnetic field. The solar observations show the increased abundances of the low FIP elements in compare to the abundances of the high FIP elements above the active regions and in the closed magnetic configurations of the low corona. Observational data of Ulysses and the Stanford Solar Observatory show high correlations between FIP effect of the solar wind, amount of the unsigned ope…
We analyse the coronal elemental abundances during a small flare using Hinode/EIS observations. Compared to the pre-flare elemental abundances, we observed a strong increase in coronal abundance of Ca XIV 193.84 Å, an emission line with low first ionisation potential (FIP < 10 eV), as quantified by the ratio Ca/Ar during the flare. This is in contrast to the unchanged abundance ratio observed using Si X 258.38 Å/S X 264.23 Å. We propose two different mechanisms to explain the different composition results. Firstly, the small flare-induced heating could have ionised S, but not the noble gas Ar,…
Our understanding of the formation and evolution of the corona and the heliosphere is linked to our capability of properly interpreting the data from remote sensing and in-situ observations. In this respect, being able to correctly connect in-situ observations with their source regions on the Sun is the key for solving this problem. In this work we aim at testing a diagnostics method for this connectivity. This paper makes use of a coronal jet observed on 2010 August 2nd in active region 11092 as a test for our connectivity method. This combines solar EUV and in-situ data together with magneti…
We examine the different element abundances exhibited by the closed loop solar corona and the slow speed solar wind. Both are subject to the First Ionization Potential (FIP) Effect, the enhancement in coronal abundance of elements with FIP below 10 eV (e.g. Mg, Si, Fe) with respect to high FIP elements (e.g. O, Ne, Ar), but with subtle differences. Intermediate elements, S, P, and C, with FIP just above 10 eV, behave as high FIP elements in closed loops, but are fractionated more like low FIP elements in the solar wind. On the basis of FIP fractionation by the ponderomotive force in the chromo…
FIP Bias Evolution in an Emerging Active Region as observed in SPICE Synoptic Observations
Southwest Research Institute（西南研究所）；University of Colorado Boulder（科罗拉多大学博尔德分校）；University College London, Mullard Space Science Laboratory（伦敦大学学院穆拉德空间科学实验室）；Naval Research Laboratory（海军研究实验室）；ETH-Zurich（苏黎世联邦理工学院）；PMOD/WRC
Anomalously Strong Localized First Ionization Potential Effect Associated with a Solar Subflare
State Key Laboratory of Lunar and Planetary Sciences and CNSA Macau Center for Space Exploration and Science, Macau University of Science and Technology（澳门科技大学月球与行星科学国家重点实验室及CNSA澳门空间探索科学中心）；School of Astronomy and Space Science and Key Laboratory of Modern Astronomy and Astrophysics, Nanjing University（南京大学天文与空间科学学院现代天体物理学重点实验室）
From a turbulent history, the study of abundances of elements in solar energetic particles (SEPs) has grown into an extensive field that probes the solar corona and the physical processes of SEP acceleration and transport. Underlying SEPs are the abundances of the solar corona, which differ from photospheric abundances as a function of the first ionization potentials (FIPs) of the elements. The FIP-dependence of SEPs also differs from that of the solar wind; each has a different magnetic environment where low-FIP ions and high-FIP neutral atoms rise toward the corona. Two major sources generat…
The elemental composition of the solar wind differs from the solar photospheric composition. Elements with low first ionization potential (FIP) appear enhanced compared to O in the solar wind relative to the respective photospheric abundances. This so-called FIP effect is different in the slow solar wind and the coronal hole wind. However, under the same plasma conditions, for elements with similar FIPs such as Mg, Si, and Fe, comparable enhancements are expected. We scrutinize the assumption that the FIP effect is always similar for different low FIP elements, namely Mg, Si, and Fe. We invest…
In \citet{Stangalini20} and \citet{Deb20}, magnetic oscillations were detected in the chromosphere of a large sunspot and found to be linked to the coronal locations where a First Ionization Potential (FIP) effect was observed. In an attempt to shed light onto the possible excitation mechanisms of these localized waves, we further investigate the same data by focussing on the relation between the spatial distribution of the magnetic wave power and the overall field geometry and plasma parameters obtained from multi-height spectropolarimetric non-local thermodynamic equilibrium (NLTE) inversion…
Chromospheric dynamics and turbulence regulate the solar FIP effect
European Space Agency (ESA), European Space Research and Technology Centre (ESTEC)（欧洲航天局（ESA），欧洲空间研究与技术中心（ESTEC））；Naval Research Laboratory（海军研究实验室）；Institute for Astronomy, University of Hawai‘i（夏威夷大学天体物理研究所）
The calcium abundance in flare plasmas is estimated using X-ray spectra from the Solar Maximum Mission Bent Crystal Spectrometer (BCS) during the decays of 194 flares (GOES classifications from B6.4 to X13) occurring between 1980 and 1989. Previous work by Sylwester et al. found that the abundance varied from flare to flare. That analysis is improved on here using updated instrument parameters and by including all calcium lines viewed by the BCS instead of only the resonance line, so greatly enhancing the photon count statistics. The abundance variations are confirmed with the average abundanc…
Sixty years ago the first observation was published showing solar energetic particles (SEPs) with a sampling of chemical elements. Thus began study of the direct products of dynamic physics in the solar corona. As we have progressed from 4-min sounding-rocket samples to continuous satellite coverage of SEP events, we have extended the observations to the unusual distribution of element abundances throughout the periodic table. Small "impulsive" SEP events from islands of magnetic reconnection on open magnetic-field lines in solar jets generate huge enhancements in abundances of 3He and of the …
We present an in-depth study of a large and long duration ($>$1.3 days) X-ray flare observed on an RS CVn type eclipsing binary system SZ Psc using observations from Swift observatory. In the 0.35$-$10 keV energy band, the peak luminosity is estimated to be 4.2$\times$10$^{33}$ erg s$^{-1}$. The quiescent corona of SZ Psc was observed $\sim$5.67 d after the flare using Swift observatory, and also $\sim$1.4 yr after the flare using the XMM-Newton satellite. The quiescent corona is found to consist of three temperature plasma: 4, 13, and 48 MK. High-resolution X-ray spectral analysis of the quie…
