Coronal Elemental Abundance: New Results from Soft X-Ray Spectroscopy of the Sun

Narendranath, S.; Sreekumar, P.; Pillai, N. S.; Panini, Singam S.; Sankarasubramanian, K.; Huovelin, J.

doi:10.1007/s11207-020-01738-5

Cited by 16 publications

(10 citation statements)

References 36 publications

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“…Also, important are studies on FIP bias in the corona (e.g., Laming 2015). Recent studies show that the FIP bias changes during flares and it is connected to the magnetic field topology in the pre-eruptive structure (Narendranath et al 2020). Disk averaged coronal abundances measured with SIXS-X can also be compared to those measured in stars.…”

Section: X-ray Measurementsmentioning

confidence: 99%

“…There was also another version of the XSM flown on-board the ISRO's Chandrayaan-1 lunar mission ), which has resulted thus far in a number of scientific studies, e.g. the investigation of elemental abundances of the solar corona by Narendranath et al (2014), and also very recently further studies reveal the changes in first ionization potential (FIP) bias during evolution of flares (Narendranath et al 2020). This is enabled by the good spectral resolution and time resolution of these instruments.…”

Section: Introductionmentioning

confidence: 99%

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Solar Intensity X-Ray and Particle Spectrometer SIXS: Instrument Design and First Results

et al. 2020

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The Solar Intensity X-ray and particle Spectrometer (SIXS) on the BepiColombo Mercury Planetary Orbiter (“Bepi”) measures the direct solar X-rays, energetic protons, and electrons that bombard, and interact with, the Hermean surface. The interactions result in X-ray fluorescence and scattering, and particle induced X-ray emission (PIXE), i.e. “glow” of the surface in X-rays. Simultaneous monitoring of the incident and emitted radiation enables derivation of the abundances of some chemical elements and scattering properties of the outermost surface layer of the planet, and it may reveal other sources of X-ray emission, due to, for example, weak aurora-like phenomena in Mercury’s exosphere. Mapping of the Hermean X-ray emission is the main task of the MIXS instrument onboard BepiColombo. SIXS data will also be used for investigations of the solar X-ray corona and solar energetic particles (SEP), both in the cruise phase and the passes of the Earth, Venus and Mercury before the arrival at Mercury’s orbit, and the final science phase at Mercury’s orbit. These observations provide the first-ever opportunity for in-situ measurements of the propagation of SEPs, their interactions with the interplanetary magnetic field, and space weather phenomena in multiple locations throughout the inner solar system far away from the Earth, and more extensively at Mercury’s orbit.In this paper we describe the scientific objectives, design and calibrations, operational principles, and scientific performance of the final SIXS instrument launched to the mission to planet Mercury onboard BepiColombo. We also provide the first analysis results of science observations with SIXS, that were made during the Near-Earth Commissioning Phase and early cruise phase operations in 2018–19, including the background X-ray sky observations and “first light” observations of the Sun with the SIXS X-ray detection system (SIXS-X), and in-situ energetic electron and proton observations with the SIXS Particle detection system (SIXS-P).

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Section: X-ray Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Solar Intensity X-Ray and Particle Spectrometer SIXS: Instrument Design and First Results

et al. 2020

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“…It is only recently, with the advent of better instrumentation, that in-depth studies of smaller flares are becoming feasible (Kuhar et al 2018;Mitra-Kraev and Del Zanna 2019;Athiray et al 2020;Cooper et al 2020;Glesener et al 2020;Duncan et al 2021;Vadawale et al 2021a). Lately, using X-ray time resolved spectroscopy, Narendranath et al (2020) have carried out abundance studies of flares as small as GOES B9-class. Like the larger ones, these small flares have also shown a depletion of low FIP elements relative to H, during their evolution.…”

Section: Introductionmentioning

confidence: 99%

Evolution of Elemental Abundances During B-Class Solar Flares: Soft X-ray Spectral Measurements with Chandrayaan-2 XSM

Mondal,

Sarkar,

Vadawale

et al. 2021

Preprint

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The Solar X-ray Spectrometer (XSM) payload onboard Chandrayaan-2 provides disk-integrated solar spectra in the 1 -15 keV energy range with an energy resolution of 180 eV (at 5.9 keV) and a cadence of 1 second. During the period from September 2019 to May 2020, covering the minimum of Solar Cycle 24, it observed nine B-class flares ranging from B1.3 to B4.5. Using time-resolved spectroscopic analysis during these flares, we examined the evolution of temperature, emission measure, and absolute elemental abundances of four elements -Mg, Al, Si, and S. These are the first measurements of absolute abundances during such small flares and this study offers a unique insight into the evolution of absolute abundances as the flares evolve. Our results demonstrate that the abundances of these four elements decrease towards their photospheric values during the peak phase of the flares. During the decay phase, the abundances are observed to quickly return to their pre-flare coronal values. The depletion of elemental abundances during the flares is consistent with the standard flare model, suggesting the injection of fresh material into coronal loops as a result of chromospheric evaporation. To explain the quick recovery of the so-called coronal "First Ionization Potential (FIP) bias" we propose two scenarios based on the Ponderomotive force model.

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“…Does this hold good in the quiet corona? • The First Ionization Potential (FIP) bias varies in flares (Phillips et al, 2003;Katsuda et al, 2020;Narendranath et al, 2020) and active regions (Baker et al, 2015;Baker et al, 2019). Measurements of abundances in quiet regions and its possible variations are very limited.…”

Section: Introductionmentioning

confidence: 99%

Multilayer Mirror Based High-Resolution Solar Soft X-Ray Spectrometer

Panini

Narendranath

Sreekumar

et al. 2021

Front. Astron. Space Sci.

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Soft X-ray spectroscopy of the Sun is an important tool to understand the coronal dynamics and composition. The solar coronal X-ray spectrum below 1 keV is the least explored with high-resolution spectroscopy. Recent observations with Hinode XRT using coarse spectroscopy along with high-resolution imaging have shown that abundances in the coronae have variability associated with structures on the Sun. Disk averaged abundances with better spectral resolution spectrometers show time variability associated with flares. Both spatial and temporal variabilities seem to be related to changes in the magnetic field topology. Understanding such short term variabilities is necessary to model the underlying dynamics and mixing of material between different layers of the Sun. A Sensitive high-resolution spectrometer that covers the range in plasma temperatures and emission line complexes would uniquely reveal the entire evolution of flares. We are investigating a design of a multi-layer mirror-based X-ray spectrograph in the spectral range from 0.5 to 7 keV. The instrument operates in four asynchronous spectral channels operating one at a time. The multi-layer mirror placed at the focus of a Wolter type I telescope reflects a narrow band X-rays to the CCD which is placed at Nasmyth defocus. Converging X-rays from the front end optics helps to increase the spectral range of each channel while preserving the spectral resolution. This design is estimated to achieve a spectral resolution of 20 eV in the spectral range of 0.5–7 keV. With such high spectral resolution, we can resolve individual spectral features e.g., 6.7 keV Fe complex which can be used to diagnose high-temperature transient plasma during flares. The instrument design estimated performance and the science capabilities of this instrument will be discussed in detail in the paper.

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Coronal Elemental Abundance: New Results from Soft X-Ray Spectroscopy of the Sun

Cited by 16 publications

References 36 publications

Solar Intensity X-Ray and Particle Spectrometer SIXS: Instrument Design and First Results

Solar Intensity X-Ray and Particle Spectrometer SIXS: Instrument Design and First Results

Evolution of Elemental Abundances During B-Class Solar Flares: Soft X-ray Spectral Measurements with Chandrayaan-2 XSM

Multilayer Mirror Based High-Resolution Solar Soft X-Ray Spectrometer

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