Coronal Elemental Abundances During A-Class Solar Flares Observed by Chandrayaan-2 XSM

Nama, Lakshitha; Mondal, Biswajit; Narendranath, S.; Paul, K. T.

doi:10.1007/s11207-023-02142-5

Cited by 6 publications

(7 citation statements)

References 57 publications

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“…XSM provides full-disk spectral data, but the XRT capabilities have allowed us to probe the AR and small flare of interest. We found evidence of elemental abundances decreasing toward photospheric values around the flare peak time while remaining at coronal values before and after the peak time, consistent with results previously studied and reported from XSM (Mondal et al 2021;Mithun et al 2022;Nama et al 2023) and MinXSS (Woods et al 2017).…”

Section: Conclusion and Discussionsupporting

confidence: 92%

“…XSM also observed multiple flaring in ARs and these data have been used to study the time evolution of the plasma parameters during A-class, B-class, and C-class flares (Mondal et al 2021;Mithun et al 2022;Nama et al 2023). These studies show that during the impulsive phase, the temperature of the flaring plasma reaches a few MK, whereas elemental abundances show a sharp transition from coronal to close to photospheric values.…”

Section: Introductionmentioning

confidence: 95%

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Multiwavelength Observations of a B-class Flare Using XSM, AIA, and XRT

Rao,

Mondal,

Del Zanna

et al. 2023

ApJ

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We present multiwavelength observations by Chandrayaan-2/Solar X-ray Monitor, Solar Dynamics Observatory/Atmospheric Imaging Assembly, and Hinode/X-Ray Telescope (XRT) of a B-class flare observed on 2021 February 25, originating from an active region (AR 12804) near the northwest limb. The microflare lasts for ∼30 minutes and is composed of hot loops reaching temperatures of 10 MK. We report excellent agreement (within 20%) for the average effective temperatures obtained at the flare peak from all the three instruments, which have different temperature sensitivities. The XRT filter combination of Be-thin and Be-med provides an excellent opportunity to measure the high temperatures in such microflare events. The elemental abundances during the evolution of the microflare are also studied and observed to drop toward photospheric values at the flare peak time, compared to coronal values during the rise and decay phase. This is consistent with previous XSM studies.

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Section: Conclusion and Discussionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 95%

Multiwavelength Observations of a B-class Flare Using XSM, AIA, and XRT

Rao,

Mondal,

Del Zanna

et al. 2023

ApJ

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“…These ARs produced many small B/A-class flares, seen as multiple spikes in the XSM light curves. Detailed studies of these small flares were reported by Mondal et al (2021) and Nama et al (2023).…”

Section: Observations and Data Analysismentioning

confidence: 99%

“…When ARs were present on-disk, XSM recorded hundreds of small flares of different classes. Elemental abundance variations during these small flares were found, for the first time, to initially drop toward photospheric values, then rapidly return to coronal values, as described by Mondal et al (2021), Mithun et al (2022), andNama et al (2023). In this paper, we analyze the temporal evolution of ARs outside of flaring activity, and for this, we have chosen to study three isolated ARs: AR 12749, AR 12758, and AR 12759.…”

Section: Observations and Data Analysismentioning

confidence: 99%

Evolution of Elemental Abundances in Hot Active Region Cores from Chandrayaan-2 XSM Observations

Mondal,

Vadawale,

Del Zanna

et al. 2023

ApJ

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The first ionization potential (FIP) bias, whereby elemental abundances for low-FIP elements in different coronal structures vary from their photospheric values and may also vary with time, has been widely studied. In order to study the temporal variation and understand the physical mechanisms giving rise to the FIP bias, we have investigated the hot cores of three active regions (ARs) using disk-integrated soft X-ray spectroscopic observations with the Solar X-ray Monitor on board Chandrayaan-2. Observations for periods when only one AR was present on the solar disk were used to ensure that the AR was the principal contributor to the total X-ray intensity. The average values of temperature and emission measure were ∼3 MK and 3 × 1046 cm−3, respectively. Regardless of the AR’s age or activity, the elemental abundances for the low-FIP elements Al, Mg, and Si with respect to the soft X-ray continuum were consistently higher than their photospheric values. The average FIP bias for Mg and Si was 2–2.5, whereas the FIP bias for the mid-FIP element, S, was almost unity. However, the FIP bias for the lowest-FIP element, Al, was observed to be a factor of 2 higher than Si, which, if real, suggests a dependence of the FIP bias of low-FIP elements on their FIP value. Another major result from our analysis is that the FIP bias of these elements is established within ∼10 hr of emergence of the AR and remains almost constant throughout its lifetime.

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“…We assume solar photospheric abundances (Asplund et al 2009) in both the radiative losses and forward model, which is consistent with observations of large solar flares (Warren 2014). Recent observations have additionally found that abundances of some elements (with low first ionization potential) vary with time during a flare, from coronal abundances toward photospheric in the impulsive phase, and then back toward coronal during the gradual phase (Mondal et al 2021;Nama et al 2023;Sylwester et al 2023). Additionally, abundances can vary spatially (Doschek & Warren 2016) and from flare to flare (Sylwester et al 1998).…”

Section: Modelmentioning

confidence: 99%

Understanding the Duration of Solar and Stellar Flares at Various Wavelengths

Reep,

Airapetian

2023

ApJ

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Recent irradiance measurements from numerous heliophysics and astrophysics missions including Solar Dynamics Observatory (SDO), GOES, Kepler, TESS, Chandra, the X-ray Multi-Mirror Mission, and NICER have provided critical input into understanding the physics of the most powerful transient events on the Sun and magnetically active stars:solar and stellar flares. The light curves of flare events from the Sun and stars show remarkably similar shapes, typically with a sharp rise and protracted decay phase. The duration of solar and stellar flares has been found to be correlated with the intensity of the event in some wavelengths, such as white light, but not in other wavelengths, such as soft X-rays, but it is not evident why this is the case. In this study, we use a radiative hydrodynamics code to examine factors affecting the duration of flare emission at various wavelengths. The duration of a light curve depends on the temperature of the plasma, the height in the atmosphere at which the emission forms, and the relative importance of cooling due to radiation, thermal conduction, and enthalpy flux. We find that there is a clear distinction between emission that forms low in the atmosphere and responds directly to heating, and emission that forms in the corona, indirectly responding to heating-induced chromospheric evaporation, a facet of the Neupert effect. We discuss the implications of our results for a wide range of flare energies.

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Coronal Elemental Abundances During A-Class Solar Flares Observed by Chandrayaan-2 XSM

Cited by 6 publications

References 57 publications

Multiwavelength Observations of a B-class Flare Using XSM, AIA, and XRT

Multiwavelength Observations of a B-class Flare Using XSM, AIA, and XRT

Evolution of Elemental Abundances in Hot Active Region Cores from Chandrayaan-2 XSM Observations

Understanding the Duration of Solar and Stellar Flares at Various Wavelengths

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