Solar X-ray Monitor Onboard Chandrayaan-2 Orbiter

Shanmugam, M.; Vadawale, S.; Patel, Alkesh B.; Adalaja, Hitesh Kumar; Mithun, N. P. S.; Ladiya, Tinkal; Goyal, Subhash; Tiwari, Neeraj K.; Singh, Nishant K.; Kumar, Sushil; Painkra, Deepak Kumar; Acharya, Y. B.; Bhardwaj, Anil; Hait, A. K.; Patinge, A.; Kapoor, Abinandhan; Kumar, Hrishikesh; Satya, Neeraj; Saxena, Gaurav; Arvind, Kalpana

doi:10.18520/cs/v118/i1/45-52

Cited by 26 publications

(19 citation statements)

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“…Chandrayaan-2 XSM measures the disk integrated solar X-ray spectra in the energy range of 1 -15 keV (Vadawale et al 2014;Shanmugam et al 2020). Its primary objective is to provide measurement of incident solar X-ray spectra on the Moon for estimation of elemental abundance on the lunar surface with remote fluorescence spectroscopy.…”

Section: Observations and Data Analysismentioning

confidence: 99%

“…Here we present the first such study of quiet corona using Chandrayaan-2/Solar X-ray Monitor (XSM) (Vadawale et al 2014;Shanmugam et al 2020) which observes the Sun as a star in the soft X-ray band. These observations carried out during the 2019/20 solar minimum, believed to be the deepest minimum in the past hundred years (Janardhan et al 2011(Janardhan et al , 2015, provided a unique opportunity for long duration solar X-ray observations in the absence of solar active regions, thereby enabling one to infer the temperature, emission measure and elemental abundances in the quiescent solar corona.…”

Section: Introductionmentioning

confidence: 99%

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Observations of the Quiet Sun During the Deepest Solar Minimum of the Past Century with Chandrayaan-2 XSM -- Elemental Abundances in the Quiescent Corona

Vadawale,

Mondal,

Mithun

et al. 2021

Preprint

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Elements with low First Ionization Potential (FIP) are known to be three to four times more abundant in active region loops of the solar corona than in the photosphere. There have been observations suggesting that this observed "FIP bias" may be different in other parts of the solar corona and such observations are thus important in understanding the underlying mechanism. The Solar X-ray Monitor (XSM) on board the Chandrayaan-2 mission carried out spectroscopic observations of the Sun in soft X-rays during the 2019-20 solar minimum, considered to be the quietest solar minimum of the past century. These observations provided a unique opportunity to study soft X-ray spectra of the quiescent solar corona in the absence of any active regions. By modelling high resolution broadband X-ray spectra from XSM, we estimate the temperature and emission measure during periods of possibly the lowest solar X-ray intensity. We find that the derived parameters remain nearly constant over time with a temperature around 2 MK, suggesting the emission is dominated by X-ray Bright Points (XBPs). We also obtain the abundances of Mg, Al, and Si relative to H, and find that the FIP bias is ∼2, lower than the values observed in active regions.

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Section: Observations and Data Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Observations of the Quiet Sun During the Deepest Solar Minimum of the Past Century with Chandrayaan-2 XSM -- Elemental Abundances in the Quiescent Corona

Vadawale,

Mondal,

Mithun

et al. 2021

Preprint

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“…The Solar X-ray Monitor (XSM) (Vadawale et al 2014;Shanmugam et al 2020) onboard the Chandrayaan-2 provides soft X-ray disk-integrated solar spectra, with a good energy resolution (180 eV @ 5.9 keV) and high cadence (1 sec). Its high sensitivity and capability of measuring elemental abundances on an absolute scale (i.e., with respect to H) enable us to perform a comprehensive study of smaller flares.…”

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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“…The Solar X-ray Monitor (XSM) (Vadawale et al 2014;Shanmugam et al 2020) on board the Chandrayaan-2 mission observed a large number of microflares in the quiet Sun. XSM provides disk integrated X-ray spectral measurements of the Sun with sensitivities down to sub-A class X-ray activity (Mithun et al 2020).…”

Section: Introductionmentioning

confidence: 99%

Observations of the Quiet Sun During the Deepest Solar Minimum of the Past Century with Chandrayaan-2 XSM -- Sub-A Class Microflares Outside Active Regions

Vadawale,

Mithun,

Mondal

et al. 2021

Preprint

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Solar flares, with energies ranging over several orders of magnitude, result from impulsive release of energy due to magnetic reconnection in the corona. Barring a handful, almost all microflares observed in X-rays are associated with the solar active regions. Here we present, for the first time, a comprehensive analysis of a large sample of quiet Sun microflares observed in soft X-rays by the Solar X-ray Monitor (XSM) on board the Chandrayaan-2 mission during the 2019-20 solar minimum. A total of 98 microflares having peak flux below GOES A-level were observed by the XSM during observations spanning 76 days. By using the derived plasma temperature and emission measure of these events obtained by fitting the XSM spectra along with volume estimates from concurrent imaging observations in EUV with the Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO-AIA), we estimated their thermal energies to be ranging from 3 × 10 26 to 6 × 10 27 erg. We present the frequency distribution of the quiet Sun microflares with energy and discuss the implications of these observations of small scale magnetic reconnection events outside active regions on coronal heating.

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Solar X-ray Monitor Onboard Chandrayaan-2 Orbiter

Cited by 26 publications

References 0 publications

Observations of the Quiet Sun During the Deepest Solar Minimum of the Past Century with Chandrayaan-2 XSM -- Elemental Abundances in the Quiescent Corona

Observations of the Quiet Sun During the Deepest Solar Minimum of the Past Century with Chandrayaan-2 XSM -- Elemental Abundances in the Quiescent Corona

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

Observations of the Quiet Sun During the Deepest Solar Minimum of the Past Century with Chandrayaan-2 XSM -- Sub-A Class Microflares Outside Active Regions

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