Biswajit Mondal

National Aeronautics and Space Administration

Nanoflares are thought to be one of the prime candidates that can heat the solar corona to its multimillion kelvin temperature. Individual nanoflares are difficult to detect with the present generation of instruments, but their presence can be inferred by comparing simulated nanoflare-heated plasma emissions with the observed emission. Using HYDRAD...

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 loo...

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 h...

We present multi-wavelength observations by Chandrayaan-2/XSM, SDO/AIA and Hinode/XRT of a B-class flare observed on 25th February, 2021, originating from an active region (AR 12804) near the North-West limb. The microflare lasts for approx 30 mins and is composed of hot loops reaching temperatures of 10 MK. We report excellent agreement (within 20...

The abundances of low first ionization potential (FIP) elements are three to four times higher in the closed loop active corona than in the photosphere, known as the FIP effect. Observations suggest that the abundances vary in different coronal structures. Here, we use the soft X-ray spectroscopic measurements from the Solar X-ray Monitor (XSM) onb...

Small-scale impulsive events, known as nanoflares, are thought to be one of the prime candidates that can keep the solar corona hot at its multimillion-Kelvin temperature. Individual nanoflares are difficult to detect with the current generation of instruments; however, their presence can be inferred through indirect techniques such as Differential...

The specific physical mechanism underpinning the coronal heating mechanism, which causes the solar corona to be significantly hotter than the solar photosphere, remains a mystery. According to our current understanding of the problem, it is believed that the corona is heated by the continual deposition of small-scale energy, so called nanoflares. I...

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 to understand the physical mechanisms giving rise to the FIP bias, we have investigated t...

Small-scale impulsive events, known as nanoflares, are thought to be one of the prime candidates that can keep the solar corona hot at its multi-million Kelvin temperature. Individual nanoflares are difficult to detect with the current generation instruments; however, their presence can be inferred through indirect techniques such as a Differential...

Spectroscopic observations in X-ray wavelengths provide excellent diagnostics of the temperature distribution in solar flare plasma. The Solar X-ray Monitor (XSM) on board the Chandrayaan-2 mission provides broadband disk-integrated soft X-ray solar spectral measurements in the energy range of 1–15 keV with high spectral resolution and time cadence...

Spectroscopic observations in X-ray wavelengths provide excellent diagnostics of the temperature distribution in solar flare plasma. The Solar X-ray Monitor (XSM) onboard the Chandrayaan-2 mission provides broad-band disk integrated soft X-ray solar spectral measurements in the energy range of 1-15 keV with high spectral resolution and time cadence...

The abundances of low First Ionisation Potential (FIP) elements are three to four times higher (FIP bias) in the closed loop active corona than in the photosphere, known as the FIP effect. Observations suggest that the abundances vary in different coronal structures. Here, we use the soft X-ray spectroscopic measurements from the Solar X-ray Monito...

We have reviewed the first year of observations of the Solar X-ray Monitor (XSM) on board Chandrayaan-2 and the available multiwavelength observations to complement the XSM data, focusing on the Solar Dynamics Observatory AIA and Hinode XRT and EIS observations. XSM has provided disk-integrated solar spectra in the 1–15 keV energy range, observing...

We have reviewed the first year of observations of the Solar X-ray Monitor (XSM) onboard Chandrayaan-2, and the available multi-wavelength observations to complement the XSM data, focusing on Solar Dynamics Observatory AIA and Hinode XRT, EIS observations. XSM has provided disk-integrated solar spectra in the 1--15 keV energy range, observing a lar...

We have derived a simple empirical relation between GOES XRS 16 flux and flare temperature using Chandrayaan-2 XSM. This enables us to get an estimate of the flare temperature for A- and sub-A class flares from GOES 16 long flux channel.

The Solar X-ray Monitor (XSM) payload on board 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 s. During the period from 2019 September to 2020 May, covering the minimum of Solar Cycle 24, it observed nine B-class flares ranging from B1.3 to B4.5....

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...

Elements with low first ionization potential (FIP) are known to be 3–4 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 underly...

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-...

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 t...

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...

Chandrayaan-2, the second Indian mission to the Moon, carries a spectrometer called the Solar X-ray Monitor (XSM) to perform soft X-ray spectral measurements of the Sun while a companion payload, CLASS, measures the fluorescence emission from the Moon. Together these two payloads will provide quantitative estimates of elemental abundances on the lu...

Multilayer X-ray mirrors consist of a coating of a large number of alternate layers of high Z and low Z materials with a typical thickness of 10 – 100 Å , on a suitable substrate. Such coatings play an important role in enhancing the reflectivity of X-ray mirrors by allowing reflections at angles much larger than the critical angle of X-ray reflect...

Multilayer X-ray mirrors consist of a coating of a large number of alternate layers of high Z and low Z materials with a typical thickness of 10-100 Angstrom, on a suitable substrate. Such coatings play an important role in enhancing the reflectivity of X-ray mirrors by allowing reflections at angles much larger than the critical angle of X-ray ref...

The Solar X-ray Monitor (abbreviated as XSM) on board India’s Chandrayaan-2 mission is designed to carry out broadband spectroscopy of the Sun from lunar orbit. It observes the Sun as a star and measures the spectrum every second in the soft X-ray band of 1 – 15 keV with an energy resolution better than 180 eV at 5.9 keV. The primary objective of t...

The Solar X-ray Monitor (abbreviated as XSM) on board India's Chandrayaan-2 mission is designed to carry out broadband spectroscopy of the Sun from lunar orbit. It observes the Sun as a star and measures the spectrum every second in the soft X-ray band of 1 - 15 keV with an energy resolution better than 180 eV at 5.9 keV. The primary objective of t...

Chandrayaan-2, the second Indian mission to the Moon, carries a spectrometer called the Solar X-ray Monitor (XSM) to perform soft X-ray spectral measurements of the Sun while a companion payload measures the fluorescence emission from the Moon. Together these two payloads will provide quantitative estimates of elemental abundances on the lunar surf...