A5027573957- Solar and Space Plasma Dynamics
- Stellar, planetary, and galactic studies
- Ionosphere and magnetosphere dynamics
- Astro and Planetary Science
- Geomagnetism and Paleomagnetism Studies
- Solar Radiation and Photovoltaics
- Geophysics and Gravity Measurements
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Atmospheric Ozone and Climate
- Astronomical Observations and Instrumentation
- Astrophysical Phenomena and Observations
- Calibration and Measurement Techniques
- Adaptive optics and wavefront sensing
- Gamma-ray bursts and supernovae
- Planetary Science and Exploration
- History and Developments in Astronomy
- Earthquake Detection and Analysis
- Magnetic confinement fusion research
- Impact of Light on Environment and Health
- Optical Polarization and Ellipsometry
- South Asian Studies and Conflicts
- Pulsars and Gravitational Waves Research
- Nonlinear Dynamics and Pattern Formation
- Structural Analysis and Optimization
Indian Institute of Astrophysics
2015-2024
Aryabhatta Research Institute of Observational Sciences
2018-2024
Indian Institute of Science Education and Research Kolkata
2015-2024
Mitchell Institute
2024
Astronomical Observatory of Rome
2024
Max Planck Institute for Solar System Research
2010-2024
Southwest Research Institute
2021-2024
Texas A&M University
2024
Emami (India)
2015-2023
Creative Commons
2023
An extremely low operating electric field has been achieved on zinc oxide (ZnO) nanowire emitters grown carbon cloth. Thermal vaporization and condensation was used to grow the nanowires from a mixture source of ZnO graphite powders in tube furnace. emission current density 1mA∕cm2 obtained at an 0.7V∕μm. Such results high enhancement factor 4.11×104 due combined effect intrinsic aspect ratio woven geometry
Spicules are rapidly evolving fine-scale jets of magnetized plasma in the solar chromosphere. It remains unclear how these prevalent originate from surface and what role they play heating atmosphere. Using Goode Solar Telescope at Big Bear Observatory, we observed spicules emerging within minutes appearance opposite-polarity magnetic flux around dominant-polarity field concentrations. Data Dynamics Observatory showed subsequent adjacent corona. The dynamic interaction fields (likely due to...
Aiming to assess the progress and current challenges on formidable problem of prediction solar energetic events since COSPAR/ International Living With a Star (ILWS) Roadmap paper Schrijver et al. (2015), we attempt an overview status global research efforts. By refer flares, coronal mass ejections (CMEs), particle (SEP) events. The emphasis, therefore, is methods flares eruptions, as well their associated SEP manifestations. This work complements COSPAR Space Weather Action Teams (ISWAT)...
Large-quantity (grams) one-dimensional ZnO nanowires of different sizes have been synthesized by a simple thermal evaporation powder in tube furnace at temperature controlled to 1000–1200 °C and pressure 1–2 Torr air. A mixture graphite was used as the source. Fine flakes were promote growth. The are key for large-quantity yield easily removed oxidation flowing O2 about 700 1–3 h. scanning- transmission-electron-microscopic studies show that diameter length vary from 20 100 nm 0.5 10 μm,...
We explore the application of terahertz spectroscopic techniques for remote determination water content paper. The aim is development a rapid diagnostic imaging tool applicable in paper fabrication processes. THz radiation offers high sensitivity water, good spatial resolution, and insensitivity to scattering at surface. advent cameras makes fast large-area image detectors feasible. In this paper, we show case 0.6-THz fixed-frequency system, that can be determined with accuracy. demonstrate...
Long and consistent sunspot area records are important for understanding the long-term solar activity variability. Multiple observatories around globe have regularly recorded areas, but such individual only cover restricted periods of time. Furthermore, there also systematic differences between them, so that these need to be cross-calibrated before they can reliably used further studies. We produce a homogeneous record total daily both projected corrected, covering period 1874 2019. A...
Abstract Chromospheric differential rotation is a key component in comprehending the atmospheric coupling between chromosphere and photosphere at different phases of solar cycle. In this study, we therefore utilize newly calibrated multidecadal Ca ii K spectroheliograms (1907–2007) from Kodaikanal Solar Observatory (KoSO) to investigate using technique image cross-correlation. Our analysis yields chromospheric rate Ω( θ ) = (14.61 ± 0.04–2.18 0.37 <?CDATA ${\sin }^{2}\theta -1.10\pm...
Decayless kink oscillations are omnipresent in the solar atmosphere, and they a viable candidate for coronal heating. Although there have been extensive studies of decayless loops with lengths few hundred megameters, properties these small-scale (∼10 mm) yet to be explored. In this study, we present small embedded quiet corona holes. We use high-resolution observations from Extreme Ultraviolet Imager on board Solar Orbiter pixel scales 210 km cadence 5 s or better. analysed 42 loop varying...
ZnO nanowires were grown in gram quantities on graphite flakes (as collector) using the vapour transport and condensation approach. The yield, defined as weight ratio of to original flakes, has been studied thoroughly by tuning various growth parameters such pressure temperature inside tube furnace, amount powder source, source collector ratio, etc. A yield high 200% achieved, equivalent a 40% conversion source. study comparing photoluminescence spectra both substrates with commercially...
<i>Context. <i/>We diagnose the properties of plume and interplume regions in a polar coronal hole role waves acceleration solar wind.<i>Aims. attempt to detect whether Alfvén are present holes through variations EUV line widths.<i>Methods. <i/>Using spectral observations performed over region with EIS spectrometer on Hinode, we study variation width electron density as function height. We use sensitive pairs Fe xii 186.88 Å 195.119 xiii 203.82 202.04 Å.<i>Results. <i/>For region, data show...
One peculiar feature of the solar cycle which is yet to be understood properly frequent occurrence double peaks (also known as Gnevyshev peaks). Not only but also multiple and spikes are often observed in any phase cycle. We propose that these generated due fluctuations Babcock-Leighton process (the poloidal field generation from tilted bipolar magnetic regions). When polar develops, large negative can reduce net abruptly. As propagated new toroidal field, promote next occur outside maximum,...
Long-term sunspot observations are key to understand and predict the solar activities its effects on space weather.Consistent which crucial for long-term variations studies,are generally not available due upgradation/modifications of observatories over course time. We present data a period 90 years acquired from persistent observation at Kodaikanal observatory in India. use an advanced semi-automated algorithm detect sunspots form each calibrated white-light image. Area, longitude latitude...
We derive the plage area evolution over last 12 solar cycles employing data from all Ca II K archives available publicly in digital form known to us, including several as yet unexplored archives. analyse more than 290,000 full-disc observations 43 datasets spanning period 1892-2019. All images were consistently processed with an automatic procedure that performs photometric calibration (if needed) and limb-darkening compensation. The processing also accounts for artefacts plaguing many of...
The global rotational profile of the solar atmosphere and its variation at different layers, although crucial for a comprehensive understanding dynamics magnetic field, has been subject to contradictory results throughout past century. In this study, we thereby unify parts multi-thermal Solar by utilizing 13 years data in 7 wavelength channels Atmospheric Imaging Assembly (AIA) atop Dynamic Observatory (SDO). Using method image correlation, find that exhibits is up 4.18% 1.92% faster equator...
Abstract Decayless kink oscillations, characterized by their lack of decay in amplitude, have been detected coronal loops varying scales active regions, the quiet Sun, and holes. Short-period (<50 s) decayless oscillations short (< 50 Mm) within regions. Nevertheless, long-period these remain relatively unexplored crucial for understanding wave modes excitation mechanisms oscillations. We present statistical analysis from two regions observed Extreme Ultraviolet Imager onboard Solar...
The Sun's polar magnetic field is pivotal in understanding solar dynamo processes and forecasting future cycles. However, direct measurements of the only available since 1970s. chromospheric Ca II K network index (PNI; fractional area regions above a certain latitude) has recently emerged as reliable proxy for fields. In this study, we derive PNI estimates from newly calibrated, rotation-corrected observations Kodaikanal Solar Observatory (1904-2007) modern data Rome Precision Photometric...
The polar magnetic field plays a crucial role in the solar dynamo model and contributes to predicting future cycles. However, continuous direct measurements of this have been available only since 1976, with data provided by Wilcox Solar Observatory (WSO). Recent findings suggest that Ca ii K Polar Network Index (PNI) can serve as promising proxy for estimating Sun. In study, we aim reconstruct pre-1976 period leveraging from Kodaikanal (KoSO; 1904-2007) modern observations Rome Precision...
Abstract Solar flares are regularly observed in extreme-ultraviolet soft X-rays (SXRs) and hard (HXRs). However, those near- mid-ultraviolet sparse. The Ultraviolet Imaging Telescope (SUIT) on board the Aditya-L1, launched 2023 September 2, provides regular observations 200–400 nm wavelength range through 11 filters. Here, we report observation of X6.3 flare 2024 February 22 using eight narrowband (NB) filters SUIT. We have also used co-spatiotemporal from Dynamics Observatory/Atmospheric...
Abstract The Sun’s polar magnetic field is pivotal in understanding solar dynamo processes and forecasting future cycles. However, direct measurements of the have only been available since 1970s. chromospheric Ca ii K network index (PNI; fractional area regions above a certain latitude) has recently emerged as reliable proxy for fields. In this study, we derive PNI estimates from newly calibrated, rotation-corrected observations Kodaikanal Solar Observatory (1904–2007) modern data Rome...