Plasma flows in the cool loop systems

We study the dynamics of low-lying cool loop systems for three datasets as observed by the Interface Region Imaging Spectrograph (IRIS). Radiances, Doppler shifts and line widths are investigated in and around observed cool loop systems using various spectral lines formed between the photosphere and transition region (TR). Footpoints of the loop threads are either dominated by blueshifts or redshifts. The co-spatial variation of velocity above the blue-shifted footpoints of various loop threads shows a transition from very small upflow velocities ranging from (-1 to +1) km/s in the Mg\,{\sc ii} k line (2796.20~\AA; formation temperature: log (T/K) = 4.0) to the high upflow velocities from (-10 to -20) km/s in Si\,{\sc iv}. Thus, the transition of the plasma flows from red-shift (downflows) to the blue-shift (upflows) is observed above the footpoints of these loop systems in the spectral line C\,{\sc ii} (1334.53~\AA; \log (T/K) = 4.3) lying between Mg\,{\sc ii} k and Si\,{\sc iv} (1402.77~\AA; log (T / K) = 4.8). This flow inversion is consistently observed in all three sets of the observational data. The other footpoint of loop system always remains red-shifted indicating downflowing plasma. The multi-spectral line analysis in the present paper provides a detailed scenario of the plasma flows inversions in cool loop systems leading to the mass transport and their formation. The impulsive energy release due to small-scale reconnection above loop footpoint seems to be the most likely cause for sudden initiation of the plasma flows evident at TR temperatures.Comment: 29 Pages, 14 figures, The Astrophysical Journal (in press

Carbon Nanotubes: Detection of Chemical and Biological Warfare Agents

Discovery of carbon nanotubes has great impact on the development of newer methodologies and devicesuseful for the analysis of various types of chemicals. The functionalisation of CNTs with biomolecules relatedto chemical and biological warfare agents makes these useful for the detection of these agents. The detectionsensitivity can be increased manyfold. Various types of chemical and biological sensors were developed usingvarious type of carbon nanotubes as well as nano particles of different metals.Defence Science Journal, 2008, 58(5), pp.617-625, DOI:http://dx.doi.org/10.14429/dsj.58.168

Velocity Response of the Observed Explosive Events in the Lower Solar Atmosphere: I. Formation of the Flowing Cool Loop System

We observe plasma flows in cool loops using the Slit-Jaw Imager (SJI) onboard the Interface Region Imaging Spectrometer (IRIS). Huang et al. (2015) observed unusually broadened Si IV 1403 angstrom line profiles at the footpoints of such loops that were attributed to signatures of explosive events (EEs). We have chosen one such uni-directional flowing cool loop system observed by IRIS where one of the footpoints is associated with significantly broadened Si IV line profiles. The line profile broadening indirectly indicates the occurrence of numerous EEs below the transition region (TR), while it directly infers a large velocity enhancement /perturbation further causing the plasma flows in the observed loop system. The observed features are implemented in a model atmosphere in which a low-lying bi-polar magnetic field system is perturbed in the chromosphere by a velocity pulse with a maximum amplitude of 200 km/s. The data-driven 2-D numerical simulation shows that the plasma motions evolve in a similar manner as observed by IRIS in the form of flowing plasma filling the skeleton of a cool loop system. We compare the spatio-temporal evolution of the cool loop system in the framework of our model with the observations, and conclude that their formation is mostly associated with the velocity response of the transient energy release above their footpoints in the chromosphere/TR. Our observations and modeling results suggest that the velocity responses most likely associated to the EEs could be one of the main candidates for the dynamics and energetics of the flowing cool loop systems in the lower solar atmosphere.Comment: In Press; The Astrophysical Journal; 14 Pages; 9 Figure

Multi-wavelength observations of a B-class flare using XSM, AIA, and XRT

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 percent) 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 towards photospheric values at the flare peak time, compared to coronal values during the rise and decay phase. This is consistent with previous XSM studies.Comment: 18, pages, 18 figures, ApJ, Accepte

The Extended Solar Cycle: Muddying the Waters of Solar/Stellar Dynamo Modeling or Providing Crucial Observational Constraints?

In 1844 Schwabe discovered that the number of sunspots increased and decreased over a period of about 11 years, that variation became known as the sunspot cycle. Almost eighty years later, Hale described the nature of the Sun's magnetic field, identifying that it takes about 22 years for the Sun's magnetic polarity to cycle. It was also identified that the latitudinal distribution of sunspots resembles the wings of a butterfly—showing migration of sunspots in each hemisphere that abruptly start at mid-latitudes (about ±35o) toward the Sun's equator over the next 11 years. These sunspot patterns were shown to be asymmetric across the equator. In intervening years, it was deduced that the Sun (and sun-like stars) possess magnetic activity cycles that are assumed to be the physical manifestation of a dynamo process that results from complex circulatory transport processes in the star's interior. Understanding the Sun's magnetism, its origin and its variation, has become a fundamental scientific objective—the distribution of magnetism, and its interaction with convective processes, drives various plasma processes in the outer atmosphere that generate particulate, radiative, eruptive phenomena, and shape the heliosphere. In the past few decades, a range of diagnostic techniques have been employed to systematically study finer scale magnetized objects, and associated phenomena. The patterns discerned became known as the “Extended Solar Cycle” (ESC). The patterns of the ESC appeared to extend the wings of the activity butterfly back in time, nearly a decade before the formation of the sunspot pattern, and to much higher solar latitudes. In this short review, we describe their observational patterns of the ESC and discuss possible connections to the solar dynamo as we depart on a multi-national collaboration to investigate the origins of solar magnetism through a blend of archived and contemporary data analysis with the goal of improving solar dynamo understanding and modeling

Long Term and Seasonal Rainfall Trend in Bapatla District of Andhra Pradesh Using Advanced Statistical Methods

The primary objective of this study is to analyse the annual and seasonal rainfall trends in the Bapatla district of Andhra Pradesh over the long term. The seasonal rainfall data for Bapatla district was collected from the NASA Power website and covering the period from January 1982 to December 2021. To gain insights into the patterns present in the rainfall data for Bapatla district, a combination of parametric methods, including linear regression, and non-parametric tests such as the Mann-Kendall test, Sen’s slope test, Modified-Mann Kendall test, Innovative trend analysis were employed in this approach. The randomness of the rainfall data under investigation was assessed using the Wallis and Moore test. To detect the single change point of the rainfall pattern Pettitt test was employed. The results of linear regression trend method exhibited both increasing and declining trends in rainfall pattern. Notably, the months of April, May and June months exhibited a statistically significant increasing trend other months exhibited no significant trend in Mann-Kendall test, modified Mann-Kendall test, Sen’s slope tests. The monsoon season exhibited a statistically significant trend and pre-monsoon, post-monsoon periods and anuual rainfall exhibited non-significant trends in Mann-Kendall and Sen’s slope tests.  Moreover, the pre monsoon and monsoon seasons exhibited significant trend in rainfall pattern of Bapatla district by modified Mann-Kendal test. This study serves to raise awareness among agricultural stakeholders, particularly farmers, regarding the fluctuations in monthly and seasonal rainfall patterns and enables them to more effectively allocate resources and prepare for anticipated water shortages during non-monsoon months