We probe the spectral hardening of solar flares emission in view of associated solar proton events (SEPs) at earth and coronal mass ejection (CME) acceleration as a consequence. In this investigation we undertake 60 SEPs of the Solar Cycle 23 alongwith associated Solar Flares and CMEs. We employ the X-ray emission in Solar flares observed by Reuven Ramaty Higly Energy Solar Spectroscopic Imager (RHESSI) in order to estimate flare plasma parameters. Further, we employ the observations from Geo-stationary Operational Environmental Satellites (GOES) and Large Angle and Spectrometric Coronagraph (LASCO), for SEPs and CMEs parameter estimation respectively. We report a good association of soft-hard-harder (SHH) spectral behavior of Flares with occurrence of Solar Proton Events for 16 Events (observed by RHESSI associated with protons). In addition, we have found a good correlation (R=0.71) in SEPs spectral hardening and CME velocity. We conclude that the Protons as well as CMEs gets accelerated at the Flare site and travel all the way in interplanetary space and then by re-acceleration in interplanetary space CMEs produce Geomagnetic Storms in geospace. This seems to be a statistically significant mechanism of the SEPs and initial CME acceleration in addition to the standard scenario of SEP acceleration at the shock front of CMEs.
The Heliospheric Imagers (HI) on board the two spacecraft of the Solar Terrestrial Relations Observatory (STEREO) provided white-light images of transients in the solar wind from dual perspectives from 2007 to 2014. In this paper, we develop a new method to identify and locate the transients automatically from simultaneous images from the two inner telescopes, known as HI-1, based on a correlation analysis. Correlation coefficient (cc) maps along the Sun-Earth line are constructed for the period from 1 Jan 2010 to 28 Feb 2011. From the maps, transients propagating along the Sun-Earth line are …
To make progress on the open questions on CME/CIR propagation, their interactions and the role and nature of the ambient solar wind, we need spatially resolved coverage of the inner heliosphere -- both in-situ and (critically) imaging -- at temporal scales matching the evolutionary timescales of these phenomena (tens of minutes to hours), and from multiple vantage points. The polar vantage is uniquely beneficial because of the wide coverage and unique perspective it provides. The ultimate goal is to achieve full $4π$ coverage of the solar surface and atmosphere by 2050.
The solar wind transients propagating out in the inner heliosphere can be observed in white-light images from Heliospheric Imager-1 (HI1), an instrument of the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) on board the Solar Terrestrial Relations Observatory (STEREO), from two perspectives. The spatial velocity distribution inside solar wind transients is key to understanding their dynamic evolution processes. We generated a velocity map of transients in 3D space based on 2D white-light images and used it to estimate the expansion rate as well as some kinematic propertie…
Small scale transients occur in the Solar corona at much higher frequencies than flares and play a significant role in coronal dynamics. Here we study three well-identified transients discovered by Hi-C and also detected by the EUV channels of Atmospheric Imaging Assembly (AIA) on board Solar Dynamics Observatory (SDO). We use 0-D enthalpy-based hydrodynamical simulations and produce synthetic light curves to compare with AIA observations. We have modeled these transients as loops of ~ 1.0~Mm length depositing energies ~ 10^23 ergs in ~ 50 seconds. The simulated synthetic light curves show rea…
Solar dynamics and turbulence occur at all heights of the solar atmosphere and could be described as stochastic processes. We propose that finite lifetime transients recurring at a certain place could trigger quasi-periodic processes in the associated structures. In this study, we developed a mathematical model for finite lifetime and randomly occurring transients, and found that quasi-periodic processes, with period longer than the time scale of the transients, are detectable intrinsically in form of trains. We simulate their propagation in an empirical solar atmospheric model with chromosphe…
Transient Structures and Stream Interaction Regions in the Solar Wind: Results from EISCAT Interplanetary Scintillation, STEREO HI and Venus Express ASPERA-4 Measurements
我们讨论的检测和演变的一系列复杂的瞬态和准静态太阳风结构的天后，著名的彗星2 P/恩克尾部断开事件在2007年4月。利用< 105 km to >欧洲非相干SCA Tter（EISCA T）雷达系统进行的行星际闪烁（IPS）1分钟时间分辨率观测，对106公里大小的瞬态太阳风结构的演变进行了表征。同时，这些特征的全球结构和演变由日地关系天文台航天器上的日光层成像仪表征，将IPS观测置于背景中。特别令人感兴趣的是观察到一个瞬态在缓慢的风显然是被席卷和夹带的流相互作用区（SIR）。后来，金星快车（VEX）航天器上的空间等离子体和高能原子分析仪（ASPERA-4）在金星现场探测到了SIR。在一系列不同的时间分辨率上提供如此多样化的数据源，使我们能够对这些复杂的事件进行全面的了解，如果单独使用这些仪器，这是不可能的。我们认为，这里讨论的太阳风瞬变的范围可能是行星际对应的瞬态结构以前报道的日冕观测，并可能对应于瞬态磁结构在行星际空间的原位测量报告。这里报道的结果也提供了第一个指示的日心距离瞬变成为夹带。
As one of the most violent eruptions on the Sun, flares are believed to be powered by magnetic reconnection. The fundamental physics involving the release, transfer and deposition of energy have been studied extensively. Taking advantage of the unprecedented resolution provided by the 1.6-m Goode Solar Telescope, here we show a sudden rotation of vector magnetic fields, about 12$^{\circ}$-20$^{\circ}$ counterclockwise, associated with a flare. Unlike the permanent changes reported previously, the azimuth-angle change is transient and co-spatial/temporal with H$α$ emission. The measured azimuth…
Densely packed coronal loops are rooted in plages in the vicinity of active regions on the Sun. The photospheric magnetic features underlying these plages are patches of mostly unidirectional magnetic field extending several arcsec on the solar surface. We aim to explore the transient nature of the magnetic field, its mixed-polarity characteristics, and the associated energetics in plages using high resolution observations and simulations. We used photospheric Fe I 6173 Å spectropolarimetric observations of a decaying active region obtained from the SST. These data were inverted to retrieve th…
Context. Recent observations by the Extreme Ultraviolet Imager (EUI) on board Solar Orbiter have characterized prevalent small-scale transient brightenings in the corona above the quiet Sun termed campfires. Aims. In this study we search for comparable brightenings in a numerical model and then investigate their relation to the magnetic field and the processes that drive these events. Methods. We use the MURaM code to solve the 3D radiation MHD equations in a box that stretches from the upper convection zone to the corona. The model self-consistently produces a supergranular network of the mag…
We report low frequency observations of the quasi-periodic, circularly polarized, harmonic type III radio bursts whose associated sunspot active regions were located close to the solar limb. The measured periodicity of the bursts at 80 MHz was $\approx$ 5.2 s and their average degree of circular polarization ($dcp$) was $\approx 0.12$. We calculated the associated magnetic field $B$ : (1) using the empirical relationship between the $dcp$ and $B$ for the harmonic type III emission, and (2) from the observed quasi-periodicity of the bursts. Both the methods result in $B \approx$ 4.2 G at the lo…
Recent studies of interplanetary radio type II bursts and their source locations are reviewed. As these bursts are due to propagating shock waves, driven by coronal mass ejections, they can be followed to near-Earth distances and can be used to predict the arrival times of geo-effective disturbances. Radio type IV bursts, on the other hand, are usually due to moving magnetic structures in the low corona and trapped particles form at least part of the emission. The observed directivity of type IV emission may also be used for space weather purposes.
Observations of the fluctuations in Interplanetary Magnetic Field around L1 point during the solar transient events of 2024 with MAG payload onboard Aditya-L1 spacecraft
Solar cycle is modeled as a forced and damped harmonic oscillator and the amplitudes, frequencies, phases and decay factors of such a harmonic oscillator are estimated by non-linear fitting the equation of sinusoidal and transient parts to the sunspot and irradiance (proxy for the sunspot) data for the years 1700-2008. We find that:(i) amplitude and frequency (or period of $\sim$11 yr) of the sinusoidal part remain constant for all the solar cycles; (ii) the amplitude of the transient part is phase locked with the phase of the sinusoidal part; (iii) for all the cycles, the period and decay fac…
Recent analysis of high-cadence white-light images taken by the Solar-Terrestrial RElations Observatory (STEREO) near solar maximum has revealed that outflowing density structures are released in an ubiquitous manner in the solar wind. The present study investigates whether these density fluctuations could originate from the transient heating of the low corona observed during Coronal Bright Points (CBPs). We assume that part of the intense heating measured during CBPs occurs at the coronal base of open magnetic fields that channel the forming solar wind. We employ the solar wind model MULTI-VP…
Low frequency dynamic spectra of radio bursts from nearby stars offer the best chance to directly detect the stellar signature of transient mass loss on low mass stars. Crosley et al. (2016) proposes a multi-wavelength methodology to determine coronal mass ejection parameters, such as Coronal Mass Ejection (CME) speed, mass, and kinetic energy. We test the validity and accuracy of the results derived from the methodology by using Geostationary Operational Environmental Satellite X-ray observations and Bruny Island Radio Spectrometer radio observations. These are analogous observations to those…
The cold-dense plasma is occasionally detected in the solar wind with in situ data, but the source of the cold-dense plasma remains illusive. Interchange reconnections (IRs) between closed fields and nearby open fields are well known to contribute to the formation of solar winds. We present a confined filament eruption associated with a puff-like coronal mass ejection (CME) on 2014 December 24. The filament underwent successive activations and finally erupted, due to continuous magnetic flux cancellations and emergences. The confined erupting filament showed a clear untwist motion, and most of…
We suggest that in the rare case of an Intermediate-Luminosity Optical Transient (ILOTs) event, evaporation of extra-solar Kuiper belt objects (ExtraKBOs) at distances of d ~ 500 - 10000AU from the ILOT can be detected. If the ILOT lasts for 1 month to a few years, enough dust might be ejected from the ExtraKBOs for the IR emission to be detected. Because of the large distance of the ExtraKBOs, tens of years will pass before the ILOT wind disperses the dust. We suggest that after an ILOT outburst there is a period of months to several years during which IR excess emission might hint at the exi…
Investigating the propagation of small-scale flare energy in the lower and upper atmosphere of solar active region
Physical Research Laboratory（物理研究实验室）；Indian Institute of Technology Gandhinagar（甘地纳加尔印度理工学院）；University of Cambridge（剑桥大学）；University of Sheffield（谢菲尔德大学）；Eötvös Loránd University（罗兰大学）；Gyula Bay Zoltán Solar Observatory (GSO)（久拉·巴伊·佐尔坦太阳观测站）
This review article summarizes the advancement in the studies of Earth-affecting solar transients in the last decade that encompasses most of solar cycle 24. The Sun Earth is an integrated physical system in which the space environment of the Earth sustains continuous influence from mass, magnetic field and radiation energy output of the Sun in varying time scales from minutes to millennium. This article addresses short time scale events, from minutes to days that directly cause transient disturbances in the Earth space environment and generate intense adverse effects on advanced technological…
Solar Radio Bursts in the metric to kilometric range
Udaipur Solar Observatory, Physical Research Laboratory（乌代浦太阳观测站，物理研究实验室）；University of Turku（图尔库大学）；Turku Collegium for Science, Medicine and Technology, University of Turku（图尔库科学、医学与技术学院，图尔库大学）；Center for mathematical Plasma Astrophysics (CmPA), KU Leuven（数学等离子体天体物理学中心，荷语鲁汶大学）；Solar-Terrestrial Centre of Excellence (STCE), Royal Observatory of Belgium（日地卓越中心，比利时皇家天文台）；Center for Solar-Terrestrial Research, New Jersey Institute of Technology（日地研究中心，新泽西理工学院）；Cooperative Programs for the Advancement of Earth System Science, University Corporation for Atmospheric Research（地球系统科学促进合作项目，大气研究大学公司）；Indian Institute of Technology, Gandhinagar（印度理工学院，甘地纳加尔）；ASTRON, The Netherlands Institute for Radio Astronomy（荷兰射电天文研究所）；National Centre for Radio Astrophysics, Tata Institute of Fundamental Research（国家射电天体物理学中心，塔塔基础研究院）
In a recent study, we took advantage of a highly tilted coronal neutral sheet to show that density structures, extending radially over several solar radii (Rs), are released in the forming slow solar wind approximately 4-5 Rs above the solar surface (Sanchez-Diaz et al. 2017). We related the signatures of this formation process to intermittent magnetic reconnection occurring continuously above helmet streamers. We now exploit the heliospheric imagery from the Solar Terrestrial Relation Observatory (STEREO) to map the spatial and temporal distribution of the ejected structures. We demonstrate t…
The recent launches of Parker Solar Probe (PSP), Solar Orbiter (SO) and BepiColombo, along with several older spacecraft, have provided the opportunity to study the solar wind at multiple latitudes and distances from the Sun simultaneously. We take advantage of this unique spacecraft constellation, along with low solar activity across two solar rotations between May and July 2020, to investigate how the solar wind structure, including the Heliospheric Current Sheet (HCS), varies with latitude. We visualise the sector structure of the inner heliosphere by ballistically mapping the polarity and …
Reconstructing solar wind inhomogeneous structures from stereoscopic observations in white-light: Solar wind transients in 3D
CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Sciences, University of Science and Technology of China（中国科学院空间环境重点实验室，地球与行星科学学院，中国科学技术大学）；CAS Center for Excellence in Comparative Planetology, University of Science and Technology of China（中国科学院比较行星学卓越创新中心，中国科学技术大学）；Mengcheng National Geophysical Observatory, University of Science and Technology of China（蒙城国家地球物理观测台，中国科学技术大学）；SIGMA Weather Group, State Key Laboratory of Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences（SIGMA天气研究组，空间天气国家重点实验室，空间科学应用研究中心，中国科学院）；Solar Physics and Space Plasma Research Center, School of Mathematics and Statistics, University of Sheffield（太阳物理与空间等离子体研究中心，数学与统计学院，谢菲尔德大学）
On 2018 November 5, about 24 hours before the first close perihelion passage of Parker Solar Probe (PSP), a coronal mass ejection (CME) entered the field of view of the inner detector of the Wide-field Imager for Solar PRobe (WISPR) instrument onboard PSP, with the northward component of its trajectory carrying the leading edge of the CME off the top edge of the detector about four hours after its first appearance. We connect this event to a very small jet-like transient observed from 1 au by coronagraphs on both the SOlar and Heliospheric Observatory (SOHO) and the A component of the Solar TE…
The origin of the slow solar wind is still a topic of much debate. The continual emergence of small transient structures from helmet streamers is thought to constitute one of the main sources of the slow wind. Determining the height at which these transients are released is an important factor in determining the conditions under which the slow solar wind forms. To this end, we have carried out a multipoint analysis of small transient structures released from a north-south tilted helmet streamer into the slow solar wind over a broad range of position angles during Carrington Rotation 2137. Comb…
We investigate the relationship between different transients such as blinkers detected in images taken at 304~Å, extreme ultraviolet coronal bright points (ECBPs) at 193~Å, X-ray coronal bright points (XCBPs) at 94~Å on AIA, and magnetic features observed by HMI during ten years of solar cycle 24. An automatic identification method is applied to detect transients, and the YAFTA algorithm is used to extract the magnetic features. Using ten years of data, we detect in total 7,483,827 blinkers, 2,082,162 ECBPs, and 1,188,839 XCBPs, respectively, with their birthrate of about $1.1\times10^{-18}$ $…
We aim to investigate the temperature enhancements and formation heights of impulsive heating phenomena in solar active-regions such as Ellerman bombs (EBs), ultraviolet bursts (UVBs), and flaring active-region fibrils (FAFs) using interferometric observations in the millimeter (mm) continuum provided by the Atacama Large Millimeter/submillimeter Array (ALMA). We examined 3 mm signatures of heating events identified in Solar Dynamics Observatory (SDO) observations of an active region and compared the results with synthetic spectra from a 3D radiative magnetohydrodynamic simulation. We estimate…
Multi-Wavelength Diagnostics of Pre-Flare Evolution with Aditya-L1: From the Solar Chromosphere to the Corona
Manipal Academy of Higher Education（马尼帕尔高等教育学院）；Physical Research Laboratory（物理研究所）；U R Rao Satellite Centre（U R Rao卫星中心）；Centre for Excellence in Space Sciences India, Indian Institute of Science Education and Research Kolkata（印度空间科学卓越中心，加尔各答科学与研究教育研究所）；Inter-University Centre for Astronomy and Astrophysics（大学间天文与天体物理中心）；Sri Dharmasthala Manjunatheshwara College (Autonomous)（斯里达尔马斯塔拉曼朱纳特什瓦拉学院（自治））
Coronal jets represent important manifestations of ubiquitous solar transients, which may be the source of significant mass and energy input to the upper solar atmosphere and the solar wind. While the energy involved in a jet-like event is smaller than that of "nominal" solar flares and coronal mass ejections (CMEs), jets share many common properties with these phenomena, in particular, the explosive magnetically driven dynamics. Studies of jets could, therefore, provide critical insight for understanding the larger, more complex drivers of the solar activity. On the other side of the size-spe…
Understanding elemental abundance variations in the solar corona provides an insight into how matter and energy flow from the chromosphere into the heliosphere. Observed variations depend on the first ionization potential (FIP) of the main elements of the Sun's atmosphere. High-FIP elements (>10 eV) maintain photospheric abundances in the corona, whereas low-FIP elements have enhanced abundances. Conversely, inverse FIP (IFIP) refers to the enhancement of high-FIP or depletion of low-FIP elements. We use spatially resolved spectroscopic observations, specifically the Ar XIV/Ca XIV intensity ra…
Interplanetary space is characteristically structured mainly by high-speed solar wind streams emanating from coronal holes and transient disturbances such as coronal mass ejections (CMEs). While high-speed solar wind streams pose a continuous outflow, CMEs abruptly disrupt the rather steady structure causing large deviations from the quiet solar wind conditions. For the first time, we give a quantification of the duration of disturbed conditions (preconditioning) for interplanetary space caused by CMEs. To this aim, we investigate the plasma speed component of the solar wind and the impact of …
We report detection of quasi-periodic (1.5 day) dimming of HD 240779, the solar-mass primary in a 5" visual binary (also TIC 284730577), by the Transiting Exoplanet Survey Satellite. This dimming, as has been shown for other "dipper" stars, is likely due to occultation by circumstellar dust. The barycentric space motion, lithium abundance, rotation, and chromospheric emission of the stars in this system point to an age of ~125 Myr, and possible membership in the AB Doradus moving group. As such it occupies an important but poorly explored intermediate regime of stars with transient dimming bet…
The solar atmosphere is full of complicated transients manifesting the reconfiguration of solar magnetic field and plasma. Solar jets represent collimated, beam-like plasma ejections; they are ubiquitous in the solar atmosphere and important for the understanding of solar activities at different scales, magnetic reconnection process, particle acceleration, coronal heating, solar wind acceleration, as well as other related phenomena. Recent high spatiotemporal resolution, wide-temperature coverage, spectroscopic, and stereoscopic observations taken by ground-based and space-borne solar telescop…
