scholarly journals The Solar and Heliospheric Observatory

1984 ◽  
Vol 86 ◽  
pp. 155-158 ◽  
Author(s):  
Giancarlo Noci
Keyword(s):  
Solar Physics ◽  
Grazing Incidence ◽  
Spectral Irradiance ◽  
The Sun ◽  
Solar Dynamics Observatory ◽  
Solar Constant ◽  
Heliospheric Observatory ◽  
Explorer Mission ◽  
Solar Dynamics ◽  
Euv Spectrum

In the past years several space missions have been proposed for the study of the Sun and of the Heliosphere. These missions were intended to clarify various different aspects of solar physics. For example, the GRIST (Grazing Incidence Solar Telescope) mission was intended as a means to improve our knowledge of the upper transition region and low corona through the detection of the solar EUV spectrum with a spatial resolution larger than in previous missions; the DISCO (Dual Spectral Irradiance and Solar Constant Orbiter) and SDO (Solar Dynamics Observatory) missions were proposed to gat observational data about the solar oscillations better than those obtained from ground based instruments; the SOHO (Solar and Heliospheric Observatory) mission was initially proposed to combine the properties of GRIST with the study of the extended corona (up to several radii of heliocentric distance) by observing the scattered Ly-alpha and OVI radiation, which was also the basis of the SCE (Solar Corona Explorer) mission proposal; the development of the interest about the variability of the Sun, both in itself and for its consequences in the history of the Earth, led to propose observations of the solar constant (included in DISCO).

scholarly journals Hot prominence spicules launched from turbulent cool solar prominences

2019 ◽  
Vol 627 ◽  
pp. L5 ◽  
Author(s):  
L. P. Chitta ◽  
H. Peter ◽  
L. Li
Keyword(s):  
Transition Region ◽  
Extreme Ultraviolet ◽  
The Sun ◽  
Solar Dynamics Observatory ◽  
Solar Prominences ◽  
Solar Filament ◽  
Solar Dynamics ◽  
Ultraviolet Observations ◽  
Hot Corona ◽  
Shed Light

A solar filament is a dense cool condensation that is supported and thermally insulated by magnetic fields in the rarefied hot corona. Its evolution and stability, leading to either an eruption or disappearance, depend on its coupling with the surrounding hot corona through a thin transition region, where the temperature steeply rises. However, the heating and dynamics of this transition region remain elusive. We report extreme-ultraviolet observations of quiescent filaments from the Solar Dynamics Observatory that reveal prominence spicules propagating through the transition region of the filament-corona system. These thin needle-like jet features are generated and heated to at least 0.7 MK by turbulent motions of the material in the filament. We suggest that the prominence spicules continuously channel the heated mass into the corona and aid in the filament evaporation and decay. Our results shed light on the turbulence-driven heating in magnetized condensations that are commonly observed on the Sun and in the interstellar medium.

scholarly journals Enormous Eruption of 2.2 X-Class Solar Flares on 10th June 2014

2014 ◽  
Vol 36 ◽  
pp. 249-257 ◽  
Author(s):  
Zety Sharizat Hamidi ◽  
N.N.M. Shariff
Keyword(s):  
Active Region ◽  
Solar Flare ◽  
The Sun ◽  
X Rays ◽  
Solar Dynamics Observatory ◽  
Time Data ◽  
High Frequencies ◽  
The North ◽  
Solar Dynamics ◽  
Radio Blackout

The observational of active region emission of the Sun contain an critical answer of the time-dependence of the underlying heating mechanism. In this case, we investigate an X2.2 solar flare from a new Active Region AR2087 on the southeast limb of the Sun. The solar flare peaked in the X-rays is around 11:42 UT. It was found that the snapshot of this event from the Solar Dynamics Observatory (SDO) channel with the GOES X-ray plot overlayed. The flare is very bright causes by a diffraction pattern. We explore a parameter space of heating and coronal loop properties. Based on the wavelength, it shows plasma around 6 million Kelvin. At the same time, data from the NOAA issued an R3 level radio blackout, which is centered on Earth where the Sun is currently overhead at the North Africa region. This temporary blackout is caused by the heating of the upper atmosphere from the flare. The blackout level is now at an R1 and this will soon pass. Other than the temporary radio blackout for high frequencies centered over Africa this event will not have a direct impact on us. Until now, we await more data concerning a possible Coronal Mass Ejections (CMEs) but anything would more than likely not head directly towards Earth. An active region AR2087 just let out an X1.5 flare peaking at 12:52 UT. This shows plasmas with temperatures up to about 10 Million Kelvin. This event is considered one of the massive eruption of the Sun this year.

scholarly journals Fine-grained Solar Flare Forecasting Based on the Hybrid Convolutional Neural Networks*

2021 ◽  
Vol 922 (2) ◽  
pp. 232
Author(s):  
Zheng Deng ◽  
Feng Wang ◽  
Hui Deng ◽  
Lei. Tan ◽  
Linhua Deng ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Solar Flare ◽  
Solar Physics ◽  
Forecast Model ◽  
Research Field ◽  
Generative Adversarial Networks ◽  
Solar Dynamics Observatory ◽  
Solar Dynamics ◽  
The Stability ◽  
Class Flare

Abstract Improving the performance of solar flare forecasting is a hot topic in the solar physics research field. Deep learning has been considered a promising approach to perform solar flare forecasting in recent years. We first used the generative adversarial networks (GAN) technique augmenting sample data to balance samples with different flare classes. We then proposed a hybrid convolutional neural network (CNN) model (M) for forecasting flare eruption in a solar cycle. Based on this model, we further investigated the effects of the rising and declining phases for flare forecasting. Two CNN models, i.e., M rp and M dp, were presented to forecast solar flare eruptions in the rising phase and declining phase of solar cycle 24, respectively. A series of testing results proved the following. (1) Sample balance is critical for the stability of the CNN model. The augmented data generated by GAN effectively improved the stability of the forecast model. (2) For C-class, M-class, and X-class flare forecasting using Solar Dynamics Observatory line-of-sight magnetograms, the means of the true skill statistics (TSS) scores of M are 0.646, 0.653, and 0.762, which improved by 20.1%, 22.3%, and 38.0% compared with previous studies. (3) It is valuable to separately model the flare forecasts in the rising and declining phases of a solar cycle. Compared with model M, the means of the TSS scores for No-flare, C-class, M-class, and X-class flare forecasting of the M rp improved by 5.9%, 9.4%, 17.9%, and 13.1%, and those of the M dp improved by 1.5%, 2.6%, 11.5%, and 12.2%.

scholarly journals Photospheric downflows observed with SDO/HMI, HINODE, and an MHD simulation

2021 ◽  
Vol 647 ◽  
pp. A178
Author(s):  
T. Roudier ◽  
M. Švanda ◽  
J. M. Malherbe ◽  
J. Ballot ◽  
D. Korda ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Surface ◽  
Outer Part ◽  
Data Cube ◽  
The Sun ◽  
Solar Dynamics Observatory ◽  
Mhd Simulation ◽  
Quiet Sun ◽  
Solar Dynamics ◽  
The Magnetic Field

Downflows on the solar surface are suspected to play a major role in the dynamics of the convection zone, at least in its outer part. We investigate the existence of the long-lasting downflows whose effects influence the interior of the Sun but also the outer layers. We study the sets of Dopplergrams and magnetograms observed with Solar Dynamics Observatory and Hinode spacecrafts and an magnetohydrodynamic (MHD) simulation. All of the aligned sequences, which were corrected from the satellite motions and tracked with the differential rotation, were used to detect the long-lasting downflows in the quiet-Sun at the disc centre. To learn about the structure of the flows below the solar surface, the time-distance local helioseismology was used. The inspection of the 3D data cube (x, y, t) of the 24 h Doppler sequence allowed us to detect 13 persistent downflows. Their lifetimes lie in the range between 3.5 and 20 h with a sizes between 2″ and 3″ and speeds between −0.25 and −0.72 km s−1. These persistent downflows are always filled with the magnetic field with an amplitude of up to 600 Gauss. The helioseismic inversion allows us to describe the persistent downflows and compare them to the other (non-persistent) downflows in the field of view. The persistent downflows seem to penetrate much deeper and, in the case of a well-formed vortex, the vorticity keeps its integrity to the depth of about 5 Mm. In the MHD simulation, only sub-arcsecond downflows are detected with no evidence of a vortex comparable in size to observations at the surface of the Sun. The long temporal sequences from the space-borne allows us to show the existence of long-persistent downflows together with the magnetic field. They penetrate inside the Sun but are also connected with the anchoring of coronal loops in the photosphere, indicating a link between downflows and the coronal activity. A links suggests that EUV cyclones over the quiet Sun could be an effective way to heat the corona.

scholarly journals How eruptions of a small filament feed materials to a nearby larger-scaled filament

2020 ◽  
Vol 498 (1) ◽  
pp. L104-L108 ◽  
Author(s):  
H Wei ◽  
Z Huang ◽  
Z Hou ◽  
Y Qi ◽  
H Fu ◽  
...  
Keyword(s):  
Magnetic Reconnection ◽  
Solar Physics ◽  
Solar Telescope ◽  
Solar Dynamics Observatory ◽  
Plasma Flows ◽  
Laboratory Plasma ◽  
Common Features ◽  
Multi Wavelength ◽  
Magnetic Channel ◽  
Solar Dynamics

ABSTRACT As one of the most common features in the solar atmosphere, filaments are significant not only in solar physics but also in stellar and laboratory plasma physics. With the New Vacuum Solar Telescope and the Solar Dynamics Observatory, here we report on multi-wavelength observations of eruptions of a small (30 arcsec) filament (SF) and its consequences while interacting with ambient magnetic features including a large (300 arcsec) filament (LF). The eruptions of the SF drive a two-side-loop jet that is a result of magnetic reconnection between the SF threads and an overlying magnetic channel. As a consequence of the eruption, the heating in the footpoints of the SF destabilizes the barbs of the LF rooted nearby. Supersonic chromospheric plasma flows along the barbs of the LF are then observed in the H α passband and they apparently feed materials to the LF. We suggest that they are shock-driven plasma flows or chromospheric evaporations, which can both be the consequences of heating in the chromosphere by non-thermal particles generated in the magnetic reconnection associated with the two-side-loop jet. Our observations demonstrate that the destabilization in the vicinity of the footpoints of a barb can drive chromospheric plasma feeding to the filament.

scholarly journals The impact of a stealth CME on the Martian topside ionosphere

2021 ◽  
Vol 503 (1) ◽  
pp. 625-632
Author(s):  
Smitha V Thampi ◽  
C Krishnaprasad ◽  
Govind G Nampoothiri ◽  
Tarun K Pant
Keyword(s):  
Field Measurements ◽  
Topside Ionosphere ◽  
The Sun ◽  
Solar Cycles ◽  
Solar Dynamics Observatory ◽  
Mars Atmosphere ◽  
Phase Measurements ◽  
Ion Escape ◽  
Solar Dynamics ◽  
The Impact

ABSTRACT Solar cycle 24 is one of the weakest solar cycles recorded, but surprisingly the declining phase of it had a slow coronal mass ejection (CME) that evolved without any low coronal signature and is classified as a stealth CME that was responsible for an intense geomagnetic storm at Earth (Dst = −176 nT). The impact of this space weather event on the terrestrial ionosphere has been reported. However, the propagation of this CME beyond 1 au and the impact of this CME on other planetary environments have not been studied so far. In this paper, we analyse the data from the Sun–Earth L1 point and from the Martian orbit (near 1.5 au) to understand the characteristics of the stealth CME as observed beyond 1 au. The observations near Earth are using data from the Solar Dynamics Observatory (SDO) and the Advanced Composition Explorer (ACE) satellite located at L1 point, whereas those near Mars are from the instruments for plasma and magnetic field measurements onboard Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. The observations show that the stealth CME has reached 1.5 au after 7 d of its initial observations at the Sun and caused depletion in the nightside topside ionosphere of Mars, as observed during the inbound phase measurements of the Langmuir Probe and Waves (LPW) instrument onboard MAVEN. These observations have implications on the ion escape rates from the Martian upper atmosphere.

scholarly journals Single and Multiwavelength Detection of Coronal Dimming and Coronal Wave Using Faster R-CNN

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Zongxia Xie ◽  
Chunyang Ji
Keyword(s):  
Deep Learning ◽  
Space Weather ◽  
Coronal Mass Ejections ◽  
Solar Physics ◽  
Automatic Detection ◽  
Solar Dynamics Observatory ◽  
Solar Events ◽  
Solar Dynamics ◽  
Coronal Dimming ◽  
Coronal Wave

Automatic detection of solar events, especially uncommon events such as coronal dimming (CD) and coronal wave (CW), is very important in solar physics research. The CD and CW are not only related to the detection of coronal mass ejections (CMEs) but also affect space weather. In this paper, we have studied methods for automatically detecting them. In addition, we have collected and processed a dataset that includes the solar images and event records, where the solar images come from the Atmospheric Imaging Assembly (AIA) of Solar Dynamics Observatory (SDO) and the event records come from Heliophysics Event Knowledgebase (HEK). Different from the methods used before, we introduce the idea of deep learning. We train single-wavelength and multiwavelength models based on Faster R-CNN. In terms of accuracy, the single-wavelength model performs better. The multiwavelength model has a better detection performance on multiple solar events than the single-wavelength model.

scholarly journals Investigations of solar plasma in the interior and corona from Solar Dynamics Observatory

2010 ◽  
Vol 6 (S274) ◽  
pp. 287-290
Author(s):  
A. G. Kosovichev
Keyword(s):  
Large Scale ◽  
Magnetic Activity ◽  
Solar Interior ◽  
Magnetized Plasma ◽  
The Sun ◽  
Solar Dynamics Observatory ◽  
Magnetic Field Generation ◽  
Multi Wavelength ◽  
Solar Dynamics ◽  
Oscillations And Waves

AbstractThe Sun is a plasma laboratory for astrophysics, which allows us to investigate many important phenomena in turbulent magnetized plasma in detail. Solar Dynamics Observatory (SDO) launched in February 2010 provides unique information about plasma processes from the interior to the corona. The primary processes of magnetic field generation and formation of magnetic structures are hidden beneath the visible surface. Helioseismic diagnostics, based on observations and analysis of solar oscillations and waves, give insights into the physical processes in the solar interior and mechanisms of solar magnetic activity. In addition, simultaneous high-resolution multi-wavelength observations of the solar corona provide opportunity to investigate in unprecedented detail the coronal dynamics and links to the interior processes. These capabilities are illustrated by initial results on the large-scale dynamics of the Sun, the subsurface structure and dynamics of a sunspot and observations of a X-class solar flare.

scholarly journals Readdressing the UV solar variability with SATIRE-S: non-LTE effects

2019 ◽  
Vol 631 ◽  
pp. A178 ◽  
Author(s):  
R. V. Tagirov ◽  
A. I. Shapiro ◽  
N. A. Krivova ◽  
Y. C. Unruh ◽  
K. L. Yeo ◽  
...  
Keyword(s):  
Solar Irradiance ◽  
Spectral Synthesis ◽  
Solar Variability ◽  
Spectral Irradiance ◽  
Solar Dynamics Observatory ◽  
Quiet Sun ◽  
Total Irradiance ◽  
Solar Dynamics ◽  
Earth’S Climate ◽  
Spectral Solar Irradiance

Context. Solar spectral irradiance (SSI) variability is one of the key inputs to models of the Earth’s climate. Understanding solar irradiance fluctuations also helps to place the Sun among other stars in terms of their brightness variability patterns and to set detectability limits for terrestrial exoplanets. Aims. One of the most successful and widely used models of solar irradiance variability is Spectral And Total Irradiance REconstruction model (SATIRE-S). It uses spectra of the magnetic features and surrounding quiet Sun that are computed with the ATLAS9 spectral synthesis code under the assumption of local thermodynamic equilibrium (LTE). SATIRE-S has been at the forefront of solar variability modelling, but due to the limitations of the LTE approximation its output SSI has to be empirically corrected below 300 nm, which reduces the physical consistency of its results. This shortcoming is addressed in the present paper. Methods. We replaced the ATLAS9 spectra of all atmospheric components in SATIRE-S with spectra that were calculated using the Non-LTE Spectral SYnthesis (NESSY) code. To compute the spectrum of the quiet Sun and faculae, we used the temperature and density stratification models of the FAL set. Results. We computed non-LTE contrasts of spots and faculae and combined them with the corresponding fractional disc coverages, or filling factors, to calculate the total and spectral irradiance variability during solar cycle 24. The filling factors have been derived from solar full-disc magnetograms and continuum images recorded by the Helioseismic and Magnetic Imager on Solar Dynamics Observatory (SDO/HMI). Conclusions. The non-LTE contrasts yield total and spectral solar irradiance variations that are in good agreement with empirically corrected LTE irradiance calculations. This shows that the empirical correction applied to the SATIRE-S total and spectral solar irradiance is consistent with results from non-LTE computations.

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