scholarly journals Spatial Inhomogeneity in Solar Faculae

2017 ◽  
Vol 13 (S335) ◽  
pp. 17-19
Author(s):  
A. Elek ◽  
N. Gyenge ◽  
M. B. Korsós ◽  
R. Erdélyi
Keyword(s):  
Solar Surface ◽  
Spatial Inhomogeneity ◽  
Longitudinal Distribution ◽  
Dynamo Model ◽  
Latitudinal Distribution ◽  
Solar Dynamics Observatory ◽  
Active Longitude ◽  
Heliospheric Observatory ◽  
Oscillatory Pattern ◽  
Solar Dynamics

AbstractIn this paper, we investigate the inhomogeneous spatial distribution of solar faculae. The focus is on the latitudinal and longitudinal distributions of these highly localised features covering ubiquitously the solar surface. The statistical analysis is based on white light observations of the Solar and Heliospheric Observatory (SOHO) and Solar Dynamics Observatory (SDO) between 1996 and 2014. We found that the fine structure of the latitudinal distribution of faculae displays a quasi-biennial oscillatory pattern. Furthermore, the longitudinal distribution of photospheric solar faculae does not show homogeneous behaviour either. In particular, the non-axisymmetric behaviour of these events show similar properties as that of the active longitude (AL) found in the distribution of sunspots. Our results, preliminary though, may provide a valuable observational constrain for developing the next-generation solar dynamo model.

scholarly journals New Homogeneous Dataset of Solar EUV Synoptic Maps from SOHO/EIT and SDO/AIA

Solar Physics ◽  
2019 ◽  
Vol 295 (1) ◽  
Author(s):  
A. Hamada ◽  
T. Asikainen ◽  
K. Mursula
Keyword(s):  
Extreme Ultraviolet ◽  
Solar Surface ◽  
Intensity Scale ◽  
Solar Dynamics Observatory ◽  
Heliospheric Observatory ◽  
Imaging Telescope ◽  
Solar Dynamics ◽  
Sensor Degradation ◽  
Full Disk

AbstractSynoptic maps of solar EUV intensities have been constructed for many decades in order to display the distribution of the different EUV emissions across the solar surface, with each map representing one Carrington rotation (i.e. one rotation of the Sun). This article presents a new solar EUV synoptic map dataset based on full-disk images from the Solar and Heliospheric Observatory/Extreme Ultraviolet Imaging Telescope (SOHO/EIT) and Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA). In order to remove the significant and complicated drift of EIT and AIA EUV intensities due to sensor degradation, we construct the synoptic maps in standardized intensity scale. We describe a method of homogenizing the SOHO/EIT maps with SDO/AIA maps by transforming the EIT intensity histograms to AIA levels. The new maps cover the years from 1996 to 2018 with 307 SOHO/EIT and 116 SDO/AIA synoptic maps, respectively. These maps provide a systematic and homogeneous view of the entire solar surface in four EUV wavelengths, and are well suited, e.g., for studying long-term coronal hole evolution.

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 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 Long-term evolution of magnetic fields in flaring Active Region NOAA 12673

2022 ◽  
Vol 21 (12) ◽  
pp. 312
Author(s):  
Johan Muhamad ◽  
Muhamad Zamzam Nurzaman ◽  
Tiar Dani ◽  
Arun Relung Pamutri
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Solar Flares ◽  
Long Term Evolution ◽  
Solar Dynamics Observatory ◽  
Active Longitude ◽  
Term Evolution ◽  
Solar Dynamics ◽  
Different Characteristics

Abstract During the lifetime of AR 12673, its magnetic field evolved drastically and produced numerous large flares. In this study, using full maps of the Sun observed by the Solar Dynamics Observatory and the Solar Terrestrial Relations Observatory, we identified that AR 12673 emerged in decayed AR 12665, which had survived for two solar rotations. Although both ARs emerged at the same location, they possessed different characteristics and different flare productivities. Therefore, it is important to study the long-term magnetic evolution of both ARs to identify the distinguishing characteristics of an AR that can produce large solar flares. We used the Space-weather Helioseismic and Magnetic Imager Active Region Patch data to investigate the evolution of the photospheric magnetic field and other physical properties of the recurring ARs during five Carrington rotations. All these investigated parameters dynamically evolved through a series of solar rotations. We compared the long-term evolution of AR 12665 and AR 12673 to understand the differences in their flare-producing properties. We also studied the relation of the long-term evolution of these ARs with the presence of active longitude. We found that the magnetic flux and complexity of AR 12673 developed much faster than those of AR 12665. Our results confirmed that a strong emerging flux that emerged in the pre-existing AR near the active longitude created a very strong and complex AR that produced large flares.

scholarly journals Impulsive coronal heating during the interaction of surface magnetic fields in the lower solar atmosphere

2020 ◽  
Vol 644 ◽  
pp. A130
Author(s):  
L. P. Chitta ◽  
H. Peter ◽  
E. R. Priest ◽  
S. K. Solanki
Keyword(s):  
Solar Surface ◽  
Magnetic Energy ◽  
Active Regions ◽  
Opposite Polarity ◽  
Space Mission ◽  
Magnetic Polarity ◽  
Coronal Heating ◽  
Coronal Loops ◽  
Solar Dynamics Observatory ◽  
Solar Dynamics

Coronal plasma in the cores of solar active regions is impulsively heated to more than 5 MK. The nature and location of the magnetic energy source responsible for such impulsive heating is poorly understood. Using observations of seven active regions from the Solar Dynamics Observatory, we found that a majority of coronal loops hosting hot plasma have at least one footpoint rooted in regions of interacting mixed magnetic polarity at the solar surface. In cases when co-temporal observations from the Interface Region Imaging Spectrograph space mission are available, we found spectroscopic evidence for magnetic reconnection at the base of the hot coronal loops. Our analysis suggests that interactions of magnetic patches of opposite polarity at the solar surface and the associated energy release during reconnection are key to impulsive coronal heating.

scholarly journals An Analysis of Spikes in Atmospheric Imaging Assembly (AIA) Data

Solar Physics ◽  
2021 ◽  
Vol 296 (12) ◽  
Author(s):  
Peter R. Young ◽  
Nicholeen M. Viall ◽  
Michael S. Kirk ◽  
Emily I. Mason ◽  
Lakshmi Pradeep Chitta
Keyword(s):  
Solar Atmosphere ◽  
Extreme Ultraviolet ◽  
Solar Surface ◽  
Coronal Holes ◽  
Active Regions ◽  
Detection Algorithm ◽  
Solar Dynamics Observatory ◽  
Processing Pipeline ◽  
High Resolution Images ◽  
Solar Dynamics

AbstractThe Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) returns high-resolution images of the solar atmosphere in seven extreme ultraviolet (EUV) wavelength channels. The images are processed on the ground to remove intensity spikes arising from energetic particles hitting the instrument, and the despiked images are provided to the community. In this article, a three-hour series of images from the 171 Å channel obtained on 28 February 2017 was studied to investigate how often the despiking algorithm gave false positives caused by compact brightenings in the solar atmosphere. The latter were identified through spikes appearing in the same detector pixel for three consecutive frames. 1096 examples were found from the 900 image frames. These “three-spikes” were assigned to 126 dynamic solar features, and it is estimated that the three-spike method identifies 19% of the total number of features affected by despiking. For any ten-minute sequence of AIA 171 Å images there are around 37 solar features that have their intensity modified by despiking. The features are found in active regions, quiet Sun, and coronal holes and, in relation to solar surface area, there is a greater proportion within coronal holes. In 96% of the cases, the despiked structure is a compact brightening with a size of two arcsec or less, and the remaining 4% have narrow, elongated structures. By applying an EUV burst detection algorithm, we found that 96% of the events could be classified as EUV bursts. None of the spike events are rendered invisible by the AIA processing pipeline, but the total intensity over an event’s lifetime can be reduced by up to 67%. Users are recommended to always restore the original intensities in AIA data when studying short-lived or rapidly evolving features that exhibit fine-scale structure.

scholarly journals Solar microflares: a case study on temperatures and the Fe XVIII emission

2019 ◽  
Vol 628 ◽  
pp. A134 ◽  
Author(s):  
U. Mitra-Kraev ◽  
G. Del Zanna
Keyword(s):  
Extreme Ultraviolet ◽  
Atomic Data ◽  
Solar Dynamics Observatory ◽  
Imaging Spectrometer ◽  
Heliospheric Observatory ◽  
X Ray ◽  
Solar Dynamics ◽  
Peak Emission ◽  
Good Agreement

In this paper, we discuss the temperature distribution and evolution of a microflare, simultaneously observed by Hinode’s X-Ray Telescope (XRT), its Extreme Ultraviolet Imaging Spectrometer (EIS), as well as the Atmospheric Imaging Assembly (AIA) on-board the Solar Dynamics Observatory (SDO). Using EIS lines, we find that during peak emission the distribution is nearly isothermal and peaked around 4.5 MK. This temperature is in good agreement with that obtained from the XRT filter ratio, validating the use of XRT to study these small events, invisible to full-Sun X-ray monitors such as the Geostationary Operational Environmental Satellite (GOES). The increase in the estimated Fe XVIII emission in the AIA 94 Å band can mostly be explained with the small temperature increase from the background temperatures. The presence of Fe XVIII emission does not guarantee that temperatures of 7 MK are reached, as is often assumed. With the help of new atomic data, we also revisit the temperatures measured by a Solar and Heliospheric Observatory (SoHO) Solar Ultraviolet Measurements of Emitted Radiation (SUMER) observation of an active region that produced microflares, also finding low temperatures (3–4 MK) from an Fe XVIII/Ca XIV ratio.

Observations for the Role of Flux rope Eruption in a Geoeffective Solar Flare

2014 ◽  
Vol 4 (2) ◽  
pp. 555-564
Author(s):  
A.M Aslam
Keyword(s):  
Solar Flare ◽  
Flux Rope ◽  
Magnetic Configuration ◽  
Solar Dynamics Observatory ◽  
Multi Wavelength ◽  
Solar Dynamics ◽  
Halo Coronal Mass Ejection ◽  
Mass Ejection ◽  
The Waves

On September 24, 2011 a solar flare of M 7.1 class was released from the Sun. The flare was observed by most of the space and ground based observatories in various wavebands. We have carried out a study of this flare to understand its causes on Sun and impact on earth. The flare was released from NOAA active region AR 11302 at 12:33 UT. Although the region had already produced many M class flares and one X- class flare before this flare, the magnetic configuration was not relaxed and still continued to evolve as seen from HMI observations. From the Solar Dynamics Observatory (SDO) multi-wavelength (131 Ã…, 171 Ã…, 304 Ã… and 1600Ã…) observations we identified that a rapidly rising flux rope triggered the flare although HMI observations revealed that magnetic configuration did not undergo a much pronounced change. The flare was associated with a halo Coronal Mass Ejection (CME) as recorded by LASCO/SOHO Observations. The flare associated CME was effective in causing an intense geomagnetic storm with minimum Dst index -103 nT. A radio burst of type II was also recorded by the WAVES/WIND. In the present study attempt is made to study the nature of coupling between solar transients and geospace.

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