216 research outputs found
The active region source of a type III radio storm observed by Parker Solar Probe during Encounter 2
Context. To investigate the source of a type III radio burst storm during
encounter 2 of NASA's Parker Solar Probe (PSP) mission.
Aims. It was observed that in encounter 2 of NASA's Parker Solar Probe
mission there was a large amount of radio activity, and in particular a noise
storm of frequent, small type III bursts from 31st March to 6th April 2019. Our
aim is to investigate the source of these small and frequent bursts.
Methods. In order to do this, we analysed data from the Hinode EUV Imaging
Spectrometer (EIS), PSP FIELDS, and the Solar Dynamics Observatory (SDO)
Atmospheric Imaging Assembly (AIA). We studied the behaviour of active region
12737, whose emergence and evolution coincides with the timing of the radio
noise storm and determined the possible origins of the electron beams within
the active region. To do this, we probe the dynamics, Doppler velocity,
non-thermal velocity, FIP bias, densities, and carry out magnetic modelling.
Results. We demonstrate that although the active region on the disk produces
no significant flares, its evolution indicates it is a source of the electron
beams causing the radio storm. They most likely originate from the area at the
edge of the active region that shows strong blue-shifted plasma. We demonstrate
that as the active region grows and expands, the area of the blue-shifted
region at the edge increases, which is also consistent with the increasing area
where large-scale or expanding magnetic field lines from our modelling are
anchored. This expansion is most significant between 1 and 4 April 2019,
coinciding with the onset of the type III storm and the decrease of the
individual burst's peak frequency, indicating the height at which the peak
radiation is emitted increases as the active region evolves
Intraoperative parathyroid hormone level in parathyroidectomy: which patients benefit from it?
EUV brightenings in the quiet-Sun: Signatures in spectral and imaging data from the Interface Region Imaging Spectrograph
Localised transient EUV brightenings, sometimes named `campfires', occur
throughout the quiet-Sun. However, there are still many open questions about
such events, in particular regarding their temperature range and dynamics. In
this article, we aim to determine whether any transition region response can be
detected for small-scale EUV brightenings and, if so, to identify whether the
measured spectra correspond to any previously reported bursts in the transition
region, such as Explosive Events (EEs). EUV brightenings were detected in a
~29.4 minute dataset sampled by Solar Orbiter's Extreme Ultraviolet Imager on 8
March 2022 using an automated detection algorithm. Any potential transition
region response was inferred through analysis of imaging and spectral data
sampled through coordinated observations conducted by the Interface Region
Imaging Spectrograph (IRIS). EUV brightenings display a range of responses in
IRIS slit-jaw imager (SJI) data. Some events have clear signatures in the Mg II
and Si IV SJI filters, whilst others have no discernible counterpart. Both
extended and more complex EUV brightenings are found to, sometimes, have
responses in IRIS SJI data. Examples of EUI intensities peaking before, during,
and after their IRIS counterparts were found in lightcurves constructed
co-spatial to EUV brightenings. Importantly, therefore, it is likely that not
all EUV brightenings are driven in the same way, with some seemingly being
magnetic reconnection driven and others not. A single EUV brightening occurred
co-spatial to the IRIS slit, with its spectra matching the properties of EEs.
EUV brightenings is a term used to describe a range of small-scale event in the
solar corona. The physics responsible for all EUV brightenings is likely not
the same and, therefore, more research is required to assess their importance
towards global questions in the field, such as coronal heating.Comment: Accepted to A&A, 9 figure
Evidence of external reconnection between an erupting mini-filament and ambient loops observed by Solar Orbiter/EUI
Mini-filament eruptions are one of the most common small-scale transients in
the solar atmosphere. However, their eruption mechanisms are still not
understood thoroughly. Here, with a combination of 174 A images of high
spatio-temporal resolution taken by the Extreme Ultraviolet Imager on board
Solar Orbiter and images of the Atmospheric Imaging Assembly on board Solar
Dynamics Observatory, we investigate in detail an erupting mini-filament over a
weak magnetic field region on 2022 March 4. Two bright ribbons clearly appeared
underneath the erupting mini-filament as it quickly ascended, and subsequently,
some dark materials blew out when the erupting mini-filament interacted with
the outer ambient loops, thus forming a blowout jet characterized by a widening
spire. At the same time, multiple small bright blobs of 1-2 Mm appeared at the
interaction region and propagated along the post-eruption loops toward the
footpoints of the erupting fluxes at a speed of ~ 100 km/s. They also caused a
semi-circular brightening structure. Based on these features, we suggest that
the mini-filament eruption first experiences internal and then external
reconnection, the latter of which mainly transfers mass and magnetic flux of
the erupting mini-filament to the ambient corona.Comment: 8 pages, 6 figures, accepted for publication in Astronomy &
Astrophysic
A multiple spacecraft detection of the 2 April 2022 M-class flare and filament eruption during the first close Solar Orbiter perihelion
CONTEXT:
The Solar Orbiter mission completed its first remote-sensing observation windows in the spring of 2022. On 2 April 2022, an M-class flare followed by a filament eruption was seen both by the instruments on board the mission and from several observatories in Earth’s orbit, providing an unprecedented view of a flaring region with a large range of observations.
AIMS:
We aim to understand the nature of the flaring and filament eruption events via the analysis of the available dataset. The complexity of the observed features is compared with the predictions given by the standard flare model in 3D.
METHOD:
In this paper, we use the observations from a multi-view dataset, which includes extreme ultraviolet (EUV) imaging to spectroscopy and magnetic field measurements. These data come from the Interface Region Imaging Spectrograph, the Solar Dynamics Observatory, Hinode, as well as several instruments on Solar Orbiter.
RESULTS:
The large temporal coverage of the region allows us to analyse the whole sequence of the filament eruption starting with its pre-eruptive state. Information given by spectropolarimetry from SDO/HMI and Solar Orbiter PHI/HRT shows that a parasitic polarity emerging underneath the filament is responsible for bringing the flux rope to an unstable state. As the flux rope erupts, Hinode EIS captures blue-shifted emission in the transition region and coronal lines in the northern leg of the flux rope prior to the flare peak. This may be revealing the unwinding of one of the flux rope legs. At the same time, Solar Orbiter SPICE captures the whole region, complementing the Doppler diagnostics of the filament eruption. Analyses of the formation and evolution of a complex set of flare ribbons and loops, of the hard and soft X-ray emissions with STIX, show that the parasitic emerging bipole plays an important role in the evolution of the flaring region.
CONCLUSIONS:
The extensive dataset covering this M-class flare event demonstrates how important multiple viewpoints and varied observations are in order to understand the complexity of flaring regions. While the analysed data are overall consistent with the standard flare model, the present particular magnetic configuration shows that surrounding magnetic activity such as nearby emergence needs to be taken into account to fully understand the processes at work. This filament eruption is the first to be covered from different angles by spectroscopic instruments, and provides an unprecedented diagnostic of the multi-thermal structures present before and during the flare. This complete dataset of an eruptive event showcases the capabilities of coordinated observations with the Solar Orbiter mission
Slow solar wind sources
Context. The origin of the slow solar wind is still an open issue. One possibility that has been suggested is that upflows at the edge of an active region can contribute to the slow solar wind.
Aims. We aim to explain how the plasma upflows are generated, which mechanisms are responsible for them, and what the upflow region topology looks like.
Methods. We investigated an upflow region using imaging data with the unprecedented temporal (3 s) and spatial (2 pixels = 236 km) resolution that were obtained on 30 March 2022 with the 174 Å channel of the Extreme-Ultraviolet Imager (EUI)/High Resolution Imager (HRI) on board Solar Orbiter. During this time, the EUI and Earth-orbiting satellites (Solar Dynamics Observatory, Hinode, and the Interface Region Imaging Spectrograph, IRIS) were located in quadrature (∼92°), which provides a stereoscopic view with high resolution. We used the Hinode/EIS (Fe XII) spectroscopic data to find coronal upflow regions in the active region. The IRIS slit-jaw imager provides a high-resolution view of the transition region and chromosphere.
Results. For the first time, we have data that provide a quadrature view of a coronal upflow region with high spatial resolution. We found extended loops rooted in a coronal upflow region. Plasma upflows at the footpoints of extended loops determined spectroscopically through the Doppler shift are similar to the apparent upward motions seen through imaging in quadrature. The dynamics of small-scale structures in the upflow region can be used to identify two mechanisms of the plasma upflow: Mechanism I is reconnection of the hot coronal loops with open magnetic field lines in the solar corona, and mechanism II is reconnection of the small chromospheric loops with open magnetic field lines in the chromosphere or transition region. We identified the locations in which mechanisms I and II work
Persistent primary hyperparathyroidism: an uncommon location for an ectopic gland - Case report and review
Evolution of dynamic fibrils from the cooler chromosphere to the hotter corona
Dynamic fibrils (DFs) are commonly observed chromospheric features in solar active regions. Recent observations from the Extreme Ultraviolet Imager (EUI) aboard the Solar Orbiter have revealed unambiguous signatures of DFs at the coronal base in extreme ultraviolet (EUV) emission. However, it remains unclear if the DFs detected in the EUV are linked to their chromospheric counterparts. Simultaneous detection of DFs from chromospheric to coronal temperatures could provide important information on their thermal structuring and evolution through the solar atmosphere. In this paper, we address this question by using coordinated EUV observations from the Atmospheric Imaging Assembly (AIA), Interface Region Imaging Spectrograph (IRIS), and EUI to establish a one-to-one correspondence between chromospheric and transition region DFs (observed by IRIS) with their coronal counterparts (observed by EUI and AIA). Our analysis confirms a close correspondence between DFs observed at different atmospheric layers and reveals that DFs can reach temperatures of about 1.5 million Kelvin, typical of the coronal base in active regions. Furthermore, the intensity evolution of these DFs, as measured by tracking them over time, reveals a shock-driven scenario in which plasma piles up near the tips of these DFs and, subsequently, these tips appear as bright blobs in coronal images. These findings provide information on the thermal structuring of DFs and their evolution and impact through the solar atmosphere
Evolution of dynamic fibrils from the cooler chromosphere to the hotter corona
Dynamic fibrils (DFs) are commonly observed chromospheric features in solar
active regions. Recent observations from the Extreme Ultraviolet Imager (EUI)
aboard the Solar Orbiter have revealed unambiguous signatures of DFs at the
coronal base, in extreme ultraviolet (EUV) emission. However, it remains
unclear if the DFs detected in the EUV are linked to their chromospheric
counterparts. Simultaneous detection of DFs from chromospheric to coronal
temperatures could provide important information on their thermal structuring
and evolution through the solar atmosphere. In this paper, we address this
question by using coordinated EUV observations from the Atmospheric Imaging
Assembly (AIA), Interface Region Imaging Spectrograph (IRIS), and EUI to
establish a one-to-one correspondence between chromospheric and transition
region DFs (observed by IRIS) with their coronal counterparts (observed by EUI
and AIA). Our analysis confirms a close correspondence between DFs observed at
different atmospheric layers, and reveals that DFs can reach temperatures of
about 1.5 million Kelvin, typical of the coronal base in active regions.
Furthermore, intensity evolution of these DFs, as measured by tracking them
over time, reveals a shock-driven scenario in which plasma piles up near the
tips of these DFs and, subsequently, these tips appear as bright blobs in
coronal images. These findings provide information on the thermal structuring
of DFs and their evolution and impact through the solar atmosphere.Comment: Accepted for publication in A&A Letters. Animation files are
available
https://drive.google.com/drive/folders/17-fqQz_P2T18llJ1jB6MJISMRvT5063F?usp=sharin
Picoflare jets power the solar wind emerging from a coronal hole on the Sun
Coronal holes are areas on the Sun with open magnetic field lines. They are a
source region of the solar wind, but how the wind emerges from coronal holes is
not known. We observed a coronal hole using the Extreme Ultraviolet Imager on
the Solar Orbiter spacecraft. We identified jets on scales of a few hundred
kilometers, which last 20 to 100 seconds and reach speeds of ~100 kilometers
per second. The jets are powered by magnetic reconnection and have kinetic
energy in the picoflare range. They are intermittent but widespread within the
observed coronal hole. We suggest that such picoflare jets could produce enough
high-temperature plasma to sustain the solar wind and that the wind emerges
from coronal holes as a highly intermittent outflow at small scales.Comment: This is the author's version of the work. The definitive version was
published in Science on 24 August 202
- …