ST1.3
Orals: Tue, 25 Apr | Room L1
The ESA/NASA Solar Orbiter mission performed its first close solar encounters at 0.32 au in March 2022 and at 0.29 au in October 2022. By combining high-resolution imaging and spectroscopy of the Sun with detailed in-situ measurements of the surrounding heliosphere, Solar Orbiter enables us to study the Sun's corona in unprecedented detail, and determine the linkage between observed solar wind streams and their source regions on the Sun. Its science return will be enhanced significantly by coordinated observations with other space missions, e.g. Parker Solar Probe, as well as new ground-based telescopes like DKIST. Over the course of the 10-year mission, Solar Orbiter's highly elliptical orbit will get progressively more inclined to the ecliptic plane. Thanks to this new perspective, Solar Orbiter will deliver images and comprehensive data of the unexplored Sun’s polar regions and the Sun's far side. This talk will provide a status update of the mission and the science operations performed during the first two science perihelia, and summarise early science results.
How to cite: Zouganelis, Y., Müller, D., De Groof, A., Williams, D., Walsh, A., Janvier, M., Nieves-Chinchilla, T., and Lario, D.: Solar Orbiter: The Sun up close, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-8923, https://doi.org/10.5194/egusphere-egu23-8923, 2023.
Upflows in the corona are of importance as they may contribute to the solar wind. Because of this, there has been interest
in the analysis of upflows at the edges of active regions (ARs). The coronal upflows that are seen at the edges of ARs have coronal
elemental composition and can contribute to the slow solar wind. The sources of the upflows have been challenging to determine
because they may be multiple.
In this talk, we will discuss the latest results of coronal upflows. This includes an example which is found unusually close to a sunspot umbra and unusually has photospheric abundance. We analyse in detail the cause of this upflow region using a combination of Solar Orbiter EUV images at high spatial and temporal resolution,
Hinode/EUV Imaging Spectrometer data, and observations from instruments on board the Solar Dynamics Observatory. This com-
bined dataset was acquired during the first Solar Orbiter perihelion of the science phase, which provided a spatial resolution of 356
km for 2 pixels. In the location of the, a small positive polarity connects to the umbra
via small-scale and very dynamic coronal loops. The Solar Orbiter EUV Imagers (EUI) high resolution data show the dynamics of these small loops, which last on timescales of only minutes. This is the location of the coronal upflow which has photospheric abundance. We attempt to determine if it is possible that they can feed into the slow solar wind. We discuss future observation potential using Solar Orbiter data along with data from other missions and ground-based observatories. This provides opportunities for multiple viewpoints, multi-wavelength measurements of these upflow regions.
How to cite: Harra, L., Mandrini, C., and Brooks, D. and the Solar Orbiter EUI collaborators: The source of unusual coronal upflows with photospheric abundance in a solar active region , EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-3094, https://doi.org/10.5194/egusphere-egu23-3094, 2023.
Observations of plasma motions in the low corona are often limited to magnetic field lines originating in active regions, which are ideal for spatial domain enhancements across individual extreme ultraviolet (EUV) images to see loops, flares, and other bright activity contrasted against dim background features.
The quiet Sun is essentially all dim background features, which requires advanced image processing and ideal observation parameters to emphasize the temporal domain in order to visualize faint, fine-scale plasma flows. We utilize time-normalized optical flow (TNOF) on large sets of high cadence EUV data by reducing instrumental noise to a high degree and then emphasizing the minor brightness variations indicative of plasma motion. Maps of plasma flow paths are produced via optical flow tracking algorithms by the computer vision method of Lucas-Kanade and the underlying velocity field is estimated with line integral convolution.
To test the effectiveness of the TNOF approach, we have applied this method to an EUV case study of data from EUI 174 and AIA 171 on 29 March 2022. This date marked a near-perpendicular line of sight orientation between the two spacecraft, had similarly short observation intervals, and provided the opportunity to compare contrast enhanced plasma features off-limb with temporally enhanced on-disk plasma motion.
In this case study, we generated movies and flow paths that show TNOF succeeds at qualitatively outlining plasma flow along magnetic field lines from both Solar Orbiter’s and SDO’s point of view which are in general agreement with potential field models. Additionally, detailed velocities of plasma motion within coronal loops, overall velocity trends, and a new quasi-magnetic flow trend within the quiet Sun are presented.
How to cite: Muro, G. and Morgan, H.: Time-normalized plasma flow mapping during the quadrature of SolO and SDO, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-15710, https://doi.org/10.5194/egusphere-egu23-15710, 2023.
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 Åimages 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 present a detailed investigation of an erupting mini-filament over a weak magnetic field region on 2022 March 4. It is clearly observed that, as the mini-filament quickly ascends, two ribbons appear underneath it. Subsequently, when the erupting mini-filament interacts with the outer ambient loops, some dark materials blow out, forming a blowout jet characterized by a widening spire. At the same time, multiple small bright blobs of size 1–2 Mm appear at the interaction region and propagate along the post-eruption loops towards the footpoints of the erupting fluxes at a speed of 100 km s1, as well as giving rise to a semi-circular brightening. These features indicate that the mini-filament eruption first undergoes the internal and then external reconnection, the latter of which mainly transfers mass and magnetic flux of the erupting mini-filament to the ambient corona.
How to cite: Li, Z., Cheng, X., Ding, M., Chitta, P., Peter, H., and Berghmans, D.: Evidence for External Reconnection Between an EruptingMini-filament and Ambient Loops Observed by Solar Orbiter/EUI, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-9221, https://doi.org/10.5194/egusphere-egu23-9221, 2023.
We report a partial filament eruption in the southern solar hemisphere that occurred on 18 March 2022 during the first science perihelion of Solar Orbiter. The filament erupted into a coronal mass ejection (CME), producing coronal dimmings at the footpoints of the erupting structure. The expanding dimming then merged with the adjacent southern polar coronal hole. This merging of two open magnetic structures is observationally rare and poorly understood. We use remote sensing data from multiple co-observing spacecraft to understand the physical processes during this merging event. The evolution of the merger is examined using Extreme-UltraViolet (EUV) images obtained from the instruments onboard the Solar Orbiter and Solar Dynamic Observatory spacecraft. The plasma dynamics are quantified using spectroscopic data obtained from the EUV Imaging Spectrometer onboard Hinode. The preliminary results show that the coronal hole and coronal dimming become indistinguishable from each other after the merging. Several plasma upflow regions were observed throughout the merging event, suggesting the opening of magnetic field lines. The brightening of bright points and coronal jets inside the merged region further imply ongoing reconnection processes. This work also has implications for the formation of coronal hole/open field regions and the origin of solar wind from coronal dimming and coronal hole boundaries.
How to cite: Ngampoopun, N., Long, D., Baker, D., Green, L., Yardley, S., James, A., and To, A.: The Merging of a Coronal Dimming with the Southern Polar Coronal Hole During Solar Orbiter’s First Perihelion, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-8269, https://doi.org/10.5194/egusphere-egu23-8269, 2023.
In this work the analysis of the SOL2022-03-30 X1.4 GOES class flare is presented. This flare was observed by Solar Orbiter during perihelion as well as from Earth based observatories including SDO’s AIA and the Extended Owens Valley Solar Array (EOVSA). It displays well correlated fast time variation in the HXR and microwave wavelengths of emission with time dependent lags. The mechanism behind such observed puslations is not yet fully understood and is important for gaining an understanding of particle acceleration and energy release in solar flares. In this flare, the oscillatory behaviour grows in time and can be split into three phases with QPP periods ~7s, ~14s and ~35s. New capabilities from Solar Orbiter’s Spectrometer Telescope for Imaging X-rays (STIX) allows for the localisation of individual bursts on short timescales which enables us to determine the spatial morphology of the HXR emission and its evolution in time. The HXR source locations are compared with the microwave sources observed by EOVSA and the ribbon structure determined from AIA 1600Å and 1700Å. The QPP source locations are found to change significantly in time. Furthermore, the electron spectral index is anti-correlated with the observed HXR emission, obeying the soft-hard-soft relation. When combined, these observations point towards a mechanism for QPP generation which involves quasi-periodic energy release and injection of electrons into the flaring loop. However, several open questions remain about how these QPPs are generated.
How to cite: Collier, H., Hayes, L., Battaglia, A., Harra, L., and Krucker, S.: SOL2022-03-30 X1.4 GOES Class Flare: Localising the source of quasi periodic pulsations in the Hard X-ray and microwave emissions with STIX onboard Solar Orbiter and EOVSA. , EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-11801, https://doi.org/10.5194/egusphere-egu23-11801, 2023.
During nearly three years of operation, STIX aboard Solar Orbiter observed thousands of flares. Many of them were simultaneously observed by Solar X-Ray Monitor (XSM) on board Indian Chandrayaan-2 circling the Moon. We present results of a multi-wavelength study for one selected flare of M GOES class as seen from 1.a.u. STIX data provided the opportunity for a detailed analysis of hard X-ray emission in several energy bands including the light curves, reconstructed hard X-ray images and spectra. The differential emission measure diagnostics of the flaring plasma have been carried out based on interpretation of the XSM X-ray spectra. Using the differential evolution (DE) approach we have determined the “full” model of emitting source including the temperature, emission measure and elemental abundances as determined simultaneously throughout the flare. We discuss patterns of elemental composition history for individual plasma temperature components.
How to cite: Kepa, A., Siarkowski, M., Awasthi, A. K., Sylwester, B., and Sylwester, J.: A multi-thermal analysis of M-class flare observed in common by STIX and XSM, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-13784, https://doi.org/10.5194/egusphere-egu23-13784, 2023.
The disparate nature of thermal-nonthermal energy partition during weak flares compared to that during the large flares is still an open issue and quantifying the relative productivity of multi-wavelength emission during weak flares can enable inferring the underlying energy release mechanism. Therefore, we analyze multi-wavelength emission from ∼150 flares during September 20-25, 2021, commonly observed from Spectrometer Telescope for Imaging X-rays (STIX) (at ∼0.6 AU), STEREO-A, GOES, and SDO observatories (significant overlap of observing field-of-view). The ratio (Qf ) of HXR (>12 keV) fluence (Fhxr ) and SXR (4-10 keV) flux (Fsxr), at the maximum of Fsxr (tp), is derived to quantify the relative productivity of HXR and SXR emission during flares. The variation of Qf with Fsxr enabled us to quantitatively identify the cases of strongly non-thermal (cold) and highly thermal (hot) flares. The identification of the source active region using the EUV images (from AIA) revealed the uniform behavior of different active regions in producing cold and hot flares. Besides, thermal-nonthermal plasma parameters as estimated by spectral-fit of STIX and XSM observations indicate a possible role of pre-flare density in flare loops to be resulting in disparate thermal-nonthermal emission partition. Therefore, we conduct case studies of flares of the aforementioned types by – synthesizing the X-ray images from STIX observations – analyzing the E/UV images, and magnetograms, and — performing the hydrodynamical simulations using the 1D Palermo-Harvard code. With such a multi-wavelength analysis of an ensemble of weak flares, we probe the energy release mechanism and evaluate the same in the framework of the standard model of energy release during large flares.
How to cite: Awasthi, A. K., Mrozek, T., Litwicka, M., Steslicki, M., Kolomanski, S., and Kulaga, K.: Thermal-nonthermal energy partition in weak flares observed by STIX, XSM, and SDO , EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-4805, https://doi.org/10.5194/egusphere-egu23-4805, 2023.
In this paper we will present preliminary results of an X-ray flare that occurred on 9th May 2021 for which the thermal and non-thermal X-ray signatures were detected both from the Earth direction by Fermi/GBM and by STIX on Solar Orbiter at 97° from the Sun-Earth line. This flare was also well observed in radio with the ground-based instruments in Nançay and in the interplanetary space by WIND/WAVES and RPW on Solar Orbiter . The X-ray event shows both an impulsive phase observed above 25 keV by STIX and FERMI and followed by a more gradual phase observed up to 15 keV by both STIX and FERMI. In the decimetric/metric radio domain, this event shows a group of type III bursts extending to the interplanetary medium as well as type IV emission. We shall discuss here the relative temporal evolutions of HXR emissions at different energies with those of the radio fluxes at different frequencies, as well as the spatial evolution of the X-ray and radio sources during the different phases of the event. We shall also investigate the evolution of the characteristics of the non-thermal electrons detected in the corona associated to both implusive and gradual phase of the flare.
How to cite: Vilmer, N., Musset, S., Zhang, M., Klein, K.-L., and Paipa, D.: Energetic electrons in the solar corona for the long duration event of 9 May 2021 as diagnosed from X-ray and radio observations., EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-11354, https://doi.org/10.5194/egusphere-egu23-11354, 2023.
Impulsive electron events observed in interplanetary space are believed to be generated by acceleration in solar flares. This notion has been supported by correlations between the characteristics of energetic electrons detected in-situ near 1 au and those in solar flares derived from hard X-ray observations. However, the details of this relation are still unclear, presumably because of the complex combination of acceleration, injection, and transport effects that are involved.
We present the first statistical results on impulsive electron events obtained by joint observations of remote-sensing and in-situ instruments on Solar Orbiter. We use the suite Energetic Particle Detector (EPD) to measure the properties of the electrons (time profile, anisotropy, maximum energy, inferring the injection time at the source, etc.), as well as to determine the particularities of the composition in the suprathermal energy range. Also, X-ray observations from the Spectrometer/Telescope for Imaging X-rays (STIX) constrain the energetic electrons in the solar flare in terms of timing, spectrum, and location. Type III radio bursts detected by the Radio and Plasma Waves (RPW) instrument are used to link the nonthermal X-ray peaks to the interplanetary electron beams. Finally, the Extreme Ultraviolet Imager (EUI) provides context on the flare evolution. We use a large event sample obtained during the first 2.5 years of the Solar Orbiter mission, which covers a wide range of radial distances ranging from as close as 0.33 au to 1.02 au.
How to cite: Warmuth, A., Schuller, F., Gómez-Herrero, R., Rodríguez-Pacheco, J., Carcaboso, F., Krucker, S., Pacheco, D., Wimmer-Schweingruber, R., Kollhoff, A., Dresing, N., Fedeli, A., Paipa, D., Maksimovic, M., Vilmer, N., Barczynski, K., Podladchikova, O., Mason, G., and Rouillard, A. and the Joint STIX-EPD-RPW-EUI Working Group: First results on interplanetary electron events obtained by joint observations of remote-sensing and in-situ instruments on Solar Orbiter, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-7482, https://doi.org/10.5194/egusphere-egu23-7482, 2023.
It is well known that flare-accelerated electrons can produce both hard X-ray (HXR) emission and Type-III radio bursts. The HXR emission is produced by the accelerated electrons propagating towards the chromosphere where they deposit their energy while Type-III radio bursts are produced by the accelerated electron beams traveling towards the outer solar atmosphere. Hence a temporal correlation between these two kinds of emission may imply a common origin of the accelerated electrons providing insight into the acceleration process, and allows us to connect electrons at the Sun to those in the heliosphere. On 2022-Nov-11 11:30 - 12:00 UT, the Spectrometer Telescope for Imaging X-rays (STIX) on Solar Orbiter observed a highly energetic flare event with an excellent time resolution of 0.5 s. Simultaneously there were observations of multiple coronal and interplanetary Type-III radio bursts from several instruments such as I-LOFAR, WIND/WAVES, NDA and ORFEES. I-LOFAR provides high-sensitivity imaging spectroscopy in the range of ~10-240 MHz with a time resolution of 1.31 ms and a frequency resolution of 195 kHz. We examine the temporal correlation between the X-ray and radio time series and discuss the relationship between the two and what it implies about the origin of the electron populations producing these two kinds of radiation.
How to cite: Bhunia, S., Hayes, L., Maloney, S., and Gallagher, P.: Detailed look at the temporal correlation between hard X-ray flare and type III radio bursts, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-16350, https://doi.org/10.5194/egusphere-egu23-16350, 2023.
Magnetic reconnection is a fundamental process in astrophysical plasma, as it enables the dissipation of energy at kinetic scales. Detecting it in-situ is therefore key to further our understanding of energy conversion in space plasma. However, ion reconnection jets usually scale from seconds to minutes in-situ, and as such they can be quite tedious to find in the months or years of data provided by Wind, ACE, Helios, PSP and Solar Orbiter.
In this work, we use a new approach to identify automatically reconnection exhausts in-situ. The method strongly relies on the Walén relation and uses Bayesian inference as well as physical considerations to detect reconnection jets in-situ. Applying the detection algorithm to one month of Solar Orbiter data at 0.7 ~AU, we find an occurrence rate of 6.4~jets/day, which is significantly higher than in previous studies performed at 1~AU. We repeat the analysis over the Solar Orbiter perihelion at 0.3 AU and show that the occurrence rate of magnetic reconnection tends to increase with radial distance.
We show that magnetic reconnection exhausts clearly cluster in the solar wind. We perform a statistical analysis, distinguishing between the exhausts associated with the heliospheric current sheet and turbulent reconnection. We find that the source and the degree of Alfvénicity of the solar wind might have an impact on magnetic reconnection occurrence.
How to cite: Fargette, N., Lavraud, B., Rouillard, A., Houdayer, P., Phan, T., Oieroset, M., Eastwood, J., Fedorov, A., Louarn, P., Owen, C., and Horbury, T.: Solar Orbiter reveals that reconnection jets cluster in the solar wind, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-16072, https://doi.org/10.5194/egusphere-egu23-16072, 2023.
Parker Solar Probe has detected abundant magnetic inversions and velocity spikes in the young solar wind, the origins of which are still highly debated. Numerous studies based on observational data and numerical simulations favor the causal correlation between interchange magnetic reconnection process and these velocity spikes. However, the specific process by which interchange magnetic reconnection leads to these structures is still inconclusive. Interchange reconnection should occur during the eruption of small bipoles in pre-existing open magnetic field regions such as coronal holes. This process is known to drive the formation of plumes and pseudo-streamer like structures and potentially mesoscale structures measured in the solar wind as well as velocity spikes. Using velocity measurements from Solar Orbiter we infer the magnetic origin of mesoscale structures and velocity spikes measured by Solar Orbiter, we find that the footpoints of the magnetic lines associated with these spikes are located at the boundary of a coronal hole observed by the Solar Dynamics Observatory (SDO), where the interchange magnetic reconnection is likely to occur. The imaging instruments aboard Solar Orbiter and SDO record one typical interchange magnetic reconnection event near the footpoints. With the high temporal/spatial resolution images obtained from multiple perspectives, we directly analyze the fluctuating motion of jet flow materials and explore the mechanism of fluctuation excitation during the interchange magnetic reconnection. We compare our observations with a 2.5D MHD simulation of interchange magnetic reconnection, we speculate that outward fluctuations may act as a kind of mediator between interchange magnetic reconnection and the formation process of velocity spikes/magnetic switchbacks.
How to cite: Hou, C., Rouillard, A., He, J., Gannouni, B., and Réville, V.: Possible Role of Fluctuation Excitation in the Formation of Alfvénic Fluctuations Originating from Interchange Magnetic Reconnection, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-15516, https://doi.org/10.5194/egusphere-egu23-15516, 2023.
The electrons in the solar wind exhibit non-thermal velocity distribution functions. Observed non-thermal features of the electron distribution in the inner heliosphere include the field-aligned strahl, the suprathermal halo, the sunward deficit, and temperature anisotropy. These features are the result of a complex interplay between global expansion effects and local interactions between the particles and the electromagnetic fields. Global effects create, for example, the strahl via the mirror force in the decreasing magnetic field and the sunward deficit via reflections in the interplanetary electric field. Local wave-particle interactions such as instabilities change the shape of these features and thus the overall properties and moments of the electron distribution.
We discuss the science opportunities that the high-resolution data of Solar Orbiter's SWA/EAS sensor open up for unprecedented studies of the causes and effects of non-thermal electron distributions in the context of the expansion of the solar wind in the inner heliosphere. We focus, in particular, on the interplay between expansion effects and instabilities related to the electron strahl and the sunward deficit.
How to cite: Verscharen, D., Owen, C., Nicolaou, G., Coburn, J., Micera, A., and Innocenti, M. E.: Using non-thermal electron distributions to probe the inner heliosphere, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-15283, https://doi.org/10.5194/egusphere-egu23-15283, 2023.
Flare-associated particles from so-called impulsive events might be efficiently reaccelerated in gradual Solar Energetic Particle (SEP) events which are typically related to coronal mass ejections (CMEs). The existence and characteristics of such a flare-associated seed population might play a key role for understanding the high variability in particle intensity under comparable CME speeds and solar wind conditions. Understanding this variability will improve predictions of large gradual SEP events that cause a severe risk for satellite and even ground-based infrastructure. We analyze a sequence of impulsive and subsequent gradual events that occurred between 5 and 11 March 2022 and were measured in-situ with Solar Orbiter at a close distance of 0.5 AU to the Sun. We study in detail the behavior of suprathermal ions during the events and relate it to the ambient solar wind plasma properties and remote-sensing observations of the respective flares and CMEs observed from SOHO, SDO, and Solar Orbiter. We find in particular a strong local enhancement of suprathermal flare-associated ions that are trapped for several hours between two ICME structures and provide therefore a natural reservoir of seed particles that can be efficiently further accelerated in ambient compression regions or occurring shocks on their way out to 1 AU.
How to cite: Janitzek, N., Moraleda, M., Walsh, A., Mason, G., Gomez-Herrero, R., Kollhoff, A., Pacheco, D., Barcynski, K., Rodríguez-García, L., Musset, S., Hayes, L., Zouganelis, I., Ho, G., Wimmer-Schweingruber, R., and Rodríguez-Pacheco, J.: Behavior of Flare-associated Suprathermal Ions at Coronal Mass Ejections observed with Solar Orbiter at 0.5 AU, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-13249, https://doi.org/10.5194/egusphere-egu23-13249, 2023.
The propagation and radial evolution of energetic particle events can only be studied by multiple-point simultaneous in-situ measurement within the heliosphere. The joint ESA/NASA Solar Orbiter mission that was launched in February 2020, is designed to study the Sun and inner heliosphere in greater detail than ever before. The Energetic Particle Detector (EPD) investigation on Solar Orbiter is a suite of four different sensors that measure the energetic particles from slightly above solar wind energies to hundreds of MeV/nucleon. Since launched, EPD already observed numerous large solar energetic particle (SEP) and energetic storm particle (ESP) events inside of 1 au in greater temporal and spectral resolutions than ever before. Many of these events were also measured by spacecraft at 1 au such as ACE and/or STEREO.
On April 2, 2022, an active region (AR 12975) on the western limb (W80) of the Sun produced a large SEP event and associated fast moving (>1400 km/s) coronal mass ejection (CME) and a CME-driven interplanetary shock (~1900 km/s). During that time, the Solar Orbiter spacecraft was cruising near its perihelion distance (~0.35 au) at W109 relative to the Earth-Sun line, and the STEREO Ahead spacecraft was at E35. Together, the particle instruments on these probes measured the SEP/ESP and the plasma and field instruments detected the associated interplanetary shock/CMEs on April 2-3, 2022. In this paper, we report the multi-spacecraft observations of this event that were measured by Solar Orbiter, and we discuss the propagation and transport of SEPs from 0.3 to 1 au.
How to cite: Ho, G., Mason, G., Allen, R., Kouloumvakos, A., Wimmer-Schweingruber, R., Rodríguez-Pacheco, J., and Gómez-Herrero, R.: April 3, 2022 in-situ ESP event as observed by Solar Orbiter, ACE and Stereo, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-4385, https://doi.org/10.5194/egusphere-egu23-4385, 2023.
With the launch of Solar Orbiter (SolO) together with STEREO A, and Wind it is again possible to study multi-spacecraft Solar Energetic Particle (SEP) events within 1 AU. Over the timespan from July 2020 up to June 2022, we identify 44 events for which a significant increase of ∼100 keV electrons has been observed for at least two spacecraft. The maximum longitudinal separation of the two furthest spacecraft ranges from ∼17 to ∼217 degree.
SEPs are expected to follow the Interplanetary Magnetic Field (IMF) which in zero-order approximation has the shape of Parker spirals. We investigate two different scenarios to identify the source of the widespread particle observation: (a) Particles are injected over a broad range of longitudes at the source surface without any perpendicular transport, hence by propagating along the IMF SEPs can be detected for distant observers. (b) Particles are injected over a narrow range of longitudes, but are distributed perpendicular to the nominal IMF by perpendicular diffusion. We discard events for which no unambiguously source location (e.g., flare) can be identified, or where an interplanetary coronal mass ejection is present. In order to investigate these scenarios a 2d SEP transport model is utilized. The simulated data are compared to selected SEP observations. We developed a χ2 minimization code in order to determine the most probable injection and transport parameters.
Here, we present our first modeling results for a selected number of multi-spacecraft SEP events involving SolO. Furthermore, we note that the multi-spacecraft event observation can be a result of a combination of case (a) and (b).
How to cite: Bruedern, M., Dresing, N., Heber, B., Kartavykh, Y., Kollhoff, A., Kühl, P., and Strauss, D. T.: Identifying the source of multi-spacecraft SEP events, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-15579, https://doi.org/10.5194/egusphere-egu23-15579, 2023.
With the launch of Solar Orbiter (SolO) on Feb. 10th 2020, a new era of multi-spacecraft solar energetic particles (SEP) observations has started. The unique orbit of the mission allows the observation of SEP events close to the Sun (<0.28 au), which can occasionally be compared to corresponding observations made by other spacecraft at 1au. Such multi-spacecraft observations of the same event at different radial distances provide an excellent opportunity to study the radial evolution of SEP events.
In this study, we identify SEP events for which SolO and either Wind or STEREO-A had a small longitudinal separation (<15°) between their magnetic foot-points at the Sun. For all SEP events that satisfy our selection criteria we determine the onset times and rise times as well as peak fluxes and peak values of the first-order anisotropy for electrons in the energy range from ∼50−85 keV. We compare the event parameters observed at the different spacecraft regarding their radial changes. In our sample we find strong event-to-event variations in the radial dependency of all derived event parameters. For the majority of events, the peak flux and the maximum value of the first-order anisotropy decrease with increasing radial distance to the Sun, while the rise time increases with radial distance in the majority of events. The derived onset delays observed between two spacecraft were found to be too long to be explained by ideal Parker spirals in multiple events.
We present an overview of the most interesting observations and discuss the wide variability in the radial dependency of the event parameters analysed in this study.
How to cite: Kollhoff, A., Berger, L., Brüdern, M., Dresing, N., Eldrum, S., Fleth, S., Gómez-Herrero, R., Heber, B., Kühl, P., Pacheco, D., Rodríguez-García, L., Rodríguez-Pacheco, J., Wimmer-Schweingruber, R. F., and Xu, Z.: Multi-spacecraft observations of near-relativistic electron events at different radial distances, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-12027, https://doi.org/10.5194/egusphere-egu23-12027, 2023.
Posters on site: Wed, 26 Apr, 14:00–15:45 | Hall X4
Onboard the Solar Orbiter spacecraft is the Polarimetric and Helioseismic Imager (SO/PHI), which has two telescopes, a high resolution telescope (HRT) and the full disk telescope (FDT). The instrument is designed to infer the photospheric magnetic field through differential imaging of the polarised light emitted from the Sun. It is the first magnetograph to move out of the Sun-Earth Line, providing excellent stereoscopic opportunities with other ground and space based instruments. Of particular interest is the comparison between SO/PHI-HRT and the Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory (SDO/HMI). They probe the same magnetically sensitive line of Fe1: 6173 Å and have the same aperture diameter. In March 2022 Solar Orbiter crossed the Sun-Earth line, providing an excellent opportunity for a comparison. Here a comparison between the magnetic fields, both line-of-sight and all three vector components, inferred by SDO/HMI and SO/PHI-HRT during the conjunction, are presented.
How to cite: Sinjan, J., Calchetti, D., Hirzberger, J., Solanki, S. K., del Toro Iniesta, J. C., Woch, J., Gandorfer, A., Alvarez-Herrero, A., Appourchaux, T., Volkmer, R., and Orozco Suárez, D.: Comparison of the Magnetic Field Inferred by SO/PHI-HRT and SDO/HMI, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-424, https://doi.org/10.5194/egusphere-egu23-424, 2023.
The Spectral Imaging of Coronal Environment (SPICE; SPICE Consortium et al. 2020) provides an extraordinary opportunity to study the chromosphere and transition region using EUV wavelengths, e.g., Ne VIII 770 Å, C III 977 Å, O VI 1032 Å, and Lyman-β 1025 Å. We present preliminary results modeling Ne VIII 770 Å intensity using images from SPICE and the COronal DEnsity and Temperature (CODET) model. This model is based on relationships between the magnetic field, density, and temperature. It uses a flux transport model, the Potential Field Extrapolation model (PFSS), an emission model based on Chianti atomic database 10.0.2, and an optimization algorithm. In addition, we assume that the emission from the top of the transition region (Ne VIII 770 Å) can be described using the magnetic field in the coronal base at 1.014 RSun (from PFSS).
How to cite: Rodríguez Gómez, J. M., Kucera, T., and Young, P.: Modeling EUV intensity at the top of the transition region using SPICE data on board Solar Orbiter, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-9380, https://doi.org/10.5194/egusphere-egu23-9380, 2023.
The Spectrometer/Telescope for Imaging X-rays (STIX) on-board Solar Orbiter measures the X-ray photons emitted by thermal and non-thermal electrons via bremsstrahlung mechanisms. STIX modulates the incident radiation by means of 30 sub-collimators that provide information on the complex values of specific Fourier components of the flaring X-ray source. This talk will illustrate this data formation process and explain how this model can be exploited to formulate image reconstruction methods including constrained maximum entropy, multi-scale CLEAN, feature augmentation, and Particle Swarm Optimization for parametric imaging. These methods will be applied against several experimental STIX observations and the reliability of the reconstructed morphologies will be validated by comparison with EUV maps recorded by the Atmospheric Imaging Assembly (AIA) on-board the Solar Dynamics Observatory.
How to cite: Piana, M., Massa, P., Volpara, A., Massone, A. M., Benvenuto, F., Perracchione, E., Battaglia, A. F., Hurford, G., and Krucker, S.: The STIX imaging concept: model for data formation and image reconstruction methods for the Spectrometer/Telescope for Imaging X-rays on-board Solar Orbiter, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-2688, https://doi.org/10.5194/egusphere-egu23-2688, 2023.
The fundamental science objective behind solar X-ray imaging spectroscopy is to gain information on the electrons accelerated by magnetic reconnection and on the temperature of the correspondingly heated plasma throughout the whole flaring volume. This talk will prove that the visibility-based technology at the base of the Spectrometer/Telescope for Imaging X-rays (STIX) allows the construction of electron flux and differential emission measure maps that are nicely smoothed along the energy and temperature directions, respectively. Using this approach, we will perform a spatially resolved analysis of the electron flux spectra associated with hard X-ray emissions measured by STIX and discuss the spatially resolved consistency of such emissions with a thermal distribution of the electrons in the flaring source.
How to cite: Volpara, A., Massa, P., Massone, A. M., and Piana, M.: Spatially resolved imaging spectroscopy with the Spectrometer/Telescope for Imaging X-rays on-board Solar Orbiter, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-3618, https://doi.org/10.5194/egusphere-egu23-3618, 2023.
Solar flares are efficient accelerators of energetic particles, mainly electrons, which transport energy from reconnection site to the chromosphere. Energetic electrons are thermalized in the chromosphere and produce hard X-ray emission (HXR) following the thick-target bremsstrahlung mechanism. The thick-target model predicts that altitude of the HXR sources in the footpoints of solar flare decreses with incresing energy. The relation was registered for the solar flares observed with Yohkoh/HXT and RHESSI. In our research, we investigated the energy-altitude relation in flare footpoints in a group of strong (>M1.0 GOES class) events recorded by the Spectrometer/Telescope for Imaging X-rays (STIX) onboard the Solar Orbiter. Here we present the results of analysis of the relation obtained from STIX data, e.g. temporal evolution and density distributions on selected examples. Thanks to unprecedented high temporal and spatial resolutions of STIX data, we can trace changes of plasma dynamics in footpoints like never before.
How to cite: Mikuła, K. and Mrozek, T.: The energy-altitude relation in solar flare footpoints observed by STIX, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-14916, https://doi.org/10.5194/egusphere-egu23-14916, 2023.
Solar Hard X-Ray (HXR) emission is observed typically in the form of localized, rather compact sources. Majority of these sources are flare related, however there is growing evidence, observational and theoretical, that we can expect HXR emission from places not directly related to primary energy release regions. From this point of view, failed eruptions are phenomena which are very interesting. Failed eruptions are events which at an early phase develop like a typical eruption which evolves into CME. However, for unclear reasons these eruptions stop abruptly somewhere in the solar corona. Many mechanisms are suspected to be responsible for stopping an eruption i.e. kink instability leading to stable configuration of erupting flux tube, magnetic tension within erupting structure or interaction and reconnection with an overlying coronal magnetic field. The last one may lead to electron acceleration and production of high temperature regions emitting in the HXR. There are only a few observations, from past instruments, showing some evidence of HXR production in failed eruptions. Recently, the Solar Orbiter has been launched giving a completely new perspective for observation and analysis of coronal dynamic events. Apart from others, it carries onboard Extreme-Ultraviolet Imager (EUI) and Spectrometer/Telescope for Imaging X-rays (STIX) telescopes open an opportunity to understand the physics of failed eruptions. The new EUV and HXR observations are important for at least two reasons. First, SO can approach the Sun closer than 0.3 a.u. which increase spatial resolution and sensitivity of telescopes, giving ocasion for registering weak HXR sources which can not be observed with previous instruments. Second, SDO/AIA instrument operating on the Earth orbit can provide stereoscopic context for SO/EUI images which may help to investigate deeper the geometry of the eruption and causes of its braking. Here, we present a very well observed flare accompanied by a failed eruption. The event occurred when longitudinal separation of the Earth and SO was 17 degrees. From the Earth perspective the event was visible very close to the west limb of a solar disc. For SO it was a behind-the-limb event with occulted footpoints which gave us a very good view, especially in the HXR range, of emission coming from the solar corona. During a flare's impulsive phase, the eruption accelerated to the velocity of a few hundreds kilometers per second and after six minutes it stopped abruptly at the height of 100 000 km above the solar surface. The eruption reconnected with overlying coronal loops leading to occurrence of at least three regions observed by STIX. The lowest source seems to be a typical, flare related coronal source, possibly consisting of two spatially unresolved sources located close to the primary reconnection site. The other two sources are located higher in the corona where reconnection of the eruption with an overlying magnetic field was observed. These sources behave significantly differently than the lowest source. Namely, their evolution is more gradual and seems to be driven by direct heating not the evaporation of chromospheric plasma which is a case for the lowest source.
How to cite: Mrozek, T., Stęślicki, M., Kołomański, S., and Barczyński, K.: Triple coronal Hard X-Ray source observed by STIX during a failed eruption of a filament., EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-14396, https://doi.org/10.5194/egusphere-egu23-14396, 2023.
Any spacecraft immersed into the solar wind builds up a non-zero electric potential with respect to the local environment by continuously collecting the charged particles from ambient plasma populations and emitting additional charged particle populations, namely photo-electrons and/or secondary electrons, from its surface materials. These newborn electrons of spacecraft origin as well as the electric fields induced in the vicinity of the spacecraft body by the so called spacecraft potential may in turn significantly distort the local plasma conditions and therefore affect any in-situ electron observations and thus potentially modify the derived electron properties. Here we present an observational analysis of these effects as seen by the SWA-EAS electron analyser in the variable plasma and electrostatic environment of the Solar Orbiter spacecraft. We provide some characteristic properties of these parasitic electron populations in order to later develop possible correction methods applied to the SWA-EAS measurements for deriving unperturbed ambient plasma properties. The analysis is performed on a statistical basis using a large set of SWA-EAS 3D electron velocity distribution functions and in comparison to other relevant in-situ measurements acquired namely by other two complementary on board plasma instruments – SWA-PAS and RPW.
How to cite: Stverak, S., Herčík, D., Hellinger, P., Nicolaou, G., Owen, C., and Maksimovic, M.: Photoelectrons and spacecraft potential effects on SWA-EAS electron measurements on board the Solar Orbiter spacecraft, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-5652, https://doi.org/10.5194/egusphere-egu23-5652, 2023.
We present an updated procedure developed to calibrate flight data from the Electron Analyser System (EAS) of the Solar Wind Analyzer (SWA) instrument onboard Solar Orbiter. By imposing specific physical conditions on the data set, like isotropy of the core electron population, and by comparing electron fluxes measured by the two EAS heads, we are able to derive consistent correction factors of the raw data set. The procedure is shown to improve the quality of the merging of the two heads dataset. We evaluate the impact of these corrections on ground moment calculation and on specific features of the electron pitch-angle distributions during the first perihelia of the mission. Anisotropy of the component of the pitch-angle electron distribution in different energy ranges is analysed. Detailed properties of specific features of the distribution including strahl and anti-strahl electrons are examined with this updated procedure.
How to cite: Berthomier, M., Lenc, A., Nicolaou, G., Owen, C., Lewis, G., Wicks, R., Fortunato, V., and Horbury, T.: Electron distribution functions measured by the SWA/EAS sensor during the first perihelia of the Solar Orbiter mission, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-6792, https://doi.org/10.5194/egusphere-egu23-6792, 2023.
Using the magnetic field properties in the interplanetary medium and near the Sun allows to trace back the trajectory of an in-situ observed parcel of solar wind. This kind of study has already shown around 1 AU an anti-correlation between the speed of the wind, and both the expansion factor of the flux tube and the magnetic field magnitude of the source (Wang & Sheeley 1990). In this study we apply the magnetic connectivity to the Solar Orbiter measurements from 0.3 AU to 1 AU, to trace back their source at the solar surface using ADAPT magnetograms. The nominal mission phase data are used (from the beginning of 2021). To better approximate the departure time of the plasma at the Sun and the location of its source, we constrain the trajectory of the solar wind using iso-poly modeling (Dakeyo et al. 2022) from the probe location until the source surface Rss. In addition, we aim to follow the classification of Maksimovic et al. 2020 and Dakeyo et al. 2022, to extrapolate sunward the magnetic condition of the different wind speed populations observed by Solar Orbiter. This statistical analysis shows that the correlation already observed at 1 AU mentioned above (bulk speed, flux tube expansion and magnitude of the magnetic field) are globally conserved getting closer the Sun between 0.3 AU and 1 AU. Depending the speed of the wind we are also able to estimate typical values of expansion factor, magnitude of the coronal magnetic field, the state of charge for each wind speed populations.
How to cite: Dakeyo, J.-B., Rouillard, A., Maksimovic, M., Réville, V., Louarn, P., and Démoulin, P.: Statistical study of the solar wind properties using the magnetic connectivity from in-situ measurements of Solar Orbiter extrapolated sunward the Solar Corona., EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-6664, https://doi.org/10.5194/egusphere-egu23-6664, 2023.
Spacecraft observations made at 1 AU from the Sun showed that the solar wind parameters are highly variable. D’Amicis and Bruno (2015) suggested that two solar wind regimes can be distinguished according to the nature of the embedded turbulent fluctuations. If the velocity and magnetic field variations are strongly correlated, Alfvénicity of the fluctuations is high, thus the first solar wind regime is called Alfvénic. Its characteristics suggest that it probably originates from coronal holes. The alpha particle parameters correspond to those usually associated with the fast solar wind. The alpha relative abundance is high (about 4 %) and alpha particles are faster and hotter than protons. The second solar wind regime has embedded non-Alvénic fluctuations. It could come from coronal streamers, but its formation remains unclear. Observations at 1 AU show that the non-Alvénic wind typically has the small alpha-proton relative drift and nearly equal temperature of both ionic components. In our study, we focus on variations of the alpha particle parameters in the non-Alvénic wind and on changes during transition from the Alfvénic to non-Alfvénic winds. We found observations of alpha particles slower than protons, for example near the termination of the corotating rarefaction regions. Using the WIND measurements, we perform a statistical study and compare the plasma properties associated with different ranges of the alpha-proton relative drift. Furthermore, we use measurements from the WIND and Solar Orbiter missions to study changes of the non-Alfvénic wind with increasing distance from the Sun. We discuss their possible origin both in terms of formation near the Sun and during propagation through the interplanetary space.
How to cite: Durovcova, T., Šafránková, J., and Němeček, Z.: Variations of alpha particle parameters in the non-Alvénic wind, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-8088, https://doi.org/10.5194/egusphere-egu23-8088, 2023.
The slow solar wind can be separated into at least two different components: a dense, variable wind produced by helmet streamers and a more tenuous and Alfvénic component emitted by coronal holes. Previous studies have shown that the slow Alfvénic wind is associated with enhanced alpha particle abundances, strong proton beams, and large alpha-to-proton temperature ratios: typical properties of the fast wind known to originate from inside large coronal holes. Recent combined in-situ and remote-observation campaigns by the Solar Orbiter mission exploiting the Proton and Alpha particle Sensor (SWA-PAS) can help us to study the relationship between the Alfvénic slow wind and coronal holes. We exploit these latest observations in conjunction with the newly-developed multi-species IRAP Solar Atmospheric Model (ISAM) model to study the coronal conditions that favour the production of an Alfvénic slow wind. ISAM simulates the coupled transport of both neutral and charged particles between the chromosphere and the corona, including a self-consistent treatment of collisional and ionisation processes, as well as detailed energy and heat flux conservation equations. In this study we discuss how the simulated alpha to proton ratios are modulated in response to different coronal heating rates and discuss these simulation results in light of recent Solar Orbiter measurements. The results presented here were funded by the European Research Council through the SLOW SOURCE project grant number DLV-819189.
How to cite: Thomas, S., Rouillard, A., Lavarra, M., Poirier, N., and Blelly, P.-L.: Investigating the Source of the Slow Solar Wind Using Solar Orbiter Observations and the IRAP Solar Atmospheric Model, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-12502, https://doi.org/10.5194/egusphere-egu23-12502, 2023.
Context: Magnetic switchbacks are localised polarity reversals in the radial component of the heliospheric magnetic field. Observations from Parker Solar Probe (PSP) have shown that they are a prevalent feature of the near-Sun solar wind. However, observations of switchbacks at 1 au and beyond are less frequent, suggesting that these structures are dissipated by yet-to-be identified mechanisms as they propagate away from the Sun.
Aims: We estimate the timescales over which magnetic switchbacks may be dissipated by magnetic reconnection and evaluate the viability of reconnection as a dissipation mechanism for switchbacks.
Methods: We analyse magnetic field and plasma data from the magnetometer and Solar Wind Analyser instruments aboard Solar Orbiter between 10 August and 30 August 2021. During this period, the spacecraft was 0.6 – 0.7 au from the Sun.
Results: We identify three instances of reconnection occurring at the trailing edge of magnetic switchbacks. Using hodographs and Walen analysis methods, we find that the reconnection exhaust region for all three events are bound by rotational discontinuities in the magnetic field, consistent with existing models describing the properties of reconnection in the solar wind. Based on these observations, we propose a scenario through which reconnection can dissipate a switchback and we estimate the timescales over which this occurs. We find that for our events the dissipation timescales are much shorter than the expansion timescale and thus, the complete dissipation of all three observed switchbacks would occur well before they reach Earth. Furthermore, assuming the observed reconnection rate has remained constant, and extrapolating back to an origin close to the Sun, we find that the spatial scale of these switchbacks would be considerably larger than is typically seen in the inner heliosphere. Hence, it is implied that the onset of reconnection must occur during transport in the solar wind. If typical, these results suggest that reconnection can play a significant role in dissipating switchbacks and could help explain the relative rarity of switchback observations at 1 au.
How to cite: Suen, G., Owen, C., Verscharen, D., Horbury, T., and Louarn, P.: Magnetic Reconnection as a Dissipation Mechanism for Magnetic Switchbacks, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-447, https://doi.org/10.5194/egusphere-egu23-447, 2023.
Context. Interplanetary collisionless shocks are known to be sources of energetic charged particles up to hundreds of MeV. However, the underlying acceleration mechanisms are still under debate.
Aims. We determine the properties of suprathermal protons accelerated by the interplanetary shock on 2021 November 3 with the unprecedented high-resolution measurements by the SupraThermal Electron Proton sensor of the Energetic Particle Detector onboard the Solar Orbiter spacecraft, in order to constrain the potential shock acceleration mechanisms.
Methods. We first reconstruct the pitch-angle distributions (PADs) of suprathermal protons in the solar wind frame. Then, we study the evolution of the PADs, flux temporal profile and velocity distribution function of this proton population close to the shock and compare the observations to theoretical predictions.
Results. We find that the suprathermal proton fluxes peak ∼12 to ∼24 seconds before the shock in the upstream region. The proton fluxes rapidly decrease by ∼50% in a thin layer (∼8000 km) adjacent to the shock in the downstream region and become constant further downstream. Furthermore, the proton velocity distribution functions in the upstream (downstream) region fit to a double power law, f (v) ∼ v−γ, at ∼1000 − 3600 km s−1, with a γ of ∼3.4 ± 0.2 (∼4.3 ± 0.7) at velocities (v) below a break at ∼1800 ± 100 km s−1 (∼1600 ± 200 km s−1) and a γ of ∼5.8 ± 0.3 (∼5.8 ± 0.2) at velocities above. These indices are all smaller than predicted by first-order Fermi acceleration. In addition, the proton PADs show anisotropies in the direction away from the shock in the close upstream region and become nearly isotropic further upstream, while downstream of the shock, they show a clear tendency of anisotropies towards 90◦ PA.
Conclusions. These results suggest that the acceleration of suprathermal protons at interplanetary shocks are dynamic on a time scale of ∼10 seconds, i.e., few proton gyro-periods. Furthermore, shock drift acceleration likely plays an important role in accelerating these suprathermal protons.
How to cite: Yang, L., Heidrich-Meisner, V., Berger, L., Wimmer-Schweingruber, R., Wang, L., He, J., Zhu, X., Duan, D., Kollhoff, A., Pacheco, D., Kühl, P., Xu, Z., Keilbach, D., Rodríguez-Pacheco, J., and Ho, G.: Acceleration of Suprathermal protons near an Interplanetary Shock, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-2236, https://doi.org/10.5194/egusphere-egu23-2236, 2023.
Energy spectra of X-ray solar flares observed by the Spectrometer-Telescope for Imaging X-rays (STIX) onboard the Solar Orbiter consist of both thermal and non-thermal parts. The thermal part is present in all solar events. When the non-thermal part of the energy spectrum begins to dominate, we can expect detection in interplanetary space of high-energy electron beams that have escaped the coronal loops. When hard X-ray flares are detected solar type III radio bursts are registered frequently with their numerous modifications like drift pairs, U-type, and structured bursts. The e-CALLISTO simple worldwide radio antenna stations allow us to identify the existence of non-thermal components in the energy spectra of strong X-ray flares. At the same time, some X-ray flares are accompanied by ejections of energetic ions including heavy ions. The specific features in X-ray bursts responsible for events with simultaneous light and heavy particle stream generation are still unclear compared with those with electron emission only.
We present preliminary results of observations gathered in December 2022 and cross-analysis of data on energetic light and heavy particle fluxes and X-ray flare parameters. The end of 2022 was distinguished by moderate to high solar activity, the presence of three periods with enhanced proton and heavy-ion fluxes at the beginning of the month, in the middle, and on 25-26 December. We demonstrate also the presence of narrow directed electron beams detected by the Electron Proton Telescope (EPT) of EPD for selected events mentioned above, and heavy ions detected by the Suprathermal Ion Spectrograph (SIS) of EPD.
How to cite: Dudnik, O., Mason, G., Ho, G., Allen, R., Wimmer-Schweingruber, R., Rodríguez-Pacheco, J., Espinosa Lara, F., Gómez Herrero, R., Mrozek, T., and Karlicky, M.: Heavy-ion-rich X-ray solar flares in December 2022 measured on Solar Orbiter, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-13609, https://doi.org/10.5194/egusphere-egu23-13609, 2023.
We report Solar Orbiter observations of six recurrent solar energetic particle injections in 2022 March 3–6 at ~0.5 au. The injections were associated with jets emanating from a plage near a large sunspot in NOAA active region 12957. We saw large jets in injections with high 3He and Fe enrichments and minor jets in injections with no or lower enrichments. Furthermore, the event with the highest enrichment showed a more compact configuration of the underlying photospheric magnetic field. The higher fluences as well as harder spectra were seen in the event with a wider jet-like eruption. However, in this case, the buildup time might be required to produce such spectra. Extreme ultraviolet images from Solar Orbiter revealed a crisscrossing network at the base of jets not seen from 1 au that might be suitable for the recurrent events.
How to cite: Bucik, R., Mason, G. M., Nitta, N. V., Krupar, V., Rodriguez, L., Ho, G. C., Hart, S. T., Dayeh, M. A., Rodríguez-Pacheco, J., Gómez-Herrero, R., and Wimmer-Schweingruber, R. F.: Recurrent 3He-rich solar energetic particle injections observed by Solar Orbiter at ~0.5 au, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-9386, https://doi.org/10.5194/egusphere-egu23-9386, 2023.
Solar Orbiter is an ESA-led mission of international collaboration with NASA to investigate how the Sun creates and controls the heliosphere, and why solar activity changes with time. One of its top-level science questions is how solar eruptions produce energetic particle radiation that fills the heliosphere. With its four viewing directions the High-Energy telescope (HET) provides critical information about the sources and transport of high-energy particles.
This study analyses relativistic electron measurements obtained by HET in the energy range from 200 keV to above 10 MeV. The purpose of this study is to analyse anisotropies of relativistic solar energetic electrons utilizing the different viewing directions of HET. Time periods with enhanced fluxes of relativistic electrons, have been identified. A list of these time periods including additional observations such as maximum energy and flux as well as the first order anistropy will be presented. This is the first time since the Helios mission that anisotropies of high energy electrons have been measured.
How to cite: Fleth, S., Kühl, P., Kollhoff, A., Wimmer-Schweingruber, R. F., Heber, B., Rodríguez-Pacheco, J., and Dresing, N.: Anisotropies of solar energetic electrons in the MeV range measured with SolO/EPD/HET, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-14698, https://doi.org/10.5194/egusphere-egu23-14698, 2023.
Posters virtual: Wed, 26 Apr, 14:00–15:45 | vHall ST/PS
Solar energetic particle (SEP) observations from Suprathermal Ion Spectrograph (SIS) which is part of the Energetic Particle Detector (EPD) suite on board the Solar Orbiter (SolO) mission, provide an unprecedented opportunity to study the composition and evolution of SEPs close at the Sun and to understand where SEPs are accelerated at the Sun and when released from their sources to interplanetary space. In this study, we examine 3He-rich time periods that last for many days. These extended 3He-rich periods that observed by SIS are particularly interesting because this rare isotope of He is not abundant in the solar corona and events rich of 3He are usually associated with transient and small "impulsive" SEP events. First, we compile a catalogue of extended 3He-rich time periods that were observed during the first three years of SolO mission and we determined and registered their characteristics (duration, composition, etc.). We also examined the spacecraft’s magnetic connectivity during these time periods and the characteristics of the connected regions. We find that, during the extended 3He-rich time periods, SolO is stably magnetically connected to an active region(s) for most cases. The connectivity usually changes near the boundaries of the time periods so the connectivity to the source region is an important element for the observation of these 3He-rich time periods. The active region(s) where SolO is magnetically connected during the time periods are typically very productive of solar events (flares, jets, CMEs).
How to cite: Kouloumvakos, A., Mason, G. M., Ho, G. C., Allen, R. C., Rouillard, A. P., Rodríguez-Pacheco, J. R., Wimmer-Schweingruber, R. F., and Gómez-Herrero, R.: Extended 3He-rich time periods observed by Solar Orbiter, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-4615, https://doi.org/10.5194/egusphere-egu23-4615, 2023.
