Imperial College London

ProfessorTimothyHorbury

Faculty of Natural SciencesDepartment of Physics

Professor of Physics
 
 
 
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Contact

 

+44 (0)20 7594 7676t.horbury Website

 
 
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Location

 

6M65Huxley BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
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276 results found

Coburn JT, Verscharen D, Owen CJ, Maksimovic M, Horbury TS, Chen CHK, Guo F, Fu X, Liu J, Abraham JB, Nicolaou G, Innocenti ME, Micera A, Jagarlamudi VKet al., 2024, The Regulation of the Solar Wind Electron Heat Flux by Wave-Particle Interactions, Astrophysical Journal, Vol: 964, ISSN: 0004-637X

The solar wind electrons carry a significant heat flux into the heliosphere. The weakly collisional state of the solar wind implicates collisionless processes as the primary factor that constrains nonthermal features of the velocity distribution function (VDF), including the heat flux. Previous observational work suggests that the electron VDF sometimes becomes unstable to the whistler wave, but reliance on model VDFs (e.g., drifting bi-Maxwellians) has proven insufficient for an exact description of the behavior of the solar wind electrons—in particular, the regulation of the heat flux. The characterization of these processes requires methods to obtain fine details of the VDF and quantification of the impact of kinetic processes on the VDF. We employ measurements of the electron VDF by Solar Orbiter’s Solar Wind Analyser and of the magnetic field by the Radio and Plasma Waves instrument to study an unstable solar wind electron configuration. Through a Hermite-Laguerre expansion of the VDF, we implement a low-pass filter in velocity space to remove velocity space noise and obtain a VDF suitable for analysis. With our method, we directly measure the instability growth rate and the rate of change of the electron heat flux through wave-particle interactions.

Journal article

Matteini L, Tenerani A, Landi S, Verdini A, Velli M, Hellinger P, Franci L, Horbury TS, Papini E, Stawarz JEet al., 2024, Alfvénic fluctuations in the expanding solar wind: Formation and radial evolution of spherical polarization, Physics of Plasmas, Vol: 31, ISSN: 1070-664X

We investigate properties of large-scale solar wind Alfvénic fluctuations and their evolution during radial expansion. We assume a strictly radial background magnetic field B ∥ R , and we use two-dimensional hybrid (fluid electrons, kinetic ions) simulations of balanced Alfvénic turbulence in the plane orthogonal to B ; the simulated plasma evolves in a system comoving with the solar wind (i.e., in the expanding box approximation). Despite some model limitations, simulations exhibit important properties observed in the solar wind plasma: Magnetic field fluctuations evolve toward a state with low-amplitude variations in the amplitude B = | B | and tend to a spherical polarization. This is achieved in the plasma by spontaneously generating field aligned, radial fluctuations that suppress local variations of B, maintaining B ∼ const. spatially in the plasma. We show that within the constraint of spherical polarization, variations in the radial component of the magnetic field, BR lead to a simple relation between δ B R and δ B = | δ B | as δ B R ∼ δ B 2 / ( 2 B ) , which correctly describes the observed evolution of the rms of radial fluctuations in the solar wind. During expansion, the background magnetic field amplitude decreases faster than that of fluctuations so that their the relative amplitude increases. In the regime of strong fluctuations, δ B ∼ B , this causes local magnetic field reversals, consistent with solar wind switchbacks.

Journal article

Rojo M, Persson M, Sauvaud JA, Aizawa S, Nicolaou G, Penou E, Barthe A, André N, Mazelle C, Fedorov A, Yokota S, Saito Y, Heyner D, Richter I, Auster U, Schmid D, Fischer D, Horbury T, Owen CJ, Maksimovic M, Khotyaintsev Y, Louarn P, Murakami Get al., 2024, Electron moments derived from the Mercury Electron Analyzer during the cruise phase of BepiColombo, Astronomy and Astrophysics, Vol: 683, ISSN: 0004-6361

Aims. We derive electron density and temperature from observations obtained by the Mercury Electron Analyzer on board Mio during the cruise phase of BepiColombo while the spacecraft is in a stacked configuration. Methods. In order to remove the secondary electron emission contribution, we first fit the core electron population of the solar wind with a Maxwellian distribution. We then subtract the resulting distribution from the complete electron spectrum, and suppress the residual count rates observed at low energies. Hence, our corrected count rates consist of the sum of the fitted Maxwellian core electron population with a contribution at higher energies. We finally estimate the electron density and temperature from the corrected count rates using a classical integration method. We illustrate the results of our derivation for two case studies, including the second Venus flyby of BepiColombo when the Solar Orbiter spacecraft was located nearby, and for a statistical study using observations obtained to date for distances to the Sun ranging from 0.3 to 0.9 AU. Results. When compared either to measurements of Solar Orbiter or to measurements obtained by HELIOS and Parker Solar Probe, our method leads to a good estimation of the electron density and temperature. Hence, despite the strong limitations arising from the stacked configuration of BepiColombo during its cruise phase, we illustrate how we can retrieve reasonable estimates for the electron density and temperature for timescales from days down to several seconds.

Journal article

Trotta D, Larosa A, Nicolaou G, Horbury TS, Matteini L, Hietala H, Blanco-Cano X, Franci L, Chen CHK, Zhao L, Zank GP, Cohen CMS, Bale SD, Laker R, Fargette N, Valentini F, Khotyaintsev Y, Kieokaew R, Raouafi N, Davies E, Vainio R, Dresing N, Kilpua E, Karlsson T, Owen CJ, Wimmer-Schweingruber RFet al., 2024, Properties of an Interplanetary Shock Observed at 0.07 and 0.7 au by Parker Solar Probe and Solar Orbiter, The Astrophysical Journal, Vol: 962, Pages: 147-147, ISSN: 0004-637X

<jats:title>Abstract</jats:title> <jats:p>The Parker Solar Probe (PSP) and Solar Orbiter (SolO) missions opened a new observational window in the inner heliosphere, which is finally accessible to direct measurements. On 2022 September 5, a coronal mass ejection (CME)-driven interplanetary (IP) shock was observed as close as 0.07 au by PSP. The CME then reached SolO, which was radially well-aligned at 0.7 au, thus providing us with the opportunity to study the shock properties at different heliocentric distances. We characterize the shock, investigate its typical parameters, and compare its small-scale features at both locations. Using the PSP observations, we investigate how magnetic switchbacks and ion cyclotron waves are processed upon shock crossing. We find that switchbacks preserve their V–B correlation while compressed upon the shock passage, and that the signature of ion cyclotron waves disappears downstream of the shock. By contrast, the SolO observations reveal a very structured shock transition, with a population of shock-accelerated protons of up to about 2 MeV, showing irregularities in the shock downstream, which we correlate with solar wind structures propagating across the shock. At SolO, we also report the presence of low-energy (∼100 eV) electrons scattering due to upstream shocklets. This study elucidates how the local features of IP shocks and their environments can be very different as they propagate through the heliosphere.</jats:p>

Journal article

Louarn P, Fedorov A, Prech L, Owen CJ, D'Amicis R, Bruno R, Livi S, Lavraud B, Rouillard AP, Génot V, André N, Fruit G, Réville V, Kieokaew R, Plotnikov I, Penou E, Barthe A, Lewis G, Berthomier M, Allegrini F, Alterman BL, Lepri ST, Raines JM, Verscharen D, Mele G, Fargette N, Horbury TS, Maksimovic M, Kasper JC, Bale SDet al., 2024, Skewness and kurtosis of solar wind proton distribution functions: The normal inverse-Gaussian model and its implications, Astronomy and Astrophysics, Vol: 682, ISSN: 0004-6361

Context. In the solar wind (SW), the particle distribution functions are generally not Gaussian. They present nonthermal features that are related to underlying acceleration and heating processes. These processes are critical in the overall dynamics of this expanding astrophysical fluid. Aims. The Proton Alpha Sensor (PAS) on board Solar Orbiter commonly observes skewed proton distributions, with a more populated high-energy side in the magnetic field direction than the Gaussian distribution. Our objectives are: (1) to identify a theoretical statistical function that adequately models the observed distributions and (2) to use its statistical interpretation to constrain the acceleration and heating processes. Methods. We analyzed the 3D velocity distribution functions (VDFs) measured by PAS and compared them to model statistical functions. Results. We show that the normal inverse Gaussian (NIG), a type of hyperbolic statistical distribution, provides excellent fits of skewed and leptokurtic proton distributions. NIG can model both the core distribution and the beam, if present. We propose an interpretation that is inspired by the mathematical formulation of the NIG. It assumes that the acceleration or heating mechanism can be modeled as a drifting diffusion process in velocity space, controlled (or subordinated) by the time of interaction of the particles with "accelerating structures". The probability function of the interaction time is an inverse Gaussian (IG), obtained by considering a random drift across structures of a given size. The control of the diffusion by interaction times that follow an IG probability function formally defines the NIG distribution. Following this model, we show that skewness and kurtosis can be used to estimate the kinetic and thermal energy gains provided by the interaction with structures. For example, in the case studies presented here, the analyzed populations would have gained kinetic energy representing approximately two

Journal article

Laker R, Horbury TS, Woodham LD, Bale SD, Matteini Let al., 2024, Coherent deflection patternãndãssociated temperature enhancements in the near-Sun solar wind, Monthly Notices of the Royal Astronomical Society, Vol: 527, Pages: 10440-10447, ISSN: 0035-8711

Measurements of transverse magnetic fieldãnd velocity components from Parker Solar Probe hav e rev ealedã coherent quasi- periodic pattern in the near-Sun solar wind. As wellãs being Alfvénicãndãrc-polarized, these deflections were characterized byã consistent orientationãndãn increased proton core temperature, which was greater parallel to the magnetic field. We show that switchbacks represent the largest deflections within this underlying structure, which is itself consistent with the expected outflow from interchange reconnection simulations. Additionally, the spatial scale of the deflections was estimated to beãround 1 Mm on the Sun, comparable to the jettingãctivity observedãt coronal bright points within the base of coronal plumes. Therefore, our results could represent the in situ signature of interchange reconnection from coronal bright points within plumes, complementing recent numericalãnd observational studies. Weãlso foundã consistent relationship between the proton core temperatureãnd magnetic fieldãngleãcross the Parker Solar Probe encountersãnd discussed how suchã persistent signature could be more indicative ofãn in situ mechanism creatingã local increase in temperature. In future, observations of minor ions, radio bursts,ãnd remote sensing images could help further establish the connection between reconnection events on the Sunãnd signatures in the solar wind.

Journal article

Laker R, Horbury TS, OBrien H, Fauchon-Jones EJ, Angelini V, Fargette N, Amerstorfer T, Bauer M, Möstl C, Davies EE, Davies JA, Harrison R, Barnes D, Dumbović Met al., 2024, Using Solar Orbiter as an Upstream Solar Wind Monitor for Real Time Space Weather Predictions, Space Weather, Vol: 22

Coronal mass ejections (CMEs) can create significant disruption to human activities and systems on Earth, much of which can be mitigated with prior warning of the upstream solar wind conditions. However, it is currently extremely challenging to accurately predict the arrival time and internal structure of a CME from coronagraph images alone. In this study, we take advantage of a rare opportunity to use Solar Orbiter, at 0.5 au upstream of Earth, as an upstream solar wind monitor. In combination with low-latency images from STEREO-A, we successfully predicted the arrival time of two CME events before they reached Earth. Measurements at Solar Orbiter were used to constrain an ensemble of simulation runs from the ELEvoHI model, reducing the uncertainty in arrival time from 10.4 to 2.5 hr in the first case study. There was also an excellent agreement in the Bz profile between Solar Orbiter and Wind spacecraft for the second case study, despite being separated by 0.5 au and 10° longitude. The opportunity to use Solar Orbiter as an upstream solar wind monitor will repeat once a year, which should further help assess the efficacy upstream in-situ measurements in real time space weather forecasting.

Journal article

Klein KG, Spence H, Alexandrova O, Argall M, Arzamasskiy L, Bookbinder J, Broeren T, Caprioli D, Case A, Chandran B, Chen L-J, Dors I, Eastwood J, Forsyth C, Galvin A, Genot V, Halekas J, Hesse M, Hine B, Horbury T, Jian L, Kasper J, Kretzschmar M, Kunz M, Lavraud B, Le Contel O, Mallet A, Maruca B, Matthaeus W, Niehof J, OBrien H, Owen C, Retinò A, Reynolds C, Roberts O, Schekochihin A, Skoug R, Smith C, Smith S, Steinberg J, Stevens M, Szabo A, TenBarge J, Torbert R, Vasquez B, Verscharen D, Whittlesey P, Wickizer B, Zank G, Zweibel Eet al., 2023, HelioSwarm: a multipoint, multiscale mission to characterize turbulence, Space Science Reviews, Vol: 219, ISSN: 0038-6308

HelioSwarm (HS) is a NASA Medium-Class Explorer mission of the Heliophysics Division designed to explore the dynamic three-dimensional mechanisms controlling the physics of plasma turbulence, a ubiquitous process occurring in the heliosphere and in plasmas throughout the universe. This will be accomplished by making simultaneous measurements at nine spacecraft with separations spanning magnetohydrodynamic and sub-ion spatial scales in a variety of near-Earth plasmas. In this paper, we describe the scientific background for the HS investigation, the mission goals and objectives, the observatory reference trajectory and instrumentation implementation before the start of Phase B. Through multipoint, multiscale measurements, HS promises to reveal how energy is transferred across scales and boundaries in plasmas throughout the universe.

Journal article

Trotta D, Horbury TS, Lario D, Vainio R, Dresing N, Dimmock A, Giacalone J, Hietala H, Wimmer-Schweingruber RF, Berger L, Yang Let al., 2023, Irregular Proton Injection to High Energies at Interplanetary Shocks, Astrophysical Journal Letters, Vol: 957, ISSN: 2041-8205

How thermal particles are accelerated to suprathermal energies is an unsolved issue, crucial for many astrophysical systems. We report novel observations of irregular, dispersive enhancements of the suprathermal particle population upstream of a high-Mach-number interplanetary shock. We interpret the observed behavior as irregular “injections” of suprathermal particles resulting from shock front irregularities. Our findings, directly compared to self-consistent simulation results, provide important insights for the study of remote astrophysical systems where shock structuring is often neglected.

Journal article

Paouris E, Vourlidas A, Kouloumvakos A, Papaioannou A, Jagarlamudi VK, Horbury Tet al., 2023, The Space Weather Context of the First Extreme Event of Solar Cycle 25, on 2022 September 5, Astrophysical Journal, Vol: 956, ISSN: 0004-637X

The coronal mass ejection (CME) on 2022 September 5 was the fastest CME yet observed and measured in situ by a spacecraft inside the corona (0.06 au for the Parker Solar Probe). Here we assess the significance of this event for space weather studies by analyzing the source region characteristics and its temporal evolution via a magnetic complexity index. We also examine the kinematics and energetics of the CME. We find that it was a very fast and massive event, with a speed greater than 2200 km s−1 and a mass of 2 × 1016 g. Consequently, this is within the top 1% of all CMEs observed by SOHO/LASCO since 1996. It is therefore natural to ask, “What if this CME was an Earth-directed one?” To answer this question, we put the CME and the associated flare properties in the context of similar previous extreme events (namely, the 2012 July 23 and 2012 March 7 eruptions), discussing the possibility that these trigger a solar energetic particle (SEP) event. We find that 2022 September 5 could have resulted in a high-energy SEP event. We also estimate the transit time and speed of the CME and calculate the likely Dst variations if this was an Earth-directed event.

Journal article

Trotta D, Pezzi O, Burgess D, Preisser L, Blanco-Cano X, Kajdic P, Hietala H, Horbury TS, Vainio R, Dresing N, Retinò A, Marcucci MF, Sorriso-Valvo L, Servidio S, Valentini Fet al., 2023, Three-dimensional modelling of the shock-turbulence interaction, Monthly Notices of the Royal Astronomical Society, Vol: 525, Pages: 1856-1866, ISSN: 0035-8711

The complex interaction between shocks and plasma turbulence is extremely important to address crucial features of energy conversion in a broad range of astrophysical systems. We study the interaction between a supercritical, perpendicular shock and pre-existing, fully developed plasma turbulence, employing a novel combination of magnetohydrodynamic and small-scale, hybrid-kinetic simulations where a shock is propagating through a turbulent medium. The variability of the shock front in the unperturbed case and for two levels of upstream fluctuations is addressed. We find that the behaviour of shock ripples, i.e. shock surface fluctuations with short (a few ion skin depths, di) wavelengths, is modified by the presence of pre-existing turbulence, which also induces strong corrugations of the shock front at larger scales. We link this complex behaviour of the shock front and the shock downstream structuring with the proton temperature anisotropies produced in the shock-turbulence system. Finally, we put our modelling effort in the context of spacecraft observations, elucidating the role of novel cross-scale, multispacecraft measurements in resolving shock front irregularities at different scales. These results are relevant for a broad range of astrophysical systems characterized by the presence of shock waves interacting with plasma turbulence.

Journal article

Horbury T, Bale S, mcmanus M, Larson D, Kasper J, Laker R, Matteini L, Raouafi N, Velli M, Woodham L, Woolley T, Fedorov A, Louarn P, Kieokaew R, Durovcova T, Chandran B, Owen Cet al., 2023, Switchbacks, microstreams and broadband turbulence in the solar wind, Physics of Plasmas, Vol: 30, ISSN: 1070-664X

Switchbacks are a striking phenomenon in near-Sun coronal hole flows, but their origins, evolution, and relation to the broadband fluctuations seen farther from the Sun are unclear. We use the near-radial lineup of Solar Orbiter and Parker Solar Probe during September 2020 when both spacecraft were in wind from the Sun's Southern polar coronal hole to investigate if switchback variability is related to large scale properties near 1 au⁠. Using the measured solar wind speed, we map measurements from both spacecraft to the source surface and consider variations with source Carrington longitude. The patch modulation of switchback amplitudes at Parker at 20 solar radii was associated with speed variations similar to microstreams and corresponds to solar longitudinal scales of around 5°–10°. Near 1 au⁠, this speed variation was absent, probably due to interactions between plasma at different speeds during their propagation. The alpha particle fraction, which has recently been shown to have spatial variability correlated with patches at 20 solar radii, varied on a similar scale at 1 au⁠. The switchback modulation scale of 5°–10°, corresponding to a temporal scale of several hours at Orbiter, was present as a variation in the average deflection of the field from the Parker spiral. While limited to only one stream, these results suggest that in coronal hole flows, switchback patches are related to microstreams, perhaps associated with supergranular boundaries or plumes. Patches of switchbacks appear to evolve into large scale fluctuations, which might be one driver of the ubiquitous turbulent fluctuations in the solar wind.

Journal article

Livi S, Lepri ST, Raines JM, Dewey RM, Galvin AB, Louarn P, Collier MR, Allegrini F, Alterman BL, Bert CM, Bruno R, Chornay DJ, D'Amicis R, Eddy TJ, Ellis L, Fauchon-Jones E, Fedorov A, Gershkovich I, Holmes J, Horbury TS, Kistler LM, Kucharek H, Lugaz N, Nieves-Chinchilla T, O'Brien H, Ogasawara K, Owen CJ, Phillips M, Ploof K, Rivera YJ, Spitzer SA, Stubbs TJ, Wurz Pet al., 2023, First results from the Solar Orbiter Heavy Ion Sensor, ASTRONOMY & ASTROPHYSICS, Vol: 676, ISSN: 0004-6361

Journal article

Zhu X, He J, Duan D, Verscharen D, Owen CJ, Fedorov A, Louarn P, Horbury TSet al., 2023, Non-field-aligned Proton Beams and Their Roles in the Growth of Fast Magnetosonic/Whistler Waves: Solar Orbiter Observations, ASTROPHYSICAL JOURNAL, Vol: 953, ISSN: 0004-637X

Journal article

Wimmer-Schweingruber RF, André N, Barabash S, Brandt PC, Horbury T, Iess L, Lavraud B, McNutt R, Provornikova E, Quemerais E, Wicks R, Wieser M, Wurz Pet al., 2023, STELLA — In situ Investigations of the Very Local Interstellar Medium, Vol. 55, Issue 3 (Heliophysics 2024 Decadal Whitepapers)

Journal article

Chen L-J, Spence H, Klein K, Matthaeus W, Lavraud B, Szabo A, Roberts OW, Génot V, Verscharen D, Horbury T, Retino A, Alexandrova O, Reynolds C, Halekas J, Dors I, Arzamasskiy L, Contel OL, TenBarge J, Forsyth C, Jian L, Galvin A, Schekochihin A, Maruca BAet al., 2023, Plasma turbulence: Challenges and next transformative steps from the perspective of multi-spacecraft measurements, Vol. 55, Issue 3 (Heliophysics 2024 Decadal Whitepapers)

Journal article

Suen GHH, Owen CJ, Verscharen D, Horbury TS, Louarn P, De Marco Ret al., 2023, Magnetic reconnection as an erosion mechanism for magnetic switchbacks, ASTRONOMY & ASTROPHYSICS, Vol: 675, ISSN: 0004-6361

Journal article

Sioulas N, Velli M, Huang Z, Shi C, Bowen TAA, Chandran BDG, Liodis I, Davis N, Bale SDD, Horbury TS, de Wit TD, Larson D, Stevens MLL, Kasper J, Owen CJJ, Case A, Pulupa M, Malaspina DMM, Livi R, Goetz K, Harvey PRR, MacDowall RJJ, Bonnell JWWet al., 2023, On the Evolution of the Anisotropic Scaling of Magnetohydrodynamic Turbulence in the Inner Heliosphere, ASTROPHYSICAL JOURNAL, Vol: 951, ISSN: 0004-637X

Journal article

Yardley SL, Owen CJ, Long DM, Baker D, Brooks DH, Polito V, Green LM, Matthews S, Owens M, Lockwood M, Stansby D, James AW, Valori G, Giunta A, Janvier M, Ngampoopun N, Mihailescu T, To ASH, van Driel-Gesztelyi L, Demoulin P, D'Amicis R, French RJ, Suen GHH, Rouillard AP, Pinto RF, Reville V, Watson CJ, Walsh AP, De Groof A, Williams DR, Zouganelis I, Mueller D, Berghmans D, Auchere F, Harra L, Schuehle U, Barczynski K, Buchlin E, Cuadrado RA, Kraaikamp E, Mandal S, Parenti S, Peter H, Rodriguez L, Schwanitz C, Smith P, Teriaca L, Verbeeck C, Zhukov AN, De Pontieu B, Horbury T, Solanki SK, Iniesta JCDT, Woch J, Gandorfer A, Hirzberger J, Suarez DO, Appourchaux T, Calchetti D, Sinjan J, Kahil F, Albert K, Volkmer R, Carlsson M, Fludra A, Hassler D, Caldwell M, Fredvik T, Grundy T, Guest S, Haberreiter M, Leeks S, Pelouze G, Plowman J, Schmutz W, Sidher S, Thompson WT, Louarn P, Federov Aet al., 2023, Slow Solar Wind Connection Science during Solar Orbiter's First Close Perihelion Passage, ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, Vol: 267, ISSN: 0067-0049

Journal article

Duan D, He J, Zhu X, Zhuo R, Wu Z, Nicolaou G, Huang J, Verscharen D, Yang L, Owen CJ, Fedorov A, Louarn P, Horbury TSet al., 2023, Kinetic Features of Alpha Particles in a Pestchek-like Magnetic Reconnection Event in the Solar Wind Observed by Solar Orbiter, ASTROPHYSICAL JOURNAL LETTERS, Vol: 952, ISSN: 2041-8205

Journal article

Bale SD, Drake JF, McManus MD, Desai MI, Badman ST, Larson DE, Swisdak M, Horbury TS, Raouafi NE, Phan T, Velli M, McComas DJ, Cohen CMS, Mitchell D, Panasenco O, Kasper JCet al., 2023, Interchange reconnection as the source of the fast solar wind within coronal holes, NATURE, Vol: 618, Pages: 252-+, ISSN: 0028-0836

Journal article

Baker D, Demoulin P, Yardley SL, Mihailescu T, van Driel-Gesztelyi L, D'Amicis R, Long DM, To ASH, Owen CJ, Horbury TS, Brooks DH, Perrone D, French RJ, James AW, Janvier M, Matthews S, Stangalini M, Valori G, Smith P, Cuadrado RA, Peter H, Schuehle U, Harra L, Barczynski K, Berghmans D, Zhukov AN, Rodriguez L, Verbeeck Cet al., 2023, Observational Evidence of S-web Source of the Slow Solar Wind, ASTROPHYSICAL JOURNAL, Vol: 950, ISSN: 0004-637X

Journal article

Fargette N, Lavraud B, Rouillard AP, Houdayer PS, Phan TD, Øieroset M, Eastwood JP, Nicolaou G, Fedorov A, Louarn P, Owen CJ, Horbury TSet al., 2023, Clustering of magnetic reconnection exhausts in the solar wind: An automated detection study, Astronomy and Astrophysics: a European journal, Vol: 674, Pages: 1-15, ISSN: 0004-6361

Context. Magnetic reconnection is a fundamental process in astrophysical plasmas that enables the dissipation of magnetic energy at kinetic scales. Detecting this process in situ is therefore key to furthering our understanding of energy conversion in space plasmas. However, reconnection jets typically scale from seconds to minutes in situ, and as such, finding them in the decades of data provided by solar wind missions since the beginning of the space era is an onerous task.Aims. In this work, we present a new approach for automatically identifying reconnection exhausts in situ in the solar wind. We apply the algorithm to Solar Orbiter data obtained while the spacecraft was positioned at between 0.6 and 0.8 AU and perform a statistical study on the jets we detect.Methods. The method for automatic detection is inspired by the visual identification process and strongly relies on the Walén relation. It is enhanced through the use of Bayesian inference and physical considerations to detect reconnection jets with a consistent approach.Results. Applying the detection algorithm to one month of Solar Orbiter data near 0.7 AU, we find an occurrence rate of seven jets per day, which is significantly higher than in previous studies performed at 1 AU. We show that they tend to cluster in the solar wind and are less likely to occur in the tenuous solar wind (< 10 cm−3 near 0.7 AU). We discuss why the source and the degree of Alfvénicity of the solar wind might have an impact on magnetic reconnection occurrence.Conclusions. By providing a tool to quickly identify potential magnetic reconnection exhausts in situ, we pave the way for broader statistical studies on magnetic reconnection in diverse plasma environments.

Journal article

Safrankova J, Nemecek Z, Nemec F, Verscharen D, Horbury TS, Bale SD, Prech Let al., 2023, Evolution of Magnetic Field Fluctuations and Their Spectral Properties within the Heliosphere: Statistical Approach, ASTROPHYSICAL JOURNAL LETTERS, Vol: 946, ISSN: 2041-8205

Journal article

Raouafi NE, Stenborg G, Seaton DB, Wang H, Wang J, DeForest CE, Bale SD, Drake JF, Uritsky VM, Karpen JT, DeVore CR, Sterling AC, Horbury TS, Harra LK, Bourouaine S, Kasper JC, Kumar P, Phan TD, Velli Met al., 2023, Magnetic Reconnection as the Driver of the Solar Wind, ASTROPHYSICAL JOURNAL, Vol: 945, ISSN: 0004-637X

Journal article

Brandt PC, Provornikova E, Bale SD, Cocoros A, DeMajistre R, Dialynas K, Elliott HA, Eriksson S, Fields B, Galli A, Hill ME, Horanyi M, Horbury T, Hunziker S, Kollmann P, Kinnison J, Fountain G, Krimigis SM, Kurth WS, Linsky J, Lisse CM, Mandt KE, Magnes W, McNutt RL, Miller J, Moebius E, Mostafavi P, Opher M, Paxton L, Plaschke F, Poppe AR, Roelof EC, Runyon K, Redfield S, Schwadron N, Sterken V, Swaczyna P, Szalay J, Turner D, Vannier H, Wimmer-Schweingruber R, Wurz P, Zirnstein EJet al., 2023, Future Exploration of the Outer Heliosphere and Very Local Interstellar Medium by Interstellar Probe, SPACE SCIENCE REVIEWS, Vol: 219, ISSN: 0038-6308

Journal article

Krasnoselskikh V, Tsurutani BT, Dudok de Wit T, Walker S, Balikhin M, Balat-Pichelin M, Velli M, Bale SD, Maksimovic M, Agapitov O, Baumjohann W, Berthomier M, Bruno R, Cranmer SR, de Pontieu B, Meneses DDS, Eastwood J, Erdelyi R, Ergun R, Fedun V, Ganushkina N, Greco A, Harra L, Henri P, Horbury T, Hudson H, Kasper J, Khotyaintsev Y, Kretzschmar M, Krucker S, Kucharek H, Langevin Y, Lavraud B, Lebreton J-P, Lepri S, Liemohn M, Louarn P, Moebius E, Mozer F, Nemecek Z, Panasenco O, Retino A, Safrankova J, Scudder J, Servidio S, Sorriso-Valvo L, Souček J, Szabo A, Vaivads A, Vekstein G, Vörös Z, Zaqarashvili T, Zimbardo G, Fedorov Aet al., 2023, ICARUS: in-situ studies of the solar corona beyond Parker Solar Probe and Solar Orbiter, Experimental Astronomy, Vol: 54, Pages: 277-315, ISSN: 0922-6435

The primary scientific goal of ICARUS (Investigation of Coronal AcceleRation and heating of solar wind Up to the Sun), a mother-daughter satellite mission, proposed in response to the ESA “Voyage 2050” Call, will be to determine how the magnetic field and plasma dynamics in the outer solar atmosphere give rise to the corona, the solar wind, and the entire heliosphere. Reaching this goal will be a Rosetta Stone step, with results that are broadly applicable within the fields of space plasma physics and astrophysics. Within ESA’s Cosmic Vision roadmap, these science goals address Theme 2: “How does the Solar System work?” by investigating basic processes occurring “From the Sun to the edge of the Solar System”. ICARUS will not only advance our understanding of the plasma environment around our Sun, but also of the numerous magnetically active stars with hot plasma coronae. ICARUS I will perform the first direct in situ measurements of electromagnetic fields, particle acceleration, wave activity, energy distribution, and flows directly in the regions in which the solar wind emerges from the coronal plasma. ICARUS I will have a perihelion altitude of 1 solar radius and will cross the region where the major energy deposition occurs. The polar orbit of ICARUS I will enable crossing the regions where both the fast and slow winds are generated. It will probe the local characteristics of the plasma and provide unique information about the physical processes involved in the creation of the solar wind. ICARUS II will observe this region using remote-sensing instruments, providing simultaneous, contextual information about regions crossed by ICARUS I and the solar atmosphere below as observed by solar telescopes. It will thus provide bridges for understanding the magnetic links between the heliosphere and the solar atmosphere. Such information is crucial to our understanding of the plasma physics and electrodynamics of the solar atmosph

Journal article

Raouafi NE, Matteini L, Squire J, Badman ST, Velli M, Klein KG, Chen CHK, Matthaeus WH, Szabo A, Linton M, Allen RC, Szalay JR, Bruno R, Decker RB, Akhavan-Tafti M, Agapitov OV, Bale SD, Bandyopadhyay R, Battams K, Berčič L, Bourouaine S, Bowen T, Cattell C, Chandran BDG, Chhiber R, Cohen CMS, D'Amicis R, Giacalone J, Hess P, Howard RA, Horbury TS, Jagarlamudi VK, Joyce CJ, Kasper JC, Kinnison J, Laker R, Liewer P, Malaspina DM, Mann I, McComas DJ, Niembro-Hernandez T, Panasenco O, Pokorný P, Pusack A, Pulupa M, Perez JC, Riley P, Rouillard AP, Shi C, Stenborg G, Tenerani A, Verniero JL, Viall N, Vourlidas A, Wood BE, Woodham LD, Woolley Tet al., 2023, Parker solar probe: four years of discoveries at solar cycle minimum, Space Science Reviews, Vol: 219, Pages: 1-140, ISSN: 0038-6308

Launched on 12 Aug. 2018, NASA’s Parker Solar Probe had completed 13 of its scheduled 24 orbits around the Sun by Nov. 2022. The mission’s primary science goal is to determine the structure and dynamics of the Sun’s coronal magnetic field, understand how the solar corona and wind are heated and accelerated, and determine what processes accelerate energetic particles. Parker Solar Probe returned a treasure trove of science data that far exceeded quality, significance, and quantity expectations, leading to a significant number of discoveries reported in nearly 700 peer-reviewed publications. The first four years of the 7-year primary mission duration have been mostly during solar minimum conditions with few major solar events. Starting with orbit 8 (i.e., 28 Apr. 2021), Parker flew through the magnetically dominated corona, i.e., sub-Alfvénic solar wind, which is one of the mission’s primary objectives. In this paper, we present an overview of the scientific advances made mainly during the first four years of the Parker Solar Probe mission, which go well beyond the three science objectives that are: (1) Trace the flow of energy that heats and accelerates the solar corona and solar wind; (2) Determine the structure and dynamics of the plasma and magnetic fields at the sources of the solar wind; and (3) Explore mechanisms that accelerate and transport energetic particles.

Journal article

Trotta D, Hietala H, Horbury T, Dresing N, Vainio R, Wilson L, Plotnikov I, Kilpua Eet al., 2023, Multi-spacecraft observations of shocklets at an interplanetary shock, MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Vol: 520, Pages: 437-445, ISSN: 0035-8711

Journal article

De Marco R, Bruno R, Jagarlamudi VK, D'Amicis R, Marcucci MF, Fortunato V, Perrone D, Telloni D, Owen CJ, Louarn P, Fedorov A, Livi S, Horbury Tet al., 2023, Innovative technique for separating proton core, proton beam, and alpha particles in solar wind 3D velocity distribution functions, ASTRONOMY & ASTROPHYSICS, Vol: 669, ISSN: 0004-6361

Journal article

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