Space physics

  • Article | | open

    Various physical mechanisms are proposed to explain the heating observed in turbulent astrophysical plasmas. Here, Chen et al. find a signature consistent with one of these mechanisms, electron Landau damping, by applying a field-particle correlation technique to in situ spacecraft data of turbulence in the Earth’s magnetosheath.

    • C. H. K. Chen
    • , K. G. Klein
    •  & G. G. Howes
  • Article | | open

    Surface waves on the boundary between a magnetosphere and the surrounding plasma might get trapped by the ionosphere forming an eigenmode. Here, Archer et al. show direct observations of this proposed mechanism at Earth’s magnetosphere by analyzing the response to an isolated fast plasma jet detected by the THEMIS satellites.

    • M. O. Archer
    • , H. Hietala
    • , M. D. Hartinger
    • , F. Plaschke
    •  & V. Angelopoulos
  • Article | | open

    Electron precipitation plays major role in magnetospheric physics and space weather. Here the authors show nonlinear behavior of the wave–particle interaction in the magnetosphere as the evolution of chorus electromagnetic waves detected by the Arase satellite and PWING observatory.

    • Mitsunori Ozaki
    • , Yoshizumi Miyoshi
    • , Kazuo Shiokawa
    • , Keisuke Hosokawa
    • , Shin-ichiro Oyama
    • , Ryuho Kataoka
    • , Yusuke Ebihara
    • , Yasunobu Ogawa
    • , Yoshiya Kasahara
    • , Satoshi Yagitani
    • , Yasumasa Kasaba
    • , Atsushi Kumamoto
    • , Fuminori Tsuchiya
    • , Shoya Matsuda
    • , Yuto Katoh
    • , Mitsuru Hikishima
    • , Satoshi Kurita
    • , Yuichi Otsuka
    • , Robert C. Moore
    • , Yoshimasa Tanaka
    • , Masahito Nosé
    • , Tsutomu Nagatsuma
    • , Nozomu Nishitani
    • , Akira Kadokura
    • , Martin Connors
    • , Takumi Inoue
    • , Ayako Matsuoka
    •  & Iku Shinohara
  • Article | | open

    There is significant interest in providing real-world applications for metamaterials. Here, the authors design an Advanced Short Backfire Antenna, augmented with anisotropic metamaterial surfaces to achieve high aperture efficiency across two frequency bands, making the antenna ideal for spaceborne applications.

    • J. Daniel Binion
    • , Erik Lier
    • , Thomas H. Hand
    • , Zhi Hao Jiang
    •  & Douglas H. Werner
  • Article | | open

    Magnetic energy in the plasma is transferred into particle energy by magnetic reconnection. Here the authors show the two-fluid dynamics of asymmetric magnetic reconnection in two different spatial scales of plasma, namely laboratory and astrophysical plasma.

    • M. Yamada
    • , L.-J. Chen
    • , J. Yoo
    • , S. Wang
    • , W. Fox
    • , J. Jara-Almonte
    • , H. Ji
    • , W. Daughton
    • , A. Le
    • , J. Burch
    • , B. Giles
    • , M. Hesse
    • , T. Moore
    •  & R. Torbert
  • Article | | open

    Magnetic reconnection is the process of releasing energy by magnetized and space plasma. Here the authors report experimental observation of magnetic reconnection in laser-produced plasma and the role of electron scaling on reconnection.

    • Y. Kuramitsu
    • , T. Moritaka
    • , Y. Sakawa
    • , T. Morita
    • , T. Sano
    • , M. Koenig
    • , C. D. Gregory
    • , N. Woolsey
    • , K. Tomita
    • , H. Takabe
    • , Y. L. Liu
    • , S. H. Chen
    • , S. Matsukiyo
    •  & M. Hoshino
  • Article | | open

    Radial diffusion is the only mechanism considered to accelerate trapped electrons to relativistic energies in Saturn’s magnetic field, forming radiation belts. Here the authors show another mechanism, electron acceleration via Doppler shifted cyclotron resonant interaction with Z-mode waves, which can form radiation belts inside the orbit of Enceladus.

    • E. E. Woodfield
    • , R. B. Horne
    • , S. A. Glauert
    • , J. D. Menietti
    • , Y. Y. Shprits
    •  & W. S. Kurth
  • Article | | open

    The origin of geomagnetic substorms is still uncertain due to lack of comprehensive quantitative analyses. Here, the authors construct an observational dispersion relation of auroral forms that correspond to the explosive energy release from substorm onset.

    • N. M. E. Kalmoni
    • , I. J. Rae
    • , C. E. J. Watt
    • , K. R. Murphy
    • , M. Samara
    • , R. G. Michell
    • , G. Grubbs
    •  & C. Forsyth
  • Article | | open

    Remote sensing of geomagnetic fields in mesosphere is both challenging and interesting to explore the magnetic field structures and atomic collision processes. Here the authors demonstrate an atomic magnetometer that utilizes the Larmor frequency in sodium atoms and operates in kilometers range.

    • Felipe Pedreros Bustos
    • , Domenico Bonaccini Calia
    • , Dmitry Budker
    • , Mauro Centrone
    • , Joschua Hellemeier
    • , Paul Hickson
    • , Ronald Holzlöhner
    •  & Simon Rochester
  • Article | | open

    Alumina is thought to be the main condensate to form in the gas outflow from oxygen-rich evolved stars. Here, the authors perform a condensation experiment with alumina in a low-gravity environment, and find spectroscopic evidence for a sharp feature at a wavelength of 13.55 μm.

    • Shinnosuke Ishizuka
    • , Yuki Kimura
    • , Itsuki Sakon
    • , Hiroshi Kimura
    • , Tomoya Yamazaki
    • , Shinsuke Takeuchi
    •  & Yuko Inatomi
  • Article | | open

    Tree rings retain information of sudden variations of ancient radiocarbon (14C) content, however the origin and exact timing of these events often remain uncertain. Here, the authors analyze a set of Arctic tree rings and link a rapid increase in 14C to a solar event that occurred during the spring of AD 774.

    • J. Uusitalo
    • , L. Arppe
    • , T. Hackman
    • , S. Helama
    • , G. Kovaltsov
    • , K. Mielikäinen
    • , H. Mäkinen
    • , P. Nöjd
    • , V. Palonen
    • , I. Usoskin
    •  & M. Oinonen
  • Article | | open

    The ionosphere can give rise to irregularities that can interfere with radio communication, navigation and satellite systems. Here the authors present unique observations from the Arecibo Radio Observatory in Puerto Rico to reveal the existence of plasma irregularities occur in the mid-latitude F-region.

    • David Hysell
    • , Miguel Larsen
    • , David Fritts
    • , Brian Laughman
    •  & Michael Sulzer
  • Article | | open

    Observations of Jupiter’s magnetosphere provide opportunities to understand how magnetic fields interact with particles. Here, the authors report that the chorus wave power is increased in the vicinity of Europa and Ganymede. The generated waves are able to accelerate particles to very high energy.

    • Y. Y. Shprits
    • , J. D. Menietti
    • , A. Y. Drozdov
    • , R. B. Horne
    • , E. E. Woodfield
    • , J. B. Groene
    • , M. de Soria-Santacruz
    • , T. F. Averkamp
    • , H. Garrett
    • , C. Paranicas
    •  & D. A. Gurnett
  • Article | | open

    The origin of the apparent impenetrable barrier in the outer Van Allen belt is still uncertain. Here, the authors report that penetration to the barrier can occur by means of ultra-low frequency wave transport, enabling ultra-relativistic electrons to reach the location of the barrier.

    • Louis G. Ozeke
    • , Ian R. Mann
    • , Kyle R. Murphy
    • , Alex W. Degeling
    • , Seth G. Claudepierre
    •  & Harlan E. Spence
  • Article | | open

    The IceCube Neutrino Observatory has been recording a flux of high-energy cosmic neutrinos since 2013. Here, the authors investigate the possibility of increasing its sensitivity by implementing wavelength shifting optics within IceCube’s drill holes.

    • Imre Bartos
    • , Zsuzsa Marka
    •  & Szabolcs Marka
  • Article | | open

    The NASA MESSENGER mission collected a rich dataset enabling determination of Mercury’s ephemeris. Here, the authors analyse MESSENGER data obtained over an extended period of time to quantify parameters related to General Relativity.

    • Antonio Genova
    • , Erwan Mazarico
    • , Sander Goossens
    • , Frank G. Lemoine
    • , Gregory A. Neumann
    • , David E. Smith
    •  & Maria T. Zuber
  • Article | | open

    Solar eruptions are large explosions occurring in the solar atmosphere. Here, the authors perform magnetohydrodynamic simulations to unveil the dynamics of a solar eruption, and find that these are dominated by nonlinear processes involving flux tube evolution and reconnection.

    • Satoshi Inoue
    • , Kanya Kusano
    • , Jörg Büchner
    •  & Jan Skála
  • Article | | open

    The violent solar eruptions known as flares are caused by magnetic reconnection. Here, the authors identify a sudden 12°–20° counter clockwise rotation of vector magnetic fields in photosphere, associated with the emissions of moving flare ribbons.

    • Yan Xu
    • , Wenda Cao
    • , Kwangsu Ahn
    • , Ju Jing
    • , Chang Liu
    • , Jongchul Chae
    • , Nengyi Huang
    • , Na Deng
    • , Dale E. Gary
    •  & Haimin Wang
  • Article | | open

    Ions produced by cosmic rays have been thought to influence aerosol and cloud processes by an unknown mechanism. Here the authors show that the mass flux of ions to aerosols enhances their growth significantly, with implications for the formation of cloud condensation nuclei.

    • H. Svensmark
    • , M. B. Enghoff
    • , N. J. Shaviv
    •  & J. Svensmark
  • Article | | open

    White-light flares are rare solar events entailing emission in the optical continuum. Here, the authors report a nearly circular white-light flare observed on March 10th 2015 that contains simultaneously both impulsive and gradual white-light kernels.

    • Q. Hao
    • , K. Yang
    • , X. Cheng
    • , Y. Guo
    • , C. Fang
    • , M. D. Ding
    • , P. F. Chen
    •  & Z. Li
  • Article | | open

    Vortex-induced reconnection originates from non-linear vortex flows due to Kelvin-Helmholtz instability in the Earth’s magnetosphere. Here, the authors perform a large-scale kinetic simulation to unveil dynamics of the vortex-induced reconnection and resulting turbulent mixing process.

    • T. K. M. Nakamura
    • , H. Hasegawa
    • , W. Daughton
    • , S. Eriksson
    • , W. Y. Li
    •  & R. Nakamura
  • Article | | open

    Radio observations of the solar atmosphere provide a unique view on the non-thermal processes in the outer atmosphere. Here the authors use LOFAR observations to demonstrate that the observed radio burst characteristics are dominated by propagation effects rather than underlying emission variations.

    • E. P. Kontar
    • , S. Yu
    • , A. A. Kuznetsov
    • , A. G. Emslie
    • , B. Alcock
    • , N. L. S. Jeffrey
    • , V. N. Melnik
    • , N. H. Bian
    •  & P. Subramanian
  • Article | | open

    14C can be absorbed by trees as a result of the interaction of cosmic rays produced by high-energy phenomena with the Earth’s atmosphere. Here, the authors observe a rapid increase of 14C in an ancient buried tree from BC 3372 to BC 3371, and suggest that it could originate from a large solar proton event.

    • F. Y. Wang
    • , H. Yu
    • , Y. C. Zou
    • , Z. G. Dai
    •  & K. S. Cheng
  • Article | | open

    Solar eruptions provide opportunities to study magnetic flux ropes, a structure of fundamental importance for both plasma physics and space weather. Here the authors reveal the dynamic formation of a flux rope through its footprint on the solar surface, revealing a highly twisted core structure.

    • Wensi Wang
    • , Rui Liu
    • , Yuming Wang
    • , Qiang Hu
    • , Chenglong Shen
    • , Chaowei Jiang
    •  & Chunming Zhu
  • Article | | open

    The Sun’s elemental composition is a vital part of understanding the processes that transport energy from the interior to the outer atmosphere. Here, the authors show that if the Sun is observed as a star, then the variation of coronal composition is highly correlated with the F10.7cm radio flux.

    • David H. Brooks
    • , Deborah Baker
    • , Lidia van Driel-Gesztelyi
    •  & Harry P. Warren
  • Article | | open

    The dynamic of plasma heating in solar flares can be effectively derived from observations of optical hydrogen H-α line emissions. Here the authors report the observation of a C1.5 class flare that produced two H-α ribbons, interpreted combining radiative models affected by an electron beam.

    • Malcolm Druett
    • , Eamon Scullion
    • , Valentina Zharkova
    • , Sarah Matthews
    • , Sergei Zharkov
    •  & Luc Rouppe Van der Voort
  • Article | | open

    Alfvén waves are fundamental plasma modes that provide a mechanism for the transfer of energy between particles and fields. Here the authors confirm experimentally the conservative energy exchange between Alfvén wave fields and plasma particles via high-resolution MMS observations of Earth’s magnetosphere.

    • Daniel J. Gershman
    • , Adolfo F-Viñas
    • , John C. Dorelli
    • , Scott A. Boardsen
    • , Levon A. Avanov
    • , Paul M. Bellan
    • , Steven J. Schwartz
    • , Benoit Lavraud
    • , Victoria N. Coffey
    • , Michael O. Chandler
    • , Yoshifumi Saito
    • , William R. Paterson
    • , Stephen A. Fuselier
    • , Robert E. Ergun
    • , Robert J. Strangeway
    • , Christopher T. Russell
    • , Barbara L. Giles
    • , Craig J. Pollock
    • , Roy B. Torbert
    •  & James L. Burch
  • Article | | open

    Back reaction of coronal magnetic fields on the solar surface may help to understand the coronal reconfiguration during a solar flare. Here the authors report observation of reversal of the rotation of a sunspot during a X1.6 flare with data from HMI.

    • Yi Bi
    • , Yunchun Jiang
    • , Jiayan Yang
    • , Junchao Hong
    • , Haidong Li
    • , Bo Yang
    •  & Zhe Xu
  • Article | | open

    Atom interferometers in microgravity environments can reach precisions unattainable on Earth. Here the authors report the operation of a dual species interferometer onboard a zero-G aircraft, testing universality of free fall in microgravity and providing a test bed for future moving inertial sensors.

    • Brynle Barrett
    • , Laura Antoni-Micollier
    • , Laure Chichet
    • , Baptiste Battelier
    • , Thomas Lévèque
    • , Arnaud Landragin
    •  & Philippe Bouyer
  • Article | | open

    Model predictions of atomic hydrogen behaviour in the terrestrial atmosphere have long-standing discrepancies with geocoronal observations. Here, using satellite measurements, Qin and Waldrop note the existence of hot hydrogen atoms in the upper thermosphere, reconciling observational modelling differences.

    • Jianqi Qin
    •  & Lara Waldrop
  • Article | | open

    Sunspots are concentration of magnetic field visible on the solar surface, which were thought to be unaffected by solar flares that take place in the solar corona. Here the authors report evidence of a flare-induced rotation of a sunspot, showing nonuniform acceleration following the peaks of X-ray emissions.

    • Chang Liu
    • , Yan Xu
    • , Wenda Cao
    • , Na Deng
    • , Jeongwoo Lee
    • , Hugh S. Hudson
    • , Dale E. Gary
    • , Jiasheng Wang
    • , Ju Jing
    •  & Haimin Wang
  • Article | | open

    The interaction between the Earth’s magnetic field and the solar wind results in the formation of a collisionless bow shock. Here, the authors study an even in which the solar wind Mach number remained steadily below one, leading to the evanescence of the bow shock and loss of electrons in the outer belts.

    • Noé Lugaz
    • , Charles J. Farrugia
    • , Chia-Lin Huang
    • , Reka M. Winslow
    • , Harlan E. Spence
    •  & Nathan A. Schwadron
  • Article | | open

    The processes that lead to losses of highly energetic particles from Earth’s radiation belts remain poorly understood. Here the authors compare observations and models of a 2013 event to show that electromagnetic ioncyclotron waves provide the dominant loss mechanism at ultra-relativistic energies.

    • Yuri Y. Shprits
    • , Alexander Y. Drozdov
    • , Maria Spasojevic
    • , Adam C. Kellerman
    • , Maria E. Usanova
    • , Mark J. Engebretson
    • , Oleksiy V. Agapitov
    • , Irina S. Zhelavskaya
    • , Tero J. Raita
    • , Harlan E. Spence
    • , Daniel N. Baker
    • , Hui Zhu
    •  & Nikita A. Aseev
  • Article | | open

    The causes behind fluctuations in Neptune's brightness as observed from Earth have proved enigmatic. Here, Aplin and Harrison use photometric observations to show that solar ultraviolet radiation and galactic cosmic rays combined are responsible for the fluctuations originating in Neptune’s atmosphere.

    • K. L. Aplin
    •  & R. G. Harrison
  • Article | | open

    Magnetic reconnection is a fundamental process giving rise to topology change and energy release in plasmas, of particular relevance for the Sun. Here the authors report the observation of fast reconnection in a solar filament eruption, which occurs between a set of ambient fibrils and the filament itself.

    • Zhike Xue
    • , Xiaoli Yan
    • , Xin Cheng
    • , Liheng Yang
    • , Yingna Su
    • , Bernhard Kliem
    • , Jun Zhang
    • , Zhong Liu
    • , Yi Bi
    • , Yongyuan Xiang
    • , Kai Yang
    •  & Li Zhao
  • Article | | open

    Natural spikes in radiocarbon have been identified at ᴀᴅ 774/5 and 993/4 and attributed to exceptional cosmic-ray events, although the cause remains uncertain. Here, the authors analyse records recovered from ice cores and suggest these spikes originated from extreme solar particle events.

    • Florian Mekhaldi
    • , Raimund Muscheler
    • , Florian Adolphi
    • , Ala Aldahan
    • , Jürg Beer
    • , Joseph R. McConnell
    • , Göran Possnert
    • , Michael Sigl
    • , Anders Svensson
    • , Hans-Arno Synal
    • , Kees C. Welten
    •  & Thomas E. Woodruff
  • Article | | open

    Relativistic electrons trapped in the Van Allen radiation belts sometimes exhibit a minimum of their pitch angle distribution at 90°. Here, the authors explain the origin of this phenomenon in terms of chorus and magnetosonic waves through simulations and observations of a geomagnetic storm data.

    • Fuliang Xiao
    • , Chang Yang
    • , Zhenpeng Su
    • , Qinghua Zhou
    • , Zhaoguo He
    • , Yihua He
    • , D. N. Baker
    • , H. E. Spence
    • , H. O. Funsten
    •  & J. B. Blake
  • Article | | open

    Since the 1970s space missions have observed `equatorial noise' — noise-like plasma waves closely confined to the magnetic equatorial region of Earth s magnetosphere. Here, the authors uncover their structured and periodic frequency pattern, revealing that they are generated by proton distributions.

    • Michael A. Balikhin
    • , Yuri Y. Shprits
    • , Simon N. Walker
    • , Lunjin Chen
    • , Nicole Cornilleau-Wehrlin
    • , Iannis Dandouras
    • , Ondrej Santolik
    • , Christopher Carr
    • , Keith H. Yearby
    •  & Benjamin Weiss
  • Article | | open

    Magnetic reconnection is a fundamental energy release process taking place in various astrophysical environments, but it is difficult to observe it directly. Here, the authors provide evidence of three-dimensional magnetic reconnection in a solar eruption using combined perspectives of two spacecraft.

    • J. Q. Sun
    • , X. Cheng
    • , M. D. Ding
    • , Y. Guo
    • , E. R. Priest
    • , C. E. Parnell
    • , S. J. Edwards
    • , J. Zhang
    • , P. F. Chen
    •  & C. Fang
  • Article | | open

    Regional surface climate response to a future decline in solar activity remains uncertain. Here, via numerical simulations, the authors show that a return to Maunder Minimum-like lows by 2050 could lead to some areas of significantly reduced surface warming via modulation of the North Atlantic Oscillation.

    • Sarah Ineson
    • , Amanda C. Maycock
    • , Lesley J. Gray
    • , Adam A. Scaife
    • , Nick J. Dunstone
    • , Jerald W. Harder
    • , Jeff R. Knight
    • , Mike Lockwood
    • , James C. Manners
    •  & Richard A. Wood
  • Article | | open

    Coronal mass ejections from the Sun play an important role in space weather, yet a full understanding of their behaviour remains elusive. Towards this aim, Möstl et al. present a suite of observations showing that an ejection was channelled away from its source region, explaining incorrect forecasts.

    • Christian Möstl
    • , Tanja Rollett
    • , Rudy A. Frahm
    • , Ying D. Liu
    • , David M. Long
    • , Robin C. Colaninno
    • , Martin A. Reiss
    • , Manuela Temmer
    • , Charles J. Farrugia
    • , Arik Posner
    • , Mateja Dumbović
    • , Miho Janvier
    • , Pascal Démoulin
    • , Peter Boakes
    • , Andy Devos
    • , Emil Kraaikamp
    • , Mona L. Mays
    •  & Bojan Vršnak
  • Article | | open

    Whistler-mode waves regulate trapped electrons in the magnetosphere, but an accurate determination of their energy budget has remained elusive. This study presents a full analysis of their magnetic and electric field contributions and finds that a large amount of energy is stored in oblique waves.

    • A.V. Artemyev
    • , O.V. Agapitov
    • , D. Mourenas
    • , V.V. Krasnoselskikh
    •  & F.S. Mozer
  • Article | | open

    Although magnetic reconnection is recognized as the dominant mode for solar wind plasma to enter the magnetosphere, Kelvin–Helmholtz waves (KHW) have been suggested to also be involved. Here, the authors use 7 years of THEMIS data to show that KHW occur 19% of the time, and may be important for plasma transport.

    • Shiva Kavosi
    •  & Joachim Raeder
  • Article | | open

    The origins of the Sun’s periodic activity, such as sunspot cycles, are poorly understood. McIntosh et al. posit that the rotational forcing of the activity bands comprising the 22-year magnetic cycle undergoes shorter-term variations, driving magnetic flux surges that impact solar output on those timescales.

    • Scott W. McIntosh
    • , Robert J. Leamon
    • , Larisza D. Krista
    • , Alan M. Title
    • , Hugh S. Hudson
    • , Pete Riley
    • , Jerald W. Harder
    • , Greg Kopp
    • , Martin Snow
    • , Thomas N. Woods
    • , Justin C. Kasper
    • , Michael L. Stevens
    •  & Roger K. Ulrich
  • Article |

    Lunar swirls are high-albedo features on the Moon whose origins are widely debated. Using observations from the Diviner Lunar Radiometer, Glotch et al. present evidence supporting the idea that the swirls arise from abnormal space weathering caused by local magnetic field deflection of solar wind.

    • Timothy D. Glotch
    • , Joshua L. Bandfield
    • , Paul G. Lucey
    • , Paul O. Hayne
    • , Benjamin T. Greenhagen
    • , Jessica A. Arnold
    • , Rebecca R. Ghent
    •  & David A. Paige
  • Article | | open

    Both fast and slow solar winds emanate from our Sun, although the source of the slow component remains elusive. Towards identifying this, Brooks et al. present full-Sun spectral images from Hinode, combined with magnetic modelling, to produce a solar wind source map.

    • David H. Brooks
    • , Ignacio Ugarte-Urra
    •  & Harry P. Warren
  • Article |

    Solar flares follow complex statistical patterns, making it hard to understand and model their underlying physical processes. Here, the authors present a model based on reconnection of magnetic flux tubes twisted by turbulent photospheric flow that reproduces flare statistics and energy–time correlations.

    • M. Mendoza
    • , A. Kaydul
    • , L. de Arcangelis
    • , J. S. Andrade Jr
    •  & H. J. Herrmann