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An enduring rapidly moving storm as a guide to Saturn's Equatorial jet's complex structure
Hueso, R.; Sánchez-Lavega, A.; Rojas, J. F. +13 more
Saturn has an intense and broad eastward equatorial jet with a complex three-dimensional structure mixed with time variability. The equatorial region experiences strong seasonal insolation variations enhanced by ring shadowing, and three of the six known giant planetary-scale storms have developed in it. These factors make Saturn's equator a natur…
Strong coronal channelling and interplanetary evolution of a solar storm up to Earth and Mars
Dumbović, Mateja; Temmer, Manuela; Vršnak, Bojan +15 more
The severe geomagnetic effects of solar storms or coronal mass ejections (CMEs) are to a large degree determined by their propagation direction with respect to Earth. There is a lack of understanding of the processes that determine their non-radial propagation. Here we present a synthesis of data from seven different space missions of a fast CME, …
Full-Sun observations for identifying the source of the slow solar wind
Warren, Harry P.; Ugarte-Urra, Ignacio; Brooks, David H.
Fast (>700 km s-1) and slow (~400 km s-1) winds stream from the Sun, permeate the heliosphere and influence the near-Earth environment. While the fast wind is known to emanate primarily from polar coronal holes, the source of the slow wind remains unknown. Here we identify possible sites of origin using a slow solar wind s…
The solar magnetic activity band interaction and instabilities that shape quasi-periodic variability
McIntosh, Scott W.; Riley, Pete; Kasper, Justin C. +10 more
Solar magnetism displays a host of variational timescales of which the enigmatic 11-year sunspot cycle is most prominent. Recent work has demonstrated that the sunspot cycle can be explained in terms of the intra- and extra-hemispheric interaction between the overlapping activity bands of the 22-year magnetic polarity cycle. Those activity bands a…
Observations of discrete harmonics emerging from equatorial noise
Dandouras, Iannis; Walker, Simon N.; Balikhin, Michael A. +7 more
A number of modes of oscillations of particles and fields can exist in space plasmas. Since the early 1970s, space missions have observed noise-like plasma waves near the geomagnetic equator known as `equatorial noise'. Several theories were suggested, but clear observational evidence supported by realistic modelling has not been provided. Here we…
Wave energy budget analysis in the Earth's radiation belts uncovers a missing energy
Artemyev, A. V.; Agapitov, O. V.; Mozer, F. S. +2 more
Whistler-mode emissions are important electromagnetic waves pervasive in the Earth's magnetosphere, where they continuously remove or energize electrons trapped by the geomagnetic field, controlling radiation hazards to satellites and astronauts and the upper-atmosphere ionization or chemical composition. Here, we report an analysis of 10-year Clu…
Using the transit of Venus to probe the upper planetary atmosphere
Piccioni, Giuseppe; Reale, Fabio; Widemann, Thomas +3 more
During a planetary transit, atoms with high atomic number absorb short-wavelength radiation in the upper atmosphere, and the planet should appear larger during a primary transit observed in high-energy bands than in the optical band. Here we measure the radius of Venus with subpixel accuracy during the transit in 2012 observed in the optical, ultr…
Observations of an extreme storm in interplanetary space caused by successive coronal mass ejections
Kajdič, Primož; Lavraud, Benoit; Nitta, Nariaki V. +8 more
Space weather refers to dynamic conditions on the Sun and in the space environment of the Earth, which are often driven by solar eruptions and their subsequent interplanetary disturbances. It has been unclear how an extreme space weather storm forms and how severe it can be. Here we report and investigate an extreme event with multi-point remote-s…
Discovery of X-ray pulsations from a massive star
Huenemoerder, David P.; Ignace, Richard; Hamann, Wolf-Rainer +4 more
X-ray emission from stars much more massive than the Sun was discovered only 35 years ago. Such stars drive fast stellar winds where shocks can develop, and it is commonly assumed that the X-rays emerge from the shock-heated plasma. Many massive stars additionally pulsate. However, hitherto it was neither theoretically predicted nor observed that …
Solar wind entry into the high-latitude terrestrial magnetosphere during geomagnetically quiet times
Wei, Y.; Zhang, H.; Zong, Q. -G. +14 more
An understanding of the transport of solar wind plasma into and throughout the terrestrial magnetosphere is crucial to space science and space weather. For non-active periods, there is little agreement on where and how plasma entry into the magnetosphere might occur. Moreover, behaviour in the high-latitude region behind the magnetospheric cusps, …