Featured
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Article |
A measurement of the equation of state of carbon envelopes of white dwarfs
Researchers have measured the equation of state of hydrocarbon in a high-density regime, which is necessary for accurate modelling of the oscillations of white dwarf stars.
- Andrea L. Kritcher
- , Damian C. Swift
- & Siegfried H. Glenzer
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Article |
Alfvénic velocity spikes and rotational flows in the near-Sun solar wind
Data collected by the Parker Solar Probe in the solar corona are used to determine the organization of Alfvén waves, revealing an increasing flow velocity peaking at 35–50 km s−1.
- J. C. Kasper
- , S. D. Bale
- & N. A. Schwadron
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Letter |
Resolved atomic lines reveal outflows in two ultraluminous X-ray sources
Ultraluminous X-ray sources are thought to be powered by accretion onto a compact object; now the discovery of X-ray emission lines and blueshifted absorption lines in the high-resolution spectra of ultraluminous X-ray sources NGC 1313 X-1 and NGC 5408 X-1 shows that in each case the compact object is surrounded by powerful winds with an outflow velocity of about 0.2 times that of light.
- Ciro Pinto
- , Matthew J. Middleton
- & Andrew C. Fabian
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Letter |
A dynamic magnetic tension force as the cause of failed solar eruptions
Coronal mass ejections are driven by a sudden release of magnetic energy stored in flux ropes in the Sun’s corona, but when the ambient magnetic field that runs toroidally along an unstable flux rope is strong enough to prevent the flux rope from kinking, a dynamic magnetic tension force halts the eruption.
- Clayton E. Myers
- , Masaaki Yamada
- & Edward E. DeLuca
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Letter |
A higher-than-predicted measurement of iron opacity at solar interior temperatures
Laboratory measurements of iron opacity made under conditions similar to those inside the Sun reveal much higher opacity than predicted, helping to resolve inconsistencies within stellar models of the internal temperatures of stars.
- J. E. Bailey
- , T. Nagayama
- & B. G. Wilson
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Letter |
Flux-freezing breakdown in high-conductivity magnetohydrodynamic turbulence
A magnetohydrodynamic simulation of a magnetized plasma at high conductivity shows that, whereas the magnetic flux can be considered ‘frozen’ into the medium for laminar flow, in a turbulent medium the motion of the field lines can become indeterministic, leading to a breakdown in flux freezing.
- Gregory Eyink
- , Ethan Vishniac
- & Alexander Szalay
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Letter |
No meridional plasma flow in the heliosheath transition region
The radially outward flow of plasma from the Sun is expected to be deflected when it meets the flow of interstellar plasma through which the Solar System moves, but the spacecraft Voyager 1 unexpectedly finds that the deflected, meridional, flow is consistent with zero within the transition region.
- Robert B. Decker
- , Stamatios M. Krimigis
- & Matthew E. Hill
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Research Highlights |
Mercury's plasma belt
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Letter |
Zero outward flow velocity for plasma in a heliosheath transition layer
- Stamatios M. Krimigis
- , Edmond C. Roelof
- & Matthew E. Hill
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Letter |
A large coronal loop in the Algol system
The close binary Algol system contains a radio-bright KIV sub-giant star in a very close and rapid orbit with a main sequence B8 star. Evidence points to the existence of an extended, complex coronal magnetosphere originating at the cooler K subgiant, but the detailed morphology of the subgiant's corona and its possible interaction with its companion are unknown. Multi-epoch radio imaging of the Algol system now reveals a large coronal loop suggestive of a persistent asymmetric magnetic field structure aligned between the two stars.
- W. M. Peterson
- , R. L. Mutel
- & W. M. Goss
Observing the onset of pressure-driven K-shell delocalization