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Continuous magnetic reconnection at Earth's magnetopause
Fuselier, S. A.; Mende, S. B.; Frey, H. U. +1 more
The most important process that allows solar-wind plasma to cross the magnetopause and enter Earth's magnetosphere is the merging between solar-wind and terrestrial magnetic fields of opposite sense-magnetic reconnection. It is at present not known whether reconnection can happen in a continuous fashion or whether it is always intermittent. Solar …
An extragalactic supernebula confined by gravity
Larkin, J. E.; Turner, J. L.; Beck, S. C. +3 more
Little is known about the origins of globular clusters, which contain hundreds of thousands of stars in a volume only a few light years across. Radiation pressure and winds from luminous young stars should disperse the star-forming gas and disrupt the formation of the cluster. Globular clusters in our Galaxy cannot provide answers; they are billio…
A strong decrease in Saturn's equatorial jet at cloud level
Hueso, R.; Sánchez-Lavega, A.; Rojas, J. F. +2 more
The atmospheres of the giant planets Jupiter and Saturn have a puzzling system of zonal (east-west) winds alternating in latitude, with the broad and intense equatorial jets on Saturn having been observed previously to reach a velocity of about 470ms-1 at cloud level. Globally, the location and intensity of Jupiter's jets are stable in …
A collimated, high-speed outflow from the dying star V Hydrae
Sahai, R.; Knapp, G. R.; Young, K. +2 more
Stars with masses in the range 1-8 solar masses (M⊙) live ordinary lives for ~109-1010 years, but die extraordinary deaths. First, during their death throes as asymptotic giant branch (AGB) stars they eject, over 104-105 years, half or more of their mass in slowly expanding, spherical winds, a…
Gravitationally redshifted absorption lines in the X-ray burst spectra of a neutron star
Mendez, M.; Paerels, F.; Cottam, J.
The fundamental properties of neutron stars provide a direct test of the equation of state of cold nuclear matter, a relationship between pressure and density that is determined by the physics of the strong interactions between the particles that constitute the star. The most straightforward method of determining these properties is by measuring t…
The signature of supernova ejecta in the X-ray afterglow of the γ-ray burst 011211
Schartel, N.; Ehle, M.; Watson, D. +8 more
Now that γ-ray bursts (GRBs) have been determined to lie at cosmological distances, their isotropic burst energies are estimated to be as high as 1054erg (ref. 2), making them the most energetic phenomena in the Universe. The nature of the progenitors responsible for the bursts remains, however, elusive. The favoured models range from t…
Ultraviolet emissions from the magnetic footprints of Io, Ganymede and Europa on Jupiter
Clarke, J. T.; Waite, J. H.; Ballester, G. +8 more
Io leaves a magnetic footprint on Jupiter's upper atmosphere that appears as a spot of ultraviolet emission that remains fixed underneath Io as Jupiter rotates. The specific physical mechanisms responsible for generating those emissions are not well understood, but in general the spot seems to arise because of an electromagnetic interaction betwee…
A pulsating auroral X-ray hot spot on Jupiter
Dougherty, M. K.; Young, D. T.; Clarke, J. T. +12 more
Jupiter's X-ray aurora has been thought to be excited by energetic sulphur and oxygen ions precipitating from the inner magnetosphere into the planet's polar regions. Here we report high-spatial-resolution observations that demonstrate that most of Jupiter's northern auroral X-rays come from a `hot spot' located significantly poleward of the latit…
Control of Jupiter's radio emission and aurorae by the solar wind
Gurnett, D. A.; Persoon, A. M.; Dougherty, M. K. +14 more
Radio emissions from Jupiter provided the first evidence that this giant planet has a strong magnetic field and a large magnetosphere. Jupiter also has polar aurorae, which are similar in many respects to Earth's aurorae. The radio emissions are believed to be generated along the high-latitude magnetic field lines by the same electrons that produc…
Identification of iron sulphide grains in protoplanetary disks
Waters, L. B. F. M.; Mutschke, H.; Henning, T. +8 more
Sulphur is depleted in cold dense molecular clouds with embedded young stellar objects, indicating that most of it probably resides in solid grains. Iron sulphide grains are the main sulphur species in cometary dust particles, but there has been no direct evidence for FeS in astronomical sources, which poses a considerable problem, because sulphur…