Search Publications
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…
Ultra-relativistic electrons in Jupiter's radiation belts
Johnson, W. T. K.; Klein, M.; Hofstadter, M. +18 more
Ground-based observations have shown that Jupiter is a two-component source of microwave radio emission: thermal atmospheric emission and synchrotron emission from energetic electrons spiralling in Jupiter's magnetic field. Later in situ measurements confirmed the existence of Jupiter's high-energy electron-radiation belts, with evidence for elect…
Transient aurora on Jupiter from injections of magnetospheric electrons
Clarke, J. T.; Waite, J. H.; Mauk, B. H. +3 more
Energetic electrons and ions that are trapped in Earth's magnetosphere can suddenly be accelerated towards the planet. Some dynamic features of Earth's aurora (the northern and southern lights) are created by the fraction of these injected particles that travels along magnetic field lines and hits the upper atmosphere. Jupiter's aurora appears sim…
The binary Kuiper-belt object 1998 WW31
Parker, Joel Wm.; Tholen, David J.; Holman, Matthew J. +6 more
The recent discovery of a binary asteroid during a spacecraft fly-by generated keen interest, because the orbital parameters of binaries can provide measures of the masses, and mutual eclipses could allow us to determine individual sizes and bulk densities. Several binary near-Earth, main-belt and Trojan…
The dusk flank of Jupiter's magnetosphere
Gurnett, D. A.; Dougherty, M. K.; Hospodarsky, G. B. +8 more
Limited single-spacecraft observations of Jupiter's magnetopause have been used to infer that the boundary moves inward or outward in response to variations in the dynamic pressure of the solar wind. At Earth, multiple-spacecraft observations have been implemented to understand the physics of how this motion occurs, because they can provide a snap…