Search Publications
The afterglow of GRB 050709 and the nature of the short-hard γ-ray bursts
Cenko, S. B.; Peterson, B. A.; Price, P. A. +33 more
The final chapter in the long-standing mystery of the γ-ray bursts (GRBs) centres on the origin of the short-hard class of bursts, which are suspected on theoretical grounds to result from the coalescence of neutron-star or black-hole binary systems. Numerous searches for the afterglows of short-hard bursts have been made, galvanized by the revolu…
A planetary system as the origin of structure in Fomalhaut's dust belt
Kalas, Paul; Graham, James R.; Clampin, Mark
The Sun and >15per cent of nearby stars are surrounded by dusty disks that must be collisionally replenished by asteroids and comets, as the dust would otherwise be depleted on timescales <107years (ref. 1). Theoretical studies show that the structure of a dusty disk can be modified by the gravitational influence of planets, but t…
An upper limit to the masses of stars
Figer, Donald F.
There is no accepted upper mass limit for stars. Such a basic quantity eludes both theory and observation, because of an imperfect understanding of the star-formation process and because of incompleteness in surveying the Galaxy. The Arches cluster is ideal for investigating such limits, being large enough to expect stars at least as massive as ~5…
Differentiation of the asteroid Ceres as revealed by its shape
Russell, C. T.; Stern, S. A.; Young, E. F. +4 more
The accretion of bodies in the asteroid belt was halted nearly 4.6billion years ago by the gravitational influence of the newly formed giant planet Jupiter. The asteroid belt therefore preserves a record of both this earliest epoch of Solar System formation and variation of conditions within the solar nebula. Spectral features in reflected sunligh…
The mass of the missing baryons in the X-ray forest of the warm-hot intergalactic medium
Elvis, Martin; Zezas, Andreas; Marshall, Herman +7 more
Recent cosmological measurements indicate that baryons comprise about four per cent of the total mass-energy density of the Universe, which is in accord with the predictions arising from studies of the production of the lightest elements. It is also in agreement with the actual number of baryons detected at early times (redshifts z > 2). Close …
Morphological differences between Saturn's ultraviolet aurorae and those of Earth and Jupiter
Kim, J.; Hill, T.; Crary, F. +10 more
It has often been stated that Saturn's magnetosphere and aurorae are intermediate between those of Earth, where the dominant processes are solar wind driven, and those of Jupiter, where processes are driven by a large source of internal plasma. But this view is based on information about Saturn that is far inferior to what is now available. Here w…
Solar wind dynamic pressure and electric field as the main factors controlling Saturn's aurorae
Coates, A. J.; Dougherty, M. K.; Kurth, W. S. +11 more
The interaction of the solar wind with Earth's magnetosphere gives rise to the bright polar aurorae and to geomagnetic storms, but the relation between the solar wind and the dynamics of the outer planets' magnetospheres is poorly understood. Jupiter's magnetospheric dynamics and aurorae are dominated by processes internal to the jovian system, wh…
An Earth-like correspondence between Saturn's auroral features and radio emission
Gurnett, D. A.; Dougherty, M. K.; Kurth, W. S. +12 more
Saturn is a source of intense kilometre-wavelength radio emissions that are believed to be associated with its polar aurorae, and which provide an important remote diagnostic of its magnetospheric activity. Previous observations implied that the radio emission originated in the polar regions, and indicated a strong correlation with solar wind dyna…
Discovery of a bright quasar without a massive host galaxy
Wisotzki, Lutz; Jablonka, Pascale; Courbin, Frédéric +4 more
A quasar is thought to be powered by the infall of matter onto a supermassive black hole at the centre of a massive galaxy. Because the optical luminosity of quasars exceeds that of their host galaxy, disentangling the two components can be difficult. This led in the 1990s to the controversial claim of the discovery of `naked' quasars. Since then,…