Search Publications
Interception of comet Hyakutake's ion tail at a distance of 500 million kilometres
Balsiger, H.; Geiss, J.; Schwadron, N. A. +6 more
Remote sensing observations and the direct sampling of material from a few comets have established the characteristic composition of cometary gas. This gas is ionized by solar ultraviolet radiation and the solar wind to form `pick-up' ions, ions in a low ionization state that retain the same compositional signatures as the original gas. The pick-u…
Identification of comet Hyakutake's extremely long ion tail from magnetic field signatures
Balogh, André; Jones, Geraint H.; Horbury, Timothy S.
Observations of the varying orientations of comet tails led to the suggestion of the existence of the solar wind-a continuous outflow of ionized material from the Sun. It is now well established that gas from comets is ionized by several processes and joins the solar wind, forming an ion (plasma) tail that points away from the Sun. The plasma envi…
A giant periodic flare from the soft γ-ray repeater SGR1900+14
Cline, T.; Hurley, K.; Golenetskii, S. +11 more
Soft γ-ray repeaters are transient sources of high-energy photons; they emit sporadic and short (about 0.1s) bursts of `soft' γ-rays during periods of activity, which are often broken by long stretches of quiescence. These objects are associated with neutron stars in young supernova remnants. The event of 5 March 1979 was the most intense burst to…
An unusual supernova in the error box of the γ-ray burst of 25 April 1998
Piro, L.; Pian, E.; Palazzi, E. +46 more
The discovery of afterglows associated with γ-ray bursts at X-ray, optical and radio wavelengths and the measurement of the redshifts of some of these events, has established that γ-ray bursts lie at extreme distances, making them the most powerful photon-emitters known in the Universe. Here we report the discovery of transient optical emission in…
Anomalously small magnetic field in the local interstellar cloud
Gloeckler, George; Geiss, Johannes; Fisk, L. A.
The solar wind carves out a cavity, known as the heliosphere, in the warm local interstellar cloud, which is itself embedded in a larger hot cloud. It is generally assumed that there is an overall pressure balance between these three regions. Thermal pressure and magnetic field pressure in the local interstellar cloud should therefore balance the …
Abundance of 3He in the local interstellar cloud
Gloeckler, George; Geiss, Johannes
THE primordial abundances of the light elements and their isotopes provide essential information regarding the nucleosynthetic processes that occurred in the Big Bang1,2. At present the best estimates of the baryon/photon ratio of the Universe, a fundamental cosmological parameter, are extrapolations to primordial times of light-element…
Propagation of solar oscillations through the interplanetary medium
Lanzerotti, Louis J.; Thomson, David J.; Maclennan, Carol G.
Time-series analysis of the fluxes of interplanetary charged particles measured by the Ulysses and Voyager spacecraft reveals many periodic components. From 1 to 140 µHz, the spectral components are consistent with those estimated (but not confirmed) for gravity-mode oscillations of the Sun: from 1,000 to 4,000 µHz, the spectral lines closely matc…
Detection of a γ-ray burst of very long duration and very high energy
Cline, T.; Hurley, K.; Fishman, G. J. +24 more
ALTHOUGH γ-ray bursts (GRBs) have been known for more than 20 years, their origin remains mysterious1. Suggestions have ranged from nearby colliding comets2 to merging neutron stars at cosmological distances3. The lack of any counterpart at wavelengths other than X-rays and γ-rays has posed a major problem in ident…
Discovery of Jovian dust streams and interstellar grains by the Ulysses spacecraft
Forsyth, R.; Balogh, A.; Bame, S. J. +20 more
ON 8 February 1992, the Ulysses spacecraft flew by Jupiter at a distance of 5.4 AU from the Sun. During the encounter, the spacecraft was deflected into a new orbit, inclined at about 80° to the ecliptic plane, which will ultimately lead Ulysses over the polar regions of the Sun1. Within 1 AU from Jupiter, the onboard dust de…
Mechanism for the acceleration and ejection of dust grains from Jupiter's magnetosphere
Horanyi, M.; Grun, E.; Morfill, G.
PERHAPS the most unexpected finding of the Ulysses mission so far has been the detection of quasi-periodic streams of high-velocity, submicrometre-sized dust particles during the spacecraft's encounter with Jupiter1. The impact geometry clearly shows that these small grains originate in the jovian system, but it is surprising that any d…