Search Publications
Discovery of a supernova explosion at half the age of the Universe
Panagia, N.; Lidman, C.; Aldering, G. +19 more
The ultimate fate of the Universe, infinite expansion or a big crunch, can be determined by using the redshifts and distances of very distant supernovae to monitor changes in the expansion rate. We can now find large numbers of these distant supernovae, and measure their redshifts and apparent brightnesses; moreover, recent studies of nearby type …
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…
X-ray flare sparks quake inside Sun
Kosovichev, A. G.; Zharkova, V. V.
Solar flares involve a release of the Sun's magnetic energy as X-radiation, particle beams and high-speed plasma flows. But we have discovered, using data from the Solar and Heliospheric Observatory (SOHO), that these flares also affect the Sun's interior, generating seismic waves similar to earthquakes. For example, a three-kilometre-high seismic…
Large-scale coronal heating by the small-scale magnetic field of the Sun
Schrijver, C. J.; Tarbell, T. D.; Shine, R. A. +6 more
Magnetic fields play a crucial role in heating the outer atmospheres of the Sun and Sun-like stars, but the mechanisms by which magnetic energy in the photosphere is converted to thermal energy in the corona remain unclear. Observations show that magnetic fields emerge onto the solar surface as bipolar regions with a broad range of length scales. …
Detection of intergalactic red-giant-branch stars in the Virgo cluster
Ferguson, Henry C.; von Hippel, Ted; Tanvir, Nial R.
It has been suspected for nearly 50 years that galaxy clusters contain a population of intergalactic stars ripped from the galaxies during cluster formation, or when the galactic orbits pass through the cluster centre. Observational support for theexistence of such a stellar population is provided both by measurements of the diffuse light in clust…
The sun's shape and brightness
Kuhn, J. R.; Bush, R. I.; Scherrer, P. +1 more
We present satellite data that show that the sun's shape and temperature vary with latitude in an unexpectedly complex way. Although the solar oblateness shows no evidence of varying with the solar cycle, we find a significant hexadecapole shape term which may vary. We also see a variation of about 1.5 K in the surface temperature with latitude. B…
Long-lived giant cells detected at the surface of the Sun
Scherrer, P. H.; Duvall, T. L.; Beck, J. G.
Giant convective cells have been predicted to exist in the Sun. Such cells should span the entire zone unstable to convective motions - now known to cover the outer 29 per cent of the Sun's radius - and could be dredging up the magnetic flux that is thought to be the source of solar activity (sunspots). Several studies have failed to detect these …
Birth and early evolution of a planetary nebula
Bobrowsky, Matthew; Sahu, Kailash C.; Parthasarathy, M. +1 more
The final expulsion of gas by a star as it forms a planetary nebula - the ionized shell of gas often observed surrounding a young white dwarf - is one of the most poorly understood stages of stellar evolution,. Such nebulae form extremely rapidly (about 100 years for the ionization) and so the formation process is inherently difficult to observe. …
Global warming on Triton
Olkin, C. B.; Franz, O. G.; Buie, M. W. +11 more
Triton, Neptune's largest moon, has been predicted to undergo significant seasonal changes that would reveal themselves as changes in its mean frost temperature. But whether this temperature should at the present time be increasing, decreasing or constant depends on a number of parameters (such as the thermal properties of the surface, and frost m…
A Cepheid distance to the Fornax cluster and the local expansion rate of the Universe
Illingworth, Garth D.; Madore, Barry F.; Freedman, Wendy L. +13 more
Both galaxy distances and velocities are required for the determination of the expansion rate of the Universe, as described by the Hubble constant H0. The radial velocities of galaxies arise not just from this expansion but also from random components and large-scale flows. To reach out to distances dominated by the overall cosmic expan…