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A test of general relativity using radio links with the Cassini spacecraft
Iess, L.; Tortora, P.; Bertotti, B.
According to general relativity, photons are deflected and delayed by the curvature of space-time produced by any mass. The bending and delay are proportional to γ + 1, where the parameter γ is unity in general relativity but zero in the newtonian model of gravity. The quantity γ - 1 measures the degree to which gravity is not a purely geometric e…
An extended upper atmosphere around the extrasolar planet HD209458b
Lecavelier des Etangs, A.; Ferlet, R.; Vidal-Madjar, A. +4 more
The planet in the system HD209458 is the first one for which repeated transits across the stellar disk have been observed. Together with radial velocity measurements, this has led to a determination of the planet's radius and mass, confirming it to be a gas giant. But despite numerous searches for an atmospheric signature, only the dense lower atm…
A class of compact dwarf galaxies from disruptive processes in galaxy clusters
Ferguson, H. C.; Hilker, M.; Drinkwater, M. J. +5 more
Dwarf galaxies have attracted increased attention in recent years, because of their susceptibility to galaxy transformation processes within rich galaxy clusters. Direct evidence for these processes, however, has been difficult to obtain, with a small number of diffuse light trails and intra-cluster stars being the only signs of galaxy disruption.…
An energetic stellar outburst accompanied by circumstellar light echoes
Munari, U.; Sparks, William B.; Bond, Howard E. +6 more
Some classes of stars, including novae and supernovae, undergo explosive outbursts that eject stellar material into space. In 2002, the previously unknown variable star V838 Monocerotis brightened suddenly by a factor of ~104. Unlike a supernova or nova, it did not explosively eject its outer layers; rather, it simply expanded to become…
The magnetic field of an isolated neutron star from X-ray cyclotron absorption lines
Caraveo, P. A.; Bignami, G. F.; Mereghetti, S. +1 more
Isolated neutron stars are highly magnetized, fast-rotating objects that form as an end point of stellar evolution. They are directly observable in X-ray emission, because of their high surface temperatures. Features in their X-ray spectra could in principle reveal the presence of atmospheres, or be used to estimate the strength of their magnetic …
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…