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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…

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…