Search Publications
Warm water vapour in the sooty outflow from a luminous carbon star
Ivison, R. J.; Blommaert, J. A. D. L.; Olofsson, G. +34 more
The detection of circumstellar water vapour around the ageing carbon star IRC +10216 challenged the current understanding of chemistry in old stars, because water was predicted to be almost absent in carbon-rich stars. Several explanations for the water were postulated, including the vaporization of icy bodies (comets or dwarf planets) in orbit ar…
Identification of iron sulphide grains in protoplanetary disks
Waters, L. B. F. M.; Mutschke, H.; Henning, T. +8 more
Sulphur is depleted in cold dense molecular clouds with embedded young stellar objects, indicating that most of it probably resides in solid grains. Iron sulphide grains are the main sulphur species in cometary dust particles, but there has been no direct evidence for FeS in astronomical sources, which poses a considerable problem, because sulphur…
Substantial reservoirs of molecular hydrogen in the debris disks around young stars
Thi, W. F.; Natta, A.; van Dishoeck, E. F. +7 more
Circumstellar accretion disks transfer matter from molecular clouds to young stars and to the sites of planet formation. The disks observed around pre-main-sequence stars have properties consistent with those expected for the pre-solar nebula from which our own Solar System formed 4.5Gyr ago. But the `debris' disks that encircle more than 15% of n…
Discovery of a massive equatorial torus in the η Carinae stellar system
de Graauw, Th.; Waters, L. B. F. M.; Mutschke, H. +10 more
The enigmatic object η Carinae is believed to represent an important, but short-lived, unstable phase in the life of the most massive stars, occurring shortly before they explode as supernovae or collapse directly to black holes. The putative binary system believed to constitute η Carinae survived an outburst in the previous century that lasted 20…
Disappearance of stellar debris disks around main-sequence stars after 400 million years
Kessler, M. F.; Siebenmorgen, R.; Metcalfe, L. +7 more
Almost 5 billion years ago, the Sun formed in a local contraction of a cloud of molecular gas. A rotating disk of gas and dust is believed to have fed material onto the proto-Sun for the first few million years of its life, and to have formed the planets, comets and other Solar System objects. Similar disks, but with less mass, have been observed …
Star formation triggered by galaxy collisions
Lutz, Dieter; Genzel, Reinhard; Tacconi, Linda
It is becoming increasingly clear that collisions between galaxies play an important role in galaxy evolution. The ultraluminous infrared galaxies are predominantly powered by enormous star-formation events that are triggered in the last phases of such collisions. These bursts occur just before the galaxies merge to form single elliptical galaxies.
The formation and evolution of galaxies.
Ellis, Richard
Galaxies represent the visible fabric of the Universe and there has been considerable progress recently in both observational and theoretical studies. The underlying goal is to understand the present-day diversity of galaxy forms, masses and luminosities. Popular models predict the bulk of the population assembled recently, in apparent agreement w…
External supply of oxygen to the atmospheres of the giant planets
Lellouch, E.; Encrenaz, T.; de Graauw, T. +3 more
The atmospheres of the giant planets are reducing, being mainly composed of hydrogen, helium and methane. But the rings and icy satellites that surround these planets, together with the flux of interplanetary dust, could act as important sources of oxygen, which would be delivered to the atmospheres mainly in the form of water ice or silicate dust…
A starburst origin of the OH-megamaser emission from the galaxy Arp220
Sturm, E.; Barlow, M. J.; Stacey, G. J. +3 more
Ultraluminous infrared galaxies have been known for more than a decade, but the source of their very large far-infrared luminosities remains controversial. It may reflect a quasar-like active nucleus surrounded by a torus of dense gas and dust, the latter absorbing the energetic photons from the nuclear region and re-emitting at infrared wavelengt…
Cool gaze at heartless galaxies
Gilmore, Gerry