Birth of a star: Bipolar outflows around the protostar HH 211

The formation of a star is a fascinating process. When an interstellar cloud of dense molecular gas and dust progressively collapses unter its own gravity, a protostar forms at its center. Upon further compression, a star gradually emerges. During this process, the protostar rotates faster and faster and ejects part of its matter in the surrounding medium, with velocities of up to 100 km/s.

Called bipolar outflows, these ejections have been observed for the first time in a detailed and complete way thanks to the Plateau de Bure Interferometer. The images reveal that the outflow is not ejected in a linear fashion, as previously thought. In fact, through interactions with the matter immediately surrounding the protostar, it actually seems to split.

Evolution of a star: The circumstellar disk around GG Tauri

The millimeter detection of this disk of dust and gas around a binary system where two stars orbit each other was a surprise for the astronomers at IRAM - it represents the only known circum-binary disk to date. The disk is composed of interstellar matter that was not used for the central stars. Its shape, including the large central void, results from the dynamic sculpting caused by the inner orbital motion of the two stars. It is in disks similar to the one around GG Tauri, best observed at millimeter wavelenghts, that planets form. Astronomers can thus explore the origins of planetary formation and analyse the chemical process leading to the creation of a solar system similar to our own.

End of a star: The star TT Cygni

Obtained by the Plateau de Bure Interferometer, this extraordinary image shows the star TT Cygni at the final stage of its evolution. It reveals a large, almost circular envelope of molecular gas, ejected about 2000 years ago and slowly expanding away from the star at velocities of 20 km/s. A more recent ejected envelope can be seen in the center, still close to the star. Once ejected, stellar shells cool off and form molecules as well as dust. At their death stars therefore become true factories of cosmic dust and are astronomers' favorite hunting grounds in the search for new molecules.

Galaxies near and far: M51, the Whirlpool galaxy

Along with Andromeda (M31), the Whirlpool galaxy (M51) is one of the closest galaxies, at a distance of only 27 million light years. Using the 30 meter telescope, IRAM astronomers made the first detailed map of the molecular gas in M51 by tracing the emission of carbon monoxide over the entire extent of the galaxy! By comparing these remarkable results with maps obtained at other wavelenghts, they have been able to derive a complete description of this nearby spiral galaxy from its stellar population to the atomic and molecular matter out of which stars are formed. 

Cosmic phenomena: The Galaxy SMM J16359

At a distance of more than 5 billion light years away, the galaxy SMM J16359 is hidden behind a galaxy cluster and should not be observable from the earth. However, due to an exceptional astronomical phenomenon, called the gravitational lens effect, it becomes visible. The gravitation of the galaxy cluster(seen in the upper right of the optical image) deflects the light of SMM J16359, dividing it into three images and amplifying its emission by a factor of more than 40.

The Plateau de Bure interferometer detected the amplified triple image of SMM J16359 and by analyzing it, astronomers could derive the mass and the dynamics of this far galaxy. They concluded that it is most likely composed of two galaxies in the process of merging!