Young stellar objects and star formation

High spatial resolution is often a key factor towards an improved understanding of young stellar objects and the star formation process. High spatial resolution is essential for the study of

The resolution we achieve with our bispectrum speckle interferometry enables us to see details as small as 5 to 10 AU in nearby star forming regions. We are thus able to directly study those regions that may be precursors of planetary systems, to investigate jets and outflows close to their origin, and to resolve a large fraction of close binaries.

Therefore, our research on young stellar objects is focused on the following main topics:

The star formation process involves an enormous range of physical scales, from whole molecular cloud complexes of the size of some hundred parsecs (10^21 cm), to individual stars of the size of only a few solar radii (10^11 cm). Understanding the very complex process of star formation thus requires observations at very different spatial scales. The mosaic of four images below demonstrates this using the example of the Orion star forming region. The mosaic shows a sequence of views closer and closer to the center of this region.

The upper left image shows an IRAS true color image of the Orion molecular cloud complex, covering an area of 20 times 20 degrees. (160 times 160 parsecs). The green ringed asterisks mark the position of the optically brightest stars which form the well known constellation Orion. The densest part of the molecular cloud complex slightly below the center of the image contains the famous Orion nebula.
The upper right image shows a near-infrared image of the Orion nebula cluster (from the Two Micron All Sky Survey ). This cluster contains several hundred young stars with typical ages of about 1 million years. The nebula is illuminated by the strong radiation of the massive young stars in the cluster center.
The lower right image shows the Trapezium system, i.e.~the system of the most massive and luminous stars at the center of the Orion nebula cluster (optical image created from Hubble Space Telescope archive data).
Finally, the lower left image shows our near-infrared high-resolution bispectrum speckle interferometry image (field of view 1.6 times 1.6 arcsec) of one of the Trapezium stars, which can be seen to be a triple star. Since the field of view of our image is 1.6 times 1.6 arcsec, its image scale is 45 000 times larger than that of the upper left image showing the full molecular cloud complex.

Last update: 20 October 1999