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Star Formation around Rho Ophiuchi

infrared optical X-ray

Date:10.6.1994 Time:3:11 UT Exposure:45m
Field of View:15o x 15o Emulsion:Scotchchrome 400 Filter:none
Instrument:f=100mm 1/2.8 Place: Cerro Tololo Observer:S. Kohle

© Copyright by the observers

The infrared image was observed by IRAS, the X-ray image by ROSAT and were obtained from the SKYVIEW webpage.

In a distance of about 500 lightyears the region around Rho Ophiuchi represents the Earth's closest star nursery. Embedded in the most dense clouds of molecular gas and dust stars are born right now. The dust is emitting light in the infrared and absorbing stellar light in the optical and X-ray regime. The blue and yellow color of the nebulae in the optical image is from interstellar light reflection of embedded stars. The red emission is mainly from ionized hydrogen.
The X-ray image is a three color composit in which emission in different Rosat energy bands is represented in different colors (1/4 keV = red, 3/4 keV = green and 1.5 keV = blue). As you can easily see the dusty molecular clouds also absorb the high energy X-rays, so that these regions appear darkly red.
The IRAS image shows the thermal emission of dust at 100 microns. The dust has different temperatures and emits at wavelengths from mm to submm. Therefore there is no perfect correlation of the dust emission at 100 microns and dust absorption in the optical.

Astronomical Institutes of the University of Bonn