Barnard 68: The Black Cloud in Ophiuchus | European Southern Observatory
Barnard 68 is a molecular cloud, dark absorption nebula or Bok globule, towards the southern constellation Ophiuchus and well within the Milky Way galaxy at a distance of about 407 light-years. It is close and dense enough that stars behind it cannot be seen from Earth. It is known as Barnard 68 (B68) after the American astronomer, Edward E. Barnard (1857-1923). He included it in a list of such objects, published in 1919. It appears as a compact, opaque and rather sharply defined object against a rich, background star field. Even on this image that registers many faint stars in the area, not a single foreground star is observed. This is a clear sign that this globule must be relatively nearby. Interstellar clouds consist of gas and dust, including many molecules that contain carbon atoms (i.e. organic).
For a long time considered to be "holes in the sky", molecular clouds are now known to be among the coolest objects in the Universe (the temperature is approx. 10 K, or -263 °C). Moreover, and most importantly, they are nurseries of stars and planets. It still remains a mystery how a dark cloud like Barnard 68 at one moment begins to contract and subsequently transforms itself into hydrogen-burning stars. However, deep images of these clouds, such as this one obtained by the FOcal Reducer and low dispersion Spectrograph (FORS1) on the European Southern Observatory's Very Large Telescope's ANTU, may provide important clues. This small cloud seems to be in its very earliest phase of collapse.
This three-color composite was reproduced from one blue (B), one green-yellow (V) and one near-infrared (I) exposure that were obtained with VLT ANTU and FORS1 in the early morning of March 27, 1999. The field measures 6.8x6.8 arcmin 2. The image consists of 2048x2048 pixels, each measuring 0.20 arcsec. North is up and East is to the left.
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Credit: European Southern Observatory (ESO)
Release Date: April 30, 1999
Release Date: April 30, 1999
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