News Release Archive:

News Release 921 of 1051

October 17, 1994 12:00 AM (EDT)

News Release Number: STScI-1994-41

Hubble Rules Out a Leading Explanation for Dark Matter


Image: Region of Globular Star Cluster NGC 6397

Region of Globular Star Cluster NGC 6397STScI-PRC1994-41c

Screen-use options: These files are created for viewing on your monitor

Highest-quality download options: The best resolution available



A NASA Hubble Space Telescope image of a small region (1.4 light-years across) in the globular star cluster NGC 6397 shows far fewer stars than would be expected in faint red dwarf stars were abundant. HST resolves about 200 stars. The stellar density is so low that HST can literally see right through the cluster and resolve far more distant background galaxies. This observation shows the surprising cutoff point below which nature apparently doesn't make many stars smaller that 1/5 the mass of our Sun. If there were lower mass stars in the cluster, then the image would contain an estimated 500 stars. This observation provides new insights into star formation in our Galaxy.


A ground-based sky survey photograph of the globular cluster NGC 6397, one of the nearest and densest agglomerations of stars to Earth. The cluster is located 7,200 light-years away in the southern constellation Ara, and is one of 150 such objects which orbit our Milky Way Galaxy. Globular clusters are ideal laboratories for studying the formation and evolution of stars. This visible-light picture was taken on March 3, 1994 with the Wide Field Planetary Camera 2, as part of the HST parallel observing program.

Object Name: NGC 6397

Image Type: Astronomical

Credit: F. Paresce, ST ScI & ESA and NASA


All images from this news release:

To access available information and downloadable versions of images in this news release, click on any of the images below: