Spectrum of Arc in Cluster 1ESO657-558 (z=3.23)

This chart displays the spectrum of the most prominent gravitational arc in the galaxy cluster 1ES 0657-558, as obtained at VLT UT1 with the FORS1 instrument in December 1998. The total exposure time was 1.5 hours. It shows absorption lines of hydrogen (Lyman-alpha and Lyman-beta) as well as lines of silicium, oxygen carbon and iron. From the measured wavelengths, the redshift of the arc is determined as z = 3.23. An earlier, much less accurate photometric redshift estimate (from the observed colours) is confirmed and refined by this spectral observation. Star forming galaxies at lower redshifts have very similar spectra. It is therefore concluded that this arc is the gravitationally distorted image of a distant galaxy caught in its formation stage, when the Universe was only about 2 billion (2,000 million) years old.



About the Image

Release date:27 February 1999
Related releases:eso9920, eso9919
Size:2997 x 1902 px

About the Object

Name:1ES 0657-558, Spectrum
Type:• Early Universe : Galaxy : Grouping : Cluster
• X - Galaxy Clusters
Distance:z=3.23 (redshift)

Image Formats

Large JPEG
596.1 KB
Screensize JPEG
128.1 KB

Colours & filters

OpticalVery Large Telescope


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