Discovery of the first gravitational Einstein ring - The luminous arc in Abell 370
Abstract
The luminous arc in Abell 370 was reobserved at ESO with EFOSC/PUMA 2 at the 3.6-m telescope in order to test the gravitational lensing model of luminous arcs in rich clusters of galaxies. The resulting data confirm that the eastern parts of the arc really show the same spectral energy distribution, so that the eastern end of the structure belongs to the arc. A narrow emission line is clearly observed at 6427 A all along the arc spectrum. The assumption that it is the forbidden O II 3727 A line leads to a redshift of 0.724, a value confirmed by the detection of absorption features corresponding to the Ca II 3933, 3968 A and the 4000 A break, the CN band at 3883 A, the Mg II 2800 A line, and several Balmer lines, still at the same redshift.
- Publication:
-
The Messenger
- Pub Date:
- December 1987
- Bibcode:
- 1987Msngr..50....5S
- Keywords:
-
- Auroral Arcs;
- Galactic Clusters;
- Gravitational Lenses;
- Absorption Spectra;
- Balmer Series;
- Cn Emission;
- Red Shift;
- Astronomy;
- Clusters of Galaxies:Luminous Arcs;
- Spectra:Luminous Arcs