Astron. Astrophys. 343, L29-L34 (1999)

Letter to the Editor

VLT and NTT observations of two EIS cluster candidates

Detection of the early-type galaxies sequence at  ^*

L. da Costa ¹, M. Scodeggio ¹, L.F. Olsen ^1,2, M. Nonino ^1,3, R. Rengelink ¹, R. Bender ⁴, M. Franx ⁵, H.E. Jorgensen ², A. Renzini ¹ and P. Rosati <sup>1

1</sup> European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei München, Germany
² Astronomisk Observatorium, Juliane Maries Vej 30, DK-2100 Copenhagen, Denmark
³ Osservatorio Astronomico di Trieste, Via G.B. Tiepolo 11, I-31144 Trieste, Italy
⁴ Universitäts-Sternwarte München, Scheinerstrasse 1, D-81679 München, Germany
⁵ Leiden Observatory, P.O. Box 9513, 2300 RA, Leiden, The Netherlands

Received 1 December 1998 / Accepted 19 January 1999

Abstract

Optical data from the ESO VLT-UT1 Science Verification observations are combined with near-infrared data from SOFI at the NTT to obtain optical-infrared color-magnitude diagrams for the objects in the fields of two EIS cluster candidates. In both cases, evidence is found for a well-defined sequence of red galaxies that appear to be significantly more clustered than the background population. These results suggest that the two systems are real physical associations. The , and colors of the red sequences are used, in conjunction with similar data for spectroscopically confirmed clusters, to obtain redshift estimates of and for these two systems. These results make these EIS cluster candidates prime targets for follow-up spectroscopic observations to confirm their reality and to measure more accurately their redshift.

Key words: galaxies: clusters: general cosmology: large-scale structure of Universe cosmology: observations

* Based on observations collected at the European Southern Observatories of Paranal (VLT-UT1 Science Verification Program) and La Silla (Chile).

Send offprint requests to: L. da Costa

SIMBAD Objects

Contents

• 1. Introduction
• 2. Observations and data reduction
• 3. Results
  • 3.1. EIS 0046-2930
  • 3.2. EIS 0046-2951
• 4. Summary
• Acknowledgements
• References

© European Southern Observatory (ESO) 1999

Online publication: March 1, 1999
helpdesk.link@springer.de