Letter to the Editor

An unusual iron Lo-BAL quasar detected by ISOCAM^*

¹ CNRS URA 2052
² CEA, DSM, DAPNIA, Service d'Astrophysique, 91191 Gif–sur–Yvette Cedex, France
³ Pontificia Universidad Católica de Chile, Departamento de Astronomía y Astrofísica, Casilla 306, Santiago 22, Chile and Princeton University Observatory, Princeton, NJ 08544-1001, USA
⁴ Instituto de Astrofisica de Canarias, Via Lactea s/n, 38200 La Laguna – Tenerife, Spain
⁵ Dipartimento di Astronomia, via G.B. Tiepolo 11, 34131 Trieste, Italy
⁶ European Southern Observatory, Santiago
⁷ Osservatorio Astronomico di Padova, vicolo dell'Osservatorio 5, 35122 Padova, Italy
⁸ DAEC/LUL, Observatoire de Paris–Meudon, 5 place Jules Janssen, 92195 Meudon, France
⁹ Dipartimento di Astronomia, Università di Padova, Vicolo dell'Osservatorio, 5, 35122 Padova, Italy
¹⁰ INAF – Osservatorio Astronomico di Trieste, via G.B. Tiepolo, 11, 34131 Trieste, Italy
¹¹ European Southern Observatory, Karl–Schwarzschild–Strasse, 2, 85748 Garching bei München, Germany

Corresponding author: P.–A. Duc, paduc@cea.fr

Received: 8 March 2002
Accepted: 2 May 2002

Abstract

We report the discovery of an unusual low–ionization broad absorption line quasar at which exhibits absorption lines from many excited states of Fe ii. This member of the rare class of “FeLoBAL” quasars was serendipitously found in a mid–infrared (MIR) survey of distant clusters carried out with the ISOCAM camera. ISO J005645.1-273816 has a high MIR to UV luminosity ratio, suggesting a strong dust obscuration plus emission from very hot dust. This characteristic makes MIR surveys particularly efficient at detecting LoBAL quasars.