EROS 2 photometry of probable R Coronae Borealis stars in the Small Magellanic Cloud^*

¹ CEA, DSM, DAPNIA, Centre d'Études de Saclay, 91191 Gif-sur-Yvette Cedex, France
² Institut d'Astrophysique de Paris, INSU CNRS, 98bis boulevard Arago, 75014 Paris, France e-mail: marquett@iap.fr
³ Cassiopée UMR 6202, Observatoire de la Côte d'Azur, BP 4229, 06304 Nice Cedex 4, France
⁴ Collège de France, Physique Corpusculaire et Cosmologie, IN2P3 CNRS, 11 place Marcelin Berthelot, 75231 Paris Cedex 05, France
⁵ Laboratoire de l'Accélérateur Linéaire, IN2P3 CNRS, Université de Paris-Sud, 91405 Orsay Cedex, France
⁶ Astronomical Observatory, Copenhagen University, Juliane Maries Vej 30, 2100 Copenhagen, Denmark
⁷ Osservatorio Astronomico di Padova - INAF, vicolo dell'Osservatorio 5, 35122 Padova, Italy
⁸ Université Paris 7 Denis Diderot, 2 place Jussieu, 75005 Paris, France
⁹ LPNHE, IN2P3 CNRS and Universités Paris 6 and Paris 7, 4 place Jussieu, 75252 Paris Cedex 05, France
¹⁰ Observatoire Midi-Pyrénées, UMR 5572, 14 avenue Édouard Belin, 31400 Toulouse, France
¹¹ European Southern Observatory, Casilla 19001, Santiago 19, Chile
¹² Department of Astronomy, Ohio State University, Columbus, OH 43210, USA
¹³ Department of Math and Science, US Merchant Marine Academy, Kings Point, NY 11024, USA
¹⁴ Observatoire de Marseille, 2 place Le Verrier, 13248 Marseille Cedex 04, France

Received: 4 March 2004
Accepted: 26 May 2004

Abstract

EROS 2 (Expérience de Recherche d'Objets Sombres) conducted a survey of the SMC between July 1996 and February 2003 in two EROS broad-band colours, V_E and R_E. The photometric data of 4.2 million stars have been searched for behaviour typical of R Coronae Borealis (RCB) candidates such as drastic changes in magnitude. Five objects have been found, four of them being catalogued in the Simbad database as RAW 21, RAW 233, RAW 476, and [MH95] 431 with confirmed carbon-rich atmospheres, characteristic of RCB. From the EROS 2 light curve of RAW 21 and its spectrum reported by [CITE], we confirm that it is the first RCB to be found in the SMC. The other objects are new RCB candidates with absolute luminosity and colour close to those found for RCBs in the LMC. We propose that 2 of them are DY Per-like RCBs.