Research Note

A photometric survey of stars with circumstellar material

¹ Institut d'Astrophysique de Paris, UMR 7095 CNRS, Université Pierre & Marie Curie, 98 bis boulevard Arago, 75014 Paris, France e-mail: lecaveli@iap.fr
² Astrophysics Research Group, Antwerp University Middelheimlaan 1, 2020 Antwerpen, Belgium
³ Niels Bohr Institute for Astronomy, Physics and Geophysics, Astronomical Observatory, Juliane Maries Vej 30, 2100 Copenhagen O, Denmark

Received: 22 November 2004
Accepted: 20 February 2005

Abstract

We present the result of a follow-up Strömgren photometric survey of sixteen southern bright stars with circumstellar material, in order to detect possible weak photometric variations. We found new variations of the Pictoris brightness from 1999 to 2002 with a weak long-term variation of ~ mag per year, over about 3 years. These variations look similar to those seen from 1975 to 1981 and from 1995 to 1998 (Nitschelm et al. 2000, A&AS, 145, 275). They can be due to differential occultation by dust inhomogeneities transiting the star through the years. We detected new periodic variations for HD 256 (HR 10) with periods ranging from 0.35 day to 6.69 days during several months. These variations may also be interpreted in terms of variable obscuration due to structures in the circumstellar disk suspected to be surrounding this star.