Stephi: A New Approach to δ Scuti Asteroseismology

Abstract

The STEPHI network (STEllar PHotometry International) is a multinational cooperation stablished in order to get as perfect data as possible on several δ Scuti stars, within a reasonable period of time. STEPHI is currently integrated by nearly 15 people, belonging to the first four institutions cited above. However, astronomers of other institutions have eventually contributed to the network. The idea was born in 1986 and the network has been working to full operation since August 1989. A campaign, observing one or two δ Scuties is normally undertaken every 15 months. They are usually order of three weeks long, avoiding full-moon periods. Up to now, four campaigns have been performed, the last ending February 1992.Very good outcomes on five δScuties [63 Herculis in June 1987 (Belmonte et al, 1991), GX Pegasi in September 1989 (Michel et al, 1992a), v650 Tauri in November 1990 (Belmonte and Michel, 1991; Michel et al, 1992b) and, finally, BN Cancri and BU Cancri in February 1992] have been obtained. Indeed, some very useful aditional information on comparison stars (see e.g. Belmonte et al, 1990) and sky conditions (transparency, brightness, scintillation, etc..) has been obtained as well. Aditionally, some key information about mostly all multiperiodic (four or more periods) δ Scuti stars studied up to March 1992, with good quality data, is presented in this report.