
We present an analysis of the pulsation behaviour of the Delta Scuti stars 7 Aql (HD 174532) and 8 Aql (HD 174589) -- a new variable star -- observed in the framework of STEPHI XII campaign during 2003 June--July. 183 hours of high precision photometry were acquired by using four-channel photometers at three sites on three continents during 21 days. The light curves and amplitude spectra were obtained following a classical scheme of multi-channel photometry. Observations in different filters were also obtained and analyzed. Six and three frequencies have been unambiguously detected above a 99% confidence level in the range 0.090 mHz--0.300 mHz and 0.100 mHz-- 0.145 mHz in 7 Aql and 8 Aql respectively. A comparison of observed and theoretical frequencies shows that 7 Aql and 8 Aql may oscillate with p modes of low radial orders, typical among Delta Scuti stars. In terms of radial oscillations the range of 8 Aql goes from n=1 to n=3 while for 7 Aql the range spans from n=4 to n=7. Non-radial oscillations have to be present in both stars as well. The expected range of excited modes according to a non adiabatic analysis goes from n=1 to n=6 in both stars.
8 pages, 7 fugures, 5 tables, accepted for publication in Astronomical Journal
Stars: Variables: delta Scuti, Aérospatiale, astronomie & astrophysique, Physique, chimie, mathématiques & sciences de la terre, Astrophysics (astro-ph), Techniques: Photometric, stars: individual (HD 174589), FOS: Physical sciences, stars: individual (HD 174532), Astrophysics, 530, Physical, chemical, mathematical & earth Sciences, Space science, astronomy & astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], [PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph], Stars: Oscillations
Stars: Variables: delta Scuti, Aérospatiale, astronomie & astrophysique, Physique, chimie, mathématiques & sciences de la terre, Astrophysics (astro-ph), Techniques: Photometric, stars: individual (HD 174589), FOS: Physical sciences, stars: individual (HD 174532), Astrophysics, 530, Physical, chemical, mathematical & earth Sciences, Space science, astronomy & astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], [PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph], Stars: Oscillations
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