Multisite Observations of delta Scuti Stars 7 Aql and 8 Aql (a New delta Scuti Variable): The Twelfth STEPHI Campaign in 2003
English
Fox Machado, L.[Observatorio Astronómico Nacional, Instituto de Astronomía, Universidad Nacional Autónoma de México, A.P. 877, Ensenada, BC 22860, Mexico.]
Pérez Hernández, F.[Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife, Spain.; Departamento de Astrofísica, Universidad de La Laguna, E-38205 La Laguna, Tenerife, Spain.]
Peña, J. H.[Instituto de Astronomía, Universidad Nacional Autónoma de México, A.P. 70-264, México, DF 04510, Mexico.]
Li, Z. P.[Beijing Observatory, Chinese Academy of Sciences, Beijing, China.]
Chevreton, M.[Observatoire de Paris, LESIA, UMR 8109, F-92195 Meudon, France.]
Belmonte, J. A.[Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife, Spain.]
Álvarez, M.[Observatorio Astronómico Nacional, Instituto de Astronomía, Universidad Nacional Autónoma de México, A.P. 877, Ensenada, BC 22860, Mexico.]
Parrao, L.[Instituto de Astronomía, Universidad Nacional Autónoma de México, A.P. 70-264, México, DF 04510, Mexico.]
Dupret, Marc-Antoine[Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique stellaire théorique >]
Pau, S.[Observatoire de Paris, LESIA, UMR 8109, F-92195 Meudon, France.]
Fernandez, A.[Observatoire de Paris, LESIA, UMR 8109, F-92195 Meudon, France.]
[en] We present an analysis of the pulsation behavior of the delta Scuti stars 7 Aql (HD 174532) and 8 Aql (HD 174589), a new variable star, observed in the framework of the STEPHI XII campaign during 2003 June and July; 183 hr 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 multichannel 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 190-300 muHz and 100-145 muHz 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 3, while for 7 Aql the range spans from n=4 to 7. Nonradial oscillations have to be present in both stars as well. The expected range of excited modes according to a nonadiabatic analysis goes from n=1 to 6 in both stars.
