HD 172189: another step in furnishing one of the best laboratories known for asteroseismic studies

¹ Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain e-mail: orlagh@iac.es
² Departamento de Astrofísica, Universidad de La Laguna, 38205 La Laguna, Tenerife, Spain
³ Laboratoire AIM, CEA/DSM-CNRS-Université Paris, Diderot; CEA,IRFU, SAp, centre de Saclay, 91191 Gif-sur-Yvette, France
⁴ Instituto de Astrofísica de Andalucía (CSIC), Camino bajo de Huétor 50, 18080 Granada, Spain
⁵ Astronomical Institute, Wrocław University, Kopernika 11, 52-622 Wrocław, Poland
⁶ Instituut voor Sterrenkunde, Celestijnenlaan, 200D, 3001 Leuven, Belgium
⁷ Laboratoire d'Astrophysique de Toulouse-Tarbes, Université de Toulouse, CNRS, 31400 Toulouse, France
⁸ Universidad de Vigo, Departamento de Física Aplicada, Campus Lagoas-Marcosende, 36310 Vigo, Spain
⁹ Mercator Telescope, Observatorio del Roque de los Muchachos, Apartado de Correos 474, 38700 Santa Cruz de La Palma, Spain
¹⁰ INAF-OABrera, Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807 Merate, Italy
¹¹ Instituto de Astronomía, Universidad Nacional Autónoma de Mexico, Apdo. Postal 70-264, 04510 Mexico D.F., Mexico
¹² UNS, CNRS, OCA, Campus Valrose, UMR 6525 H. Fizeau, 06108 Nice Cedex 2, France
¹³ UPMC Univ. Paris 06, UMR 7585, Laboratoire de Physique Nucléaire et des Hautes Énergies (LPNHE), 75005 Paris, France
¹⁴ Astronomical Institute, Academy of Sciences, Boční II 1401, 141 31 Praha 4, Czech Republic
¹⁵ INAF Catania Astrophysical Observatory, via S. Sofia 78, 95123 Catania, Italy

Received: 20 May 2009
Accepted: 27 August 2009

Abstract

HD 172189 is a spectroscopic eclipsing binary system with a rapidly-rotating pulsating δ Scuti component. It is also a member of the open cluster IC 4756. These combined characteristics make it an excellent laboratory for asteroseismic studies. To date, HD 172189 has been analysed in detail photometrically but not spectroscopically. For this reason we have compiled a set of spectroscopic data to determine the absolute and atmospheric parameters of the components. We determined the radial velocities (RV) of both components using four different techniques. We disentangled the binary spectra using KOREL, and performed the first abundance analysis on both disentangled spectra. By combining the spectroscopic results and the photometric data, we obtained the component masses, 1.8 and 1.7 , and radii, 4.0 and 2.4 , for inclination , eccentricity , and orbital period  days. Effective temperatures of 7600 K and 8100 K were also determined. The measured are 78 and 74 km s^-1, respectively, giving rotational periods of 2.50 and 1.55 days for the components. The abundance analysis shows [Fe/H] = –0.28 for the primary (pulsating) star, consistent with observations of IC 4756. We also present an assessment of the different analysis techniques used to obtain the RVs and the global parameters.