Asteroseismological modeling of the multiperiodic λ bootis star 29 Cygni
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AuthorCasas del Castillo, Ricardo; Moya Bedón, Andrés; Suárez Yanes, Juan Carlos; Martín-Ruiz, Susana; Amado González, Pedro; Rodríguez-López, Cristina; Garrido Haba, Rafael
Institute of Physics (IOP); The American Astronomical Society
StarsFundamental parametersRotationOscillationsVariables29 CygniAstroseismology
Casas del Castillo, R.; et al. Asteroseismological modeling of the multiperiodic λ bootis star 29 Cygni. The Astrophysical Journal, 697: 522–534 (2009). [http://hdl.handle.net/10481/41210]
SponsorshipThis work was partially financed by the Spanish Plan Nacional del Espacio, under project ESP2004-03855-C03-01, and by the Spanish Plan Nacional de Astronomía y Astrofísica, under proyect AYA2003-04651.; J.C.S. acknowledges support by the Instituto de Astrofísica de Andalucía by an I3P contract financed by the European Social Fund and from the Spanish Plan Nacional del Espacio under project ESP2007-65480-C02-01. P. J. A. ackowledges financial support from a "Ramón y Cajal" contract of the Spanish Ministry of Education and Science. A. M. ackowledges financial support from a "Juan de la Cierva" contract of the Spanish Ministry of Education and Science.
The present work focuses on the discussion of the λ Bootis nature of the multiperiodic δ Scuti star HD 192640 (29 Cyg), through a comprehensive asteroseismic modeling. Some of the most recent asteroseismic tools are used to check whether the observed low metallicity is internal, i.e., intrinsic, present throughout the star, or due to superficial processes as accretion, diffusive settling, radiative levitation, mass loss, etc. The modeling method uses some of the most recent tools, including: (1) effects of rotation on equilibrium models, on the adiabatic oscillation spectrum, and its influence in multicolor observables, (2) nonadiabatic stability of radial and nonradial modes, (3) inclusion of the atmosphere–pulsation interaction for a more accurate multicolor mode identification, and (4) ratio between radial modes n = 4 and n = 5 in the framework of Petersen diagrams. The analysis performed reveals that the models fulfilling all the constraints are those in the middle of the main sequence (MS), with subsolar metallicity, except some other unlikely possibilities. Therefore, this study does not support the idea of the λ Bootis stars being zero-age MS or pre-MS stars interacting with their primordial cloud of gas and dust, but suggest the explanation of their nature as submetallic MS objects. Nevertheless, more accurate multicolor photometric observations are required for a more conclusive study using the procedure presented here, since the observational errors are too large for a definitive rejection of any of the possible explanations.