The MACHO project sample of galactic bulge high-amplitude δ Scuti stars: Pulsation behavior and stellar properties

C. Alcock, R. A. Allsman, D. R. Alves, T. S. Axelrod, A. C. Becker, D. P. Bennett, K. H. Cook, K. C. Freeman, M. Geha, K. Griest, M. J. Lehner, S. L. Marshall, B. J. Mcnamara, D. Minniti, C. Nelson, B. A. Peterson, P. Popowski, M. R. Pratt, P. J. Quinn, A. W. RodgersW. Sutherland, M. R. Templeton, T. Vandehei, D. L. Welch

Resultado de la investigación: Contribución a una revistaArtículorevisión exhaustiva

23 Citas (Scopus)

Resumen

We have detected 90 objects with periods and light-curve structures similar to those of field δ Scuti stars using the Massive Compact Halo Object (MACHO) Project database of Galactic bulge photometry. If we assume similar extinction values for all candidates and absolute magnitudes similar to those of other field high-amplitude δ Scuti stars (HADS), the majority of these objects lie in or near the Galactic bulge. At least two of these objects are likely foreground δ Scuti stars, one of which may be an evolved nonradial pulsator, similar to other evolved, disk-population δ Scuti stars. We have analyzed the light curves of these objects and find that they are similar to the light curves of field δ Scuti stars and the δ Scuti stars found by the Optical Gravitational Lens Experiment (OGLE). However, the amplitude distribution of these sources lies between those of low- and high-amplitude δ Scuti stars, which suggests that they may be an intermediate population. We have found nine double-mode HADS with frequency ratios ranging from 0.75 to 0.79, four probable double- and multiple-mode objects, and another four objects with marginal detections of secondary modes. The low frequencies (5-14 cycles day-1) and the observed period ratios of ∼0.77 suggest that the majority of these objects are evolved stars pulsating in fundamental or first overtone radial modes.

Idioma originalInglés
Páginas (desde-hasta)798-815
Número de páginas18
PublicaciónAstrophysical Journal
Volumen536
N.º2 PART 1
DOI
EstadoPublicada - 20 jun 2000

Áreas temáticas de ASJC Scopus

  • Astronomía y astrofísica
  • Ciencias planetarias y espacial

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