A&A 369, 986-992 (2001)
DOI: 10.1051/0004-6361:20010181
CCD-based observations of PG 0856+121 and a theoretical analysis of its oscillation modes
A. Ulla1, M. R. Zapatero Osorio2, 3, F. Pérez Hernández2, 4 and J. MacDonald51 Universidade de Vigo, Departamento de Física Aplicada, Área de Física da Terra, Astronomía e Astrofísica, Facultade de Ciencias, Campus Lagoas-Marcosende, 36200 Vigo, Spain
2 Instituto de Astrofísica de Canarias, c/ Vía Láctea s/n, 38200 La Laguna, Tenerife, Spain
3 CALTECH, MS 150-21, Pasadena, CA 91125, USA
4 Departamento de Astrofísica, Universidad de La Laguna, Tenerife, Spain
5 Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA
(Received 5 July 2000 / Accepted 29 January 2001 )
Abstract
BVRI CCD-based and near-IR (J) imaging, together with unfiltered photometry of the hot subdwarf B star PG 0856+121, are reported. Two close, faint, red,
point-like sources are resolved.
They account for the previously reported IR excess observed in this
hot subdwarf. In addition, the new unfiltered differential photometry of PG 0856+121 confirms its previously reported pulsational
nature. A comparison with the oscillation modes
of stellar models suggests the presence of g modes.
Key words: binaries: close -- stars: individual: PG 0856+121 -- stars: oscillations -- subdwarfs
Offprint request: A. Ulla, ulla@uvigo.es
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