Discovery of the 'missing' mode in HR 1217 by the Whole Earth Telescope
Fecha
2002Autor
Materia
Abstract
HR1217 is a prototypical rapidly oscillating Ap star that has presented a test to the theory of non-radial stellar pulsation. Prior observations showed a clear pattern of five modes with alternating frequency spacings of 33.3 and 34.6 μmHz, with a sixth mode at a problematic spacing of 50.0 μHz (which equals 1.5 x 33.3 μHz) to the high-frequency side. Asymptotic pulsation theory allowed for a frequency spacing of 34 μHz, but Hipparcos observations rule out such a spacing. Theoretical calculati ...
HR1217 is a prototypical rapidly oscillating Ap star that has presented a test to the theory of non-radial stellar pulsation. Prior observations showed a clear pattern of five modes with alternating frequency spacings of 33.3 and 34.6 μmHz, with a sixth mode at a problematic spacing of 50.0 μHz (which equals 1.5 x 33.3 μHz) to the high-frequency side. Asymptotic pulsation theory allowed for a frequency spacing of 34 μHz, but Hipparcos observations rule out such a spacing. Theoretical calculations of magnetoacoustic modes in Ap stars by Cunha predicted that there should be a previously undetected mode 34 μHz higher than the main group, with a smaller spacing between it and the highest one. In this Letter, we present preliminary results from a multisite photometric campaign on the rapidly oscillating Ap star HR1217 using the ‘Whole Earth Telescope’. While a complete analysis of the data will appear in a later paper, one outstanding result from this run is the discovery of a newly detected frequency in the pulsation spectrum of this star, at the frequency predicted by Cunha. ...
En
Monthly notices of the Royal Astronomical Society. Oxford. Vol. 330, no. 3 (Mar. 2002), p. L57-L61
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