Multi-periodic photospheric pulsations and connected wind structures in HD64760
We report on the results of an extended optical spectroscopic monitoring campaign on the early-type B supergiant HD64760 (B0.5Ib) designed to probe the deep-seated origin of spatial wind structure. This new study is based on high-resolution echelle spectra obtained with the FEROS instrument at ESO L...
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Main Authors | , , , |
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Format | Journal Article |
Language | English |
Published |
18.10.2005
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Subjects | |
Online Access | Get full text |
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Summary: | We report on the results of an extended optical spectroscopic monitoring
campaign on the early-type B supergiant HD64760 (B0.5Ib) designed to probe the
deep-seated origin of spatial wind structure. This new study is based on
high-resolution echelle spectra obtained with the FEROS instrument at ESO La
Silla. 279 spectra were collected over 10 consecutive nights in 2003. From the
period analysis of the line-profile variability of the photospheric lines we
identify three closely spaced periods around 4.810 hrs and a splitting of
+/-3%. The velocity - phase diagrams of the line-profile variations for the
distinct periods reveal characteristic prograde non-radial pulsation patterns
of high order corresponding to pulsation modes with l and m in the range 6-10.
The three pulsation modes have periods clearly shorter than the characteristic
pulsation time scale and show small horizontal velocity fields and hence are
identified as p-modes. The beating of the three pulsation modes leads to a
retrograde beat pattern with two regions of constructive interference
diametrically opposite on the stellar surface and a beat period of 162.8hrs
(6.8days). This beat pattern is directly observed in the spectroscopic time
series of the photospheric lines. The wind-sensitive lines display features of
enhanced emission, which appear to follow the maxima of the photospheric beat
pattern. |
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DOI: | 10.48550/arxiv.astro-ph/0510511 |