Jeffery, C. S., Kurtz, D., Shibahashi, H., Starling, R. L. C., Elkin, V., Montanes-Rodriguez, P. and McCormac, J. (2015) Subaru and Swift observations of V652 Herculis: resolving the photospheric pulsation. Monthly Notices of the Royal Astronomical Society, 447 (3). pp. 2836-2851. ISSN 0035-8711
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Official URL: http://dx.doi.org/10.1093/mnras/stu2654
High-resolution spectroscopy with the Subaru High Dispersion Spectrograph, and Swift ultraviolet photometry are presented for the pulsating extreme helium star V652 Her. Swift provides the best relative ultraviolet photometry obtained to date, but shows no direct evidence for a shock at ultraviolet or X-ray wavelengths. Subaru has provided high spectral and high temporal resolution spectroscopy over six pulsation cycles (and eight radius minima).
These data have enabled a line-by-line analysis of the entire pulsation cycle and provided a description of the pulsating photosphere as a function of optical depth. They show that the photosphere is compressed radially by a factor of at least 2 at minimum radius, that the phase of radius minimum is a function of optical depth and the pulse speed through the photosphere is between 141 and 239 km s−1 (depending how measured) and at least 10 times the local sound speed. The strong acceleration at minimum radius is demonstrated in individual line profiles; those formed deepest in the photosphere show a jump discontinuity of over 70 kms−1 on a time-scale of 150 s. The pulse speed and line profile jumps imply a shock is present at minimum radius. These empirical results provide input for hydrodynamical modelling of the pulsation and hydrodynamical plus radiative transfer modelling of the dynamical spectra.
|Uncontrolled Keywords (separate with ;):||shock waves – techniques: radial velocities – stars: atmospheres – stars: chemically peculiar – stars: individual: V652 Her – stars: oscillations.|
|Subjects:||Physical sciences > Astronomy|
|Schools:||Faculty of Science and Technology > School of Physical Sciences and Computing > Jeremiah Horrocks Institute|
|Deposited By:||Nuala Jones|
|Deposited On:||28 Apr 2015 10:25|
|Last Modified:||23 Oct 2016 18:30|
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