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Astronomy & Astrophysics manuscript no. (will be inserted by hand later)

Summary: Astronomy & Astrophysics manuscript no.
(will be inserted by hand later)
Time-resolved spectral analysis of the pulsating helium star
V652 Her. ?
C.S. Je ery 1 , V.M. Woolf 1 , and D.L. Pollacco 2
1 Armagh Observatory, College Hill, Armagh BT61 9DG, Northern Ireland.
2 School of Physical Sciences, Queen's University Belfast, Belfast BT7 9NN, Northern Ireland
Received . . . , 2001; accepted . . .
Abstract. A series of 59 moderate-resolution high signal-to-noise spectra of the pulsating helium star V652 Her
covering 1.06 pulsation cycles was obtained with the William Herschel Telescope. These have been supplemented
by archival ultraviolet and visual spectrophotometry and used to make a time-dependent study of the properties
of V652 Her throughout the pulsation cycle. This study includes the following features: the most precise radial
velocity curve for V652 Her measured so far, new software for the automatic measurement of e ective temperature,
surface gravity and projected rotation velocities from moderate-resolution spectra, self-consistent high-precision
measurements of e ective temperature and surface gravity around the pulsation cycle, a demonstration of excessive
line-broadening at minimum radius and evidence for a pulsation-driven shock front, a new method for the direct
measurement of the radius of a pulsating star using radial velocity and surface gravity measurements alone, new
software for the automatic measurement of chemical abundances and microturbulent velocity, updated chemical
abundances for V652 Her compared with previous work (Paper IV), a reanalysis of the total ux variations
(cf. Paper II) in good agreement with previous work, and revised measurements of the stellar mass and radius


Source: Armagh Observatory


Collections: Physics