Query : 1997A&A...322..493T

1997A&A...322..493T - Astronomy and Astrophysics, volume 322, 493-506 (1997/6-2)

A period analysis of the optical line variability of β Cephei: evidence for multi-mode pulsation and rotational modulation.


Abstract (from CDS):

We investigate the optical line-profile variability of the prototype of the β Cephei stars. From more than 600 spectra, with a typical signal to noise ratio of over 200 and high spectral resolution, we deduce that the variations show periodicity with at least five different frequencies. We find variability at the previously known frequencies f1=5.25cycles/day (radial pulsation) and f2=5.38c/d and f3=4.92c/d. Additionally, we report two new frequencies f4=5.08c/d and f5=5.42c/d. These five frequencies are present in periodograms of the velocity moments of all of the absorption lines considered (SiIII λ 4552, 4567, 4574 and OII λ 4591), and also in periodograms of the intensity variations in these lines. The variations at frequencies f1 and f2 can be successfully modelled by a radial and a non-radial (l=2 or l=1, m=1) pulsation, respectively. Following results of studies of the UV resonance lines of β Cep, we interpret the frequency spacings f1-f3≃0.33c/d, f1-f4≃0.17c/d, f5-f1≃0.17c/d as multiples of the rotation frequency of the star. We discuss the influence of the presence of a (surface) magnetic field on the apparent modulation of the line-profile variability of the radial pulsation mode.

Abstract Copyright:

Journal keyword(s): line: profiles - stars: early-type - oscillations - rotation - stars: individual: beta Cep

Simbad objects: 2

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Number of rows : 2
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
1 HD 83368 a2* 09 36 25.40686 -48 45 04.2549   6.480 6.232     A8VSrCrEu+F9V 262 0
2 * bet Cep bC* 21 28 39.5968513 +70 33 38.574681 2.05 3.01 3.23 3.33 3.55 B0.5IIIs 701 0

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