The variations of BW Vul.

Goldberg, Bruce; Walker, G. A. H.; Odgers, G. J.

doi:10.1086/111904

Cited by 12 publications

(9 citation statements)

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“…There is a bump on the radial velocity curve at the proper phase. The radius dependence agrees well with that of Goldberg et al (1976). However, the amplitude is far too large, 2K = 320 Km/sec as compared with an observed amplitude of 2K = 160 Km/sec The original theoretical amplitude was increased due to the application of the Stellingwerf SPS method to obtain a full amplitude oscillation.…”

Section: Non-linear Calculationssupporting

confidence: 74%

The Light and Velocity Curve Bumps for BW Vulpeculae

Pesnell

Cox

1980

International Astronomical Union Colloquium

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BW Vulpeculae (HD 199140) is a well known Beta Cenhei star, with several unusual characteristics. It possesses the largest amplitude in both light and radial velocity variations, of any star in this classification. The most outstanding feature of the observations is a standstill or bump, on the light curve, accompanied by doubled lines in the radial velocity observations. In this paper, we have attempted to explain these phenomena with two different models. Firstly, the resonance mechanism, from Simon and Schmidt, and secondly, a non-linear calculation.

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Section: Non-linear Calculationssupporting

confidence: 74%

The Light and Velocity Curve Bumps for BW Vulpeculae

Pesnell

Cox

1980

International Astronomical Union Colloquium

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“…A related issue is the cause of the line doubling itself. Odgers (1955) and Goldberg, Walker & Odgers (1976) suggested that the doubling occurs from velocity discontinuities below and above a shock and suggested that this shock accelerates the line‐forming regions of the atmosphere from the lower photosphere to create a density discontinuity. The semi‐ejected ‘shell’ coasts to some maximum height and returns ballistically to these lower strata.…”

Section: Introductionmentioning

confidence: 99%

Spectral response of the pulsationally induced shocks in the atmosphere of BW Vulpeculae

Smith¹,

Jeffery

2003

Monthly Notices of the Royal Astronomical Society

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BW Vulpeculae (BW Vul) is remarkable for exciting an extremely strong radial pulsation mode which grows through its outer envelope and forms visible shock features in the atmosphere. Material propelled upwards by the shock returns violently to the lower photosphere where it creates a second shock just before the start of the next cycle. We have obtained three nights of echelle data for this star over about five pulsation cycles (P= 0.201 d) in 2000 September in order to investigate the effects of atmospheric shocks on important lines in the optical red spectrum. These lines include He iλ5875 and λ6678, C iiλλ6578–83 doublet, and other moderate and high excitation lines. To these data we have added 37 archival IUE/SWP echelle spectra obtained in 1994. We have investigated the equivalent widths and shapes of the optical lines for evidence of inter alia lags and have compared our results to the IUE fluxes extracted from the far‐ultraviolet continuum, He iiλ1640, and several resonance lines. A comparison of He iλ5875 and λ6678 line profiles during the peak of the infall activity suggests that differences in the development of a second blue lobe in the profile at this time are due to heating and a short‐lived formation of an optically thin layer above the region compressed by the infall. This discovery and the well‐known decreases in equivalent widths of the C ii doublet at the two shock phases further suggest that shock heating flattens the atmospheric temperature gradient. Except for evidence of wind absorption in the far blue wings of the ultraviolet resonance lines, we find no evidence for a shock delay arriving at different photospheric strata (i.e., a ‘Van Hoof effect’). Line‐to‐line differences in the relative strengths of double lobes can be false indicators arising from varying degrees of desaturation of multiple lines, such as for the red He i lines.

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“…This apparent increase seems to be supported by the large value of 2K found in the high resolution spectroscopic study by Goldberg et al (1976). As Goldberg et al themselves point out, however, the increase in 2K is mainly due to the increased spectral and time resolution of the observations.…”

Section: Amplitude Changesmentioning

confidence: 69%

“…The detailed qualitative aspects of this model were studied by Goldberg et al (1976), using high time and spectral resolution. An even more detailed spectroscopic study, with simultaneous photometry, has been made recently by Young et al (1980), using a CCD as a detector.…”

Section: Atmospheric Effectsmentioning

confidence: 99%

Beta Cephei and related stars

Percy

1980

Space Sci Rev

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The variations of BW Vul.

Cited by 12 publications

References 0 publications

The Light and Velocity Curve Bumps for BW Vulpeculae

The Light and Velocity Curve Bumps for BW Vulpeculae

Spectral response of the pulsationally induced shocks in the atmosphere of BW Vulpeculae

Beta Cephei and related stars

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