Radial velocity variability in post-AGB stars: V448 Lac

To investigate the binary hypothesis in the formation of planetary nebulae, we have been doing long-term photometry and radial velocity (RV) monitoring of bright post-AGB stars which possess bipolar or ellipsoidal nebulae but no indication of a disk in their spectral energy distribution, indicative...

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Bibliographic Details
Published in:Proceedings of the International Astronomical Union 2018-08, Vol.14 (S343), p.533-534
Main Authors: Van de Steene, G. C., Hrivnak, B. J., Van Winckel, H.
Format: Article
Language:English
Subjects:
Astronomy
Asymptotic giant branch stars
Binary stars
Companion stars
Correlation analysis
Cross correlation
Line spectra
Nebulae
Parameters
Periodic variations
Photometry
Planet formation
Planetary nebulae
Radial velocity
Spectral energy distribution
Velocity
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Summary:To investigate the binary hypothesis in the formation of planetary nebulae, we have been doing long-term photometry and radial velocity (RV) monitoring of bright post-AGB stars which possess bipolar or ellipsoidal nebulae but no indication of a disk in their spectral energy distribution, indicative of a binary companion. RV’s are determined by cross correlating high-resolution spectra with a line mask. Stellar variability and companions both deform the cross correlation function (CCF) and induce periodic variations in the RV. To uniformly quantify the asymmetry of the CCF from a Gaussian, we propose to fit the CCF profile with a Gauss-Hermite series and determine all CCF parameters (RV, skewness, FWHM, and depth) in one single fit. We analyze the correlation and time series of these CCF parameters for V448 Lac and conclude that its RV variability is most likely due to stellar pulsation and not to an orbiting body.
ISSN:1743-9213
1743-9221
DOI:10.1017/S1743921318007214