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THE ECLIPSING SYSTEM V404 LYR: LIGHT-TRAVEL TIMES AND DORADUS PULSATIONS

THE ECLIPSING SYSTEM V404 LYR: LIGHT-TRAVEL TIMES AND DORADUS PULSATIONS We present the physical properties of V404 Lyr exhibiting eclipse timing variations and multiperiodic pulsations from all historical data including the Kepler and SuperWASP observations. Detailed analyses of 2922 minimum epochs showed that the orbital period has varied through a combination of an upward-opening parabola and two sinusoidal variations, with periods of P3 = 649 days and P4 = 2154 days and semi-amplitudes of K3 = 193 s and K4 = 49 s, respectively. The secular period increase at a rate of +1.41 × 107 days yr1 could be interpreted as a combination of the secondary to primary mass transfer and angular momentum loss. The most reasonable explanation for both sinusoids is a pair of light-travel-time effects due to two circumbinary objects with projected masses of M3 = 0.47 Mand M4 = 0.047 M. The third-body parameters are consistent with those calculated using the Wilson-Devinney binary code. For the orbital inclinations i4 43°, the fourth component has a mass within the hydrogen-burning limit of 0.07 M, which implies that it is a brown dwarf. A satisfactory model for the Kepler light curves was obtained by applying a cool spot to the secondary component. The results demonstrate that the close eclipsing pair is in a semi-detached, but near-contact, configuration; the primary fills approximately 93% of its limiting lobe and is larger than the lobe-filling secondary. Multiple frequency analyses were applied to the light residuals after subtracting the synthetic eclipsing curve from the Kepler data. This revealed that the primary component of V404 Lyr is a Dor type pulsating star, exhibiting seven pulsation frequencies in the range of 1.85-2.11 day1 with amplitudes of 1.38-5.72 mmag and pulsation constants of 0.24-0.27 days. The seven frequencies were clearly identified as high-order low-degree gravity-mode oscillations which might be excited through tidal interaction. Only eight eclipsing binaries have been known to contain Dor pulsating components and, therefore, V404 Lyr will be an important test bed for investigating these rare and interesting objects. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Astronomical Journal IOP Publishing

THE ECLIPSING SYSTEM V404 LYR: LIGHT-TRAVEL TIMES AND DORADUS PULSATIONS

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Copyright
Copyright © 2014. The American Astronomical Society. All rights reserved.
ISSN
0004-6256
eISSN
1538-3881
DOI
10.1088/0004-6256/148/2/37
Publisher site
See Article on Publisher Site

Abstract

We present the physical properties of V404 Lyr exhibiting eclipse timing variations and multiperiodic pulsations from all historical data including the Kepler and SuperWASP observations. Detailed analyses of 2922 minimum epochs showed that the orbital period has varied through a combination of an upward-opening parabola and two sinusoidal variations, with periods of P3 = 649 days and P4 = 2154 days and semi-amplitudes of K3 = 193 s and K4 = 49 s, respectively. The secular period increase at a rate of +1.41 × 107 days yr1 could be interpreted as a combination of the secondary to primary mass transfer and angular momentum loss. The most reasonable explanation for both sinusoids is a pair of light-travel-time effects due to two circumbinary objects with projected masses of M3 = 0.47 Mand M4 = 0.047 M. The third-body parameters are consistent with those calculated using the Wilson-Devinney binary code. For the orbital inclinations i4 43°, the fourth component has a mass within the hydrogen-burning limit of 0.07 M, which implies that it is a brown dwarf. A satisfactory model for the Kepler light curves was obtained by applying a cool spot to the secondary component. The results demonstrate that the close eclipsing pair is in a semi-detached, but near-contact, configuration; the primary fills approximately 93% of its limiting lobe and is larger than the lobe-filling secondary. Multiple frequency analyses were applied to the light residuals after subtracting the synthetic eclipsing curve from the Kepler data. This revealed that the primary component of V404 Lyr is a Dor type pulsating star, exhibiting seven pulsation frequencies in the range of 1.85-2.11 day1 with amplitudes of 1.38-5.72 mmag and pulsation constants of 0.24-0.27 days. The seven frequencies were clearly identified as high-order low-degree gravity-mode oscillations which might be excited through tidal interaction. Only eight eclipsing binaries have been known to contain Dor pulsating components and, therefore, V404 Lyr will be an important test bed for investigating these rare and interesting objects.

Journal

The Astronomical Journal – IOP Publishing

Published: Aug 1, 2014

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