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

Abstract

We present the physical properties of V404 Lyr exhibiting eclipse timing variations and multiperiodic pulsations from all historical data including the Kepler and Super-WASP observations. Detailed analyses of 2,922 minimum epochs showed that the orbital period has varied through a combination with an upward-opening parabola and two sinusoidal variations, with periods of P 3 =649 d and P 4 =2,154 d and semi-amplitudes of K 3 =193 s and K 4 =49 s, respectively. The secular period increase with a rate of +1.41 ×10 −7 d yr −1 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 M 3 =0.47 M ⊙ and M 4 =0.047 M ⊙ . The third-body parameters are consistent with those calculated using the Wilson-Devinney binary code. For the orbital inclinations i 4 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 through 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 γ Dor type pulsating star, exhibiting seven pulsation frequencies in the range of 1.85−2.11 d −1 with amplitudes of 1.38−5.72 mmag and pulsation constants of 0.24−0.27 d. 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 γ Dor pulsating components and, therefore, V404 Lyr will be an important test-bed for investigating these rare and interesting objects.

A comprehensive study of theKeplertriples via eclipse timing

“…They now provide third body LTTE solutions for seven EBs. Additional studies of a possible third body affecting the ETVs of individual EBs in the Kepler-field have also been reported in Steffen et al (2011, for KOI-928(=KIC 09140402)) Borkovits et al (2013, for HD 181068(=KIC 05952403)), Lee et al (2013, for KIC 02856960), Lee et al (2014, for V404 Lyr(=KIC 03228863)), Lee et al (2015, for KIC 05621294). Most recently, Baran et al (2015) reported the detection of a planet-mass companion in the sdB+dM EB 2M1938+4603(=KIC 09472174).…”

“…Unfortunately, the times of minima obtained from these data bases often offer only lesser benefits because of the restricted extension of the data span and, in several cases, the sampling rate of the observations of each EB was so infrequent that the data do not yield times of individual eclipses with useful accuracy. For these reasons we did not determine and utilize the times of minima from the observations of the above listed surveys for all systems, we make use of the data only for those EBs for which the eclipse times were determined by Lee et al (2014) and Zasche et al (2015).…”

The effect of tides on near-core rotation: analysis of 35 Kepler γ Doradus stars in eclipsing and spectroscopic binaries

“…The known γ Dor binaries whose period spacings were not previously measured are: KIC 3228863 (Lee et al 2019(Lee et al , 2014; KIC 4150611 (Hełminiak et al 2017); KIC 6048106 (Lee 2016;Samadi Ghadim, Lampens & Jassur 2018); KIC 6206751 (Lee & Park 2018); KIC 8569819 (Kurtz et al 2015); KIC 9236858 (Kjurkchieva & Atanasova 2016); and KIC 9851944 (Guo et al 2016). These works focused mainly on the dynamics of the binary systems, hence they did not measure the period spacings of g modes.…”

The Eclipsing δ Scuti Star EPIC 245932119

“…The PERIOD04 program (Lenz & Breger 2005) was carried out in the frequency range from 0 to the Nyquist limit of f Ny =24.47 days −1 . After the successive prewhitening of each frequency peak (see Lee et al 2014), we detected the frequencies based on the empirical threshold of the signal-to-noise amplitude ratio (S/N) larger than 4.0 (Breger et al 1993). Third, we removed the pulsation signatures from the observed K2 data.…”