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Register a new userA new eclipsing binary system with a pulsating component detected by CoRoT
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We report the discovery of CoRoT 102980178 (R.A.= 06:50:12.10, Dec.= -02:41:21.8, J2000) an Algol-type eclipsing binary system with a pulsating component (oEA). It was identified using a publicly available 55 day long monochromatic lightcurve from the CoRoT initial run dataset (exoplanet field). Eleven consecutive 1.26m deep total primary and the equal number of 0.25m deep secondary eclipses (at phase 0.50) were observed. The following light elements for the primary eclipse were derived: HJD_MinI= 2454139.0680 + 5.0548d x E. The lightcurve modeling leads to a semidetached configuration with the photometric mass ratio q=0.2 and orbital inclination i=85 deg. The out-of-eclipse lightcurve shows ellipsoidal variability and positive OConnell effect as well as clear 0.01m pulsations with the dominating frequency of 2.75 c/d. The pulsations disappear during the primary eclipses, which indicates the primary (more massive) component to be the pulsating star. Careful frequency analysis reveals the second independent pulsation frequency of 0.21 c/d and numerous combinations of these frequencies with the binary orbital frequency and its harmonics. On the basis of the CoRoT lightcurve and ground based multicolor photometry, we favor classification of the pulsating component as a gamma Doradus type variable, however, classification as an SPB star cannot be excluded.
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KIC 8560861 (HD 183648) is a marginally eccentric (e=0.05) eclipsing binary with an orbital period of P_orb=31.973d, exhibiting mmag amplitude pulsations on time scales of a few days. We present the results of the complex analysis of high and medium-resolution spectroscopic data and Kepler Q0 -- Q16 long cadence photometry. The iterative combination of spectral disentangling, atmospheric analysis, radial velocity and eclipse timing variation studies, separation of pulsational features of the light curve, and binary light curve analysis led to the accurate determination of the fundamental stellar parameters. We found that the binary is composed of two main sequence stars with an age of 0.9+-0.2 Gyr, having masses, radii and temperatures of M_1=1.93+-0.12 M_sun, R_1=3.30+-0.07 R_sun, T_eff1=7650+-100 K for the primary, and M_2=1.06+-0.08 M_sun, R_2=1.11+-0.03 R_sun, T_eff2=6450+-100 K for the secondary. After subtracting the binary model, we found three independent frequencies, two of which are separated by twice the orbital frequency. We also found an enigmatic half orbital period sinusoidal variation that we attribute to an anomalous ellipsoidal effect. Both of these observations indicate that tidal effects are strongly influencing the luminosity variations of HD 183648. The analysis of the eclipse timing variations revealed both a parabolic trend, and apsidal motion with a period of (P_apse)_obs=10,400+-3,000 y, which is three times faster than what is theoretically expected. These findings might indicate the presence of a distant, unseen companion.
We present the preliminary results of the study of an interesting target in the first CoRoT exo-planet field (IRa1): CoRoT 102918586. Its light curve presents additional variability on the top of the eclipses, whose pattern suggests multi- frequency pulsations. The high accuracy CoRoT light curve was analyzed by applying an iterative scheme, devised to disentangle the effect of eclipses from the oscillatory pattern. In addition to the CoRoT photometry we obtained low resolution spectroscopy with the AAOmega multi-fiber facility at the Anglo Australian Observatory, which yielded a spectral classification as F0 V and allowed us to infer a value of the primary star effective temperature. The Fourier analysis of the residuals, after subtraction of the binary light curve, gave 35 clear frequencies. The highest amplitude frequency, of 1.22 c/d, is in the expected range for both gamma Dor and SPB pulsators, but the spectral classification favors the first hypothesis. Apart from a few multiples of the orbital period, most frequencies can be interpreted as rotational splitting of the main frequency (an l = 2 mode) and of its overtones.
We report time-resolved VR-band CCD photometry of the eclipsing binary RZ Cas obtained with 38-cm Cassegrain telescope at the Crimean Astrophysical Observatory during July 2004 - October 2005. Obtained lightcurves clearly demonstrates rapid pulsations with the period about 22 minutes. Periodogram analysis of such oscillations also is reported. On the 12, January, 2005 we observed rapid variability with higher amplitude (~0.^m 1) that, perhaps, may be interpreted as high-mass-transfer-rate event and inhomogeneity of accretion stream. Follow-up observations (both, photometric and spectroscopic) of RZ Cas are strictly desirable for more detailed study of such event.
Eclipsing binaries with a $delta$ Sct component are powerful tools to derive the fundamental parameters and probe the internal structure of stars. In this study, spectral analysis of 6 primary $delta$ Sct components in eclipsing binaries has been performed. Values of $T_{rm eff}$, $v sin i$, and metallicity for the stars have been derived from medium-resolution spectroscopy. Additionally, a revised list of $delta$ Sct stars in eclipsing binaries is presented. In this list, we have only given the $delta$ Sct stars in eclipsing binaries to show the effects of the secondary components and tidal-locking on the pulsations of primary $delta$ Sct components. The stellar pulsation, atmospheric and fundamental parameters (e.g., mass, radius) of 92 $delta$ Sct stars in eclipsing binaries have been gathered. Comparison of the properties of single and eclipsing binary member $delta$ Sct stars has been made. We find that single $delta$ Sct stars pulsate in longer periods and with higher amplitudes than the primary $delta$ Sct components in eclipsing binaries. The $v sin i$ of $delta$ Sct components is found to be significantly lower than that of single $delta$ Sct stars. Relationships between the pulsation periods, amplitudes, and stellar parameters in our list have been examined. Significant correlations between the pulsation periods and the orbital periods, $T_{rm eff}$, $log g$, radius, mass ratio, $v sin i$, and the filling factor have been found.
Eclipsing binary systems with pulsating components allow the determination of several physical parameters of the stars, such as mass and radius, that, when combined with the pulsation properties, can be used to constrain the modeling of stellar interiors and evolution. Hereby, we present the results of the study of CoRoT 105906206, an eclipsing binary system with a pulsating component located in the CoRoT LRc02 field. The analysis of the CoRoT light curve was complemented by high-resolution spectra from the Sandiford at McDonald Observatory and FEROS at ESO spectrographs, which revealed a double-lined spectroscopic binary. We used an iterative procedure to separate the pulsation-induced photometric variations from the eclipse signals. First, a Fourier analysis was used to identify the significant frequencies and amplitudes due to pulsations. Second, after removing the contribution of the pulsations from the light curve we applied the PIKAIA genetic-algorithm approach to derive the best parameters that describe the orbital properties of the system. The light curve cleaned for pulsations contains the partial eclipse of the primary and the total eclipse of the secondary. The system has an orbital period of about 3.694 days and is formed by a primary star with mass M1 = 2.25 +/- 0.04 solar masses, radius R1 = 4.24 +/- 0.02 solar radii, and effective temperature Teff1 = 6750 +/- 150 K, and a secondary with M2 = 1.29 +/- 0.03 solar masses, R2 = 1.34 +/- 0.01 solar radii, and Teff2 = 6152 +/- 162 K. The best solution for the parameters was obtained by taking into account the asymmetric modulation observed in the light curve, known as the OConnell effect, presumably caused by Doppler beaming. The analysis of the Fourier spectrum revealed that the primary component has p-mode pulsations in the range 5-13 c/d, which are typical of Delta Scuti type stars.
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