We present Kepler photometry and ground based spectroscopy of KIC 4544587, a short-period eccentric eclipsing binary system with self-excited pressure and gravity modes, tidally excited modes, tidally influenced p modes, and rapid apsidal motion of 182 y per cycle. The primary and secondary components of KIC 4544587 reside within the delta Scuti and gamma Dor instability region of the Hurtzsprung-Russell diagram, respectively. By applying the binary modelling software PHOEBE to prewhitened Kepler photometric data and radial velocity data obtained using the William Herschel Telescope and 4-m Mayall telescope at KPNO, the fundamental parameters of this important system have been determined, including the stellar masses, 1.98+/-0.07 MSun and 1.60+/-0.06 MSun, and radii, 1.76+/-0.03 RSun and 1.42+/-0.02 RSun, for the primary and secondary components, respectively. Frequency analysis of the residual data revealed 31 modes, 14 in the gravity mode region and 17 in the pressure mode region. Of the 14 gravity modes 8 are orbital harmonics: a signature of tidal resonance. While the measured amplitude of these modes may be partially attributed to residual signal from binary model subtraction, we demonstrate through consideration of the folded light curve that these frequencies do in fact correspond to tidally excited pulsations. Furthermore, we present an echelle diagram of the pressure mode frequency region (modulo the orbital frequency) and demonstrate that the tides are also influencing the p modes. A first look at asteroseismology hints that the secondary component is responsible for the p modes, which is contrary to our expectation that the hotter star should pulsate in higher radial overtone, higher frequency p modes.
Amongst the intermediate mass pulsating stars known as $δ$ Sct stars is a subset of high-amplitude and predominantly radial-mode pulsators known as high-amplitude $δ$ Sct (HADS) stars. From more than 2000 $δ$ Sct stars observed by the Kepler space mission, only two HADS stars were detected. We investigate the more perplexing of these two HADS stars, KIC5950759. We study its variability using ground- and space-based photometry, determine its atmospheric parameters from spectroscopy and perform asteroseismic modelling to constrain its mass and evolutionary stage. From spectroscopy, we find that …
Heartbeat stars are a class of eccentric binary stars with short-period orbits and characteristic "heartbeat" signals in their light curves at periastron, caused primarily by tidal distortion. In many heartbeat stars, tidally excited oscillations can be observed throughout the orbit, with frequencies at exact integer multiples of the orbital frequency. Here, we characterize the tidally excited oscillations in the heartbeat stars KIC 6117415, KIC 11494130, and KIC 5790807. Using Kepler light curves and radial velocity measurements, we first model the heartbeat stars using the binary modeling so…
We study the $δ$ Scuti -- red giant binary KIC9773821, the first double-pulsator binary of its kind. It was observed by \textit{Kepler} during its four-year mission. Our aims are to ascertain whether the system is bound, rather than a chance alignment, and to identify the evolutionary state of the red giant via asteroseismology. An extension of these aims is to determine a dynamical mass and an age prior for a $δ$ Sct star, which may permit mode identification via further asteroseismic modelling. We determine spectroscopic parameters and radial velocities (RVs) for the red giant component usin…
KIC~8975515: a fast-rotating ($γ$ Dor - $δ$ Sct) hybrid star with Rossby modes and a slower $δ$ Sct companion in a long-period orbit
{KIC~8975515是一个具有混合脉动的\emph{Kepler}双线光谱双星系统。两个分量具有相似的大气特性（T $_{\rm eff}$ $\sim$ 7400~K），其中一个是快速旋转体（$v\sin i = 162$对32 km/s）。我们的目标是非常详细地研究\emph {开普勒}光变曲线，以确定脉动的频率，在傅立叶光谱中寻找规则的间隔模式，如果有的话，并在二元性和快速旋转的背景下讨论它们的起源。在本文中，我们研究的基础上仔细分析的低，中，高频率区域的傅立叶频谱的恒星脉动的性质。这是通过对频谱中检测到的所有重要频率进行连续的预白化来执行重复的频率搜索分析来完成的。此外，我们寻找的$g$模式之间的定期间隔，以及$g$和$p$模式之间的频率分裂。在低频区，检测到五个规则的周期间隔图案，包括一个系列的逆$g$模式和四个系列的逆$r$模式。的$r$模式是均匀分布的谐波的旋转频率的快速旋转的恒星$f_{\rm rot}$ = 1.647 d $^{-1}$。主要的$g$模式是$f_{2}$ = 2.37 d $^{-1}$。最强的p模在$f_{1}$ = 13.97 d $^{-1}$处形成单重态。在高频区，我们确定了两个多重的定期分裂$p$模式的平均频率间隔为0.42 d $^{-1}$和1.65 d $^{-1}$。我们探测到一些系列的逆行$r$和逆$g$模式，以及两个多重…
WASP-33 is one of the few $δ$ Sct stars with a known planetary companion. By analyzing the stellar oscillations, we search for possible star-planet interactions in the pattern of the pulsation. We made use of the Transit and Light Curve Modeller (TLCM) to solve the light curve from the Transiting Exoplanet Survey Satellite (TESS). We include gravity darkening into our analysis. The stellar oscillation pattern of WASP-33 clearly shows signs of several tidally perturbed modes. We find that there are peaks in the frequency spectrum that are at or near the $3$rd, $12$th and $25$th orbital harmonic…
Context. Thanks to the high-precision photometry from space missions such as Kepler and TESS, tidal perturbations and tilting of pulsations have been detected in more than a dozen binary systems. However, only two of these were g-mode pulsators. Aims. We aim to detect tidally perturbed g modes in additional binary systems and characterise them observationally. Methods. We perform a custom data reduction of the available Kepler and TESS photometry of a well-studied sample of 35 binary systems with gamma Doradus pulsators. For each target, we model the binary signal using a sum of 100 sine waves…
Strong magnetic fields in chemically peculiar A-type (Ap) stars typically suppress low-overtone pressure modes (p modes) but allow high-overtone p modes to be driven. KIC 11296437 is the first star to show both. We obtained and analysed a Subaru spectrum, from which we show that KIC 11296437 has abundances similar to other magnetic Ap stars, and we estimate a mean magnetic field modulus of $2.8\pm0.5$ kG. The same spectrum rules out a double-lined spectroscopic binary, and we use other techniques to rule out binarity over a wide parameter space, so the two pulsation types originate in one $δ$ …
IM Per is a triple star system whose eclipsing pair masses and radii are accurate to within 1 \%. The TESS light curve of the program target exhibits partial eclipses and multiple oscillations with mmag-level amplitudes. It is found that the oscillations affect eclipse timing measurements. Binary modeling of the high-quality TESS data indicates that the eclipsing components of the triple system are twin dwarfs with parameters of $M_2$/$M_1$ = 0.995, $R_2$/$R_1$ = 0.901, and $Δ$($T_{\rm eff,1}$--$T_{\rm eff,2}$) = 12 K in an eccentric ($e$ = 0.049), detached configuration. The third light of $l…
We present a comprehensive study of the eclipsing binary system KIC 10661783. The analysis of the whole Kepler light curve, corrected for the binary effects, reveals a rich oscillation spectrum with 590 significant frequency peaks, 207 of which are independent. In addition to typical $δ$ Sct frequencies, we find small-amplitude signals in the low-frequency range that, most probably, are a manifestation of gravity-mode pulsations. We perform binary-evolution computations for this system in order to find an acceptable model describing its current stage. Our models show that the binary KIC 106617…
In this paper, we analyze the light variations of KIC 10975348 using photometric data delivered from $Kepler$ mission. This star is exceptionally faint ($K_{p}$ = 18.6 mag), compared to most well-studied $δ$ Scuti stars. The Fourier analysis of the short cadence data (i.e. Q14, Q15 and Q16, spanning 220 days) reveals the variations are dominated by the strongest mode with frequency F0 = 10.231899 $\rm{d^{-1}}$, which is compatible with that obtained from $RATS-Kepler$. The other two independent modes with F1 (= 13.4988 $\rm{d^{-1}}$) and F2 (= 19.0002 $\rm{d^{-1}}$) are newly detected and have…
Previously, a series of tidally-excited oscillations were discovered in the eccentric eclipsing binary KIC 3230227. The pulsation amplitudes and phases suggest the observed oscillations are prograde quadruple modes. In this paper, we refine the analysis and extract more oscillation frequencies. We also study the temporal variations of amplitudes and phases and show that almost all modes have stable phases and amplitudes. We then focus on the non-orbital-harmonic oscillations. We consider two formation mechanisms: 1) nonlinear response of the surface convective layer, and 2) nonlinear three/mul…
KIC 4150611: a rare multi-eclipsing quintuple with a hybrid pulsator
我们目前的结果，我们的分析KIC 4150611（HD 181469）-一个有趣的，明亮的五元组系统，其中包括一个混合$δ$ Sct/ $γ$ Dor reflectator。开普勒卫星观测到了四个日食周期-- 94.2、8.65、1.52和1.43 d，在高角分辨率图像中可以看到三个点源（A、B和C）。根据冈山天文台（OAO）1.88米望远镜上的HIDES摄谱仪进行的光谱观测，我们首次计算了B分量--一对G型恒星的径向速度（RV），并将它们与开普勒测光结合，以获得这对恒星的绝对物理参数。我们还设法直接测量了蒸发器的RV，这也是第一次。此外，我们模拟了1.52和1.43天的光变曲线，并测量了它们的日食时间变化（ETV）。我们还对凯克II望远镜的NIRC 2相机拍摄的图像上的三个源进行了相对天体测量和测光。最后，我们比较了我们的结果与理论等时线。最亮的部分Aa是溷合双星，每94.2天由一对K/M型恒星（Ab 1 + Ab 2）经过，它们本身形成一个1.52天的食双星。Ba和Bb是晚G型星，形成了另一个周期为8.65天的食对。其质量和半径分别为：原发灶为$M_{Ba}=0.894\pm0.010$ M $_\odot$，$R_{Ba}=0.802\pm0.044$ R $_\odot$，继发灶为$M_{Bb}=0.888\pm0.010$ M $_\odot$，$R_{Bb}=0.85…
KIC 6951642 has been reported as a candidate hybrid pulsator of type-$γ$ Doradus-$δ$ Scuti from observations of the first quarters of the Kepler mission. We aim to investigate the pulsating nature of KIC 6951642 and to search for the signature of rotation and/or activity in the light curves. We performed an iterative frequency search of both Fourier spectra, and searched for regular patterns in them. We applied spectrum synthesis to determine the atmospheric stellar parameters. Since KIC 6951642 was reported to belong to a spectroscopic binary system, we fitted the time delays derived from the…
