Over the past two decades, helioseismology has revolutionized our understanding of the interior structure and dynamics of the Sun. Asteroseismology will soon place this knowledge into a broader context by providing structural data for hundreds of Sun-like stars. Solar-like oscillations have already been detected from the ground in several stars, and NASA's Kepler mission is poised to unleash a flood of stellar pulsation data. Deriving reliable asteroseismic information from these observations demands a significant improvement in our analysis methods. In this paper we report the initial results of our efforts to develop an objective stellar model-fitting pipeline for asteroseismic data. The cornerstone of our automated approach is an optimization method using a parallel genetic algorithm. We describe the details of the pipeline and we present the initial application to Sun-as-a-star data, yielding an optimal model that accurately reproduces the known solar properties.
The Kepler mission has been fantastic for asteroseismology of solar-type stars, but the targets are typically quite distant. As a consequence, the reliability of asteroseismic modeling has been limited by the precision of additional constraints from high-resolution spectroscopy and parallax measurements. A precise luminosity is particularly useful to minimize potential biases due to the intrinsic correlation between stellar mass and initial helium abundance. We have applied the latest version of the Asteroseismic Modeling Portal (AMP) to the complete Kepler data sets for 30 stars with known ro…
We used the Robo-AO laser adaptive optics system to image 99 main sequence and subgiant stars that have Kepler-detected asteroseismic signals. Robo-AO allows us to resolve blended secondary sources at separations as close as 0.15" that may contribute to the measured Kepler light curves and affect asteroseismic analysis and interpretation. We report 8 new secondary sources within 4.0" of these Kepler asteroseismic stars. We used Subaru and Keck adaptive optics to measure differential infrared photometry for these candidate companion systems. Two of the secondary sources are likely foreground ob…
The Kepler space telescope observed over 15,000 stars for asteroseismic studies. Of these, 75% of dwarfs (and 8% of giants) were found to show anomalous behavior: such as suppressed oscillations (low amplitude) or no oscillations at all. The lack of solar-like oscillations may be a consequence of multiplicity, due to physical interactions with spectroscopic companions or due to the dilution of oscillation amplitudes from "wide'" (AO detected; visual) or spectroscopic companions introducing contaminating flux. We present a search for stellar companions to 327 of the Kepler asteroseismic sample,…
Studies using asteroseismic ages and rotation rates from star-spot rotation have indicated that standard age-rotation relations may break down roughly half-way through the main sequence lifetime, a phenomenon referred to as weakened magnetic braking. While rotation rates from spots can be difficult to determine for older, less active stars, rotational splitting of asteroseismic oscillation frequencies can provide rotation rates for both active and quiescent stars, and so can confirm whether this effect really takes place on the main sequence. We obtained asteroseismic rotation rates of 91 main…
We perform photometric (the Lomb-Scargle periodogram, autocorrelation, and wavelet) and asteroseismic analyses of 92 Kepler solar-like main-sequence stars to understand the reliability of the measured stellar rotation periods. We focus on the 70 stars without reported stellar companions, and classify them into four groups according to the quarter-to-quarter variance of the Lomb-Scargle period and the precision of the asteroseismic period. We present detailed individual comparison among photometric and asteroseismic constraints for these stars. We find that most of our targets exhibit significa…
The Kepler Asteroseismic Legacy Project provided frequencies, separation ratios, error estimates, and covariance matrices for 66 Kepler main sequence targets. Most of the previous analysis of these data was focused on fitting standard stellar models. We present results of direct asteroseismic inversions using the method of optimally localized averages (OLA), which effectively eliminates the surface effects and attempts to resolve the stellar core structure. The inversions are presented for various structure properties, including the density stratification and sound speed. The results show that…
Asteroseismology has proven to be an excellent tool to determine not only the global stellar properties with a good precision but also to infer stellar structure, dynamics, and evolution for a large sample of Kepler stars. Prior to the launch of the mission the properties of Kepler targets were inferred from broadband photometry, leading to the Input Catalog (KIC Brown et al. 2011). The KIC was later revised in the Kepler Star Properties Catalog (Huber et al. 2014), based on literature values and an asteroseismic analysis of stars which were unclassified in the KIC. Here we present an asterose…
We present the results of analysis and modelling of the eclipsing binary system, KIC 10661783. The Fourier analysis of the Kepler light curve, corrected for the binary effects, reveals 750 frequency peaks in both p and g-mode regions. Those with the highest amplitudes concentrate in the range of 20-30 d$^{-1}$. To reproduce observed spectrum of frequencies we construct seismic models accounting for the mode instability. In order to obtain instabilities in the g-mode regime we modify the opacity tables data near the Z-bump. In order to reproduce system parameters, we construct evolutionary mode…
The Kepler space telescope yielded unprecedented data for the study of solar-like oscillations in other stars. The large samples of multi-year observations posed an enormous data analysis challenge that has only recently been surmounted. Asteroseismic modeling has become more sophisticated over time, with better methods gradually developing alongside the extended observations and improved data analysis techniques. We apply the latest version of the Asteroseismic Modeling Portal (AMP) to the full-length Kepler data sets for 57 stars and the Sun, comprising planetary hosts, binaries, solar-analo…
The simultaneous presence of variability due to both pulsations and binarity is no rare phenomenon. Unfortunately, the complexities of dealing with even one of these sources of variability individually means that the other signal is often treated as a nuisance and discarded. However, both types of variability offer means to probe fundamental stellar properties in robust ways through asteroseismic and binary modelling. We present an efficient methodology that includes both binary and asteroseismic information to estimate fundamental stellar properties based on a grid-based modelling approach. W…
In the past few years, the CoRoT and Kepler missions have carried out what is now called the space photometry revolution. This revolution is still ongoing thanks to K2 and will be continued by the Tess and Plato2.0 missions. However, the photometry revolution must also be followed by progress in stellar modelling, in order to lead to more precise and accurate determinations of fundamental stellar parameters such as masses, radii and ages. In this context, the long-lasting problems related to mixing processes in stellar interior is the main obstacle to further improvements of stellar modelling.…
只要有高精度的数据，就可以用星震方法详细研究恒星的结构和演化。我们使用我们的高分辨率卫星数据，确定了44个开普勒小行星地震目标的有效温度（Teff）、表面重力（log g）、金属丰度和投影旋转速度（v sin i）。（R > 20，000）光谱观测;这些参数将被用来计算这些恒星的星震模型，并解释开普勒光变曲线。我们使用互相关的方法来测量我们的目标的径向速度（RV），而大气参数推导使用ROTFIT代码和光谱合成方法。我们发现了三个双线光谱双星，HIP 94924，HIP 95115和HIP 97321 -对于最后一个系统，我们提供了轨道解，我们报告了两个可疑的单线光谱双星，HIP 94112和HIP 96062。对于所有的恒星从我们的样本中，我们得出RV，v sin i，Teff，log g和金属丰度，并为6颗恒星，我们进行了详细的丰度分析。对33个目标进行了光谱分类。最后，我们表明，早期型星HIP 94472旋转缓慢（v sin i = 13公里/1），我们确认其分类为上午光谱类型，这使得它成为一个有趣的和有前途的目标，为asteroseismic建模。本文报道的结果与开普勒输入目录（KIC）中的信息的比较表明，迫切需要验证和改进的KIC中列出的大气参数。这种改进对于充分利用开普勒提供的数据至关重要，只有通过详细的地面研究才能实现。
The importance of studying the Gaia DR2 parallax zero-point by external means was underlined by Lindegren et al. (2018), and initiated by several works making use of Cepheids, eclipsing binaries, and asteroseismology. Despite a very efficient elimination of basic-angle variations, a small fluctuation remains and shows up as a small offset in the Gaia DR2 parallaxes. By combining astrometric, asteroseismic, spectroscopic, and photometric constraints, we undertake a new analysis of the Gaia parallax offset for nearly 3000 red-giant branch (RGB) and 2200 red clump (RC) stars observed by Kepler, a…
Context. The Kepler space mission led to a large amount of high-precision time series of solar-like oscillators. Using a Bayesian analysis that combines asteroseismic techniques and additional ground-based observations, the mass, radius, luminosity, and distance of those stars can be estimated with good precision. This has given a new impetus to the research field of galactic archeology. Aims. The first data release of the Gaia space mission contains the TGAS catalog with parallax estimates for more than 2 million stars, including many of the Kepler targets. Our goal is to make a first proper …
Asteroseismic modelling of main-sequence solar-like stars and Kepler exoplanet host stars with the FICO procedure I. Catalogue of fundamental stellar properties
Uppsala University（乌普萨拉大学）；Observatoire de Paris, Université PSL, Sorbonne Université, Université Paris Cité, CY Cergy Paris Université, CNRS（巴黎天文台，巴黎文理研究大学，索邦大学，巴黎西岱大学，CY塞吉-蓬图瓦兹大学，法国国家科学研究中心）；STAR Institute, Université de Liège（列日大学天体物理、恒星和系外行星研究所）；Istituto Nazionale di Astrofisica – Osservatorio Astronomico di Roma（意大利国家天体物理研究所罗马天文台）；Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP（波尔图大学空间科学与天体物理研究所）
Asteroseismic Modeling of 1,153 Kepler Red Giant Branch Stars: Improved Stellar Parameters with Gravity-Mode Period Spacings and Luminosity Constraints
We use asteroseismic data from the Kepler satellite to determine fundamental stellar properties of the 66 main-sequence targets observed for at least one full year by the mission. We distributed tens of individual oscillation frequencies extracted from the time series of each star among seven modelling teams who applied different methods to determine radii, masses, and ages for all stars in the sample. Comparisons among the different results reveal a good level of agreement in all stellar properties, which is remarkable considering the variety of codes, input physics and analysis methods emplo…
Testing the asteroseismic estimates of stellar radii with surface brightness-colour relations and {\it Gaia} DR3 parallaxes. II. Red giants and red clump stars from the {\it Kepler} catalogue
A Homogeneous Catalog of Oscillating Solar-Type Stars Observed by the Kepler Mission and a New Amplitude Scaling Relation Including Chromospheric Activity
Columbia University（哥伦比亚大学）；University of Hawai‘i（夏威夷大学）；University of Sydney（悉尼大学）；Princeton University（普林斯顿大学）
We test asteroseismic radii of Kepler main-sequence and subgiant stars by deriving their parallaxes which are compared with those of the first Gaia data release. We compute radii based on the asteroseismic scaling relations as well as by fitting observed oscillation frequencies to stellar models for a subset of the sample, and test the impact of using effective temperatures from either spectroscopy or the infrared flux method. An offset of 3%, showing no dependency on any stellar parameters, is found between seismic parallaxes derived from frequency modelling and those from Gaia. For parallaxe…
In this work we combine information from solar-like oscillations, high-resolution spectroscopy and Gaia astrometry to derive stellar ages, chemical abundances and kinematics for a group of seven metal-poor Red Giants and characterise them in a multidimensional chrono-chemo-dynamical space. Chemical abundance ratios were derived through classical spectroscopic analysis employing 1D LTE atmospheres on Keck/HIRES spectra. Stellar ages, masses and radii were calculated with grid-based modelling, taking advantage of availability of asteroseismic information from Kepler. The dynamical properties wer…
Given the potential of ensemble asteroseismology for understanding fundamental properties of large numbers of stars, it is critical to determine the accuracy of the scaling relations on which these measurements are based. From several powerful validation techniques, all indications so far show that stellar radius estimates from the asteroseismic scaling relations are accurate to within a few percent. Eclipsing binary systems hosting at least one star with detectable solar-like oscillations constitute the ideal test objects for validating asteroseismic radius and mass inferences. By combining r…
Data from the space missions {\it Gaia}, {\it Kepler}, {\it CoRoT} and {\it TESS}, make it possible to compare parallax and asteroseismic distances. From the ratio of two densities $ρ_{\rm sca}/ρ_π$, we obtain an empirical relation $f_{Δν}$ between the asteroseismic large frequency separation and mean density, which is important for more accurate stellar mass and radius. This expression for main-sequence (MS) and subgiant stars with $K$-band magnitude is very close to the one obtained from interior MS models by Yıldız, Çelik \& Kayhan. We also discuss the effects of effective temperature and p…
Asteroseismology has been impressively boosted during the last decade mainly thanks to space missions such as Kepler/K2 and CoRoT. This has a large impact, in particular, in exoplanetary sciences since the accurate characterization of the exoplanets is convoluted in most cases with the characterization of their hosting star. Until the expected launch of the ESA mission PLATO 2.0, there is almost a decade where only two important missions will provide short-cadence high-precision photometric time-series: NASA--TESS and ESA--CHEOPS missions, both having high capabilities for exoplanetary science…
