标题： 基于SONG-Tenerife、SONG-Australia和TESS的G8次巨星β天鹰座振荡研究 显示英文标题

标题： Asteroseismology of the G8 subgiant beta Aquilae with SONG-Tenerife, SONG-Australia and TESS

摘要： 我们展示了2022年和2023年使用SONG-Tenerife以及首次使用SONG-Australia获得的G8亚巨星星beta Aql的时间序列径向速度数据。我们还分析了TESS测光数据中与2022年SONG数据重叠的部分。由此得到的功率谱清楚地显示了以430微赫为中心的类似太阳的振荡。TESS光曲线显示出较低信噪比的振荡，反映了光度测量比径向速度更易受到粒状背景的影响这一事实。速度和测光的同时观测代表了除太阳以外任何恒星的最佳此类测量。它们使我们能够测量出总辐射光度振幅与速度振幅之比为26.6 ± 3.1 ppm/(m/s)。我们从已发表的SOHO数据中测量到太阳的这一比值为19.5 ± 0.7 ppm/(m/s)，并在考虑了太阳与beta Aql的有效温度差异后，这些值符合预期。在太阳和beta Aql中，测光与速度的比率似乎都是频率的函数。我们还测量了SONG和TESS在beta Aql中的振荡相位偏移，结果为-113 ± 7度，这与太阳的值一致，并且与具有类似性质的beta Aql的三维模拟结果相符。对于系外行星搜索来说，重要的是，我们论证了同时进行的测光可以用来预测振荡对径向速度的贡献。我们测定了beta Aql的22个振荡模式的频率，并进行了星震学建模，得到了频率的极佳拟合。我们得出了准确的质量和年龄值，并能够对混合长度参数施加相当强的限制。最后，我们表明beta Aql的振荡特性与疏散星团M67中的恒星非常相似。 显示英文摘要

摘要： We present time-series radial velocities of the G8 subgiant star beta Aql obtained in 2022 and 2023 using SONG-Tenerife and, for the first time, SONG-Australia. We also analyse a sector of TESS photometry that overlapped with the 2022 SONG data. The resulting power spectrum clearly shows solar-like oscillations centred at 430 muHz. The TESS light curve shows the oscillations at lower signal-to-noise, reflecting the fact that photometric measurements are much more affected by the granulation background than are radial velocities. The simultaneous observations in velocity and photometry represent the best such measurements for any star apart from the Sun. They allowed us to measure the ratio between the bolometric photometric amplitude and the velocity amplitude to be 26.6 +/- 3.1 ppm/(m/s). We measured this ratio for the Sun from published SOHO data to be 19.5 +/- 0.7 ppm/(m/s) and, after accounting for the difference in effective temperatures of and the Sun, these values align with expectations. In both the Sun and beta Aql, the photometry-to-velocity ratio appears to be a function of frequency. We also measured the phase shift of the oscillations in beta Aql between SONG and TESS to be -113 +/- 7 deg, which agrees with the value for the Sun and also with a 3-D simulation of a star with similar properties to beta Aql. Importantly for exoplanet searches, we argue that simultaneous photometry can be used to predict the contribution of oscillations to radial velocities. We measured frequencies for 22 oscillation modes in beta Aql and carried out asteroseismic modelling, yielding an excellent fit to the frequencies. We derived accurate values for the mass and age, and were able to place quite strong constraints on the mixing-length parameter. Finally, we show that the oscillation properties of beta Aql are very similar to stars in the open cluster M67.