探测两颗ZZ Ceti星的脉动性质
Exploring the pulsational properties of two ZZ Ceti stars
摘要：
上下文我们继续我们的地面观测项目，在Konkoly天文台对鲸鱼座ZZ恒星进行了长达一个季节的观测。我们目前的目标是新发现的PM J22299+3024和已知的LP 119-10变星。LP 119-10也被TESS（凌日系外行星巡天卫星）太空望远镜以120秒的节奏模式观测到。方法.我们对每日、每周和整个数据集进行了标准傅立叶分析，并对每周观察的不同组合的测试数据进行了分析。然后，我们利用观测到的和计算出的脉动周期进行了星震拟合。为了计算拟合所需的模型网格，我们应用了2018年版本的白矮星演化代码。结果我们推导出PM J22299+3024的六种可能的脉动模式和LP 119-10的五加两个TESS脉动频率。请注意，数据集中可能存在更多的脉动频率，但我们发现它们的检测不明确，因此我们从最终频率列表中省略了它们。我们对PM J22299+3024的星震拟合给出了11400 K和0.46 Msun的有效温度和恒星质量。温度高出约800 K，而模型恒星的质量与早期通过光谱学得出的质量完全相同。我们的LP~119-10模型拟合将有效温度置于11 800 - 11 900 K的范围内，这再次高于光谱11 290 K值，而我们的最佳模型解决方案给出该目标的M* = 0.70 Msun质量，接近光谱值0.65 Msun，同样在PM J22299+3024的情况下。最佳拟合模型星的地震距离与PM J22299+3024和LP 119-10的盖亚天体测量距离在误差范围内一致，验证了我们的模型结果。
英文摘要：
Context. We continued our ground-based observing project with the season-long observations of ZZ Ceti stars at Konkoly Observatory. Our present targets are the newly discovered PM J22299+3024, and the already known LP 119-10 variables. LP 119-10 was also observed by the TESS (Transiting Exoplanet Survey Satellite) space telescope in 120-second cadence mode. Methods. We performed standard Fourier analysis of the daily, weekly, and the whole data sets, together with test data of different combinations of weekly observations. We then performed asteroseismic fits utilising the observed and the calculated pulsation periods. For the calculations of model grids necessary for the fits, we applied the 2018 version of the White Dwarf Evolution Code. Results. We derived six possible pulsation modes for PM J22299+3024, and five plus two TESS pulsation frequencies for LP 119-10. Note that further pulsation frequencies may be present in the data sets, but we found their detection ambiguous, so we omitted them from the final frequency list. Our asteroseismic fits of PM J22299+3024 give 11 400 K and 0.46 Msun for the effective temperature and the stellar mass. The temperature is ~800 K higher, while the mass of the model star is exactly the same as it was earlier derived by spectroscopy. Our model fits of LP~119-10 put the effective temperature in the range of 11 800 - 11 900 K, which is again higher than the spectroscopic 11 290 K value, while our best model solutions give M* = 0.70 Msun mass for this target, near to the spectroscopic value of 0.65 Msun, likewise in the case of PM J22299+3024. The seismic distances of our best-fitting model stars agree with the Gaia astrometric distances of PM J22299+3024 and LP 119-10 within the errors, validating our model results.
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