Kepler and TESS Observations of PG 1159-035
Kepler and TESS Observations of PG 1159-035
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DOI：
10.3847/1538-4357/ac8871
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发表时间：
2022-08
期刊：
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通讯作者：
Gabriela Oliveira da Rosa;S. O. Kepler;A. H. C'orsico;J. E. S. Costa;J. Hermes;S. Kawaler;K. Bell;M. Montgomery;J. Provencal;D. Winget;G. Handler;B. Dunlap;J. Clemens;M. Uzundag
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作者：
Gabriela Oliveira da Rosa;S. O. Kepler;A. H. C'orsico;J. E. S. Costa;J. Hermes;S. Kawaler;K. Bell;M. Montgomery;J. Provencal;D. Winget;G. Handler;B. Dunlap;J. Clemens;M. Uzundag
PG 1159-035是PG 1159热（预）白矮星脉动的原型。这个重要的天体在开普勒卫星K2任务中以59秒的节奏模式观测了69天，由TESS卫星以20秒的节奏模式观测了25天。我们对这些数据进行了详细的星震分析。我们总共确定了107个频率代表32个r = 1模态，27个频率代表12个r = 2模态，以及8个组合频率。组合频率和k值非常高的模态代表新的探测。当α = 1和α = 2时，其平均分裂率分别为4.0±0.4 μHz和6.8±0.2 μHz，表明在周期形成区域的旋转周期为1.4±0.1 d。在光曲线的傅里叶变换中，我们发现在8.904±0.003 μHz处有一个显著的峰，表明表面旋转周期为1.299±0.002天。我们还提供证据表明，观测到的周期在时间尺度上的变化比当前进化模型预测的要短。我们的星震分析发现，当r = 1时，平均周期间隔为21.28±0.02 s。2模的平均间距为12.97±0.4 s。通过将观测到的周期与演化模型的周期进行比较，我们进行了详细的星震拟合。在光谱测定的不确定度范围内，最佳拟合模型的T = 129,600±11 100 K, M * = 0.565±0.024M⊙,logg=7.41−0.54+0.38。由于最佳拟合模型并不能预测PG 1159-035中检测到的所有脉动的激发，因此我们主张对当前模型进行未来的改进，例如在he燃烧阶段的超调。
PG 1159-035 is the prototype of the PG 1159 hot (pre-)white dwarf pulsators. This important object was observed during the Kepler satellite K2 mission for 69 days in 59 s cadence mode and by the TESS satellite for 25 days in 20 s cadence mode. We present a detailed asteroseismic analysis of those data. We identify a total of 107 frequencies representing 32 ℓ = 1 modes, 27 frequencies representing 12 ℓ = 2 modes, and eight combination frequencies. The combination frequencies and the modes with very high k values represent new detections. The multiplet structure reveals an average splitting of 4.0 ± 0.4 μHz for ℓ = 1 and 6.8 ± 0.2 μHz for ℓ = 2, indicating a rotation period of 1.4 ± 0.1 days in the region of period formation. In the Fourier transform of the light curve, we find a significant peak at 8.904 ± 0.003 μHz suggesting a surface rotation period of 1.299 ± 0.002 days. We also present evidence that the observed periods change on timescales shorter than those predicted by current evolutionary models. Our asteroseismic analysis finds an average period spacing for ℓ = 1 of 21.28 ± 0.02 s. The ℓ = 2 modes have a mean spacing of 12.97 ± 0.4 s. We performed a detailed asteroseismic fit by comparing the observed periods with those of evolutionary models. The best-fit model has T eff = 129, 600 ± 11 100 K, M * = 0.565 ± 0.024M ⊙, and logg=7.41−0.54+0.38 , within the uncertainties of the spectroscopic determinations. We argue for future improvements in the current models, e.g., on the overshooting in the He-burning stage, as the best-fit model does not predict excitation for all of the pulsations detected in PG 1159-035.