Red giants in the updated APOGEE-Kepler catalogue, with estimates of mass, chemical composition, surface gravity and effective temperature, have recently challenged stellar models computed under the standard assumption of solar calibrated mixing length. In this work, we critically reanalyse this sample of red giants, adopting our own stellar model calculations. Contrary to previous results, we find that the disagreement between the effective temperature scale of red giants and models with solar calibrated mixing length disappears when considering our models and the APOGEE-Kepler stars with scaled solar metal distribution. However, a discrepancy shows up when alpha-enhanced stars are included in the sample. We have found that assuming mass, chemical composition and effective temperature scale of the APOGEE-Kepler catalogue, stellar models generally underpredict the change of temperature of red giants caused by alpha-element enhancements at fixed [Fe/H]. A second important conclusion is that the choice of the outer boundary conditions employed in model calculations is critical. Effective temperature differences (metallicity dependent) between models with solar calibrated mixing length and observations appear for some choices of the boundary conditions, but this is not a general result
Spectroscopic identification of rapidly rotating red giant stars in APOKASC-3 and APOGEE DR16
快速旋转的红巨星在天体物理学上很有趣，但很罕见。在本文中，我们提出了一个目录的3217个活跃的红巨星候选人在APOGEE DR 16调查。我们使用一个控制样本中的开普勒领域的充分研究，以证明一个强大的旋转和异常之间的关系，在光谱解决方案相对于典型的巨人。在整个调查中具有类似解决方案的明星被确定为候选人。我们使用vsin \textiti测量来确认50+/- 1.2%的候选者是确定的快速旋转者，而开普勒控制样本为4.9+/-0.2%。在开普勒控制样本和来自DR 16的控制样本中，我们发现有3-4倍于5 < vsini < 10 km s $^{-1}$ compared to vsini >10 km s $^{-1}$的巨星旋转，这是红巨星异常旋转的传统阈值。绝大多数的中间旋光子在光谱上并不是反常的。我们使用来自APOGEE和\textit{Gaia}的二元诊断来推断二元分数为73+/-2.4%。我们确定了一个显着的偏差，在报告的金属丰度的候选人与完整的光谱解决方案，与中位偏移量为0.37德克斯在[M/H]从对照样品。因此，高达10%的[M/H]<-1的恒星并不是真正的贫金属恒星。最后，我们使用盖亚数据来确定一个子人口的主序列光度双星错误地归类为巨人。
A catalogue of asteroseismically calibrated ages for APOGEE DR17. The predictions of a CatBoost machine learning model based on the [Mg/Ce] chemical clock and other stellar parameters
Distance and extinction determination for APOGEE stars with Bayesian method
使用贝叶斯技术，我们推导出的距离和距离超过100,000红巨星观察到的阿帕奇点天文台星系演化实验（APOGEE）调查考虑到光谱的限制，从APOGEE恒星参数和光度的限制，从2 MASS，以及对银河系的先验知识。导出的距离与其他四种独立方法的距离进行了比较，即依巴谷星团，星团，APOGEE红团星，以及APOKASC（Rodrigues et al. 2014）和SAGA目录（Casagrande et al. 2014）的星震距离。这些比较涵盖了从0.02千秒差距到20千秒差距的距离尺度上的四个数量级。结果表明，我们的距离与其他方法的距离吻合得很好：我们的贝叶斯距离与其他方法的贝叶斯距离的平均相对差在-4.2%~+3.6%之间，离散度在15%~ 25%之间。对所有恒星的消光系数也被推导出来，并与其他几种独立的方法进行了比较：Rayleigh-Jeans Color Excess（RJCE）方法，Gonzalez的二维消光图，以及三维消光图和模型。比较表明，总体而言，估计的反射率非常一致，但RJCE往往高估了冷恒星和低logg天体的反射率。
A New Catalogue of Galactic Red Supergiants for direct detection of episodic mass-loss events
INAF-Osservatorio Astronomico di Palermo（意大利国家天体物理研究所巴勒莫天文台）；Dipartimento di Fisica e Astronomia, Università degli Studi di Padova（帕多瓦大学物理与天文学系）；Dipartimento di Fisica e Chimica, Università degli Studi di Palermo（巴勒莫大学物理与化学系）；INAF-Osservatorio Astronomico di Padova（意大利国家天体物理研究所帕多瓦天文台）；INAF-Osservatorio Astronomico di Roma（意大利国家天体物理研究所罗马天文台）
