造父变星投影因子的观测刻度I。II型孔雀造父星
Observational calibration of the projection factor of Cepheids I. The Type II Cepheid kappa Pavonis
摘要：
脉动恒星的距离，特别是造父变星，通常使用脉动视差技术测量。该技术的不同版本结合了线性直径变化（来自光谱学）和角直径变化（来自光度测量或干涉测量）幅度的测量，以准几何方式检索距离。然而，线性直径振幅与投影因子（下文称为p因子）成正比，投影因子用于转换光谱径向速度（即，盘集成）到脉动（即，光球）速度。p因子的值及其对脉动周期的可能依赖性仍然存在广泛的争论。我们的目标是测量II型造父星kappa Pavonis的p因子的观测值，使用HST/FGS测量其视差的准确度为5%。我们使用这种视差作为出发点来推导kappa Pav的p因子，使用SPIPS技术，这是一种采用径向速度，干涉测量和光度测量数据的脉动松弛方法的鲁棒版本。我们将这种技术应用于新的VLTI/PIONIER光学干涉角直径，新的CORALIE和HARPS径向速度，以及多色测光和径向速度的文献相结合。我们获得的kappa Pav的p因子值为p = 1.26 +/- 0.07。这一结果与最近从文献中导出的周期p因子关系以及先前对造父变星的观测结果一致。个别估计的p-因子是根本的校准视差的脉动距离的造父变星。与以前的观测估计一起，我们得到的投影因子指向p因子对周期的弱依赖性。
英文摘要：
The distances of pulsating stars, in particular Cepheids, are commonly measured using the parallax of pulsation technique. The different versions of this technique combine measurements of the linear diameter variation (from spectroscopy) and the angular diameter variation (from photometry or interferometry) amplitudes, to retrieve the distance in a quasi-geometrical way. However, the linear diameter amplitude is directly proportional to the projection factor (hereafter p-factor), which is used to convert spectroscopic radial velocities (i.e., disk integrated) into pulsating (i.e., photospheric) velocities. The value of the p-factor and its possible dependence on the pulsation period are still widely debated. Our goal is to measure an observational value of the p-factor of the type-II Cepheid kappa Pavonis, whose parallax was measured with an accuracy of 5% using HST/FGS. We used this parallax as a starting point to derive the p-factor of kappa Pav, using the SPIPS technique, which is a robust version of the parallax-of-pulsation method that employs radial velocity, interferometric and photometric data. We applied this technique to a combination of new VLTI/PIONIER optical interferometric angular diameters, new CORALIE and HARPS radial velocities, as well as multi-colour photometry and radial velocities from the literature. We obtain a value of p = 1.26 +/- 0.07 for the p-factor of kappa Pav. This result agrees with several of the recently derived Period-p-factor relationships from the literature, as well as previous observational determinations for Cepheids. Individual estimates of the p-factor are fundamental to calibrating the parallax of pulsation distances of Cepheids. Together with previous observational estimates, the projection factor we obtain points to a weak dependence of the p-factor on period.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
