论文标题
RR AQL和MIRA PL关系的VLBA三角差异
A VLBA Trigonometric Parallax for RR Aql and the Mira PL Relation
论文作者
论文摘要
我们将VLBA观测值22 GHz H $ _ {2} $ o和43 GHz SIO MASERS向Mira变量RR AQL报告。通过将SIO MASER排放拟合到圆环，我们估计RR AQL的绝对恒星位置，并与Gaia Astrestremitry达成协议，以在$ \ \ \ \ \ 1 $ MAS的关节不确定性内。使用MASER ASTORMENERY，我们测量的恒星视差为2.44 $ \ pm $ 0.07 MAS，对应于410 $^{+12} _ { - 11} $ PC的距离。 Maser视差显着偏离Gaia EDR3差异为1.95 $ \ pm $ 0.11 MAS，表明无线电和光学测量之间存在$3.8σ$的张力。这种张力很可能是由于光学中心变化限制了该MIRA变量的GAIA星体准确性引起的。将红外幅度与RR AQL和其他MIRA的视差相结合，我们使用MCMC采样的贝叶斯方法拟合了周期的luminusity关系，而LMC的斜率为-3.60 $ \ pm $ 0.30。我们发现使用vlbi视差和-7.08 $ \ $ \ pm $ 0.29 mag使用Gaia parallaxes，我们发现-6.79 $ \ pm $ 0.15 mag的$ k $ -band零点（定义为logp（days）= 2.30）为-6.79 $ \ pm $ 0.15 mag。 Gaia零点在统计上与更准确的VLBI值一致。
We report VLBA observations of 22 GHz H$_{2}$O and 43 GHz SiO masers toward the Mira variable RR Aql. By fitting the SiO maser emission to a circular ring, we estimate the absolute stellar position of RR Aql and find agreement with Gaia astrometry to within the joint uncertainty of $\approx1$ mas. Using the maser astrometry we measure a stellar parallax of 2.44 $\pm$ 0.07 mas, corresponding to a distance of 410$^{+12}_{-11}$ pc. The maser parallax deviates significantly from the Gaia EDR3 parallax of 1.95 $\pm$ 0.11 mas, indicating a $3.8σ$ tension between radio and optical measurements. This tension is most likely caused by optical photo-center variations limiting the Gaia astrometric accuracy for this Mira variable. Combining infrared magnitudes with parallaxes for RR Aql and other Miras, we fit a period-luminosity relation using a Bayesian approach with MCMC sampling and a strong prior for the slope of -3.60 $\pm$ 0.30 from the LMC. We find a $K$-band zero-point (defined at logP(days) = 2.30) of -6.79 $\pm$ 0.15 mag using VLBI parallaxes and -7.08 $\pm$ 0.29 mag using Gaia parallaxes. The Gaia zero-point is statistically consistent with the more accurate VLBI value.
