论文标题
视差测量的AGB恒星的距离估计值
Distance estimates for AGB stars from parallax measurements
论文作者
论文摘要
使用其视差的光学测量值估算渐近巨星（AGB）恒星的距离并不直接，因为它们的尘土式信封，较大的角度尺寸和表面亮度变异性引入了较大的不确定性。我们将Gaia DR3的视差与用Maser观测值测量的视差进行了比较，其基线干涉法（VLBI）使用33个Maser Exygen富含氧气的AGB附近的AGB恒星的子样本来确定DR3视差的统计校正因子。我们发现，对于最亮的来源，Gaia DR3票数的标称错误被低估了5.44（$ G <8 $ mag）。 FAINTER来源（$ 8 \ leq G <12 $）要求较低的视差误差通货膨胀系数为2.74。我们获得了gaia dr3视差零点的偏移-0.077 MAS，用于明亮的AGB恒星。对于Fainter AGB恒星而言，偏移变得更加负面。我们使用校正后的DR3可视性上的贝叶斯统计方法计算了死亡之星项目中约200颗AGB恒星的距离，并根据先前确定的AGB恒星的银河系分布的先验。我们发现，派生的Gaia距离与我们样本中40％以上来源的显着，不对称误差有关。我们根据从Maser parallaxes得出的距离确定恒星和灰尘发射的辐射转移模型，以确定VLBI子样本中源的发光度，并得出了新的冲线周期 - 光度 - 光度关系，用于银河系氧气富含Mira的Mira富变。根据这些结果，为死亡之星样本中的来源提供了基于这些结果的新距离目录。我们发现1.4以下的RUWE（重新标准化的单位重量误差）不能保证可靠的距离估计值，我们建议不要仅使用RUWE来测量单个AGB恒星的GAIA DR3星体数据的质量。
Estimating the distances to asymptotic giant branch (AGB) stars using optical measurements of their parallaxes is not straightforward because of the large uncertainties introduced by their dusty envelopes, their large angular sizes, and their surface brightness variability. We compared the parallaxes from Gaia DR3 with parallaxes measured with maser observations with very long baseline interferometry (VLBI) to determine a statistical correction factor for the DR3 parallaxes using a sub-sample of 33 maser-emitting oxygen-rich nearby AGB stars. We found that the nominal errors on the Gaia DR3 parallaxes are underestimated by a factor of 5.44 for the brightest sources ($G<8$ mag). Fainter sources ($8\leq G<12$) require a lower parallax error inflation factor of 2.74. We obtain a Gaia DR3 parallax zero-point offset of -0.077 mas for bright AGB stars. The offset becomes more negative for fainter AGB stars. We calculated the distances of about 200 AGB stars in the DEATHSTAR project using a Bayesian statistical approach on the corrected DR3 parallaxes and a prior based on the previously determined Galactic distribution of AGB stars. We found that the derived Gaia distances are associated with significant, asymmetrical errors for more than 40% of the sources in our sample. We performed radiative transfer modelling of the stellar and dust emission to determine the luminosity of the sources in the VLBI sub-sample based on the distances derived from maser parallaxes, and derived a new bolometric period-luminosity relation for Galactic oxygen-rich Mira variables. A new distance catalogue based on these results is provided for the sources in the DEATHSTAR sample. We found that a RUWE (re-normalised unit weight error) below 1.4 does not guarantee reliable distance estimates and we advise against the use of only the RUWE to measure the quality of Gaia DR3 astrometric data for individual AGB stars.
