DISTANCE AND KINEMATICS OF THE RED HYPERGIANT VY CMa: VERY LONG BASELINE ARRAY AND VERY LARGE ARRAY ASTROMETRY
DISTANCE AND KINEMATICS OF THE RED HYPERGIANT VY CMa: VERY LONG BASELINE ARRAY AND VERY LARGE ARRAY ASTROMETRY
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DOI：
10.1088/0004-637x/744/1/23
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
B. Zhang;M. Reid;K. Menten;X. Zheng
中科院分区：
文献类型：
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作者：
B. Zhang;M. Reid;K. Menten;X. Zheng
我们报告的天体测量结果的相位参考甚长基线干涉测量观测的43 GHz的SiO脉泽发射的红色超巨星VY大犬座（VY CMa）使用甚长基线阵列（VLBA）。我们测得的三角视差为0.83 ± 0.08 mas，对应的距离为1.20+0.13−0.10 kpc。与以前的研究相比，SiO脉泽的空间分布发生了很大的变化，而其总的范围保持不变。脉泽斑的内部运动高达1.4 mas yr-1，相当于8 km s-1，并显示出膨胀的趋势。在模拟了脉泽斑点的膨胀之后，我们得到了中心星星的绝对自行，分别为μx = −2.8 ± 0.2和μy = 2.6 ± 0.2 mas yr−1。根据VLBA观测的脉泽分布和甚大天线阵补充观测的43 GHz SiO脉泽辐射与射电光球的相对位置，我们估计了VY CMa在平历元2006.53的绝对位置为αJ2000 = 07h22m58.<$3259 ± 0.<$0007。δJ2000 = −25°46′03.″063 ± 0.″010。VLBA观测得到的VY CMa的位置和自行与依巴谷卫星的观测值有很大差异。这些差异很可能与星周包层中的不均匀性和尘埃散射光学光有关。VLBA测量的绝对自行表明VY CMa可能正从其东面的巨大分子云中漂移出来。
We report astrometric results of phase-referencing very long baseline interferometry observations of 43 GHz SiO maser emission toward the red hypergiant VY Canis Majoris (VY CMa) using the Very Long Baseline Array (VLBA). We measured a trigonometric parallax of 0.83 ± 0.08 mas, corresponding to a distance of 1.20+0.13−0.10 kpc. Compared to previous studies, the spatial distribution of SiO masers has changed dramatically, while its total extent remains similar. The internal motions of the maser spots are up to 1.4 mas yr−1, corresponding to 8 km s−1, and show a tendency for expansion. After modeling the expansion of maser spots, we derived an absolute proper motion for the central star of μx = −2.8 ± 0.2 and μy = 2.6 ± 0.2 mas yr−1 eastward and northward, respectively. Based on the maser distribution from the VLBA observations, and the relative position between the radio photosphere and the SiO maser emission at 43 GHz from the complementary Very Large Array observations, we estimate the absolute position of VY CMa at mean epoch 2006.53 to be αJ2000 = 07h22m58.ˢ3259 ± 0.ˢ0007, δJ2000 = −25°46′03.″063 ± 0.″010. The position and proper motion of VY CMa from the VLBA observations differ significantly with values measured by the Hipparcos satellite. These discrepancies are most likely associated with inhomogeneities and dust scattering the optical light in the circumstellar envelope. The absolute proper motion measured with VLBA suggests that VY CMa may be drifting out of the giant molecular cloud to the east of it.