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arXiv 1710.02462astro-ph.GA
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由Subaru Suprime-Cam观测六分仪矮星系的自行

Proper Motion of the Sextans Dwarf Galaxy from Subaru Suprime-Cam Data

Dana I. Casetti-Dinescu, Terrence M. Girard, Michael Schriefer

摘要:

我们已经测量了六分仪矮球状星系的绝对自行使用斯巴鲁Suprime-Cam图像在三个时代,时间基线为10年。我们通过从最好的斯巴鲁Suprime-Cam抖动数据集和Gaia DR 1位置构建失真校正图来对每个时期进行天体测量校准。自行研究的星等极限为V ~ 24。覆盖面积为26.7 x 23.3弧分,仍然在六分仪的核心半径之内。由此导出的自行为(mu_a,mu_d)=(-0.409 +/-0.050,-0.047 +/-0.058)mas/yr。运动方向垂直于星系的长轴。我们的测量,结合径向速度和距离从文献中,意味着一个低偏心率的轨道,与银河系平面的适度倾斜,和3 Gyr的周期。六分仪现在距离它的近心(r_apo ~ 75 kpc)约0.4 Gyr,正在向远心(r_apo ~ 132 kpc)移动。它的轨道与银河系卫星庞大的极地结构不一致。

英文摘要:

We have measured the absolute proper motion of the Sextans dwarf spheroidal galaxy using Subaru Suprime-Cam images taken at three epochs, with a time baseline of ~ 10 years. We astrometrically calibrate each epoch by constructing distortion-correction maps from the best available Subaru Suprime-Cam dithered data sets and from Gaia DR1 positions. The magnitude limit of the proper-motion study is V ~ 24. The area covered is 26.7 x 23.3 arcmin, which is still within the core radius of Sextans. The derived proper motion is (mu_a, mu_d) = (-0.409 +/- 0.050, -0.047 +/- 0.058) mas/yr. The direction of motion is perpendicular to the major axis of the galaxy. Our measurement, combined with radial velocity and distance from the literature, implies a low eccentricity orbit, with a moderate inclination to the Galactic plane, and a period of 3 Gyr. Sextans is now some 0.4 Gyr away from its pericenter ( r_peri ~ 75 kpc), moving toward its apocenter (r_apo ~ 132 kpc). Its orbit is inconsistent with membership to the vast polar structure of Galactic satellites.

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。

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