Imaging of the Stellar Population of IC 10 with Laser Guide Star Adaptive Optics and the Hubble Space Telescope
Imaging of the Stellar Population of IC 10 with Laser Guide Star Adaptive Optics and the Hubble Space Telescope
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使用激光导星自适应光学器件和哈勃太空望远镜对 IC 10 的恒星群进行成像
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发表时间：
2007
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通讯作者：
J. Graham
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作者：
W. Vacca;C. Sheehy;J. Graham
我们展示了矮不规则星系 IC 10 中心星暴区域的自适应光学 (AO) 图像。凯克 II 望远镜激光导星用于在 H 和 K' 处实现接近衍射极限的性能（斯特列尔比分别为 18% 和 32%）。这些图像以假定的沃尔夫-拉叶 (W-R) 天体 [MAC92]24 为中心。我们将 AO 图像与 HST 的 F814W 数据相结合。通过将 K′ 与 [F814W] - K′ 颜色星等图 (CMD) 与理论等时线进行比较，我们发现恒星群最好由至少两次恒星形成爆发来代表，一次约为 10 Myr 之前，一次更古老（150-500 Myr）。年轻的蓝色恒星集中在[MAC92]24 附近。该群体代表半光半径约为 3 pc 的 OB 关联。我们将 W-R 对象 [MAC92] 24 解析为至少六颗蓝星。其中四个组件具有近红外颜色和亮度，使它们成为强大的 WN 恒星候选者。通过将 CMD 中 C 星的位置与 SMC 中的位置进行匹配，我们得出 IC 10 的距离模量约为 24.5 星等，前景红化为 E(B - V) = 0.95 星等。我们通过在 F814W、H 和 K' 光度函数中定位巨型分支的尖端来找到更精确的距离。我们发现加权平均距离模为 24.48 ± 0.08。由于 IC 10 和 SMC 中 RGB 群体的特性可能存在差异，该测量中的系统误差为 ±0.16 mag。
We present adaptive optics (AO) images of the central starburst region of the dwarf irregular galaxy IC 10. The Keck II telescope laser guide star was used to achieve near diffraction-limited performance at H and K′ (Strehl ratios of 18% and 32%, respectively). The images are centered on the putative Wolf-Rayet (W-R) object [MAC92]24. We combine our AO images with F814W data from HST. By comparing the K′ versus [F814W] - K′ color-magnitude diagram (CMD) with theoretical isochrones, we find that the stellar population is best represented by at least two bursts of star formation, one ~10 Myr ago and one much older (150-500 Myr). Young, blue stars are concentrated in the vicinity of [MAC92]24. This population represents an OB association with a half-light radius of about 3 pc. We resolve the W-R object [MAC92] 24 into at least six blue stars. Four of these components have near-IR colors and luminosities that make them robust WN star candidates. By matching the location of C stars in the CMD with those in the SMC we derive a distance modulus for IC 10 of about 24.5 mag and a foreground reddening of E(B - V) = 0.95 mag. We find a more precise distance by locating the tip of the giant branch in the F814W, H, and K′ luminosity functions. We find a weighted mean distance modulus of 24.48 ± 0.08. The systematic error in this measurement, due to a possible difference in the properties of the RGB populations in IC 10 and the SMC, is ±0.16 mag.