arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2408.03467astro-ph.GA
收藏

彩色银河系中心:利用高自行恒星测量消光

The Galactic Center in Color: Measuring Extinction with High-Proper-Motion Stars

Z. Haggard, A. M. Ghez, S. Sakai, A. K. Gautam, T. Do, J. R. Lu, M. Hosek, M. R. Morris, S. Granados

AI总结:

本文通过追踪银河系中心145颗高自行恒星约10年的多波段观测,发现约30%的恒星因局域尘埃屏运动而出现消光变化,并据此测定了1至4微米的相对消光关系,揭示银河系中心尘埃颗粒可能比前景尘埃更大。

摘要:

银河系中心秒差距区域是一个高度消光的区域,其中存在一群高自行恒星。我们在1至4微米的波长范围内对145颗恒星进行了约10年的跟踪观测,以分析它们在颜色-星等空间中的消光效应。该样本中约有30%的恒星在数年内变暗并变红,这很可能是由于源相对于不均匀尘埃屏的运动所致。我们修正了之前对内在光变比例测量中差分消光效应的影响,得到恒星光变比例降低为34%。消光变化子样本表明,消光物质具有亚角秒尺度,其变化远小于先前报道的尺度。观测到的消光事件意味着消光物质的典型截面为500 AU,密度约为3×10^4 atoms/cm^3,这与银河系中心丝状尘埃和气体的测量结果一致。此外,鉴于表现出消光变化的恒星往往比样本中其余恒星更加红化,消光变化很可能源于局限于银河系中心区域的物质。我们估算1至4微米之间的相对消光为 A_H:A_K':A_L' = 1.67±0.05:1:0.69±0.03。我们在更长波长——L'(3.8 μm)——上的消光测量结果与最近对中心秒差距区域积分消光的估算不一致。对这一差异的一种解释是,本实验所敏感的尘埃变化——即银河系中心局域的尘埃变化——由半径比前景尘埃更大的颗粒主导。

英文摘要:

The Milky Way's central parsec is a highly extinguished region with a population of high-proper-motion stars. We have tracked 145 stars for $\sim$10 years at wavelengths between 1 and 4 microns to analyze extinction effects in color-magnitude space. Approximately $30\%$ of this sample dims and reddens over the course of years, likely from the motion of sources relative to an inhomogeneous screen of dust. We correct previous measurements of the intrinsic variability fraction for differential extinction effects, resulting in a reduced stellar variability fraction of $34\%$. The extinction variability sub-sample shows that the extinguishing material has sub-arcsecond scales, much smaller variations than previously reported. The observed extinction events imply a typical cross-section of 500 AU and a density of around $3 \times 10^{4} \ \mathrm{atoms/cm^{3}}$ for the extinguishing material, which are consistent with measurements of filamentary dust and gas at the Galactic Center. Furthermore, given that the stars showing extinction variability tend to be more highly reddened than the rest of the sample, the extinction changes are likely due to material localized to the Galactic Center region. We estimate the relative extinction between 1 and 4 microns as, $\mathrm{A}_{\mathrm{H}}:\mathrm{A}_{\mathrm{K'}}:\mathrm{A}_{\mathrm{L'}} = 1.67 \pm 0.05:1:0.69 \pm 0.03$. Our measurement of extinction at longer wavelengths -- L' (3.8 $μ$m) -- is inconsistent with recent estimations of the integrated extinction towards the central parsec. One interpretation of this difference is that the dust variations this experiment is sensitive to -- which are local to the Galactic Center -- are dominated by grains of larger radius than the foreground.

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。

↑