The Triangulum Extended (TREX) Survey: The Stellar Disk Dynamics of M33 as a Function of Stellar Age
The Triangulum Extended (TREX) Survey: The Stellar Disk Dynamics of M33 as a Function of Stellar Age
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DOI：
10.3847/1538-3881/ac5324
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发表时间：
2022-02
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影响因子：
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通讯作者：
A. Quirk;P. Guhathakurta;K. Gilbert;L. Chemin;J. Dalcanton;B. Williams;A. Seth;E. Patel;Justin T. Fung;Pujita Tangirala;Ibrahim Yusufali
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作者：
A. Quirk;P. Guhathakurta;K. Gilbert;L. Chemin;J. Dalcanton;B. Williams;A. Seth;E. Patel;Justin T. Fung;Pujita Tangirala;Ibrahim Yusufali
三角星系 (M33) 是一个低质量、相对不受干扰的螺旋星系，它提供了一种测试动态加热模型的新机制。尽管距离很近，M33 的动态加热历史尚未得到很好的限制。在这项工作中，我们介绍了 TREX 巡天，这是 M33 盘面最大的恒星光谱巡天。我们将恒星盘运动学呈现为年龄的函数，以研究 M33 过去和正在进行的动态加热。我们测量了约 4500 颗盘状恒星的视线速度。我们使用哈勃太空望远镜和加拿大-法国-夏威夷望远镜光度目录将恒星分为一个子集：大质量主序星和氦燃烧星（∼80 Myr）、中等质量渐近分支星（∼1 Gyr）和低质量红巨星分支星（∼4 Gyr）。我们使用现有的 H i、CO 和 Hα 运动学将恒星盘动力学与气体动力学进行比较。我们发现M33的盘面具有相对较低的速度色散（∼16 km s−1），并且与银河系和仙女座星系不同，速度色散作为恒星年龄的函数没有强烈的趋势。最年轻的盘状恒星的动态热度与最古老的盘状恒星一样热，并且比 Illustris 中大多数类似 M33 的低质量模拟类似物预测的动态热度更高。年轻恒星的速度色散是高度结构化的，大的速度色散相当局部化。从此处提供的观察和模拟类似物来看，这种高速色散的原因并不明显。
Triangulum (M33) is a low-mass, relatively undisturbed spiral galaxy that offers a new regime in which to test models of dynamical heating. In spite of its proximity, M33's dynamical heating history has not yet been well-constrained. In this work, we present the TREX Survey, the largest stellar spectroscopic survey across the disk of M33. We present the stellar disk kinematics as a function of age to study the past and ongoing dynamical heating of M33. We measure line-of-sight velocities for ∼4500 disk stars. Using a subset, we divide the stars into broad age bins using Hubble Space Telescope and Canada–France–Hawaii Telescope photometric catalogs: massive main-sequence stars and helium-burning stars (∼80 Myr), intermediate-mass asymptotic branch stars (∼1 Gyr), and low-mass red giant branch stars (∼4 Gyr). We compare the stellar disk dynamics to that of the gas using existing H i, CO, and Hα kinematics. We find that the disk of M33 has relatively low-velocity dispersion (∼16 km s−1), and unlike in the Milky Way and Andromeda galaxies, there is no strong trend in velocity dispersion as a function of stellar age. The youngest disk stars are as dynamically hot as the oldest disk stars and are dynamically hotter than predicted by most M33-like low-mass simulated analogs in Illustris. The velocity dispersion of the young stars is highly structured, with the large velocity dispersion fairly localized. The cause of this high-velocity dispersion is not evident from the observations and simulated analogs presented here.