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arXiv 0704.0478astro-ph
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M82核星暴中的超星团速度色散和维里质量

Super Star Cluster Velocity Dispersions and Virial Masses in the M82 Nuclear Starburst

Nate McCrady, James R. Graham

摘要:

利用Keck天文台的高分辨率近红外光谱仪测量了M82核星爆中19个超星团的恒星速度频散。星团的年龄大约为1000万年,这比它们的速度色散和半径所暗示的交叉时间要长很多倍。因此,我们应用维里定理推导出15个SSC的运动质量。SSC的质量为2 x 10^5至4 x 10^6太阳质量,总人口质量为1.4 x 10^7太阳质量。比较年轻的M82 SSC和老的银河系球状星团的半径-速度色散曲线表明,SSC是一个潜在的球状星团的人口。我们提出了SSC的质量函数,并找到了指数为gamma = -1.91 +/- 0.06的幂律拟合。这一结果与银河系中年轻SSC的质量函数几乎相同。

英文摘要:

We use high-resolution near-infrared spectroscopy from Keck Observatory to measure the stellar velocity dispersions of 19 super star clusters (SSCs) in the nuclear starburst of M82. The clusters have ages on the order of 10 Myr, which is many times longer than the crossing times implied by their velocity dispersions and radii. We therefore apply the Virial Theorem to derive the kinematic mass for 15 of the SSCs. The SSCs have masses of 2 x 10^5 to 4 x 10^6 solar masses, with a total population mass of 1.4 x 10^7 solar masses. Comparison of the loci of the young M82 SSCs and old Milky Way globular clusters in a plot of radius versus velocity dispersion suggests that the SSCs are a population of potential globular clusters. We present the mass function for the SSCs, and find a power law fit with an index of gamma = -1.91 +/- 0.06. This result is nearly identical to the mass function of young SSCs in the Antennae galaxies.

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