We discuss the total mass and dark halo properties of the Small Magellanic Cloud (SMC) for reasonable $V$-band stellar-to-mass-to-light ratios ($M_{\rm s}/L_{\rm V}$) based on the high-resolution neutral hydrogen (HI) observations of the SMC. We adopt both the Burkert and the NFW profiles for the dark matter halo of the SMC in order to model the radial profile of the observed rotation curve. We show that the mass ($M_{\rm dm}$) and the mean density ($ρ_{\rm dm}$) of the dark matter halo within the optical radius ($\sim 3$ kpc) of the SMC can be significantly low for $M_{\rm s}/L_{\rm V}=2-4$ reasonable for a galaxy dominated by older stellar populations. For example, the estimated $M_{\rm dm}$ and $ρ_{\rm dm}$ are $7.5 \times 10^7 {\rm M}_{\odot}$ and $6.7 \times 10^{-4} {\rm M}_{\odot}$ pc$^{-3}$, respectively, for $M_{\rm s}/L_{\rm V} = 3.8$. The models with lower $M_{\rm s}/L_{\rm V}$ ($<1.0$) can show higher $M_{\rm dm}$ and $ρ_{\rm dm}$ yet have difficulties in reproducing the inner rotation curve profile both for the Burkert and the NFW profiles. The Burkert profile with a larger core radius ($>1$ kpc) (thus a low density) and a large mass (${\rm M}_{\rm dm} > 3 \times 10^9 {\rm M}_{\odot}$) can be better fit to the observed slowly rising rotation curve than the NFW one for a reasonable $M_{\rm s}/L_{\rm V} \sim2$. This means that most of the dark halo mass can be initially located outside the optical radius in the SMC and thus that the dark halo would have already lost a significant fraction of its original mass due to the strong tidal interactions with the Galaxy and possibly with the Large Magellanic Cloud (LMC).
We model the dynamics of Magellanic Stream with the ram-pressure scenario in the logarithmic and power-law galactic halo models and construct numerically the past orbital history of Magellanic clouds and Magellanic Stream. The parameters of models include the asymptotic rotation velocity of spiral arms, halo flattening, core radius and rising or falling parameter of rotation curve. We obtain the best fit parameters of galactic models through the maximum likelihood analysis, comparing the high resolution radial velocity data of HI in Magellanic Stream with that of theoretical models. The initia…
We present our analysis of archival Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC2) observations in F450W (~B) and F555W (~V) of the intermediate- age populous star clusters NGC 121, NGC 339, NGC 361, NGC 416, and Kron 3 in the Small Magellanic Cloud. We use published photometry of two other SMC populous star clusters, Lindsay 1 and Lindsay 113, to investigate the age sequence of these seven populous star clusters in order to improve our understanding of the formation chronology of the SMC. We analyzed the V vs (B-V) and M_V vs (B-V)_0 color-magnitude diagrams of these populous Sm…
The small-scale structure of the Magellanic Stream
我们已经绘制了两个地区在麦哲伦流的北端中性氢21厘米发射使用阿雷西博望远镜。新的数据被用来研究远离麦哲伦云的银河流的形态和性质，以及提供对星系晕性质的间接约束。我们调查禁闭机制的流云，并得出结论，这些云不能重力约束或自由膨胀。最可能的云约束机制是来自热星系晕气体的压力支持。这使得我们可以对晕密度设定一个上限：n（15 kpc）= 10 ^-3 cm ^-3和/或n（45 kpc）= 3 x 10 ^-4 cm ^-3，具体取决于距离。这些值明显高于等温分层Halo的预测值。
High-Velocity Clouds Related to the Magellanic System
通过几个与麦哲伦云相连的高速复合体，揭示了银河系与麦哲伦云相互作用的结果。它们形成的确切机制还存在一些争议，但它们仍然是唯一一组我们有起源和大致距离的高速云（HVC）。鉴于此，麦哲伦HVC可以用作其他HVC的校准器，同时也提供了密切研究相互作用系统残余物的机会。这些HVC可能持有的关键，恒星形成的历史，运动学结构，并目前哈勃类型的麦哲伦云，和他们的接近银河系允许我们估计关键的银河系参数。与麦哲伦星系有关的HVC可以分为三个主要的复合体：麦哲伦桥，云之间的HI连接;麦哲伦流，它跟随云，是我们银河系以外天空中最大的HI特征之一;和引导臂，一个更分散的HI灯丝，引导云。就HVC而言，这些特征已被广泛研究。在这篇综述中，我将首先描述每个复杂的观察结果，随后讨论它们的起源和整体HVC人口的关系。所有的HI数据都来自HI Parkes全天巡天（HIPASS）（Barnes et al. 2001; Putman et al. 2001）。
Optical Gravitational Lensing Experiment. Distance to the Magellanic Clouds with the Red Clump Stars: Are the Magellanic Clouds 15% Closer than Generally Accepted?
The Optical Gravitational Lensing Experiment. Cepheids in the Magellanic Clouds. II. Single-Mode Second Overtone Cepheids in the Small Magellanic Cloud
EROS2 microlensing search towards the Magellanic Clouds
EROS 2是自1996年中期以来在拉西拉（智利）的欧洲南方天文台（ESO）运行的第二代微透镜实验。本文介绍了我们对小麦哲伦云（SMC）微透镜搜索的两年分析，并报告了对MACHO-SMC-98-1焦散穿越事件的密集观测和对透镜位置的限制。我们也给出了我们对大麦云云（LMC）的搜索的初步结果，25平方度的分析和两个候选人已经被发现。这使我们能够设置另一个限制晕质量分数组成的紧凑对象。
