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The stellar content and dynamics of superbubbles in the Large Magellanic Cloud.

机译:麦哲伦星云中超级气泡的恒星含量和动力学。

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摘要

The interaction between massive stars and the ISM is a fundamental process determining the structure and composition of the ISM. This work examines the stellar content and resulting dynamics of superbubbles in the LMC. We first show analytically that for 2 single-O star bubbles in M33, the evolution of wind power as the stars evolve is important in the bubble evolution. In a second prototype study, we find that the LMC superbubble DEM 152 shows evidence for sequential star formation, based on differing ages between the stars interior and exterior to the shell. We construct a numerical form of the standard Weaver et al. (1977) evolutionary model for wind-driven bubbles, and use the stellar census to compare the predicted shell evolution with the observed kinematics. There is a substantial discrepancy: shell's observed expansion velocity too large relative to its radius. I then find that the CMDs of the associations within 7 LMC superbubbles and 5 classical H II regions are indistinguishable. The HRDs, constructed with spectral types for 6 superbubble clusters, also appear similar to those in classical H II regions, implying that the shell formation timescale is shorter than the cluster evolutionary timescale. The stellar winds of the 1-2 most massive stars must therefore dominate the shell formation. The star-forming events for the superbubble associations are also no more extended in duration than that of other OB associations. The IMF slopes appear normal. Numerical modeling of the 6 superbubbles shows results falling into two distinct categories: "high-velocity" objects showing anomalous kinematics like DEM 152 and "low-velocity" objects which appear fairly consistent with the model. X-ray evidence suggests that the high-velocity objects have been accelerated by SNR impacts. Results for both categories imply an overestimate in the growth rate equivalent to an effective input power of up to an order of magnitude too large. I find that the superbubbles are likely to be struck and "burst" by such SNR impacts if the prior stellar wind power is log L(w) ≲ 37.8 erg s⁻¹. The interior coronal gas is then expelled by the pressure differential with the environment, which could greatly enhance the dispersal and distribution of the hot ionized medium. A minority of superbubbles with stellar wind power above the threshold are more likely to grow to the sizes of supergiant shells.
机译:大质量恒星与ISM之间的相互作用是确定ISM的结构和组成的基本过程。这项工作检查了LMC中的恒星含量和超级气泡的动态。我们首先通过分析表明,对于M33中的2个单O型星型气泡,随着星型的发展,风力的发展对于气泡的发展至关重要。在第二个原型研究中,我们发现LMC超泡DEM 152根据壳内部与外部的恒星年龄不同,显示出连续恒星形成的证据。我们构造了标准的Weaver等人的数字形式。 (1977年)的风驱动气泡的演化模型,并使用恒星普查将预测的壳演化与观察到的运动学进行比较。有一个很大的差异:观察到的壳的膨胀速度相对于其半径太大。然后,我发现在7个LMC超气泡和5个经典H II区域内的关联的CMD是无法区分的。用6个超气泡簇的光谱类型构造的HRD看上去也与经典H II区域的HRD相似,这意味着壳形成的时间尺度比簇的演化时间尺度短。因此,1-2个最大质量恒星的恒星风必须主导壳层的形成。超级气泡关联的恒星形成事件的持续时间也不会比其他OB关联的持续时间更长。 IMF斜率看起来很正常。对6个超级气泡的数值建模显示结果分为两个不同的类别:“高速”对象显示异常运动学,如DEM 152,“低速”对象显示与模型相当一致。 X射线证据表明,高速物体已被SNR影响所加速。这两个类别的结果都暗示增长率被高估了,相当于有效输入功率高达一个数量级。我发现,如果先前的恒星风能为log L(w)≲37.8 ergs⁻¹,那么这种SNR影响可能会使超气泡撞击并“爆裂”。内部冠状气体随后通过与环境的压力差被排出,这可以大大增强热电离介质的分散和分布。少数具有恒星风能超过阈值的超级气泡更有可能长成超大型壳的大小。

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    Oey Marion Siang-li.;

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  • 年度 1995
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  • 正文语种 en
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