THE GALACTIC CENTER CLOUD G2—A YOUNG LOW-MASS STAR WITH A STELLAR WIND
THE GALACTIC CENTER CLOUD G2—A YOUNG LOW-MASS STAR WITH A STELLAR WIND
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银河中心云 G2——一颗带有恒星风的年轻低质量恒星
DOI：
10.1088/0004-637x/768/2/108
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
Andi Burkert
中科院分区：
文献类型：
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作者：
N. Scoville;Andi Burkert
我们探索落入 SgrA* 的 G2 气体云是一颗年轻的金牛座 T 星的质量损失包络线的可能性。当恒星坠落到 1000–6000 km s−1 的较小半径时，在 SgrA* 附近的热 X 射线发射气体影响恒星风的地方，会形成强烈的弓形激波。对于 4 × 10−8 M☉ yr−1 的恒星质量损失率和 100 km s−1 的风速，弓形激波将在距离 ∼1016 cm 处具有发射测量值 (EM = n2vol)，类似于从红外发射线推断的发射测量值。密集弓形激波气体的电离可能是由激波前沿处的碰撞电离和来自后激波气体的冷却辐射（X 射线和紫外线）提供的。前者将预测作为距 SgrA* 距离的函数的恒定线通量，而后者将在较小距离处增加发射。在这个模型中，恒星及其质量损失风应该能够在通过近心点时幸存下来，因为风可能是在 0.2 个天文单位处发射的，而这远小于近心点的罗希半径（对于 2 M☉ 的恒星质量，约为 3 个天文单位）。在此模型中，发射云可能会在近中心通道中幸存下来，从而将这种情况与其他情况区分开来。
We explore the possibility that the G2 gas cloud falling in toward SgrA* is the mass-loss envelope of a young T Tauri star. As the star plunges to smaller radius at 1000–6000 km s−1, a strong bow shock forms where the stellar wind is impacted by the hot X-ray emitting gas in the vicinity of SgrA*. For a stellar mass-loss rate of 4 × 10−8 M☉ yr−1 and wind velocity 100 km s−1, the bow shock will have an emission measure (EM = n2vol) at a distance ∼1016 cm, similar to that inferred from the IR emission lines. The ionization of the dense bow shock gas is potentially provided by collisional ionization at the shock front and cooling radiation (X-ray and UV) from the post shock gas. The former would predict a constant line flux as a function of distance from SgrA*, while the latter will have increasing emission at lesser distances. In this model, the star and its mass-loss wind should survive pericenter passage since the wind is likely launched at 0.2 AU and this is much less than the Roche radius at pericenter (∼3 AU for a stellar mass of 2 M☉). In this model, the emission cloud will probably survive pericenter passage, discriminating this scenario from others.
DOI：
10.1088/0004-637x/750/1/58
发表时间：
2012-01
期刊：
The Astrophysical Journal
影响因子：
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作者：
A. Burkert;M. Schartmann;C. Alig;S. Gillessen;R. Genzel;T. Fritz;F. Eisenhauer
通讯作者：
A. Burkert;M. Schartmann;C. Alig;S. Gillessen;R. Genzel;T. Fritz;F. Eisenhauer