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arXiv · 1411.7972

Collisionally excited filaments in HST H$\alpha$ and H$\beta$ images of HH~1/2

A. C. Raga·B. Reipurth·A. Castellanos-Ramírez·Hsin-Fang Chiang·J. Bally
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Abstract

We present new H$\alpha$ and H$\beta$ images of the HH~1/2 system, and we find that the H$\alpha$/H$\beta$ ratio has high values in ridges along the leading edges of the HH~1 bow shock and of the brighter condensations of HH~2. These ridges have H$\alpha$/H$\beta=4\to 6$, which is consistent with collisional excitation from the $n=1$ to the $n=3$ and 4 levels of hydrogen in a gas of temperatures $T=1.5\to 10\times 10^4$~K. This is therefore the first direct proof that the collisional excitation/ionization region of hydrogen right behind Herbig-Haro shock fronts is detected.

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A. C. Raga, B. Reipurth, A. Castellanos-Ramírez, Hsin-Fang Chiang, J. Bally. 2014-11-28. Collisionally excited filaments in HST H$\alpha$ and H$\beta$ images of HH~1/2. https://doi.org/10.1088/2041-8205%2F798%2F1%2Fl1

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