FAST search for circumstellar atomic hydrogen–I: the young planetary nebula IC 4997. (arXiv:2205.06170v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Ouyang_X/0/1/0/all/0/1">Xu-Jia Ouyang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhang_Y/0/1/0/all/0/1">Yong Zhang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zijlstra_A/0/1/0/all/0/1">Albert Zijlstra</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhang_C/0/1/0/all/0/1">Chuan-Peng Zhang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nakashima_J/0/1/0/all/0/1">Jun-ichi Nakashima</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Parker_Q/0/1/0/all/0/1">Quentin A Parker</a>
Using the Five-hundred-meter Aperture Spherical radio Telescope (FAST) in
Guizhou, China, we detect the 21cm neutral atomic hydrogen absorption in the
young planetary nebula IC 4997. The absorption arises from a shell also
associated with Na I D lines. The H I shell has a mass of $1.46times10^{-2}$
M$_odot$ and a dynamic age of 990yr. The column density of H I is estimated to
be $7.1times10^{20}$ cm$^{-2}$, which can be well explained in terms of a
photodissociation region around the ionized nebula, limited by self shielding
of H$_2$. We find that the atomic-to-ionized hydrogen ratio is 0.6, suggesting
that H I substantially contributes to overall nebular mass.
Using the Five-hundred-meter Aperture Spherical radio Telescope (FAST) in
Guizhou, China, we detect the 21cm neutral atomic hydrogen absorption in the
young planetary nebula IC 4997. The absorption arises from a shell also
associated with Na I D lines. The H I shell has a mass of $1.46times10^{-2}$
M$_odot$ and a dynamic age of 990yr. The column density of H I is estimated to
be $7.1times10^{20}$ cm$^{-2}$, which can be well explained in terms of a
photodissociation region around the ionized nebula, limited by self shielding
of H$_2$. We find that the atomic-to-ionized hydrogen ratio is 0.6, suggesting
that H I substantially contributes to overall nebular mass.
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