Questions tagged [interstellar-medium]

Questions about the gas that lays between stars in galaxies.

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Cooling timescale for an interstellar dust grain

I would like to estimate the cooling timescale for an interstellar dust grain, starting at 200K, down to 100 K. The equation I have come up with is: $\displaystyle t_{cooling} = \frac{mC\Delta T}{Q_{...
lucas's user avatar
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5 votes
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Significantly blueshifted Lyman-$\alpha$

Lyman-$\alpha$ line in galaxies is notably known to show a double peaked profile, mainly due to its scattering in a moving medium, see e.g., the very recent Matthee et al. 2021, The X-SHOOTER Lyman-α ...
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3 votes
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Hydrogen Frost Line? Where, if anywhere, is it cold enough for Oort Cloud objects or rogue planets to have solid hydrogen on their surfaces?

I like the idea of Oort Cloud objects all being crusted with a thin layer of hydrogen snow, though what little information I've managed to find on the topic seems to imply that that is unlikely, ...
Mr. Nichan's user avatar
3 votes
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For chemical reactions occurring in the interstellar medium, which involve metal-ions, will the metal ions be solvated or not?

Usually, metal-ions in terrestrial chemistry will be solvated - either by gas-phase solvent molecules or by liquid-phase solvent molecules. But the interstellar medium (ISM) is never in local ...
RaRa's user avatar
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2 votes
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What "long chain of carbon chemistry" in the interstellar medium produces cyclopropenylidene? (C3H2)

Wikipedia's Cyclopropenylidene; Titan (Moon of Saturn); Formationsays: The major formation reaction of c-C3H2 is the dissociative recombination of c-C3H3+. C3H3+ + e− → C3H2 + H c-C3H3+ is a product ...
uhoh's user avatar
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2 votes
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Software for simulating/calculating a known EMW pulse propagating in ISM, including dispersion, scattering, etc

Could you please let me know, if there is any software/code/tool for simulating/calculating the result of a short EMW pulse (waveform is exactly known) propagating in the ISM for long distance, ...
Wein's user avatar
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1 vote
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Why does rotation prevent the further contraction of the cloud?

In the book Horizons: Exploring the Universe (2018) by M.Seeds and D.Backman, chapter 9, page 170-171, it states that: At least four factors resist the compression of an interstellar gas cloud, and ...
Jack the Ranger's user avatar
1 vote
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Virial coefficient when computing dynamical mass enclosed by a rotating galactic disk of gas

Suppose I have a large thin disk of rotating gas in a galaxy -- the disk has a maximum inclination-corrected $V_{max}$ and a maximum radial extent of $R_{max}$ corresponding to that $V_{max}$ ...
quantumflash's user avatar
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Electron Temperature of a Gas Cloud

Would a gas cloud made of HII and OIII have a higher electron temperature than a cloud just consisting of HII? I understand that electron temperature is the temperature of the electrons in a plasma, ...
Astrovis's user avatar
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