Questions tagged [interstellar-medium]
Questions about the gas that lays between stars in galaxies.
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Can there be free electrons in interstellar gas in the long term?
If I'm not mistaken, in interstellar gas, there can be clouds of free electrons (not "attached" to any atomic nucleus)
But can they stay like that indefinetely? Or will they inevitably end ...
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How to count observable number of galaxies at a given latitude considering interstellar extinction?
If galaxies are uniformly distributed in space, then in the absence of extinction, the number of galaxies per square degree brighter than magnitude m is given by $$\log_{N_0}(m) = 0.6m + C$$
How will ...
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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, ...
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Molecule formation when an atomic gas cools down
I have read about the actual formation of interstellar molecules; although interstellar chemistry is very different from solvent-based chemistry on earth, I understand it to be driven by the presence ...
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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_{...
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Why does dust affect UV light more severe than it affects X-rays?
My supervisor told me that the UV photons emitted from AGN are heavily affected by ISM (dust extinction), but not X-rays, as described in Extinction - a powerful discriminator of dust size. Since X-...
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How do we estimate the amount and distribution of Helium in interstellar and intergalactic space?
Quoting from wikipedia: Helium
... is the second lightest and second most abundant element in the observable universe (hydrogen is the lightest and most abundant). It is present at about 24% of the ...
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What are the differences between Intergalactic Medium, Interstellar medium and Intracluster medium?
The Intergalactic Medium, Interstellar medium (ISM) and Intracluster medium (ICM) are mediums that fills the space between galaxies/pace between the star systems in a galaxy. What are the differences ...
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What is the meaning of integrated emission maps for these chemical species?
In the Astrobites article Spectral Line Survey Reveals New Molecules in Two Protoplanetary Disks integrated emission maps depict the spatial distribution of the flux received from each "line.&...
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Largest projected images (such as shadows) observed
Serpens Nebula around the star HBC 672 (source: heic1819b)
Which are the largest observed images projected onto interstellar bodies (such as nebulae) by means of electromagnetic radiation? By “largest”...
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Is oxygen an alpha element?
Type II (core-collapse) supernovae occur shortly after star formation and enrich a galaxy with $\alpha$ elements such as O, C, NE, Mg, Ca and Si. On the other hand, Type Ia supernovae occur on a more ...
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What does it mean for cold clouds to be in pressure equilibrium with a diffuse hot medium?
I often read about cold objects (namely cold clouds in the Galactic halo or cold filaments accreting into high-redshift galaxies) being in pressure equilibrium with the diffuse hot ambient gas. What ...
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Why space-based VLBI scattering sub-structure is "Hopefully, a new promising tool to reconstruct the true image of observed background target(s)"?
@HDE226868 mentioned in the observatory that the GBT@20 – The Celebration; Twenty Years of Innovation and Discovery was going on. There are plenty of YouTube videos and slide sets available as links. ...
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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 ...
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Why isn't most hydrogen in the universe molecular (diatomic), instead of atomic (monoatomic)?
Similar questions have been asked before; but, why?
Is the monoatomic hydrogen left over from the Big Bang? And hasn't had the opportunity to collide with other hydrogen atoms yet?
Or are hydrogen ...
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Interstellar Dust properties
While practicing for an upcoming examination, I ran into this problem:
Which of the following best describes dust grains in the interstellar medium:
They are a few hundred nanometers in size (size ...
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Can circumstances exist such that as seen from some solar system all stars are obscured?
I am mostly active on Physics Stack Exchange but a question occurred to me that I think is best submitted here.
This question is about a thought experiment: whether the circumstances of the intended ...
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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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Interaction of stellar winds in binary star systems
Binary star systems are fairly common but I am unable to find any information on how the stars interact with one another on aspects other than gravitational affects. Using Alpha Centauri as the ...
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What "long chain of carbon chemistry" in the interstellar medium produces cyclopropenylidene (C3H2)?
In the Wikipedia article of Cyclopropenylidene, it says:
The major formation reaction of c-C3H2 is the dissociative recombination of c-C3H3+.
C3H3+ + e− → C3H2 + H
c-C3H3+ is a product of a long ...
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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, ...
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Gravitational waves and gamma ray burst: how were the error bars determined for this speed of gravity calculation? Was $H_0$ used?
This newly updated answer to How precise are the observational measurements for the speed of gravity? and this answer to How is the most accurate value of 𝐺 measured? cites the November 2017 arXiv ...
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Galactic winds/outflows: why and how are they detected via blueshifted absorption lines in spectra?
I know that galaxies can eject gas due to supernovae, accreting black holes, etc. These galactic "winds/outflows" are often defined/detected observationally using blueshifted absorption ...
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Why did it take five years to "figure out" how to use astrometric calibration sources to deblur LOFAR images?
Quanta Magazine's The Hidden Magnetic Universe Begins to Come Into View is a fascinating review of a rapidly evolving field in astronomy.
It contains some statements:
In their paper last year, van ...
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What do these statements about interstellar magnetic fields really mean?
Quanta Magazine's The Hidden Magnetic Universe Begins to Come Into View is a fascinating review of a rapidly evolving field in astronomy.
It contains some statements that I feel are important to ...
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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, ...
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Do pulsar beams interact with the interstellar medium?
Pulsars are rotating objects that emit a beam in a direction that is not aligned with the axis of rotation. Because of this, we see them as a periodic pulse. If the beam isn't towards us, we don't see ...
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Are there examples of the effect of shock waves on chemical evolution in of interstellar medium or circumstellar medium?
Are there any examples of calculations or observations of suspected effects of shock waves on chemical evolution in interstellar medium or circumstellar medium?
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Why is blue light extincted more strongly than red?
We know that blue light suffers extinction more strongly than red (examples include ISM, atmosphere etc.), but why? Is it a property of the shorter wavelength itself? Can someone provide a conceptual ...
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Voyager 1 and 2 detected a 20-fold increase in plasma density, significantly different refractive index?
As reported by Nature.com, Voyager 1 and 2 detected a 20-fold increase in plasma density going from the heliosphere out to interstellar space. Does that 20-fold difference in density imply a ...
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How much of a molecular cloud can end up as "starstuff"?
Stars form within molecular clouds. These clouds can be up to 6 millions solar masses. When the cloud collapses into stars, is it possible to know a rough figure for how much of this material actually ...
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Local Bubble in space
Is the Local Bubble alone in space or is there another bubble similar to the Local Bubble in space, i.e., do we live in a special place or is this a more general phenomenon?
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Why do these astronomers say that "Carbon chains with more than nine atoms are unstable"?
The Phys.org article Interstellar iron isn't missing, it's just hiding in plain sight links to the paywalled article On the Structure, Magnetic Properties, and Infrared Spectra of Iron Pseudocarbynes ...
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Does interstellar cloud obstruct or reduce the visibility?
We just pictured a medium distant black hole by combining data from various observatories around the world. That's when I wondered if interstellar cloud blocks the visibility at multiple position in ...
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Has "GHz-spinning dust" ever been demonstrated in the laboratory?
This excellent answer to the question What is the physics of the “spinning dust” contribution to Cosmic Microwave Background measurements? includes the figure below which helps show what it was the ...
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What is the specific heat capacity of interstellar clouds?
Star forming molecular clouds and especially Bok globules are low temperature $\sim 10 $ K environments with density on the order of $10^{-18}$ kg/m$^3$, mostly hydrogen with about 1% dust. What is ...
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Deep space radiation distribution
What frequency distribution law applies to a random point in deep space that is assumed to be far away from any particular source of radiation.
Can it be expressed by some form of Plancks/Bose-...
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What is the diffuse ionized gas?
I've been trying to find a clean definition what people mean by when they talk about diffuse ionized gas in the interstellar medium, but I couldn't find anything so far.
Apparently it's supposed to be ...
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How dark would the sun become if we traversed a Bok globule?
Bart Bok gave his name to dust clouds of 2-50 solar masses, which by their darkness may be 100 times more frequent than telescopes can detect.
If the solar system traversed a Bok Globule, how dark ...
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carbonaceous content of galaxies?
There is a phrase in a Science Daily article which appears to be wrong:
The Milky Way has a very high content of carbonaceous dust, which has been shown to be very rare in other galaxies.
Is there ...
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Why is the Warm-Hot Intergalactic Medium (WHIM) so hot, and what is "collisionless shock heating"?
The Phys.org article Researchers find last of universe's missing ordinary matter says:
Ordinary matter, or "baryons," make up all physical objects in existence, from stars to the cores of ...
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How is interstellar gas density mapped from GAIA data?
I found the image below in Space.com's article This 3D Color Map of 1.7 Billion Stars in the Milky Way Is the Best Ever Made.
The caption for this image reads:
The Gaia spacecraft gathered ...
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Potential formation mechanisms of the interstellar asteroid 'Oumuamua
NASA recently discovered 'Oumuamua, an interstellar asteroid that appears to have a very elongated shape, unseen in solar system asteroids.
What physical mechanisms, in the progenitor stellar system ...
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Would Bussard Ramjets work in other places in or near the galaxy? [closed]
Sorry if this this doesn't really fit this forum, but WorldBuilding does not like questions like these. I cannot find the minimum density of hydrogen a Bussard ramjet (an interstellar ship propelled ...
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Metals and dust locked into planets
I wonder what is the contribution of metals and dust locked into planets, with respect to the amount in the interstellar medium (ISM). In other words, when we measure the metallicity and the dust mass ...
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Does the sun blow a bubble into the interstellar medium?
I once read that the solar wind is more or less blowing a "bubble" into the interstellar medium. However, the numbers I found while trying to verify this don't give me a clear picture yet:
The ...
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Can the shape and fluctuations of the heliopause be attributed to specific nearby stars and clusters?
The heliopause is where the Solar wind is counter balanced by the particle winds from other stars. This boundary seems to not be spherical and also to fluctuate in shape.
Can the shape of the ...
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Why isn't interstellar medium pulled in towards nearest massive object?
How does the ISM resist gravity? That's the only force acting on it, and all other particles seem to collect together to form stars. What makes the ISM so special among other particles?
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Is the expected time for a star in an elliptical galaxy to collide with another star less than the average age of elliptical galaxies?
According to the Wikipedia article Elliptical galaxy, elliptical galaxies have a much lower concentration of gas between the stars than spiral galaxies. I know that until the gas is below a certain ...
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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 ...
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