Questions tagged [interstellar-matter]
43 questions
104
votes
7 answers
What is the speed of sound in space?
Given that space is not a perfect vacuum, what is the speed of sound therein? Google was not very helpful in this regard, as the only answer I found was $300\,{\rm km}\,{\rm s}^{-1}$, from Astronomy Cafe, which is not a source I'd be willing to…
Josh Glover
- 1,113
17
votes
1 answer
How vacuous is intergalactic space?
You often hear intergalactic space is an example for a very good vacuum. But how vacuos is space between galaxy clusters and inside a huge void structure? Are there papers quoting a measurement/approximation method (building the difference of a very…
Hauser
- 721
13
votes
1 answer
Does tritium hydride exhibit measurable spontaneous fusion via proton tunneling?
In a fascinating 30 June 2013 article in Nature Chemistry, researchers from the University of Leeds found that when molecules of hydroxyl (OH, a fairly stable radical) and methanol (CH$_3$OH) are cold enough to adhere to each other in deep space…
Terry Bollinger
- 22,299
- 6
- 87
- 136
13
votes
5 answers
Interstellar dust/matter distribution
It is known that one of the main problems of interstellar flight is a presence of matter between stars in form of very fine dust and huge asteroids. Which can slowly (or fast) destroy any ship.
What are the most recent estimations about the…
Asphir Dom
- 665
13
votes
2 answers
The interstellar medium reflects extremely low-frequency radio waves. Could we use this fact to build a more efficient photon rocket?
According to the equations of MHD, electromagnetic waves cannot propagate in a plasma if they are below the plasma frequency. (For more information, see this question about astronomical-wavelength radio waves and this question about the plasma…
Thorondor
- 4,110
- 2
- 23
- 46
9
votes
1 answer
What is the quantum structure of the interstellar matter?
Consider an interstellar medium of one hydrogen atom/cm$^3$ with $500$ photons/cm$^3$ coming from CMB. This density of particles is very weak according to quantum decoherence. So, according to Schrödinger equation, the wave function of each atom…
8
votes
1 answer
Will interstellar helium condense to a liquid as space expands and cools?
Intergalactic space is 2.7K (https://en.wikipedia.org/wiki/Outer_space) Interstellar space is a little warmer. My understanding is that these will decrease over time.
The phase diagrams of helium I can find vary a little bit; eg
but they all show a…
Alex K
- 488
8
votes
1 answer
Voyager 1 cosmic ray strips
In the last months Voyager 1 has experienced a dramatic drop in the cosmic ray radiation, which was been exceptionally uniform for the last 10 years, except for the past july 28 and august 14 events, when the radiation suddenly had big drops. After…
lurscher
- 14,933
7
votes
1 answer
Why is $\text{CO}$ a good tracer for $\text{H}_2$? How are those molecules correlated?
One often hears that $\text{CO}$ is a good tracer for $\text{H}_2 .$ How are they correlated? How can you deduce from the (measurable) $\text{CO}$ the amount of the (unmeasurable) $\text{H}_2$ in the interstellar medium?
rtime
- 557
- 3
- 17
6
votes
2 answers
relativistic spaceship, CMB radiation and thermodynamics
Scenario: a spaceship is travelling at a high fraction of $c$. The interstellar gas and CMB radiation has blueshifted significantly and we are facing a possible melting of the front radiation shield!
but the ship has good radiator area in the back…
diffeomorphism
- 2,299
5
votes
1 answer
Density distribution of the interstellar medium
Can anyone point me in the direction of some resources - or know themselves - regarding the density distribution of the ISM? So far googling has turned up very little.
I realise there will be nuances relating to 'lumpiness' or turbulence, but any…
user1887919
- 1,791
4
votes
0 answers
Interstellar electron velocity distributions
I've found an estimation for interstellar electron density which ranges from $3.0 \times 10^4$ electrons per cubic meter (pcm), to $5.0 \times 10^4$ electrons pcm close to the galactic plane.
However, this estimation doesn't provide any range for…
lurscher
- 14,933
3
votes
1 answer
Do stars lose spin angular momentum, to planets, radiation, or gravitational waves, or in some other way get a longer period?
A spinning star is throwing off stellar wind, and electromagnetic radiation, which might be carrying away angular momentum, so that the star loses angular momentum, and its angular momentum per unit mass may get reduced as result. I'm wondering…
3
votes
2 answers
What star processes throw strange matter into space?
My understanding is that strange matter is stable in low pressures or vacuum, but correct me if this is wrong
I'm wondering how likely is to find strange matter in empty space. What physical processes in decaying stars (supernovae, magnetars, etc.)…
lurscher
- 14,933
3
votes
2 answers
Why Hydrogen is not solid in the outer space?
Why Hydrogen doesn't get solidified in the outer space?
Matt
- 61