Graviational Lensing Data
Can anyone provide me with (or point me to) real life gravitational lensing data that I can plug in to the first equation on this page (the standard lensing equation):...
View ArticlePure hydrogen star
What is the smallest mass of pure hydrogen that can ignite fusion? That is can population III stars have tiny masses? How would such stars develop? How long would such a star last?
View ArticleHow can contact binaries persist?
This answer discusses contact binaries, which I did not even know existed. I can understand how they could exist for a short time (maybe) as gravitational waves carry off energy that causes the stars’...
View ArticleDo the arms of spiral galaxies differ based on the speed of which the galaxy...
If I were to take a circle with strings attached to it and spin it, the strings would behave differently based on how fast the circle is rotating. Do galaxies behave the same way?
View ArticleDo supernovae produce an appreciable amount of lithium?
David Z’s answer to this question got me wondering – is any appreciable amount of lithium produced as the result of a supernova explosion, either by fusion (which seems unlikely to me, but I don’t have...
View ArticleWhat is the physical meaning of source function in radiative transfer?
I know that it’s the ratio between emission and absorption coefficients.But what does it actually mean? Can you please explain?
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Will the Sun ever get 100x powerful? If so, when?
I was doing a theoretical research regarding life on Titan. The temperature of Titan is so low, and it needed more sunlight, as a result, the Sun would require to get hotter. My question is, when will...
View ArticleWhat is the bigger number of particles crossing an area: the number of...
Take an squared area with (10²)² m² in front of the sun. What is the bigger number of particles crossing an area: the number of photons or the number of neutrinos? Just for clarification: you can...
View ArticleCan less gravity speed up time? [closed]
We know more gravity slows down time per Einsteins Theory of Relativity. However will a significantly less gravitational pull speed up time? Or is “our time” aka earth standard of time the fastest...
View ArticleTime evolution of the temperature of the CMB Radiation
Observations have shown Carbon absorption lines in the spectrum of a quasar (called $Q1331 + 70$), due to the fact that the light from this object passing through gas clouds that are in the “distance”...
View ArticleGood books or resources for Stellar Astrophysics at graduate level?
I wanted to know if there is a well established resource in the field of Stellar Astrophysics which is not very outdated. I have seen plenty of books at my university library but I do not know if there...
View Articleastrophysics , dark energy and a text? [on hold]
some days ago i have seen a verse in our religion book and i was very excited how it is true! because it proved and astrophysics theory (Dark energy) and F=ma isaak newton formula !it says : Quran...
View ArticleWhy do astronomers call all elements heavier than helium “metals”?
I understand that a scientific term need not be constrained by its etymology. But is there some significant reason why astronomers choose to call all elements heavier than helium “metals”? Are metals...
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How to cool down a moon? [on hold]
I’m doing an Astronomy project and need to terraform a moon. It is about the size of Mars and orbits a gas giant which is at a distance of 1.28 AU of its star. I though about putting a sunshade at the...
View ArticleSound speed vs Speed of sound
Are ‘sound speed’ and ‘speed of sound’ the same thing? If not, what is the difference? If they are, could you clarify how the speed of sound applies in the below description of gaseous clouds?...
View ArticleDirect vs indirect detection of dark matter
Background There are two categories of searches for dark matter. Direct Detection via reproducible experiments Indirect detection Detection of e.g. annihilation signal from astrophysical sources For a...
View ArticleOrigin of the minimum speed formula for relativistic jets
I am studying superluminal motion in relativistic jets. I understand that the velocity of an emitting part of the jet $v$ can be related to the transverse velocity $v_t$ via $$ frac{v}{c} =...
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Dark matter “hair” flowing through the earth
Gary Prézeau of NASA’s JPL has done some calculations of how dark matter might be focussed by the Earth’s gravitational field (publication preprint), and the results show some remarkable hairy...
View ArticleVisible Mass Distribution in a Galaxy [closed]
Is there any known relationship between stellar density and distance from the galactic centre? I want to know how the visible matter is distributed in the galaxy, especially at the bulge.
View ArticleWhat is the average temperature of mass in the universe?
That is, ignoring speculative concepts like Dark Matter and just summing across stars and gas clouds etc
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