Astronomy Stack Exchange
Astronomy Stack Exchange

Questions tagged [astrophysics]

Questions involving the physics of the universe, especially the nature of astronomical objects, energy fields, and/or regions, rather than their positions or motions in space.

674 questions
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How to be an astrophysicist?

For a high-school students, what are the ways to become an astrophysicist? What should he/she take in college? What is the career path to become an astrophysicist?
Salazar
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Are there real uses of abstract algebra in astrophysics?

It is known that a physicist must have, at least in general, a good level in mathematics in order to research and understand other people's works. Linear algebra is a good example, as ODEs and calculus. I suppose that some astrophysicists have deep…
Javier
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Relationship between absolute magnitude of a star and its luminosity?

Why does this relationship involves the absolute magnitude of the sun and its luminosity? How to derive an expression relating the absolute magnitude of a star to its luminosity? So according to the magnitude equation, $$m - M =…
J.S. M
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If the Universe has a positive curvature and a closed spatial geometry, does it therefore have a finite volume and a geometric center?

Based on the recent Planck Legacy 2018 release confirming the presence of an enhanced lensing amplitude in the cosmic microwave background (CMB) power spectra compared to that predicted by the standard ΛCDM model, several authors (Di Valentino et…
John Freeman
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What does "by an amount" mean here?

In A Very Short Introduction: Black Holes by Katherine Blundell, the author discusses the emptiness pf the space: One of the surprising consequences of this new theory was that there were fleeting moments when it seems like energy needn’t be…
Ahmed Samir
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Why carbon is considered volatile?

Carbon is considered volatile by planetary science, eg Moon lacks volatiles and thus lacks carbon. However volatiles are defined as "elements or substances with low boiling point", but Carbon boiling point is very high! Its sublimation point is…
Rahlis Alexander
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If I want to learn about astrophysics, should I study up on mathematics?

I am currently reading A Brief History of Time and while the book itself does not contain much mathematics in it, I want to learn more about the concepts Prof. Hawkings talks about more in-depth. Now I am aware that I will never get the expansive…
writerboy
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Mysterious factor of 30 in Coulomb cross section for electron–electron collisions

I’m a bit stuck trying to understand where a numerical constant in an old paper comes from. The number in question is in eq. (A1) in Shull & van Steenberg (1985) (which gives the cross section for Coulomb collisions between…
Socob
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Will all galaxies eventually become elliptical galaxies?

According to the Wikipedia article Elliptical galaxy, elliptical galaxies have a sparse interstellar medium. I know that probably sometimes two spiral galaxies collide then exponentially approach the state of being an elliptical galaxy. For a spiral…
Timothy
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Is phys.org/space-news reliable source?

I found this page: http://phys.org/space-news/ . It seems to me pretty good page with interesting news and so on and I like that it is free. But I noticed in comments people arguing about the validity of the information and so on. Are they just…
Vojta Klimes
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How would Jupiter's brightness relative to our sun seem to a remote observer (observing from a remote star)

Given that Jupiter is 5 AU from our sun and a remote observer viewing our solar system from some other part of our galaxy looks at it. We assume that Jupiter's radius is $11 \times 6700$ km. What would be the relative brightness (luminosity?) of…
vondip
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Potential energy in an expanding universe

A question you wonderful geniuses can hopefully answer. Imagine a piece of string drawn between two galaxies. Space between the galaxies is expanding. What force is being applied to the string? Where is the energy generating this force coming from…
Maciej
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Can we affect an object that's already passed beyond the Hubble volume, and if so, why?

This paper by Toby Ord states this: "There is substantial confusion about how to interpret the Hubble volume, with widespread erroneous claims that we could never affect (or see) galaxies beyond this limit.19 In fact, this radius is about 14.4…
the-protean
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How can a busy high school student get into learning Astronomy?

I'm a high school student that has loved physics for quite some time, but have only started dabbling with the more complex things. I know a fair bit about quantum mechanics and such as I like it, but a documentary I watched a couple months ago…
Caw
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Earth and moon gravitational ratios and proportionalities

This question is for an astronomy class of mine. I don't believe the question is particularly difficult, but rather I'm having trouble understanding what it wants me to do. We haven't covered ratios and proportionalities and as a result I'm very…
user37712
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