Questions tagged [stellar-astrophysics]

Questions about inducing chemistry, physics, and many more branches of science into astronomy.

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4
votes
1answer
526 views

Is the Sun slightly blue in the center? - Wavelength-dependent limb darkening of the Sun

I've slightly modified the title to try to attract some attention. If we call sunlight "white" and limb darkening is a result of seeing deeper at normal incidence and shallower at oblique incidence, ...
26
votes
1answer
884 views

Why are there no green stars?

There are red stars, and orange stars, and yellow stars, and blue stars, and they are all understandable save the fact that there is a 'gap': There are no green stars. Is this because of hydrogen's ...
16
votes
2answers
741 views

Open problems in astronomy that an amateur (with a PhD in some other field) would have a chance of solving?

What are some open problems in astronomy that an amateur would have a chance of solving? Suppose the amateur has a PhD in some other field, owns a basic telescope, a set of filters, diffraction ...
13
votes
0answers
291 views

What was the absolute limit to the possible sizes of the first stars formed from “primordial material with no metals”?

This answer to Why don't or (can't) stars be more than 325 or so times the mass of the sun? What limits their size? includes the following: ...The upper limit you refer to is for compositions similar ...
4
votes
2answers
14k views

How do we find the exact temperature of a star?

This is a very basic question, but I am a little confused. As far as I know, the temperature of a star is analyzed based on the color of the light it emits. So, if a star is moving away from us, then ...
14
votes
1answer
913 views

What would the Sun be like if nuclear reactions could not proceed via quantum tunneling?

Without quantum tunneling our Sun wouldn't be hot or massive enough to produce the energy it does at the moment. So what would have been the temperature or mass of our Sun without quantum tunneling of ...
2
votes
0answers
28 views

Is the magnetic field strength of a star predictable from mass, composition, age and angular momentum alone?

This answer to Which stellar properties can we describe as “first principles” in which we can derive the rest? contains an intriguing bit: That states that composition and mass are the two key ...
1
vote
0answers
46 views

What does the Sun “look like” below 100 MHz?

Radio2space.com's The Radio Sun says: At very low frequencies (below 0.1 GHz) and therefore at very long wavelengths (> 3m) the solar disk appears much bigger and brighter in the center, and its ...
0
votes
1answer
122 views

Thought experiment about our location in the Universe [closed]

[I am sorry if this isn't the best place for this - it was either here or maybe on the Worldbuilding SE.] I recently re-read one of my favourite childhood sci-fi books (Chocky by John Wyndham), and ...