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39 votes

Is Jupiter a failed star?

No. Besides the 13 Jupiter-masses required to ignite deuterium burning, and make Jupiter into a Brown Dwarf, there is a clear difference between the formation pathways of Brown Dwarves and Gas ...
AtmosphericPrisonEscape's user avatar
15 votes

Is Jupiter a failed star?

Short answer: no It all of course depends on how you define the term failed star. In general, a star should be able to generate heat by fusing atoms together, and it requires about 13 times the mass ...
tuomas's user avatar
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14 votes
Accepted

What is the most appropriate way to estimate the helium composition of a star?

Nearly all the helium in the photosphere of the sun comes from the helium in the interstellar gas that collapsed to form the sun. That helium was produced shortly after the Big Bang (in about the ...
James K's user avatar
  • 125k
7 votes
Accepted

Can I slice off a piece of the Sun?

The idea of removing material from the sun for either fuel or to lengthen its lifespan is called "star lifting". Various hypothetical methods have been suggested, including heating parts of the ...
Anders Sandberg's user avatar
7 votes
Accepted

How much helium has been created since the Big Bang?

We can estimate the answer by considering the "mass to light ratio" for baryons, and assuming that ratio hasn't changed too much over the time that there has been galaxies, say for ten billion years. ...
Ken G's user avatar
  • 5,336
6 votes

What is the percentage of ortho- vs. parahelium in the sun?

This is an interesting question! The Sun is a dynamical ball of hot plasma maintaining various types of equilibrium: hydrostatic, thermal, and nuclear. Observations over the last century have improved ...
Daddy Kropotkin's user avatar
5 votes
Accepted

Where can I find Helium 3 in our solar system?

Where is Helium 3 most abundant after the Sun? Jupiter, by mass, and Uranus and Neptune, by accessibility. This ignores that getting to and returning from Uranus and Neptune is extremely difficult. ...
David Hammen's user avatar
  • 34.1k
5 votes

Where can I find Helium 3 in our solar system?

You wouldn't need to travel too far, the moon has been bombarded with large amounts of Helium3. https://www.esa.int/Enabling_Support/Preparing_for_the_Future/Space_for_Earth/Energy/Helium-...
MiscellaneousUser's user avatar
5 votes
Accepted

What is the elemental composition of the Sun overall, rather than at the photosphere?

Both your estimate and @ProfRob's answer are roughly in the right area. I've done the integration on an older standard solar model, Model S (Christensen-Dalsgaard J., et al., 1996, Sci, 272, 1286) and ...
Warrick's user avatar
  • 2,847
5 votes
Accepted

Helium rain inside metallic hydrogen within Jupiter, conditions and experiments?

Different sources give significantly different values for the conditions under which hydrogen shifts from molecular to metallic. See the discussion in the comments associated with this question. ...
Steve Linton's user avatar
  • 10.3k
4 votes
Accepted

Why Helium could be produced in first minutes of big bang but not heavier elements

The triple alpha process requires very high densities, very high (but not too high) temperatures, and a good amount of time. Large stars have all three. In particular, they have millions of years ...
David Hammen's user avatar
  • 34.1k
4 votes

Fate of helium moving toward a singularity

I'll take the reference of an observer falling with the helium atom. At the Event horizon, the tidal force across a helium atom is still minute, $10^{-29}N$ much less than the Coulomb forces between ...
James K's user avatar
  • 125k
4 votes

What is the elemental composition of the Sun overall, rather than at the photosphere?

I think you are right. Metals are not produced in the Sun (though lithium is destroyed), so will be distributed throughout. To first order you can ignore radiative diffusion and chemical ...
ProfRob's user avatar
  • 155k
3 votes

How do we estimate the amount and distribution of Helium in interstellar and intergalactic space?

Helium in the interstellar medium is detected, and its abundance measured, essentially the same way as it is in stars: through emission or absorption lines. For example, here is a paper that observes ...
Eric Jensen's user avatar
  • 4,894
3 votes

What percentage of Helium-3 is primordial vs produced in stars

My question is 2-fold:   1. Is the primordial amounts of $^3$He significant or insignificant compared to what stars produce and eject by coronal mass ejections or blowing up into nebulas, ...
Rob's user avatar
  • 2,656
3 votes

At what density does helium burning start in a star?

Your question inspired me to have a look at the data that is used in plots produced by the stellar evolution code MESA. Here's a $\rho$-$T$ diagram showing boundaries of roughly where various nuclear ...
Warrick's user avatar
  • 2,847
2 votes

At what density does helium burning start in a star?

But note that high-mass stars begin helium fusion when the electrons are still an ideal gas, but lower-mass stars like the Sun begin helium fusion when the electrons are degenerate. So that produces ...
Ken G's user avatar
  • 5,336
1 vote

Did liquid helium help the solar system to form by cooling the nebula that collapsed to form it?

No, because the pressure was never close to 1 atmosphere and the nebula that condensed into the solar system was hotter than 3 K. The surface density of the protoplanetary disk was maximally about 4.3 ...
Anders Sandberg's user avatar
1 vote

Are red giants still primarily made of hydrogen? What is their exact composition?

Yes, red giants are still primarily hydrogen, even after leaving the main sequence The problem however is, that although red giants are still primarily hydrogen, this hydrogen is "inert" i.e....
Alastor's user avatar
  • 2,668
1 vote

Can I slice off a piece of the Sun?

A "space knife" is a non-starter: You can't cut a plasma with a knife because it behaves like a gas, not like a solid. You can't put anything into the sun or go anywhere near it because it is hot ...
James K's user avatar
  • 125k
1 vote

Can I slice off a piece of the Sun?

We do not have, so far, have the technology to gather the Suns resources, besides Solar Panels here on Earth. A Dyson's Sphere is a theorized technology that could be able to harness the Suns energy. ...
user21598's user avatar
1 vote

Fate of helium moving toward a singularity

The answer from @JamesK is pretty much all you need to know on this topic. Since you mention the word "singularity" in the title, let me add this - the singularity is not a thing. I know how pop sci ...
Florin Andrei's user avatar

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