# Questions tagged [core]

Questions regarding the material at or near the center of an astronomical object.

41 questions
Filter by
Sorted by
Tagged with
1 vote
69 views

### Question about the core mass fraction of planets and its relation to the magnetic field

I have a question about planetary cores and their relation to the magnetic field. Around how massive (using this in the sense of mass, not size, for clarity) does a core need to be in relation to the ...
81 views

### Clarifications on Planetary Magnetic Fields

I believe I understand this equation for the dynamo effect of planets as far as iron-nickel cores go, where ρ is density in kilograms per cubic meter, Ω is rotation speed in radians per second, σ is ...
• 291
8k views

### Is the Solar core hard?

This may seem like a weird question, but something got me thinking about it just recently. The Sun's core is composed of mainly hydrogen and helium, and is present in the form of a extremely hot ...
• 2,613
260 views

### What is the maximum size for a solid celestial body such that it still can be tunneled down to the core?

Old science fiction had lots of stories that involved people exploring the center of Earth, like for example Journey to the Center of the Earth, by Jules Verne. As Earth sciences advanced, this sort ...
• 1,109
514 views

### Why do stars usually stop fusion at iron, even though nickel-62 has the highest binding energy per nucleon?

We know that iron is often regarded as 'nuclear ash' because of its inability to fuse with other atoms, as it has a high binding energy per nucleon. However I found that Nickel-62, grabs the title of ...
55 views

### What's the relationship between the mass of a star and the mass of its core?

What's the mathematical relationship between the mass of a star and the mass of its core? For simplicity's sake, I'm asking about the cores of main sequence stars at birth, and by "core" I ...
• 1,718
205 views

### How massive does a moon have to be to have a stable magnetic field?

Is there a minimum mass or other minimum properties necessary for a body to have a strong, stable dynamo to create a magnetic field conducive for life? For example, would it be possible for Titan to ...
57 views

### Regarding core fragmentation of a gas giant in the envelope of a red giant

We know that large gas giants, such as Jupiter, have degenerate cores. Let's say there is a hot Jupiter ($5M_J$) that orbits an F-type star. When the star expands into a red giant, the hot Jupiter's ...
2k views

### Why do massive stars not undergo a helium flash

I understand that for low-mass stars the helium flash occurs due to their degenerate helium cores. Thus the answer to this question is probably that more massive stars do not have a degenerate core, ...
• 305
72 views

### Relation between core mass and red giant mass?

Yes, the title might be confusing (I'd appreciate some more clarification on it :D ). I have an estimated mass of hydrogen in the core of a star, and how much hydrogen will be in the core when the ...
• 6,633
3k views

### What's the temperature of Pluto's core?

The surface is freezing-nitrogen cold, but it's typical for the temperature to increase towards the core. What's the temperature of the core of Pluto? Is the planet icy and rocky all the way through? ...
3k views

### Does the luminosity of a star on its main sequence increase or remain approximately constant?

From my understanding, the luminosity of a main sequence star should increase because, in its core, hydrogen is being burnt into helium which means that the number density of hydrogen decreases and ...
• 41
2k views

### Replenishing hydrogen in the core of the sun

How is hydrogen supplied to the core of the sun? Shouldn't the radiative zone prevent this? Shouldn't heavier helium fill the core? How much of the hydrogen can the sun fuse?
• 455
476 views

### The compatibility of the Grand Tack hypothesis with the "core-warping impact" theory of Jupiter's diffuse core

In recent years, the Juno mission revealed that Jupiter's core was much more diffuse than astronomers had expected. One theory is that "within a few million years" of its formation, Jupiter ...
5k views

### Are there any planets or moons denser than Earth?

Earth has the highest density out of all planets, planetoids and moons of our planetary system, and also has a higher density than the Sun. Do we know any exoplanets or moons denser than Earth?
• 1,220
632 views

### Why is the Earth's magnetic field stronger than its neighbors?

[Edited] I've learned that the Earth's core is hot due to decay of radioactive elements, causing the liquid part of the core to stay liquid. This was stated as an explanation to why the Earth has a ...
• 577
894 views

### What do the fusing 'onion layers' of a pre-supernova star look like to scale?

I'm sure we've all seen the diagrams of various layers of element fusion from hydrogen to silicon in a star that's just about to go supernova. (Picture from courses.lumenlearning.com) I suspect ...
• 4,157
54 views

### Frequency of Earth type cores?

I've read many interesting threads concerning the composition of different planet cores in the solar system while trying to see if this question has already been asked. It appears as if Earth is ...
1k views

### What could possibly save an atmosphere other than a magnetic field? Why can't a magnetic field save the atmosphere in certain cases?

Similar question here. We know as a fact that the magnetic field protects planets from Solar Wind, a damaging, continuous, atmosphere-stripping wind of charged ions. Thus, a magnetic field protected ...
• 1,862
514 views

### Is Naboo's core possible in real life?

In Star Wars, the planet Naboo has a plasma core, instead of a molten one. Can a planet really have a plasma core?
• 103
2k views

### What is the underwater temperature of Europa?

If Europa has an oxygen atmosphere with a water mantle, is it possible that there could be life under the crust of Europa ice on the ocean where it is warmer? What could be the temperature under the ...
• 1
510 views

### What are the possible star fuels?

I always thought the only fuel for a star was hydrogen, which is fused into helium. But while reading some questions and answers here in ASO, I saw phrases like "This balance stays relatively stable ...
• 427
1 vote
225 views

### Can you recommend a book about big bang nucleosynthesis and chemical abundances?

I am interested in learning about big bang nucleosynthesis, nuclear fusion up to iron in stellar cores and beyond iron in supernovas, and into the lithium problem (galactic abundance anomoly for ...
1 vote
46 views

### Is there a connection between Jupiter's orbital period and the Sun's solar cycles? [duplicate]

The cycle of solar maximums and solar minimums are each about 11 years, which is close to the orbital period of Jupiter. I thought it was a numerical coincidence, until google turned up some results ...
432 views

### Are planets more likely to have dense materials at their cores?

When planets are forming, does the densest material sink the core and the less dense material "float" on top? What I'm asking is that are the more dense materials more likely to appear in the core ...
• 911
3k views

### Has the iron core of Mars really solidified?

In the Nova episode "Origins: Earth is Born", Neil DeGrasse Tyson states, "But Mars is just a fraction the size of the Earth, so it cooled more rapidly. And as it cooled, its molten iron core hardened....
• 161
3k views

### Will a planet's core always be very hot?

Including formed & forming planets, will the core of a planet always be very hot, or are there any planets with cold cores?
• 624
3k views

### Definition of stellar core?

This is a basic question, but I may as well ask it. I had always thought that the core of a main-sequence star is defined as the part hot enough for nuclear fusion. Some dictionaries seem to agree ...
• 8,109
23k views

### Do all planets have a molten core?

As we know, according to Wikipedia on Earth's inner core: The Earth's inner core is the Earth's innermost part and according to seismological studies, it is primarily a solid ball with a radius of ...
116 views

### Could evaporating hot Jupiters have metallic hydrogen on their surfaces?

Jupiter is believed to have metallic hydrogen in its core. And gas giants that migrate to become hot Jupiters are believed to evaporate, have their atmospheres blown away by their nearby star. Can ...
• 11.4k
1k views

### Is Mercury's core liquid?

A very basic question, but one to which I keep finding different answers: does Mercury have a liquid core, or is it all solid? Whatever the reason, what are the causes of it being so?
• 676
21k views

### What will happen when landing on Jupiter?

Jupiter is a gas giant, so landing on it will not be like landing on Earth, our Moon or Mars etc., as it does not have a solid surface like these. If we have a hypothetical spaceship or probe landing ...
• 701
12k views

### Is Jupiter made entirely out of gas?

I heard that Jupiter is made out of gas. But in school I learned that Jupiter has gravity which is 2.5 times that of Earth (Gravity that can tear apart a comet) and gravity is proportional to mass. ...
• 1,089
1k views

### Could we fly/drive through Jupiter?

If Jupiter is made of gas, could we fly or drive through it or would its center be too dense?
• 183
1k views

### Mass of sun's core

It is estimated that the sun's core is about 1/5 of the radius of the sun (from Wikipedia). I know that the density of the plasma increases substantially the near the center, and that the volume of ...
• 2,036
2k views

### How do we detect if a planet has a liquid core?

In case of Earth, we have many hints about the internal structure of our planet, from what I know, the most important of which is analyzing seismic waves. Do we have any instruments to detect if ...
• 1,538
506 views

### Were effects of a planetary magnetic field reversal observed on other planets than Earth?

From geological records in rocks and minerals we know that the magnetic field of Earth changed its polarity multiple times in the history. See Geomagnetic reversal. Was a similar process of a ...
449 views

### Earth and ferromagnetism [closed]

Earth's core is a giant liquid iron ball actually. If I know well, the magnetic field of our planet (that protects the surface from some particles comes from the Sun) can exist because as Earth ...
• 2,278
1k views

### What is the current accepted theory as to why Mercury, despite its size, has a similar density to Earth?

According to the NASA web page overview about Mercury, despite the planet being just a bit larger than our moon, it's density is about 98.4% of Earth's. This high density suggests a comparatively ...