Questions tagged [stellar-structure]

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Solution of stellar structure equation for Sun in Convective Zone

Consider the following problem: Sun has a convection zone from $0.7 R_\odot$ to the solar surface, when $R_\odot$ is the radius of Sun. If the matter is marginally convectively unstable and the ...
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5 votes
2 answers
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Does the transition between total convection and partial convection cause a significant decrease in lifespan?

A star with less than a certain mass M, which is somewhere between 0.5 and 0.35 solar masses, is fully convective, the hydrogen in the core is constantly being replenished, so it takes much longer for ...
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What does the surface of a star with a radiative envelope look like?

This image on Wikipedia shows that main sequence stars above 1.5 solar masses have a convective core and a radiative envelope. The sun's surface looks grainy because of convection cells happening ...
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Do elements like magnesium and sulfur form a layer inside massive stars?

For an evolved massive star, elements such as hydrogen, helium, carbon, oxygen, magnesium ... iron are involved, but from the picture below, there doesn't seem to have a layer of magnesium fusion ...
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Can the energy transport by radiation occur in the convection region of a star?

I am new to stellar astrophysics and trying to understand the energy transports in the interior of stars. Can the energy transport by radiation occur in the convection region of a star? Here are my ...
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How to understand exactly why gravity darkening happens on rotating stars?

Phys.org's TESS delivers new insights into an ultrahot world links to KELT-9 b's Asymmetric TESS Transit Caused by Rapid Stellar Rotation and Spin–Orbit Misalignment (readable in arXiv) The assymetric ...
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About Radius and Surface Area

I am researching about the radius of a star and a its surface area. One question I have is about the effect of changing radii in stars. If for example we have one star with radius $r$ and another one ...
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Maxwell stress contribution to $\nabla \cdot \mathbf{P}$ in the Navier-Stokes equation for fluid in stars

I was reading through the following extract outlining how the Maxwell stress contributes to the $\nabla \cdot \mathbf{P}$ term of the Navier-Stokes equation for fluids in a star. Here $\mathbf{P}$ is ...
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Do neutron stars have something like a gamma-ray photosphere? Are gamma rays from below it limited more by the nuclei or electrons?

@RobJeffries' answer to Is there evidence of super-heavy elements in the x-ray and gamma-ray spectrums of neutron stars? includes the sentence: However, the only things that contribute to a neutron ...
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4 votes
2 answers
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Stellar electromagnetic signatures

By using only the electromagnetic signature of a star, could a star be distinguished with reliable accuracy from any other star? To elaborate a little, say we have a collection of about 200,000 stars. ...
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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 ...
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Are larger stars rounder?

The Earth is a very smooth sphere, and the Sun even more so, with only minor fluctuations. I am wondering: are larger stars even rounder? Intuitively, that seems self evident, but I am not so sure. ...
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3 votes
1 answer
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When is it a good aproximation to consider a star to be an ideal gas?

I am currently taking a first course on stellar astrophysics, and I noticed that in some cases we use the ideal gas equation of state for stars, so we also use $\gamma =5/3$. Of course it can only be ...
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21 votes
4 answers
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Metallicity of Celestial Objects: Why "Metal = Non-metal"?

Metallicity of objects refers to the amount of chemical elements present in it other than Hydrogen and Helium. Note: The other elements may or may not be actual ...
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How well can we in principle determine $T_{\textrm{eff}}$ of a star?

This is a question about the basics of astronomy, which I have never happened to see a good discussion for. It is about how well would we be able to measure effective temperature of a star, if we had ...
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14 votes
1 answer
346 views

Stars at near break-up rotation rates

Accretion discs are ubiquitous in astrophisics. As a direct corollary, they are important for the following question. Consider the following model, representing one of the most simple models for ...
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