Questions tagged [stars]

Stars are astronomical bodies that are (usually) mainly composed of Hydrogen, Helium, and Lithium. They are massive enough that their gravity compresses the matter to the point where nuclear fusion occurs, which creates a lot of heat and tends to make stars output radiation along a blackbody curve. Typically the radiative output is significant in the visible spectrum making stars very bright objects.

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Is really Researchers discover a new type of matter inside neutron stars?

I have read this day here that a Finnish research group has found strong evidence for the presence of exotic quark matter inside the cores of the largest neutron stars in existence, I want to know ...
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Number of seemingly brightest stars: minimum around G-stars

This plot gives the amount of the seemingly 10000 brightest stars. Can someone help me to explain why there's a minimum at number 3, I know how to explain 1 (there are less big stars) and 2 (small ...
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Stellar nucleosynthesis

I would like to learn more about fusion in stars. The question I have is whether there exists a graph showing exactly which elements take part in the reactions. Here, I managed to find some data ...
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Investigating colour of a star when in motion [closed]

The star Alpha Centauri is 4 light years from Earth. For an astronaut travelling at $c/2$ from Earth to Alpha Centauri. So, this apparently means The colour of a distant star perpendicular to the ...
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Trouble understanding exactly why core of sun does not mix with outer layers

I’ve had trouble understanding exactly why there is not more mixing of plasma at the core of the sun with the outer layers. I understand the difference between the radiative zone and the convective ...
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Galactic bars and star formation

I have recently been reading on barred galaxies and am confused as to whether they aid or obstruct star formation as a general rule. Some papers state that they aid star formation, whilst others ...
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Comparing Luminosity of a star calculated from absolute magnitude to its actual luminosity

If the luminosity of a star is calculated in terms of the solar constant (the suns luminosity) by comparing the absolute magnitude (apparent magnitude at a distance of 10 parsecs) of the star in ...
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Why does the sun and gas planets in our solar system weigh more than the earth?

I was reading a space.com article about What Is The Sun Made Of? The article says that the sun is made of plasma and gas. If this is the case, how is it that the earth which is solid weighs less than ...
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What will be the mass of the sun when the core is depleted of hydrogen about 5 billion years from now?

Our sun converts 600 million tons of H to He every second, that is 5 million tons of matter into energy through nuclear fission. However, as the core of the sun continues to shrink the outer layers of ...
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How does Buchdahl's interior solution satisfy the Einstein field equations?

I was reading Schutz A First Course in General Relativity (2nd Edition) Section 10.6, where the Buchdahl exact solution was written down as follows: For $Ar'\le\pi$, $$ \exp(2\Phi) = (1-2\beta)(1-\...
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Understanding the Chandrasekhar limit for white dwarfs and its relation with supernovas

So if I understand correctly, the Chandrasekhar limit ($\sim 1.4 \ M_{\odot}$) is the maximum mass that a white dwarf can have. Beyond this mass, the degeneracy pressure of the electrons can no longer ...
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Stellar structure integration

I have some issue regarding the stellar structure. I know analytically the equation of state, and I have been asked to build the structure of the star from these two equations $\frac{dP}{dr}=-\frac{G ...
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Why doesn't the nuclear fusion in a star make it explode?

I have a rather naive question. In stars such as the Sun, what prevents the whole thing exploding at once? Why is the nuclear fusion happening slowly? I can only assume that something about the fusion ...
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In fusion inside stars (sun) or very hot gasses, how do the electrons get bound and what about tritons and D-T vs D-D fusion?

Most texts I've read focus on just the nuclei to begin with, but eventually start talking about Helium (or other) atoms and isotopes. A few aspects aren't clear to me and I'd be grateful for some ...
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Solving coupled integral + differential equations for ionoization and combination of gases near a star

The following set of coupled differential + integral equations appear regularly in the literature (e.g Osterbrock, "Astrophysics of Gaseous Nebulae and Active Galactic Nebulae"): $ n_H(r) \int_{\...
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Electron degeneracy in white dwarfs

Consider a plasma in a star. Now in a plasma electrons are so excited that they can no longer be held by the electromagnetic field of the nucleus. But then when we are talking about cores or red ...
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How are the relative distances of celestial objects from the Earth calculated using observations at a single time instant?

How does one find the distances of celestial objects in the night sky, such as the Moon and the stars, from the Earth using a snapshot of information (including, say, the intensity and wavelength of ...
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What is a simple argument to prove that the stars in the sky are further away from the Earth than the Moon?

How do we know, without using modern equipment, that the stars are further away than the moon in the night sky? Further, is there a simple and actionable argument to prove that this is indeed the case?...
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When the star formation begins?

We can separate the history of the universe in different epochs. Radiation dominated epoch, matter dominated epoch, and dark energy dominated epoch, and we can divide the epochs in different ways. ...
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Why is the $\rm CNO$ cycle is much more efficient than the $p$-$p$ cycle?

Why is the $\rm CNO$ cycle is much more efficient than the $p$-$p$ cycle?
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A question on Przybylski's Star

Przybylski's Star is a rapidly oscillating AP star of 4 solar masses, 355 light years from earth. It contains high levels of unusual elements like strontium, holmium, niobium, scandium, yttrium, ...
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Im trying to prove that a star can be described by a polytrope by deriving the polytropic relation of $P\sim p^n$ from the stellar structure equations

Suppose that in a star, the only source of energy generation is radioactive decay, so the energy production per unit mass is constant and independent of density and temperature. Further suppose that ...
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Measuring the interior temperature of the Sun

We frequently measure the "temperature of the Sun" using Wien law: $\lambda_m T = b$ where $b$ is the displacement constant, $\lambda_m$ is the peak wavelength obtained from the spectrum, and $T$ is ...
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Is it possible to know in advance that Alpha Centauri has exploded?

Alpha Centauri is 4.3 light years away. If it exploded suddenly, would we be able to know this in advance? As the light from the supernova will not reach us before 4.3 years.
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distinguishing redshift from star's color

How do scientists find out the true color of the star's light as well as the true doppler shift (relative speed)? Seems to me you wouldn't know how to separate out those 2 values.
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How to tell a population 3 star in red shifted galaxy?

I read that population 3 are metal poor stars especially those very very massive ones will quickly exhaust their fuel and goes into supernovae when their internal pressure drops due to pair ...
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How does a spectral line tell us about the magnetic field of a star?

An absorption line in the spectrum can indicate the abundance of a chemical element in a star; but according to NASA, it can also tell us about the magnetic field of the star. Can a spectral line ...
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Why is the second stellar structure equation first-order ODE?

the 2nd structure equation is first order, but we seem to have two boundary conditions (e.g., $dP/dr = 0$ in a star’s center and $P=0$ at the surface) – but first-order ordinary differential equations ...
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Effect (if any) of strong(ish) gravity radiation on stars

Two black holes merge, and a good few percent of their total mass is converted into gravitational radiation. Years or decades later, the resulting gravity wave passes through nearby stars. Does it ...
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Are the muon/tau neutrinos produced in the Sun? If not, then where?

I was reading about Solar Neutrinos, and apparently they are all Electron Neutrinos. However, there are two other types of neutrinos, the Muon and Tau Neutrinos. Does the Sun produce them? If not, ...
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A star or a galaxy?

When we look into the beautiful sky in the night, exclaiming how beautiful these shining stars are. My question is how could we tell, whether any of these shining "point" is a star or a galaxy? If ...
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HD 140283 and the age of universe

I am watching a video on a star that is supposedly older than the universe. HD140283 (Methuselah). According to the first 20 years of research on the star, scientists believed the star is just over ...
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Why do later fusion stages in a star last shorter?

When most of the hydrogen in the core of a massive star has fused to form helium, the next fusion stages (helium, carbon, neon, oxygen, ...) produce less and less energy in a single fusion reaction. ...
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Existence and evolution of P-type “asymmetrical binaries”

I'm not sure how those are called so let me explain what I mean by "P-type asymmetrical binaries" - I'm thinking of two stars of very different masses (originally) that orbit each-other fairly closely....
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Can I destroy a star faster by trapping it in a spherical mirror? [duplicate]

What would happen, if I were to trap the Sun in an almost perfectly reflective spherical mirror? I'm assuming this would accelerate the life of the sun and reduce the timescale required to turn it ...
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How to find the transverse component of a stars velocity given it's proper motion and distance from the observation point?

If $\mu$ is the proper motion of a star in arcseconds per year, and $d$ is the star’s distance from us, then the transverse speed, $v_t$ will be $$v_t=d\sin\mu$$ For small motions (assumed for ...
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Is hydrogen produced in the universe? [duplicate]

Since stars use hydrogen initially for fusion which then produces heavier elements. Where does all this hydrogen come from? Does all the hydrogen come from the birth of universe? If yes then will new ...
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Effect of star's binding energy due to general relativity?

Due to the curvature of space-time the distances near the star are length contracted. So if that's the case then doesn't that mean that the binding energy of star should be more since the distance ...
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How would a quark star maintain degeneracy near the surface?

I'm still not exactly understanding how a quark star could possibly exist for more than a fraction of a second. Neutron stars are already hypothesized to have degenerate quark matter at their cores, ...
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Why is the temperature of a star not intensive?

The temperature of a star obviously depends on its mass. Does this mean that temperature is not always intensive?
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What would the effect of an antimatter star be upon a normal matter planet? (Thought experiment)

Based on the answers from this question: Would the solar wind from an antimatter star be any different from a non-antimatter star?, it seems that an antimatter Sol type star would conduct fusion ...
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What's lowest mass object that can form from collapsing gas?

Is there a minimum mass for an object that can form on its own from collapsing interstellar gas without being bound to a larger star's protoplanetary disk first? There are red dwarfs, brown dwarfs, ...
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Would the solar wind from an antimatter star be any different from a non-antimatter star?

Antimatter is any element of matter with an opposite charge than normal matter. As such, would an antimatter sun conduct fusion normally such that it would it radiate photons, or would it radiate ...
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Molecular cloud and star formation surveys

I just had a quick question about molecular clouds. Why is it that we survey them using $CO$ lines instead of $HII$? Is it because $CO$ has better emission? It doesn't make sense to me when I read ...
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Query concerning black holes [duplicate]

What information can be conveyed from a black hole about the substances and radiations it absorbs into it's singularity.
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Thermal fission of gold? [closed]

Here's a slightly silly idea that arose from this question "What elements would be created in a star composed entirely of gold?": If we accumulate a lot of gold (really a lot) fast enough, it will ...
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Theoretically, Is it possible to create a nova by firing large masses into a sun?

In a science fiction story (Bobiverse) a nova is created by accelerating two small planets at relativistic speeds into a sun from opposite sides.The shockwave creates hydrogen fusion on opposite sides ...

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