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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Why Cepheids have Period Luminosity relation?
According to my astronomy teacher, Cepheids is a type of variable stars that has Luminosity-Period relationship:
$M \propto log(T)$
, where $T$
is the pulsation period of Cepheids.
But I have a ...
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Why is pressure in the outermost layer of a star lower than at its center?
I have done the math and I have obtained the hydrostatic pressure in a star is lower at the outermost layer of a star than in its center, where the pressure is actually maximum. Although the equations ...
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What would happen if the sun became the size of the earth? [closed]
Imagine that a sudden force crushed the Sun from its current size down to the size of the earth,held it at that size for a few moments and then disappeared. What'd happen?
I haven't done any of the ...
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Mass-volume relation for a star - explanation
In the game Universe Sandbox, I created a gas giant (made of pure hydrogen) and begun increasing its mass and watched how its radius changed and how it evolved into a star. While it was already a ...
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Stars that have fairly high gravitational redshift and calculation of their surface temperature by Planck emition spectra?
How high can the ratio between gravitational redshift and planck emition spectra be depending on the mass of the star so by how much this gravitational redshift could elongate the Planck spectra of ...
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Relationship between gravitational force and fusion energy in stars [duplicate]
From what I understand, stars like our Sun constantly have a gravitational force on their surface due to their mass, which is balanced out by the fusion reactions taking place in the core of the Sun.
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Trajectory of supergiants on HR diagrams
I am a secondary school student currently studying cosmology. My A Level textbook supplies the following HR diagram with regards to what trajectories different stars follow:
I found myself unable to ...
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If gravity is not a force, what makes massive objects spheroid?
For most of my life, the explanation given for why celestial bodies like stars, planets, etc. are round is due to gravitational force. Simply put, if an object has enough mass, it will, in turn, have ...
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Sudden drop in temperature in Sun convective zone
In the solar temperature graph, why does the temperature drop suddenly in the convective zone? Is it because some energy is needed for ionisation?
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Obtaining TOV equations
I am trying to obtain the first TOV equation
$$
(\rho+p) \frac{\mathrm{d} \Phi}{\mathrm{d} r}=-\frac{d p}{\mathrm{~d} r}
$$
using the metric
$$
\mathrm{d} s^2=-\mathrm{e}^{2 \Phi} \mathrm{d} t^2+\...
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If a star's luminosity doubles, does its received flux double?
If the luminosity of a star increases or decreases in some way, would the received flux increase or decrease by the same amount (linearly) or would it change by the square of the luminosity (inverse ...
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Is there a way to calculate the habitable zone distances of a star?
What would you need to calculate the habitable zone distances of a star? I am aware of the Stefan-Boltzmann Law and Wein's Law to calculate the Luminosity of the star, and that the flux decreases with ...
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Is the sun multinucleated or is there just one point at or near the center of the sun where fusion is occurring?
I was just reflecting upon my thinking and probably any illustration in books or movies: I assumed a single general area near the "geographical" center where the actual fusion occurs.
But ...
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A general theory of convection currents using continuity equations
In an Astrophysics & Cosmology summer programme I attended last summer at UCL we were taught that stars seem to transport matter from the regions near the core to the surface through convective ...
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Luminosity and absolute magnitude relationship
Context : an exercise gives the temperature, mass, distance and apparent magnitude of Sirius B and asks to calculate its density.
One key step of the calculation is to get the luminosity from the ...
