Questions tagged [star]
Questions regarding large spheres of plasma undergoing fusion.
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questions with no upvoted or accepted answers
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What does the surface of a star with a radiative envelope look like?
This image from Wikipedia shows that main sequence stars above 1.5 solar masses have a convective core and a radiative envelope. The surface of our sun grainy because of convection cells right below ...
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What are the twinkling stars in the New Horizons Arrokoth approach?
I've circled them in this edit:
Source: https://commons.m.wikimedia.org/wiki/File:New_Horizons_Approach_to_Arrokoth.ogv
Note, this has generated frames, see the source....
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Using tail-fit Gaussian distribution to compensate for saturated sensors
Main Question
I have a project goal, where I have an image of light sources (stars or lamps doesn't matter). The image is split up into channels for each expected band of 'color'. There are occasional ...
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What is the reason for the dispute over the variation of core mass with heavy metal abundance?
In Metal-Poor Stars IV: The Evolution of Red Giants, Rood writes
The differences in the results of these papers are large enough to introduce appreciable uncertainties into the study of the ...
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Do narrow lines in the spectra of O- and B- type stars always indicate magnetic fields?
I was reading a paper on the differential emission measures of a set of hot O- and B- type stars. As the authors discuss in Section 3 (page 959), two stars, $\tau$ Sco and $\theta^1$ Ori C, have ...
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Could non-supernova carbon, oxygen, or silicon flashes be observed?
I was reading about the helium flash, the short but sudden onset of helium fusion in certain red giant stars. As I understand, the upper (nondegenerate) layers of the star absorb the energy as they ...
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Type Ia supernova by fallback?
Is it possible for a massive star of more than 1.4 solar masses (probably around 3 or more but below the threshold for type II) to collapse into a white dwarf and a planetary nebula, then go supernova ...
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Obtaining the derived period of $\omega$ Canis Majoris
I have read these two papers:
On the nature of the Be phenomenon I. The case of ω Canis Majoris
Stellar and circumstellar activity of the Be star ω CMa
II. Periodic line-profile variability
In the ...
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Strength of core-envelope coupling in stars
For a star with a given Zero-Age Main Sequence (ZAMS) mass, as a function of metallicity how strongly is the star's core coupled to its envelope?
I understand that the core-envelope boundary is only (...
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How often do comet occultations of stars happen?
By travelling to specific places, astronomers can see three thousand star comet transition events every year at m15 for the major (50km+) comets and asteroids averaging about 20 seconds, perhaps that'...
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How is the age of a star on the Henyey track calculated?
I was reading Stellar Evolution in Early Phases of Gravitational Contraction, by Chushiro Henyey, where he writes,
If $L \propto R^{-\alpha}$ along the path, the age of a star from the time when $R=...
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Calculation of average FWHM by PSF fitting of all the detected stars in the fits image
I need to calculate the FWHM of all the stars detected via the DaoStarFinder package/any other package by performing PSF fitting in Python. Here is the code for my detection.
...
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What is the contribution of star-produced axions to the dark matter budget of the Milky Way?
I try to follow the discussion of axions since Peccei, Quinn, Wilzcek and Weinberg. What I still don't understand is how much the speculated stellar production of axions could add to the galactic dark ...
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M Dwarf radiation and habitability at the terminator of a tidally-locked planet?
I know that M Dwarf stars emit intense solar flares, which is thought to pose a potential problem for the emergence of life on planets that orbit them. But I was wondering if the life that might exist ...
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What happens to the non-fusion formed metals in stars?
Let’s consider a population I star of some given metallicity.
I know that depending on the type of star, different structures are possible with convection zones and radiative zones trading around ...
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How are plage regions related to the density of medium and velocity FeII ions?
During a literature review (abstract), I found that the intensity of FeII (298.5 nm) ions in the last solar minimum was higher than the two previous solar minima 21 & 22. The velocity of FeII ions ...
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Sun (star) spots (size)
My question is about sunspots size.
Does these spots have a 'typical' size for all kinds of stars (dwarves or super giants), or are they dependent on a star size? In another words, is the statement ...
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From what distances do the atoms in you come from?
If the atoms of a human come from stars, comets, nebulas and magnetrons, then what is the greatest distance that two atoms of a human can possibly have been away from each other previously? Perhaps ...
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What does the surface of a star look like in visible light?
False colour images of the Sun show a highly complex structure near the surface with matter ejected and suspended in magnetic fields. But are solar prominences and coronal mass ejections visible to ...
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When did astronomers accept that fixed stars aren't fixed and are at different distances?
Was it when heliocentric model was spreading in the whole world? I saw a model of the solar system that was made in the 18th century where the sun was in the middle and the planets and comets around ...
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Finding ones way around the sky
Thinking about this recent question Identify T-shaped constellation the first thing I have to say is that I applaud the poster for actually looking up and noticing the stars: something that becomes ...
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What is the average and the median mass and luminosity of a star?
I've heard in many places that the Sun is an average star, but in Wikipedia it says that about 75% of stars are M-type stars that are way less massive and fainter that the Sun. So how massive and ...
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How can I calculate evolutionary timescales of low mass stars?
How can I calculate how long a star of a given mass will spend on an evolutionary branch before evolving off it?
I'm thinking about the evolution of low mass stars from the subgiant branch to the red ...
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Pulsations in massive stars
Why are tidally induced pulsations not typical for massive binary stars? For which kind of binaries they are typical? I read it in the last but one paragraph in Discussion of https://iopscience.iop....
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Estimate the shape of an object based on flux curve
Is there an aproximation to know the shape of a dust cloud,etc based on the magnitude/flux curves of stars they transit? Example, can I know if the shape is (at least in 2 dimensions) elliptical, ...
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How to distinguish primary hosts (stars) and orbiting satellites (planets) and tertiary bodies (moons) by their mass and trajectory?
Suppose one has run a gravitational simulation of N bodies (has the mass, vector positions, vector velocities, etc for each body), but knows nothing a priori about ...
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How to determine the temperature of a star according to the strength of the line in the spectra?
Based on the comments, I have changed some things.
Below is a graph showing the relative strength of $H_\gamma$ and Fe I lines of two stars. Which star is hotter?
This is a question from the book:An ...
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What is the theoretical maximum variability a pulsating red giant can have such that a habitable planet can stay habitable for long periods of time?
I was reading about red giants and came across this statement:
Some research suggests that, during the evolution of a 1 M☉ star along the red-giant branch, it could harbor a habitable zone for ...
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Strength of core-envelope coupling in stars (again)
I asked this on the physics SE but it received little attention:
Consider a high-mass zero-age main-sequence (ZAMS) (e.g., $m_{\rm ZAMS} \gtrsim 30\,$M$_{\odot}$) star.
I understand that the core-...
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Why do some stars twinkle more than others?
This is a child's question I failed to answer. When observing some stars with naked eye, some stars (e.g. Regulus) appeared to blink significantly more than others, but I did not have the patience to ...
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Can mass loss via accretion occur on stellar remnants?
We know that normal stars can lose mass to a binary companion. But can this happen to neutron stars and white dwarfs? Let's say a stellar black hole is being orbited by a white dwarf or neutron star. ...
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New method for exoplanet detection based on iridescence?
Could it be possible to detect exoplanets that have an abundance of iridescent minerals by analyzing their star's spectra over time as the angle in observation would lead to changes in absorbed ...
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Can "rock stars" form from interstellar dust?
Imagine a large and massive dust cloud made of solid phase micrometeoroids, asteroids and larger planetoids, all material in it is in solid phase, and contains no hydrogen or other volatiles in gas ...
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How to fit lorentzian to lyman alpha cross section?
This is my data and purpose of this assignment is to fit a lorentzian to this data.
And.. i dont know how to do that....:(
First, there is sharply lowered region.
Couple of hours of googling isn't ...
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How are the numerical stellar subclassifications determined?
From Wikipedia:
The spectral classes O through M, as well as other more specialized classes discussed later, are subdivided by Arabic numerals (0–9), where 0 denotes the hottest stars of a given ...
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Is Nomad data heliocentric or geocentric?
I'm wondering if the data in star catalogues are heliocentric equatorial coordinates or geocentric equatorial coordinates. Also given the distance between stars compared to the distance between the ...
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Distribution of Galaxy sizes (star count)
First off, I realize how hard this is to even come close to estimating, but I'm trying to get a "general feel" for the distribution of galaxies by star count. I realize everything from rogue ...
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Which static spherically symmetric perfect fluid solutions of Einstein field equations are known to be suitable for stellar models?
Wikipedia's (Static spherically symmetric perfect fluid) short list ends in 2005 and lists only in total 5 such solutions. Does somebody know more?
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Can a quasi-star develop a stable crust?
Could a quasi-star potentially develop a stable outer layer or crust during its early stage of formation if it were to be bombarded with substantial amounts of matter, coexisting with its core and the ...
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What is the correct way to represent the Parallax angle?
I was recently reading about the parallax effect and hence had a doubt about the parallax angle.
A lot of places mention the parallax angle as (θ1 + θ2)/2 while in ...
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Finding the uncertainty in period for String-Length Minimization calculation
I wrote a Python script that calculates the period of an unevenly sampled data set using the String-Length Minimization method.
You can read about that method here: A period-finding method for sparse ...
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Velocity of the object in Binary system
how to i can calculate the velocity of the object? If i know the distance of the object from the center of mass, and i know distance between the two (identical) ellipse center... (the two object has ...
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Equation describing Energy Transport due to Radiation in the interiors of stars
I am considering a very elementary stellar structure and I'm required to derive an equation to describe the energy transport due to radiation. The answer I am supposed to obtain is:
$$\frac{dT}{dr}= -\...
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How to show that $P_c=(9GM^2)/(14\pi R^4)$ from equation of hydrostatic equilibrium
I need to show that $$P_c=\frac {9GM^2}{14\pi R^4}$$
from the equation of hydrostatic equilibrium: $\frac {dP}{dr}=-\frac{GM\rho}{r^2}$
in the exercise before, we show that $\rho_c=\frac {6M}{5 \pi R^...
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How do I calculate the flux density of a substellar object?
I am currently trying to generate photometric passband colors for brown dwarfs and planets generated through MESA (Modules for Experiments in Stellar Astrophysics). I believe I understand the ...
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"Opacity" in red dwarfs
One day, while researching on blue dwarfs in Wikipedia, I stumbled across something that I cannot understand:
Rather than expanding, however, red dwarfs with less than 0.25 solar
masses are predicted ...
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Where can I find galaxy rotational data?
I want to do a small project of generating rotational curves for different galaxies, and need data for some prominent stars in other galaxies (data needed: distance from center, rotational velocity) ...
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Formula for calculating if an object can cast a visible shadow on the ground or not
I know that we can see the shadow cast by the light of Venus on the ground. I also talk with one person who said they were able to see the shadow even from Jupiter.
Recently I've read something like ...
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How big could a regular star in supergiant/hypergiant phase theoretically get, not counting quasi-stars?
For clarity, I'm not asking about the super-behemoths that are quasi-stars. I'm interested in knowing how large a regular star could theoretically get once it reached supergiant/hypergiant phase, ...
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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 ...
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