Questions tagged [star]
Questions regarding large spheres of plasma undergoing fusion.
1,017
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How many stars are in the Milky Way galaxy?
So, I've always heard that the Milky Way hosts between 100 billion to 400 billion stars.
My problem is very simple: I'm unable to find any research papers on that topic or giving those estimates. I'm ...
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2answers
83 views
Can we estimate the number of stars which have died in the observable universe?
We know there are currently between 10^22 and 10^24 stars in the observable universe, but can we make an estimate of how many stars have died so far? Or, in other words, how many supernovæ have taken ...
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2answers
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How can we know if a star which is visible in our night sky goes supernova?
Let's say there is a star about 3000 light-years away from earth visible in our night sky. If this star were to go supernova tomorrow(not relative to earth's night sky), we would know about it 3000 ...
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1answer
38 views
Extracting specific star data from Gaia DR2?
I would like to extract all Gaia DR2 sources which have six-parameter solutions as well as their radial velocities and effective temperatures. Is this possible as DR2 only specifies that there are 1,...
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2answers
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What's the percentage of strange matter inside a star at any time?
Is there any amount of strange matter (or "top matter"?) inside stars?
By strange matter I mean matter made out of flavours of quark other than up/down.
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Where can I buy Map of the Universe 2.000 poster?
I have the original Map of the Universe star poster by Tomas Filsinger. Recently, I bought the 1500 piece Ravensburger jigsaw puzzle Map of the Universe 2.000 and it is amazing! However, the puzzle ...
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0answers
39 views
How far can a star's visual colour deviate from black body radiation?
The primary driver of a star's colour is its temperature, by way of black-body radiation.
Black body radiation restricts stellar colour to a narrow slice of the full RGB spectrum.
However, all stars ...
2
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1answer
87 views
If Proxima Centauri was replace with a quasi-star, would our telescopes be able to see it in fine detail?
Quasi-stars, if they ever existed, were stupid big and stupid bright; many times bigger, brighter, and more massive than any star supported by fusion can be. There's no question that it could be seen ...
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38 views
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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2answers
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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'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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1answer
443 views
Why does metallicity increase the opacity inside stars?
A vague answer I've seen is that it has something do with a greater number of possible excited states, but I don't know what this means for a partially ionized plasma - much less a fully ionized ...
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Is there a metallicity threshold past which star formation is impossible?
I've learned that metallicity is a very important factor to consider when talking about a star's formation and lifecycle. That gets me wondering whether a high enough metallicity could prevent the ...
5
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1answer
124 views
Why is it that lithium and deuterium are burned before hydrogen?
Protium ($^1H$) has a nuclear binding energy near 0. Meanwhile, lithium and deuterium have higher binding energies. Why is it that they are burned first (or at lower temperatures)? Is it perhaps ...
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1answer
90 views
What is the most powerful events in the universe?
Is this idea disproved these days, please? What are the most powerful events in the universe?
The evolution of hot stars usually ends as core-collapse supernovae,
the most powerful and incredibly ...
4
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1answer
45 views
How does pair production cause a pair-instability supernova instead of leading to the formation of a black hole?
The Wikipedia article on pair-instability supernovas (PISNs) doesn't seem to give a very good explanation of what causes a PISN. My understanding of the process it describes is this: Once the core ...
4
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1answer
188 views
Why is it safe to assume that K = 3/2kT in a self-gravitating gas
I encountered a question:
"Find the ratio of Kinetic Energy and Total Energy of a star, made out of a monoatomic ideal gas, You may not consider density to be uniform. Kinetic energy is the ...
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2answers
109 views
Life span of massive stars?
I was told that the following statement is inaccurate, but could somebody please help why exactly the sentence is wrong?
Hot stars are very massive, and therefore live for only a relatively short ...
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6answers
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Are there other life giving sources of energy in space apart from stars (like nebulae, radiation, etc.)?
Are there other life giving sources of energy in space apart from stars? (like nebulae, radiation, etc.)? Or are all possible life giving potential sources some variation of a star?
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2answers
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Why nuclear fusion with hydrogen alone, why not with others?
Are there any stars that use any other elements as its fuel besides hydrogen? If not why not?
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31 views
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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2answers
156 views
What is the bright star that never seems to move and sometimes the only star in sky?
I have very little astronomy background; so apologies in advance with elementary terminology with this question. I am located in Northeast Pennsylvania and no matter what time of night 7pm, 1am, 5am ...
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Distance between Stars
If one looks up at the night sky, the Stars appear to be so close to one another and yet they are very, very, far away from one another. Why is this?
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2answers
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Is it possible for stars to not begin fusing hydrogen at all?
As far as I know, stars (virtually all stars) begin fusing hydrogen into helium, and the rest happens based on the mass and luminosity and etc.
Out of curiosity, I was wondering: is it even possible ...
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1answer
497 views
Will interstellar medium slow down the rotation of stars?
This is a side question from my previous one, will interstellar medium slow down the rotation of stars? Will it be significant enough to be considered as a factor? What are the other factors that slow ...
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2answers
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Will pulsars stop spinning eventually?
In the book "Horizons: exploring the universe-Cengage learning (2018)", page 224, it states that:
When a pulsar first forms, it is spinning fast, perhaps a hundred times a second. The ...
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2answers
65 views
What is use of Greek Letters in Astronomy? [closed]
We see letters such as $\epsilon$ or $\alpha$ or $\beta$ or $\eta$ etc... (possibly all Greek letters)
Can Somebody state the use of all Greek letters in astronomy?
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2answers
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If Newton said a sphere acts as if its entire mass is at its center,why are there no black holes between any two ordinary stars of 4 Solar Masses?
A paper('A QuasiHeuristic View On The Occurrence Of Singularity Forms of Ordinary Matter') discussed at a recent colloqium at our institution postulated,since 4 Solar masses is what is needed for ...
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1answer
43 views
Nightsky observation : a light/star suddenly disappeared, why?
For starter, I'm a beginner/noob in astronomy so it might be an obvious answer but I keep asking it to myself
I was watching the sky in the night looking for shooting stars, there was plenty of them, ...
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1answer
122 views
What actually is the mass? [closed]
Since high school, I've been told that the definition of mass is "quantity of matter" (which is absolutely wrong, I guess). If mass is actually a quantity of matter and it is a measure of ...
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0answers
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How to find published data with the article?
How to find data published with an article, please? For instance, let us consider this paper. There are data products and the link to SIMBAD on the right. Then, the table with objects appears, but ...
12
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2answers
749 views
Radius to which all hydrogen-burning stars are known?
For the purposes of this question, I wish to consider active, hydrogen-burning stars, not deuterium-burning brown dwarfs, or stellar remnants like black holes or neutron stars. (Though including ...
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2answers
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What does an electron-capture supernova leave behind? A white dwarf, a neutron star or nothing?
Somehow, none of the many articles I've read about the recent discovery of electron-capture supernovae has specifically said what they leave behind as remnants.....
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1answer
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Which star has the faintest absolute magnitude (largest magnitude) yet is still visible with the naked eye from Earth (either hemisphere)?
I am thinking about the Bright Star Catalogue and how it is not a good representation of a typical population of stars. The Bright Star Catalogue includes all the visible stars from Earth when viewing ...
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2answers
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What is the closest stellar neighbour to Sirius?
What is the closest star to the Sirius system, excluding Sirius B?
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1answer
104 views
Exploded star or object on earth?
I don’t have a telescope 🔭 (which is sad)
Anyways…
Usually in the city, all stars are covered by the light pollution, and that’s my case.
I stare out my window every night, but yesterday night I saw ...
2
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1answer
50 views
Calculate the habitable zone of a star based on NASA Exoplanet Archive
I am completely new to this! I am trying to find if an exoplanet in the Exoplanet Archive is the habitable zone of its host star. My intention is to create a new boolean column in a Pandas Dataframe ...
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0answers
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How to determine time when a photo of star trails was taken?
I was asked to define a time (most likely the month) and location of the picture below.
I hope I understood it right that it is the south pole, because we don't see a Polar star in the middle. ...
2
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1answer
81 views
Spectra of different stellar classes?
I'm beyond an amateur, but I've been failing to find this information and it makes me think I'm missing something.
Anyway: I am trying to write a procedurally generated simulation that includes ...
3
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0answers
38 views
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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2answers
200 views
How to actually obtain the parallax angles that are used to determine distances of stars?
I’m trying to understand how to measure the distance to nearby stars using the parallax method.
My question is: how do you get the value of the p angle?
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2answers
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Setting of stars [duplicate]
In the book Thinking Physics by Lewis Caroll I came accross the following exercise:
Using a good digital watch, get the exact time when a bright star goes behind a distant building or tower. A day ...
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3answers
1k views
Can a small black hole orbit a large star?
I recently read about the discovery of a tiny black hole (with only three times the mass of the sun) nicknamed ‘The unicorn’ about 1500 light years from earth. This got me thinking, can this black ...
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3answers
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How are constellations intact if the stars are rotating around galactic nuclei?
From what I understood, the Milky Way (or stars in the Milky Way) doesn't rotate like a collection of points in a disc due to the presence of some invisible matter. In theory, the angular velocities ...
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1answer
62 views
What colors do other stars have when seen from space close to them?
The Sun looks yellow from Earth because we see it through the atmosphere; in space the Sun looks rather white. Do A-, B- and O-type stars look blue from both their planet's atmospheres and outer space?...
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3answers
201 views
How do astronomers know that distant galaxies aren't actually nearby star clusters?
When reading about the recent release of data from the Dark Energy Survey, and the 'pictures' of well over 200 million distant galaxies, I got to wondering:
How can they know that a small, faint, ...
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Bright light in sky that slowly faded away [closed]
North Carolina June 5th 2021 at about 1:45 a.m. my boyfriend walked to me to my car just to see a bright like just above the tree line. Didn’t think anything of it. Finished our goodnight talk and ...
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2answers
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How can the (in my eyes quite ridiculous) conjecture of Sheldrake be disproven? [closed]
In this question on the physics site, it is asked if astronomical objects can be conscious. Now, in a sense, every object has to be "conscious" somehow, as every object is composed of the ...
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1answer
128 views
If Proxima Centauri goes supernova will it negatively affect the Earth? [duplicate]
Proxima Centauri is the closest star to the Earth (besides our Sun). If it went supernova, would such an event negatively affect the Earth? Can Proxima Centauri negatively affect the Earth in some ...
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1answer
154 views
Can Stellar Spaghetti ever escape?
Spaghettification is the deformation of a body into long, thin strips due to tidal forces as the body passes through a powerful gravitational field. Image from wikipedia:
Stellar spaghetti has been ...
