Questions tagged [star]

Questions regarding large spheres of plasma undergoing fusion.

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17 views

What color would stars have with an apparent magnitude of ~-30?

The light of the Sun is white because our eyes are evolved to work with it as the primary light source. Other stars look white in the night sky because they are too faint to activate the color ...
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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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Can you tell me which star this is?

Back-story: My adopted daughter, age 2, looked up in the Ohio sky (we have very poor star-viewing compared to Arizona) and pointed at a light. She said "what is that". I said "that is ...
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126 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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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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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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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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148 views

Which star has the highest mass loss rate?

We have known lists of stars with high luminosity, temperature, mass, size, and much more. However, I have not seen a list that compares each star's mass loss rates. So, which star (or stars) have the ...
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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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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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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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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 ...
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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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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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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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Why is our Sun hotter than UY Scuti?

As Wikipedia says the surface temperature of UY Scuti is 3,365 K and the sun is 5,778 K Why is the Sun hotter than a supergiant star like UY Scuti?
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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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1answer
45 views

Can the shape and fluctuations of the heliopause be attributed to specific nearby stars and clusters?

The heliopause is where the Solar wind is counter balanced by the particle winds from other stars. This boundary seems to not be spherical and also to fluctuate in shape. Can the shape of the ...
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1answer
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Physical properties of the stellar corona?

I am after the basic physical properties of the corona of a star, here some questions for which I would like to have an answer, even only for a subset of them: I know some things about the corona of ...
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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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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 ...
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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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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 ...
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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 ...
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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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160 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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134 views

Blackbody curve in RGB for objects less than 1500 K?

We know the colors of stars that have a temperature greater than 1000-1500 K, shown here. However, I am wondering about those stars/brown dwarfs with surface temperatures of less than 1500 K. Is there ...
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186 views

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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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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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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119 views

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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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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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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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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1answer
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Catalogs for type K stars and their planetary systems?

I am doing data collection on all type K stars, and their planetary system so I may develop an algorithm for a planetary formation simulation with the Unity game engine. Where could such a catalog of ...
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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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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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1answer
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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
225 views

Can someone calculate the age of the KOI-4878 star?

The star’s low metallicity and fairly high space velocity suggest that KOI-4878 is older than the Sun. But I don't know how to calculate an estimation for the age. KOI-4878 data on Simbad
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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 ...
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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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What is the closest stellar neighbour to Sirius?

What is the closest star to the Sirius system, excluding Sirius B?
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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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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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1answer
503 views

How many stars are in the Sculptor Dwarf Galaxy?

The Sculptor Dwarf Galaxy is a small satellite Galaxy of the Milky Way. There are many such satellites galaxies and I'm trying to compile basic data on them. However, I can't find an estimate for the ...
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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 ...
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Distance between stars Epsilon Eridani and Tau Ceti?

I am working on a story. It would be helpful if someone could provide the distance in light years between star Epsilon Eridani and star Tau Ceti.
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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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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 ...

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