Questions tagged [star]

Questions regarding large spheres of plasma undergoing fusion.

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How many bright IR sources would you expect to see in a young gas cloud? [closed]

During the 10 million years of star formation in a gas cloud, a typical star spends 2 million years of its life as an IR bright protostar. At any particular moment, How many bright IR sources would ...
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What if hypothetically Ton 618 could have been a star

Assuming Ton 618, the largest ultra massive black hole wasn’t the result of feasting on near by matter but was hypothetically once a single star body. How large in terms of size would TON 618 have ...
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I need help identifying what stars these are

I took these photos in the early morning. I’m in North America for a general location. I’m just curious on what they are as I can’t tell.I edited one so only the stars show, if that’s any help
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If Betelgeuse dimmed because of dust, what became of the dust?

This question started as a clarification request of a question from Glorfindel, answered at least in part by James K, and I realized it would probably be best as a stand-alone question. The most ...
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1answer
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Why does apparent magnitudes get increased fourfold when distances get halved, instead of simply getting doubled?

This website explains: The apparent brightness of a star is proportional to 1 divided by its distance squared. That is, if you took a star and moved it twice as far away, it would appear 1/4 as ...
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Brightness and flux density

The alpha star in a constellation has the highest brightness, but does that mean it has the highest flux density among the other stars in the constellation?
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What was the erratically jumping star like object [duplicate]

Oct 31st'21 around 11.15 pm. we saw a bright star like object, jumping erratically in all directions, constantly twinkling,occasionally looking coloured. All other stars were still. We were Looking ...
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1answer
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Star like moving object in the sky [duplicate]

Today morning, around 4 am, I saw a star like object moving from right to left with a speed faster than airplane and then it started moving from left to right and then vanished in the sky. After few ...
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Star map decode to location [closed]

I have a printed star map. I need to break it down to get alt and azimuth. I need to figure out the exact location. I just have no idea how to do it.
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Rising time of a planet or a star and its correlation with the angle subtended at the Earth

While preparing for Astronomy Olympiad I came across many problems in which we had to calculate at what time a planet or a star would rise at the Earth, and to solve this many solutions found the ...
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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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When will Alpha Centauri A and B overtake Proxima Centauri as the closest stars to us?

There are 3 stars in the Alpha Centauri system: 2 large stars orbting around each other (A & B) and a distant Proxima Centauri (C) orbiting around both. Right now it just happens that Proxima ...
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Is there any planet bigger than a star?

Or a star smaller than a planet? Which star and planet would be an example of this?
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How do I say the luminosity class aloud?

I have need to say the spectral type of a star for a poster presentation I'm making, which includes the luminosity class. However, I've been unable to determine the standard way of doing so, and ...
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How rapidly does a main-sequence star become a giant star? [duplicate]

I do not mean when in a star's lifetime it starts to develop into a subgiant, then a red giant, then briefly shrinks again, then becomes a giant or supergiant again, or whatever.... I mean how many ...
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How else can a star form, other than gravitational collapse?

I read this paragraph on the Sun's page on Wikipedia: [The Sun] formed approximately 4.6 billion years ago from the gravitational collapse of matter within a region of a large molecular cloud. Most ...
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Calculating the position of stars at a given point in time

Is there any particular methods that help us calculate the position of a star at a certain point in time? This question is what I am trying to achieve, but for me, I do not want to use the data ...
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What are the exact properties and evolution of a star with 1.23 Solar masses?

I'm working on a project where the star at the centre of the planetary system is 1.23 Solar masses. What would it's properties and evolutionary track be (i.e. main sequence lifespan, length of the red ...
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Is there a way to convert a list of stellar fluxes to a star type?

If I look up a star on Simbad, (for instance this one), a list of fluxes in different bands might be given. Star classes (O, B, A, F, G, K or M) depend on the color of the star. The color of a star ...
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Why can't 'dead' galaxies start forming stars again if they merge with another, 'active' galaxy?

I heard Matthew O'Dowd mention on PBS Space-Time that dead galaxies cannot start re-forming stars even if they collect gas and/or dust from elsewhere, or even merge with another galaxy.... Why? And ...
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1answer
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Effects of a supernova shockwave or gravitational wave to a nearby planet's orbit?

I've been reading about recent reports regarding COCONUTS-2B, a planet with the longest orbital period known - 1.1 million years. As a previous question asked, What precisely leads to planets like ...
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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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What color would stars have with an apparent magnitude of ~-30? [duplicate]

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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Can you tell me which star this is?

Back-story: My 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 a star, ...
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1answer
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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 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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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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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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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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1answer
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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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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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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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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 ...
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1answer
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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
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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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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
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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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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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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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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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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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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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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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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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