Questions tagged [star]

Questions regarding large spheres of plasma undergoing fusion.

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8
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3answers
234k views

Star like light moving in the sky, what could it be? [closed]

I was camping this weekend away from the city, so my friends and I decided to spend one of the nights watching the sky, since it's impossible to see anything around where we live. After a little while,...
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2answers
4k views

What exactly is the “paradox” in Olber's Paradox?

To the extent of my understanding, Olber’s paradox states that if the universe was static and homogeneous, we should see a star at every point in the night sky and therefore the night sky should be ...
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3answers
1k views

Is there enough hydrogen left after a star dies so another star will have enough to light up?

A star consumes quite a lot of hydrogen in its life, and is pretty much "vacuuming" everything in its vicinity. After it dies (eventually by supernova which will spread all its composition over light ...
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6answers
7k views

Where can I find a catalog of all stars in the Milky Way?

Is there a catalog of all known stars or brightest stars in our galaxy? Preferably with some sort of galactic coordinates instead of just night sky coordinates (right ascension, etc.) I'm trying to ...
26
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3answers
11k views

Is there a theoretical maximum size limit for a star?

Some stars are simply huge. Eventually, though, wouldn't there be simply too much pressure or mass for the star to sustain itself? Wouldn't it eventually collapse into a black hole? Is there a ...
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5answers
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Does the Sun turn around a big star?

The Moon orbits the Earth. The Earth orbits the Sun. Does the Sun orbit another bigger star? If so, does this star orbit, in turn, a very big star? ... etc ... What are all the intermediate ...
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6answers
23k views

Is the light we see from stars extremely old?

Our nearest star Proxima Centauri is 4.243 light years away from Earth. Does that mean we are seeing light that is 4.243 years old everyday?
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2answers
2k views

How often do stars pass close (~1ly) to the Sun?

Interstellar exchange of massive objects is difficult across several light years. But as the stars orbit the galaxy the distances between them change. I don't find data for neighbor star distances ...
8
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1answer
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What are the chances of a star colliding with another during a galactic collision?

My specific example for the question is the future collision of the galaxies Milky Way (our own galaxy) and Andromeda in a couple billion years. The star in question is obviously the sun in this case. ...
19
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2answers
956 views

Will new stars stop forming at some point of time?

New stars keep forming in the universe thanks to all the nebulae. Now, we need Hydrogen to form stars and there would a time when all the hydrogen will get exhausted, and no more star formation will ...
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2answers
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Why does iron consume more energy in the fusion process than it produces?

I understand that once a star starts fusing iron, it's doomed to collapse because iron fusion requires more energy than it releases in the process, allowing the opposing gravity of the star to cause ...
6
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1answer
198 views

Requesting book references for a non-expert person with math background or just a non-expert person

I've just finished my masters degree (to be exact previous week ^_^). And I'm completing my collection of applications of my studies. During previous year I started reading about Robotics and Coding ...
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4answers
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Why are orbits elliptical instead of circular?

Why do planets rotate around a star in a specific elliptical orbit with the star at one of it's foci? Why isn't the orbit a circle?
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3answers
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Are we made of the stuff of one star or more stars?

[T]his coincidence enabled stars in the late stages of their lives to turn helium into carbon, oxygen and most of the other atoms that you and I are made of. [...] [W]e're made of star stuff. Max ...
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3answers
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What is this web on the surface of the Sun?

I was going through my Social Media Feed and found the attached post too frequent. The caption reads this is the best image of our Sun. Just as an example, the Universe Today's This is the Highest ...
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2answers
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Does any iron fuse in stars before they go supernova?

I understand that iron and all heavier elements consume more energy to produce than they make, and that is what eventually leads to a supernova. I also understand that a lot of the heavier elements ...
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2answers
608 views

What would happen if a Sun-like star were to consume a Jupiter-like planet?

A substantial number of discovered exoplanet systems are likely contain more than one gas giant with distances far closer to the star than in our solar system. It is known that in solar system ...
8
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1answer
348 views

Is it possible to determine an observer's position on Earth from a photo of the night sky and the time of the shot?

To my knowledge, this question can be related to celestial navigation on one hand and to attitude (or orientation) determination from stars direction on the other hand. However the combination of this ...
2
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1answer
99 views

What equipment and techniques were used to study Betelgeuse's diameter in 1920?

Comments below What is the maximum distance measurable with parallax? discuss challenges associated with parallax measurements of Betelgeuse and link to Wikipedia’s Betelgeuse; Distance measurements ...
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2answers
12k views

How can 'HD 140283' be older than the universe?

Scientists have known about the star HD 140283, informally nicknamed the Methuselah star, for more than 100 years, since it cruises across the sky at a relatively rapid clip. The star moves at about ...
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3answers
2k views

Calculate Distance To Stars

I was just watching a lecture from Carl Sagan. He talked about figuring out the distance to the stars; it got me interested in learning more about the subject. As far as I know, the Inverse square ...
26
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1answer
984 views

Why are there no green stars?

There are red stars, and orange stars, and yellow stars, and blue stars, and they are all understandable save the fact that there is a 'gap': There are no green stars. Is this because of hydrogen's ...
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2answers
440 views

What was the absolute limit to the possible sizes of the first stars formed from “primordial material with no metals”?

This answer to Why don't or (can't) stars be more than 325 or so times the mass of the sun? What limits their size? includes the following: ...The upper limit you refer to is for compositions similar ...
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3answers
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Statistically, what would the average distance of the closest black hole be?

The closest confirmed black hole is several thousand light years away from earth. Our galaxy has about 100 billion stars. I didn't find any reliable information on the black hole count of ratio versus ...
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3answers
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What are the odds that the Sun hits another star?

The Sun moves around the Milky Way disk in the same direction as most of the other stars in our galaxy (prograde). But there are a number of older stars in the galactic halo that move in retrograde ...
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4answers
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Metallicity of Celestial Objects: Why “Metal = Non-metal”?

Metallicity of objects refers to the amount of chemical elements present in it other than Hydrogen and Helium. Note: The other elements may or may not be actual ...
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2answers
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Mass of black holes compared to parent star

What is the range of percentage mass of parent star left in a stellar black hole directly after its formation? What factors determine this number for a specific case?
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5answers
566 views

Without using absolute magnitudes or isochrones, how might we tell a star's age and evolutionary status?

Usual methods of estimating stellar ages involve isochrone approximations. It can also help to estimate a star's radius by correlating its absolute magnitude with effective temperature and apparent ...
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2answers
933 views

Why are there no stars on New Horizons images of Pluto

I followed the New Horizons Mission a little, and saw among others this image of Pluto: I wonder, why you can't see any stars on it. As far as my very basic knowledge in astronomy goes, I think you ...
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2answers
7k views

Where do the heavier elements come from?

Partly inspired by this question, the end result of stellar fusion is Iron-56 (eventually, after some decay). Then it explodes. How/where then to the heavier elements come from. The answer here ...
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3answers
174 views

What is the spectral reflectance of starlight in a close binary?

Ignore the Blender Monkey! (from here) In a close-orbiting binary pair, a small but significant fraction of the light from each star falls upon the other, and the result has to be carefully modeled ...
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2answers
3k views

Why do stars appear to twinkle?

Sometimes at night you will look up to the stars and they will appear to twinkle, getting brighter and darker in bursts. Why does this happen? Is this because of our atmosphere? Would they twinkle ...
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1answer
204 views

Is there a retrograde star that passes closer to the galactic center than our Sun?

Our Sun is moving in a prograde orbit around the galactic center with a distance of about 8 kpc. This paper says there are many retrograde stars in the galactic halo 10-20 kpc from the galactic ...
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3answers
914 views

Why do stars twinkle but planets don't [duplicate]

Many people say that stars twinkle because of Earth's atmosphere. However, the atmosphere is still there when we look at planets and don't see they twinkling. Is there a clear scientific consensual ...
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2answers
194 views

Best way to simulate star sizes to scale in celestial sphere

Using the Hipparcos catalogue, I am trying to create a celestial sphere. As all the stars are a fixed distance from the centre of this sphere, the only way to differentiate the distances and magnitude ...
27
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2answers
23k views

How many stars and galaxies can be seen by the naked eye?

How many of the luminous dots that we see naked are galaxies and not stars from our galaxy? I imagine that the majority of the luminous points that we see naked eye during the night, are actually ...
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4answers
6k views

How do scientists determine the age of stars?

I was Googling about the oldest galaxies in the Universe. Everywhere is written that their age is known by the light. Referring to this line "Since light travels at a set speed, if you look at a star ...
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2answers
2k views

What causes a star to become a pulsar?

What processes does a star undergo to become a pulsar? Does it take a very specific star with a certain set of qualities such as "Just the right mass, diameter, and composition," or is it a freak ...
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1answer
2k views

Why don't (or can't) stars be more than 325 or so times the mass of the sun? What limits their size?

Is there a particular reason why stars cannot grow as massive as they want to? And why doesn't this limit apply to supermassive black holes?
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2answers
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Is S2 still the fastest known star in the galaxy?

Wikipedia's entry for the star S2 says that it has the fastest known ballistic orbit, reaching speeds exceeding 5,000 km/s (11,000,000 mph, or ​1⁄60 the speed of light) and acceleration of about 1.5 ...
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1answer
2k views

How can neutron stars have gaseous atmospheres?

Neutron stars can have small atmospheres. However, they also have extremely strong gravitationally pulls. Shouldn't the all the gas molecules be drawn to the star's surface, and become solids under ...
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3answers
4k views

Can there be an infinity of stars in the Universe? [duplicate]

I have a mind puzzle. Can there be an infinity of stars in the Universe ? I have 2 opposed reasonings, yet I don’t find any flaw in them. Can you help me here ? Answer A : No, the number of stars ...
4
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1answer
163 views

Evolution of galaxies with time

I am doing an Introductory course in astrophysics UG level. I have studied that mass of the gases ($M_{gas}$) decreases with time as new stars are formed but mass of stars ($M_{star}$) doesn't ...
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2answers
677 views

How many stars can stay close to each other without collapsing?

Is it possible for two stars to exist close to each other? "Close" is relative; let's assume that two stars are close to each other if they are at the center of the same solar system. It's ...
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2answers
3k views

How much mass will the Sun have when it becomes a white dwarf?

In 4 billion years, when our Sun sheds all of its outer gas layers and turns into a white dwarf, how much mass will the white dwarf have compared to what the sun has today? Will the planets still ...
8
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4answers
102k views

What is this rapidly twinkling red, blue, and white star I saw?

Last night, I was on my balcony at 1AM (PST) and I looked up and saw two stars near the horizon (I'd guess ~30 degrees above the horizon), and they were "twinkling" about twice as fast as other stars ...
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2answers
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Do/Can Ringed Stars Exist?

The other night, while playing Elite: Dangerous, I came across a rather strange celestial body - one I never imagined possible. It was a Brown Dwarf star with a very large ring. Is something like ...
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2answers
1k views

Why is the core of a gas giant supported by electron degeneracy pressure instead of nuclear fusion?

After a Sun-sized protostar forms, its core will become denser over time due to radiation. The core eventually gets dense and hot enough for hydrogen fusion to take place. In the late phases of the ...
5
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1answer
399 views

3D Positions of Nearby Stars

I have come across a number of star catalogs that list stars by right ascension and declination, along with other data such as magnitude. Is there a star catalog that lists the 3-D position of stars (...
4
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1answer
2k views

What is the largest hydrogen-burning star?

I am wondering what is the largest known core hydrogen-burning star? A look at the list of largest known stars on Wikipedia seems to indicate VV Cephei B (at the bottom of the list), but I would like ...