Questions tagged [star]

Questions regarding large spheres of plasma undergoing fusion.

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8
votes
4answers
103k 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 ...
7
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2answers
1k views

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 ...
5
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1answer
402 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 (...
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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 ...
4
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1answer
384 views

Brown dwarfs and planets

As far as I know, a brown dwarf is a 'star' whose core never underwent a fusion reaction, so it never became a star. So I was wondering if, apart from orbiting a star, is there any difference ...
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 ...
2
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2answers
1k views

What is the minimum size of a ball of gas to become a star?

I know there are two criteria to meet in order for nuclear fusion to occurs. High temperature (many times temperature at Sun's core) High pressure (protons are very close to each other) [Goal] ...
2
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1answer
179 views

What is the dielectric constant of a star?

What is the dielectric constant of a star, especially its corona? Is it of order 1 or is it quite large? How much do "impurities" (elements other than H and He) affect the dielectric ...
2
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1answer
159 views

Distance of extra-galactic Classical Cepheids

There have been many questions and answers about finding the distance of a star from the earth. But as I did some research on the net, I found that we have specific approaches for finding the ...
9
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3answers
5k views

Why are stars so far apart?

So, this is mere musing, but it seems that stars are quite extremely far apart. I tried to determine the mean distance between nearest neighbors for stars (in just our galaxy) but I'm not sure what it ...
6
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1answer
245 views

Proxima as Supernova

Follow this question. If a star at the same distance from us as, say, Proxima Centauri had exploded as a Supernova 4 years ago (I know, it can't explode as supernova, let's say it can)... How bright ...
5
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2answers
1k views

Are sulfur and phosphorus also created in the nucleosynthesis of big stars?

There are as far as I know two fusion reactions by which stars convert hydrogen to helium: The CNO cycle (for carbon–nitrogen–oxygen) and the proton–proton chain reaction. The elements created in ...
5
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2answers
623 views

Why are stars more metallic closer as you move closer to the galactic bulge?

As I see it, most of the stars in the galactic bulge are Population I stars. However, as one moves farther from the galactic bulge, star metallicity decreases. In fact, halo stars are almost entirely ...
5
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1answer
180 views

South-eastern sky above the tree line just now, NE Cape Cod, I saw a very bright, twinkling “star”

I live in New England, Cape Cod to be exact. I saw a very bright, twinkling object. I watched it for several minutes and it never moved. It was in the east just above the tree line, what might it be?...
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3answers
3k views

What causes horizontal and vertical lines coming out of pictures of stars?

What causes the horizontal and vertical lines coming out of pictures of stars, instead of them simply appearing as circles? For example, this picture from Wikipedia: .
4
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1answer
389 views

Estimating a star's radius, temperature, and luminosity based on its mass

(See updated figure and description below.) I've been trying to generate ballpark estimates for the radius, temperature and luminosity of stars in the main sequence based solely on their masses (...
4
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1answer
621 views

How do we measure the brightness of the stars?

How do scientists measure the brightness of so distant stars?
4
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2answers
723 views

Why don't we see purple stars

I know that we don't see green stars because in blackbody radiation star doesn't produce one spectrum. The stars that have peaks in the green spectrum produce other spectrum in nearly same amout. ...
4
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1answer
235 views

What is the distance from Alpha Centauri to Barnard's Star?

Alpha Centauri AB is the closest star system to Earth (4.366 ly), followed closely by Barnard's star (5.988 ly). The closest star system to Alpha Centauri is Luhman 16 (3.8 ly from α Cen). So I am ...
2
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1answer
1k views

How to calculate B-V colour index value percentage difference

I need to calculate a percentage difference of a B-V colour index between its estimated and actual value. So I tried doing this by difference between values/actual value x 100. However as B-V values ...
2
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2answers
161 views

Why doesn't smashing larger and larger bodies incrementally into a rocky planet create a star?

Let's start with a stationary Earth. If we smash a few Mercury-sized objects into the Earth, the Earth begins to accrete mass. Repeat this step with larger and larger objects, until we start impacting ...
2
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1answer
6k views

Moving lights in the sky looks like they were moving coordinated [duplicate]

I was out with a couple friends a night and we looked up to the sky just watching the stars. I noticed what looked like a star moving then told my friends and they saw it too. After we saw the one ...
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1answer
156 views

Calculating the orientation of the night sky

How would one calculate the rotation/tilt of the earth to simulate the Night Sky in a self-written tool or app. I am trying to built an app for my telescope to show me on my phone what I am looking at....
1
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1answer
226 views

Travelling, flashing Star? [closed]

I have recently gotten into observing the night skies and learning about the stars/ star systems that are visible to me using an app on my phone. For the last month or so Venus and Mars appear in the ...
0
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1answer
167 views

In the closest stars, can you see the stellar corona?

Stars appear larger than they are, could that be the stellar corona here around Sirius, making it appear n-times larger than the stellar body? NASA recently mapped the solar corona to extending 12 ...
0
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1answer
20k views

How to calculate the temperature of a star

I need a way to calculate the effective temperature (surface temperature) of a star for a stellar model. I need something in the form Te=.... I have: Radius in m mass in kg the composition of ...
9
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2answers
3k views

Multiple Star-system percentages

What are the percentages of systems that have x number of stars in them? What I have found thus far is something like: Single Star Sytems = 69% Double Star Systems = ~10% Triple Star Systems = <...
41
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5answers
8k views

Why does gas form a star instead of a black hole?

When a space gas gets pulled together a star is formed. On the other hand, when a massive star dies, it collapses to a black hole. You would think that the initial mass of the gas would be bigger ...
36
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2answers
4k views

Are there any stars that orbit perpendicular to the Milky Way's galactic plane?

Most stars orbit in the Milky Way's galactic disc. But is it possible for one to orbit perpendicular to it? Here on Earth since we're inside the galactic plane we can't get a good view of what the ...
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2answers
1k views

Which stellar properties can we describe as “first principles” in which we can derive the rest?

Mass, size, temperature, luminosity, chemical composition, the initial abundance of the molecular cloud, distance, brightness, age, and evolutionary cycle can all be used to characterize a star. A ...
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2answers
3k views

Can lightning occur in stars like the Sun?

In the Wikipedia article about lightining, the following explanation is given about the electrification process in clouds: The details of the charging process are still being studied by scientists, ...
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3answers
3k views

Can I sense a bright star pointing an eight foot antenna towards it?

If I connect an eight foot Yagi or other comparable sized antenna to my oscilloscope and point the antenna at a bright star will I see a voltage on my oscilloscope? I am not interested in turning the ...
16
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1answer
416 views

How do large solar flares compare to flares on other stars?

Solar are violent releases of solar magnetic energy. Other stars are also known to have magnetic fields, in some cases much stronger than the Sun. How do the largest stellar flares compare to the ...
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2answers
3k views

Can a star have a ring system?

I often hear about planetary ring systems, and even some moons might have them, but how about stars? Can a star also have rings?
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3answers
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What decides the direction in which the accretion disk spins?

Planets lie on the same plane because of the accretion disk formed during the Protostar stage, as I read in this question. I also read about the collision of particles in the gas cloud causing the ...
7
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6answers
103k views

Very bright star in the east at northern hemisphere. What is it?

From some time now (few weeks as far as I can remember), there is a very bright star in the eastern sky. I first thought it was Venus, but according to this link, Venus is in the western sky and ...
6
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1answer
190 views

Is it possible for two stars to be in a horseshoe orbit around a much larger star?

I was reading about how Saturn has two moons, Janus and Epimetheus, that swap orbits once every four years. Could something like this happen on a much larger scale, but with stars instead of a planet ...
19
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4answers
1k views

What is the upper and lower limit of temperatures found on stars?

What are the most extreme temperatures (both hot and cold) stars have been detected at? Is there an upper and lower limit for the detected temperature of stars?
16
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2answers
1k views

What is radiation pressure and how does it prevent a star from forming?

This is a follow up to: Is there a theoretical maximum size limit for a star? The answer there talks about the radiation pressure preventing a star from forming. What reaction is causing this ...
14
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2answers
8k views

What is this bright “glow” in the center of galaxies?

It was always my belief that at the center of many galaxies, there are supermassive black holes. If this is the case, then we should not see a "light" coming out from the center since light get's ...
13
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2answers
2k views

How are binary star systems created?

I don't know how common it is for a system to have two stars (or perhaps even more) but how do they arise? Is that due to the stellar accretion disc, or the composition of the stellar nebula? Or are ...
11
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1answer
676 views

What was the “brilliant new star in Aquila” on June 8, 1918, just after the solar eclipse?

This great answer about the US Naval Observatory's $3,500 expedition to Baker City Oregon to observe the June 8, 1918 total solar eclipse links to the January 1919 Popular Astronomy article about the ...
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2answers
255 views

Could a star closely orbit a black hole long enough for the star to have lost 0.5B+ years to time dilation?

I was wondering how stable a close star-black hole system could plausibly be, and thus how much time a star could plausibly miss out on (from an outside observer's perspective) due to being in an ...
8
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1answer
462 views

The colour of blue dwarf stars

The paper "M dwarfs: planet formation and long term evolution" describes blue dwarf stars, a hypothetical next-stage in the lifespan of red dwarf stars within a certain mass range, after which they ...
8
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1answer
343 views

Do all massive stars explode?

I've read a few articles written in $2008$ that some stars which have enough mass just collapse into black holes without a supernova, is this proven?
7
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1answer
867 views

Mechanism for Brown Dwarf Fusion

I've read (at here, among other places) that during the Degenerate Era, star formation will end and the last stars will go out. But it was noted that there is still the possibility of star birth, ...
7
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1answer
484 views

Stars in the sky

Are the stars we can see with the naked eye in the night sky only from our Milky Way galaxy or can we see stars from Andromeda? I am aware we can see other celestial objects like nebulas and the ...
7
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4answers
7k views

Can we compress any object to create black Holes?

In general, when a star runs out of nuclear fuel, gravity gets the upper hand and the material in the core is compressed even further and creates black holes. I am clear till here. Now the question ...
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2answers
2k views

Rate of Mass Loss from the Solar Wind

This is problem 1-4 from Principles of Stellar Evolution and Nucleosynthesis by Clayton: Assuming at the Earth a characteristic velocity of 400km/s and density of 10amu/cm$^{3}$ for the solar wind, ...
5
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2answers
279 views

Do constellations change?

Many stars are part of constellations. Due to dark matter the stars have velocities which are nearly the same unregardless their radius of orbit around the centre of the Milky Way. Also, it takes ...