Questions tagged [star]

Questions regarding large spheres of plasma undergoing fusion.

Filter by
Sorted by
Tagged with
4
votes
1answer
192 views

The life course for a massive star from birth to death using the HR Diagram

could you explain to me the life course for a massive star (30-40 solar masses) from birth to death using the HR Diagram (by showing key events in its life on the HR Diagram)? thanks
9
votes
1answer
799 views

If we were to see the Sun with our naked eyes from the Orion belt, would all planets be encompassed inside the star? Is this calculable?

When we see a star it looks much bigger in diameter to us than it really is, this picture (extracted from here) explains what I mean: Notice that the point we see in the skynight, represented by the ...
16
votes
3answers
2k views

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?
6
votes
1answer
341 views

Can I see the star of Bethlehem at Christmas? [closed]

In the Christian tradition the first Christians are believed to be three wise men who followed the star of Bethlehem to the stable where Jesus was supposed to be born. Is it with some accuracy known ...
3
votes
2answers
7k views

How to calculate Longitude from Right Ascension?

Considering that a star of certain declination is crossing the local meridian at the observer's zenith at an unknown location on the earth. Here, the declination of the star is equal to the observer's ...
9
votes
2answers
459 views

Find distance from star to star?

How do you find the distance from a star/planet/black hole to another? I know people can calculate the distance from Earth to a star, but what about from one to another?
12
votes
1answer
490 views

How do you figure out the magnitude of stars?

How do you figure out the star magnitude of a star? Do they just give it a guess or what? If not, how do they figure it out accurately?
10
votes
4answers
488 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 ...
19
votes
1answer
13k 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 ...
14
votes
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 ...
5
votes
1answer
222 views

How can we be sure that we have identified very distant stars correctly?

From reading this question on calculating distance to stars and from a bit of background reading on the standard candle theory I still don't see how we can confirm that a star we see at one distance ...
9
votes
1answer
184 views

Appearance (frequency) ranking of stars?

Is there some ranking / statistics that shows how common given type of celestial objects is? A table that would allow the answers to questions like: What type of star is most common per volume of our ...
15
votes
3answers
1k 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 ...
11
votes
1answer
6k views

What happens to a star after it has become a red giant?

When our sun reaches the end of its lifetime , it will turn into a red giant. How long will it be a red giant, and what happens after a star has been a red giant? Does it turn into a planet after a ...
5
votes
1answer
99 views

Why is there billowing dust in nebulae?

Why do some nebulae look like the billowing clouds? Wouldn't that require something like a viscosity in empty space?
15
votes
2answers
791 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 ...
7
votes
6answers
64k 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 ...
10
votes
1answer
193 views

Have we observed any rogue/wandering stars?

Do we know (have we observed and cataloged) any rogue star, being not part of galaxy, but drifting somewhere in inter-galactic space? I know that determining if a star is a part of galaxy or not is a ...
24
votes
6answers
19k 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?
15
votes
1answer
385 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 ...
10
votes
1answer
358 views

Why does squinting make hard-to-see objects clearer?

So I, like most other astronomy enthusiasts, have, at some point, not been able to see something clearly, such as a star, and have had to squint to be able to see it better. When this happens, the ...
9
votes
1answer
3k views

What is the origin of the OBAFGKM classification system?

Once a body has been identified as a star it is classified into a subsection of either O,B,A,F,G,K or M (I think there are also 3 more letters recently added) What is the origin of this ...
23
votes
3answers
9k 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 ...
11
votes
1answer
1k views

What is a hypernova and have we observed any?

Inspired by the question "What does it mean for a star to go nova or supernova? Can I safely observe these?", I am curious about what hypernovas are? Have we observed any occurring, or the at least ...
19
votes
1answer
6k views

What does it mean for a star to go nova or supernova? Can I safely observe these?

What does it mean for a star when people say it goes 'nova' or super nova, what are the differences? More importantly, can I safely observe these with an amateur telescope? I imagine they would be ...
6
votes
2answers
2k views

What gases are needed to make a star?

What gases do you need to start the creation of a star, and why do you need these gases? What are their functions?
12
votes
2answers
718 views

How do stellar temperatures vary?

The temperature of the surface of the Sun (photosphere) is between 4500° - 6000° Kelvin. Inside the core, it's around 15.7 million degrees Kelvin. In other types of stars (neutron stars, white ...
19
votes
2answers
2k 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 ...
7
votes
1answer
12k views

How long does it take to produce a star? Why does it take that long?

I wonder, why stars take a really long time to become stars? Is it because it needs to gain mass? Or heat up? Something like that? And could it be sped up at all?
15
votes
4answers
308 views

Are there ways other than the collapse of a star which have been observed to form black holes?

Every time I hear about a black hole, it's always in conjunction with the collapse of a star. Have any other processes been observed to create a black hole?
15
votes
3answers
1k views

How hot must a star get before it is considered to be a star?

How hot must a star get before it actually becomes a star? Why does it need to get so hot? Please find an official site to quote from, if you can.
19
votes
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?
17
votes
2answers
590 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 ...
14
votes
1answer
126 views

How would the pocket cellular clock work?

In a museum in Lviv, I saw a pocket cellular clock. I don't have a photo, but it was a small disc that had 2 or 3 filaments in it which were pointed at the stars (one of them was Andromeda, I think). ...
28
votes
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 ...