Stars Definition and 878 Threads

Homework Statement The sun mass MS = 2.0 E30 kg revolves around the center of the milky way which has a total extension of 2.2 E20 m. The sun takes 2.5 E8 years to complete one revolution. Estimate the number of star in our galaxy based on this data. Suppose that the distribution is...

From the first few hits I found on the internet, here's what I gather: They are the same as they appear from Earth, except they do not twinkle (no atmosphere). They are like small points of light. The contrast between stars and black background sky is also greater than on Earth. They can...

I would not have recognized many of them. http://www.nbcsandiego.com/entertainment/music/NATLRock-Stars-Then-and-Now-97329329.html

I've been looking up some information regarding the Owl Nebula, in order to make some calculations of my own. I've only been able to find the V magnitude or the general magnitude of the nebula as a whole. Is there any way to find the B magnitude or the B-V measurement of the star, given what...

In our milky way, do all stars have same revolving speed? This Question is in my mind because we always sees that all star are always in same position with respect to other, i mean if take an example of orion constellation then it seems that betalgeous is always in a same position with respect...

Homework Statement An open cluster is observed to contain 1000 stars. Clusters contain many more low mass stars compared to high mass stars, reflecting the star formation process. This depen- dence of the number of stars formed in a given mass range is expressed in the so-called initial mass...

I have just attended a talk, where the speaker (a professor in Hong Kong University) claims that neutron stars don't collapse due to "nuclear forces". He further explains that those nuclear forces are residual strong forces (i.e. exchange of pions). However, the mainstream saying (according to...

I have been looking for the density profile ( density vs radial distance ) of a Wolf-Rayet star. Kindly suggest me some resources.

I intend to learn numerical simulations of collapsing stars. Could you suggest me some useful resources? i am familiar with matlab.

It is said that massive stars spin faster than less massive ones and I am always wondering why.Could someone please tell me the reason? Thanks a lot.

I've just watched the Extreme Stars program in How the Universe Works and it states that when a massive star starts to make iron, the fusion is quenched and the core collapses. From the program, it sounds like the process is fast and will happen when a few grams of iron is formed. I find this...

I am writing a novel set on a ringed planet. The plot calls for the rings to be about a thousand years young, more a torus of gas and dust and speeding moonlets. Would a person standing on the night side of this planet be able to see stars? Or would the rings scatter enough light from the sun...

On page 5 of the link http://www.maths.qmul.ac.uk/~rpn/ASTM735/Week9-powerpoint.pdf , there are 2 graphs. I'm referring to the 2nd graph (the one with the flared disk fit). What is the green plot supposed to represent?

Just a thought - does the universe have the equal of a refractive index so to speak, to measure where stars are, due to gravity curving spacetime. thanks

Homework Statement Vague class discussion. Stars are points and a telescope does not magnify them. How then can more stars be seen with a telescope? Homework Equations I know magnification for a telescope is fo/fe but that is not much help The Attempt at a Solution Is it because...

The Schwarzschild metric allows to calculate the precession of an elliptic orbit of a particle around a large central mass, provided the mass of the particle is much smaller than the central mass M. This condition is not met in the case of binary stars m1 and m2 revolving around each other...

OK, maybe this is a silly question but, if you look at the sky in a program like Stellarium say, and then look north, why can you see stars at points on the celestial sphere corresponding to points on the other side of Earth from where you are? I hope this question is clear, what I mean is the...

I have a scientific background in materials science. However this is one type of material that we don't exactly learn about! Let's say you have a neutron star approaching a comparable mass black hole. As the neutron star approaches the event horizon for such a comparable black hole, tidal...

Homework Statement A binary system consists of two stars of equal mass m orbiting each other in a circular orbit under the influence of gravitational forces. The period of the orbit is τ . At t = 0, the motion is stopped and the stars are allowed to fall towards each other. After what time t...

Would you "Hear" a Stars Nuclear reactions if you were close to it? Hey all, This is more of a thought problem, but last night I was wondering about what it would be like to see a star up close (relatively speaking). Since stars are essentially a massive nuclear chain reaction you would think...

At t = 0 a star of mass 5.0×1030 kg has velocity < 6.0×10^4, 7.0×10^4, -7.0×10^4 > m/s and is located at < 1.00×10^12, -4.00×10^12, 4.00×10^12 > m relative to the center of a cluster of stars. There is only one nearby star that exerts a significant force on the first star. The mass of the second...

I am currently reading E=Mc^2 and have a quick question regarding some of the nuclear fusion they describe that takes place in stars: When proton fusion occurs, one of the protons decays into a neutron + positron + neutrino – due to the weak interaction. And the proton and neutron , acted...

Pretty self explainable. Why do they not create a sonic boom when they enter Earths atmosphere

I recently read an article about elliptical galaxies. The article mentioned that the stars have basically radial motions. What does that mean ? Do these stars oscillate between the center and some mid-radius? Stars in spiral galaxies have on average orbital motions in one direction around...

Hello. Given a binary system with two identical components (in particular de B-V index of both is the same), how would you calculate the B-V index of the system? and, how would it change during eclipses? I have my own answer, but want to contrast it against yours.

I read this article in Nature (http://www.nature.com/nature/journal/vaop/ncurrent/full/nature10768.html) as it describes two circumbinary planets. If it is assumed that most stars have a planet orbiting it and most Binary Star systems are elliptical, then wouldn't the majority of Binary Stars...

I have been unable to find any data or formula's on how long red giant type stars last other than a few million years!One would suppose that it is a function of its original mass and chemical composition. Any ideas...

Why giant stars are so low in density?

Okay, so so you got two forces acting on a star. Gravity trying to compress it, and the internal pressure, caused by fusion, pushing it out. For the star's life they are at equilibrium, but the star dies when it runs out of nuclear fuel. Then why do some stars explode? Shouldn't they all...

Why is it considered the 'end of the universe' when the stars go dark?? As I understand it, there were two main theories accepted regarding the expansion of the universe after the big bang. One of them assumed that the expansion would start to contract, the other that it would continue to...

The sun appears yellow because is made of white light and blue,green,indigo gets scattered.My question is why the planets and the moon appear white with their case the same thing should happen and even they should appear yellow.

The intensity of light observed from a given source decreases as the square of the distance between the observer and the source. Hence, if stars are truly receding from the earth, the intensity of light observed from any such star should be getting dimmer as time goes by. But the intensity of...

Hey everybody, I'm new here and what better way to start then jump right in! I have a few questions concerning hypervelocity stars for a sci fi book that I want to write. First of all, what is the agreed upon "average" speed of a hypervelocity star? I have done a bit of googling, but I have...

http://www.bbc.co.uk/programmes/b018nn7l I did enjoy Brian Cox's program on quantum mechanics last night, but one bit left me thinking "no, that's not right!". The gist of it was that all the electrons in the universe have to be in constant communication to ensure that no two of them are...

Simple enough question. I know there are two types of black holes; the type formed after a star collapses in a supernova and the supermassive variety like the one at the center of the milky way. If a star continued to grow by swallowing up other stars and solar systems is it possible that at a...

I need help to solve this problem: The initial mass function (IMF) of main-sequence stars, n(M) follows a shape called the Salpeter function,which is described by n(M)=kM^-2.35, where k is a normalising constant and M is the stellar mass in solar masses. The IMF is similar in some sense to a...

1. Can a human travel to distant stars? If the faster you go the slower the time passes for you, then you could technically travel to stars several thousands of years distant from you. It could take thousands of years for someone on Earth, but just a few days for you. 2. Why can't we travel...

Homework Statement A binary star system has two star of equal luminosity. The apparent magnitude of the two stars together is 11.2, and they are at a distance is 76pcs. How do I work out the apparent and absolute magnitudes of just one star? Homework Equations m=-2.5log(L)...

Homework Statement What is the minimum angular separation an eye could resolve when viewing two stars, considering only diffraction effects? Homework Equations Rayleigh criterion: θ=(1.22*λ)/D The Attempt at a Solution This problem doesn't give very much to go on so I think...

I was reading news article: http://www.sciencedaily.com/releases/2011/11/111115095911.htm Article explains in beginning that when star explodes as supernova, heavier elements are formed which later become part of new generations of stars. And in concluding paragraph, article says "reason why...

Hi, I have a conceptual and mathematical question about gases in stars. The information we have from stars is due to the motion of particles in one dimension: along our line of sight. We assume that this motion is isotropic and that regardless of where on the star we look, we'll get the...

Hi, I have a conceptual and mathematical question about gases in stars. The information we have from stars is due to the motion of particles in one dimension: along our line of sight. We assume that this motion is isotropic and that regardless of where on the star we look, we'll get the...

Can a variable star become a non variable one? Or viceversa, can a non variable, as it is (almost) the sun, become quickly (say few thousands of years) a variable one? Is there any record (e.g. in the geological records) which shows that the sun had once a very different luminosity? Has this...

Introduction Deep in the vastness of space, beyond our solar system, stars are born in primordial nebulae, gaseous molecular clouds on the spiral arms of galaxies extending across the heavens. Intense gravitational forces compress the cloud causing temperature and pressure to increase...

I would like to know how many stars are within 150 light years of Earth. There must be a website somewhere that has the number, or perhaps a graph correlating distance with number of stars. I've done some searching, but you folks are much smarter than I am. Thanks

Will some of the stars of the Milky Way crash into those of Andromeda if these galaxies merge? What are the odds? How large a share of the stars will this happen to? Thanks

why galaxies are having uneven distribution of stars, in the form of arms? actually stars should have been like a thin disk like distribution of stars.

If a globular cluster is a dense(relatively speaking) collection of stars, why don't the stars attract each other gravitationally? Why don't they all collide to form a mega-star?

The Goldwater scholarship application is approaching, and I think it's an excellent opportunity. However, I have a GPA less than the average of 3.95 (but above 3.8), have published no papers (but have been researching since late July), and all around am not a highly motivated individual. I'm...

what is the difference between a neutron star and a black hole?