Stars Definition and 878 Threads

Hello, I have a novice question. I know that the sky color is blue (at noon, when there is no clouds), because the air particles (mostly N2 and a little O2 ...and other) scatter short-wavelength light more than longer wavelengths. That is why we can't see the stars trought the atmosphere...

My latest thoughts about the life, universe and everything has brought me to this scenario: [in a stars core, but a perfect thought situation, for the sake of illustration] there is a proton, electron and proton on one line in this particular sequence. I think, that the electron, witch has...

in general how to calculate binding energy of neutron star? in simple details, what tricks may be included in such a problem..

Early Population III stars in the universe were very metal poor if not metal free and were apparently required to be much larger than todays stars, up to hundreds of solar masses, to form. What does the metallicity have to do with this?

The Milky Way is a Barred Spiral Galaxy 100,00 -120,000 Across. I was wondering if there is a website or list of what Stars of Constellations exist in what Spiral Arm. I there exists: Orion-Cygnus Arm Perseus Arm Scutum-Centaurus Arm Norma and Outer Arm Carina-Sagitarius Arm...

Hello everyone, there is a classification of PMS based on color-color diagram as class 0, class I and class II. can some one please explain more about this classification or provide me with some useful link. I am trying to plot color-color diagram of an Open cluster using Wise Band data.

Stars database download? Stars database download? I found "NStars", it sounds like they have what I'm after, but the site is not online as is currently undergoing major redesign. Is there any other place? I'm looking for coordinates data, size, spectrum, luminosity and such. Maybe some free...

Homework Statement Two stars move in circular orbits about one another with period T due to their mutual gravitational attraction. If the objects are suddenly stopped, show that they will then collide with one another after a time T /(4√2) Homework Equations T = ∫dt dA/dt = (1/2)r2d∅/dt Fg=...

Few years ago while traveling to Bosnia, my cousin and I looked at the sky. We were in a very small village where almost no lights disrupted the visibility of the stars. While looking we noticed that there were two stars which were a bit brighter, almost like the north star, except that the...

Homework Statement A planet orbits a star of mass M = (3*10^30)kg in an elliptical orbit. The planet is r_1 = (0.8*10^11)m from the star at its closest approach (periastron), and r_2 = (1.6*10^11)m at its furthest (apastron). (G = (6.67*10^-11) Nm^2kg^-2) (a) Calculate the semi-major...

Are there any known examples of colliding stars? has the phenomena ever been observed? tex

Hey folks, A couple of weeks ago I took a photo of the moon, not sure if you will be able to see this in the image, but if you zoom in a bit after downloading it, you can see what I think are stars all over the background... ...The reason I say think is that I can see them through the...

I am trying to do the problems in this set: http://farside.ph.utexas.edu/teaching/336k/lectures/node13.html They seem quite hard, but I think I've managed to get to #4. The statement of the problem is at Problem 4 in the above link. My attempted solution is the following: The...

Homework Statement Three stars, each with the mass of our sun (1.9891E31 kg), form an equilateral triangle with sides long. The triangle has to rotate, because otherwise the stars would crash together in the center. What is the period of rotation? Homework Equations F1=GM2/r2 ƩF=0...

We can know about distant stars temperature,its elements etc by observing its spectra... But that star has a velocity related to us... The spectra will be shifted... Then how do we know the correct spectra? Another ques... Suppose, something emits a X ray... Then will its characteristic will...

Homework Statement Estimate the hydrogen burning lifetimes of stars on the lower and upper ends of the main sequence. Lower end: M = 0.085 solar masses; log10(Teff/K) = 3.438; log10(L/Lsolar) = -3.279 Upper end: M = 90 solar masses; log10(Teff/K) = 4.722; log10(L/Lsolar) = 6.045...

Does the strong force have any major role in neutrons stars other than obviously holding individual nuclei together? Would low energy neutrons tend to "clump" together in the core?

I have a problem where two stars are at a certain time r0 apart from each other. They both has the mass of m, and at that time one of them is at rest and the other has the speed of v0 in the opposite direction of the gravity force that the other star exerts upon him. I need to find the maximal...

This thing just popped into my head last night while describing to a friend, possible end of our universe. Which one is higher? the number of stars in our universe or the number of MOSFETs we mass-fabricated in our civilization ? My guess is though number of stars. What do you think...

If Neutron stars are what they are... I mean made of literally only neutrons ...how do they generate such immense magnetic field (of the order 10^8 or something) .. I think the name is somewhat misleading and it ought to have a near half ratio of protons ...But still being so compact how...

In the Letters section of the August issue of Physics Today, a reader claims that when he asks 'newly minted physics PhDs' to explain why stars have different colors, that 75% of them answer incorrectly. How would you answer the question?

The title speaks for itself. I'm just curious and I couldn't find anything on it. Particularly, what if they are a close binary (period less than 50 days)?

Does entropy decrease when stars are created from a dust? Does etropy decrease when water freezes?

2 closely orbiting massive objects are predicted to deserve the fabric of spacetime so much that they will release a ripple of gravitational waves. When geavitational waves are released, they slowly loose velocity energy and spiral into one another. 2 pulsars were discovered orbiting each other...

The situation is this: In a neutron star the Coriolis force induces Rossby waves, just like on Earth. These are waves with very long wavelength -- like halfway around the Earth -- and very large volume but very little amplitude, like fifty meters. On Earth they have a big effect on climate...

Would people on the north pole see a totally different set of stars than people standing on the south pole..? Would the Big Dipper be visible from the South Pole..? Would people living on the equator see even a different set of stars..?

Positions of stars as seen from Mars--different than from Earth? I'm reading a novel that says , "On Mars the stars seemed a bit out of place, not in their correct position[s]." Could that be true? I suspect that if you disregard anything within our solar system, the stars would be so far...

Ok so I was at the Hayden Planetarium and a plaque was describing a star billions of light years away that we can see because it is so much brighter. I was puzzled thinking about this. If the speed of light is constant there is no reason the intensity of it's light should affect how far away we...

the law of gravity states that objects accelerate at a constant speed, but I'm wondering that if you take into consideration that time travels slower the closer you are to the surface of the earth. doesn't that imply that although it seems to us that it is constant acceleration that, it is...

How come in pictures taken from space, we cannot see stars or the sun? Is it the atmosphere that allows us to see them? Click on image to make bigger

Hi all. I have been looking for a formula that gives me the angular separation of two stars. So far I just found this one :http://www.skythisweek.info/angsep.pdf but it uses the RA and DEC of the 2 stars, and I need to use the hour angle and DEC. Is it the same thing? Do I just replace HA by...

Pretty straight forward. The same generally holds true with moons belonging to the same planet. If we don't have concrete reason why this occurs, are their any strong theories?

Hi, In the case of the gravitational collapse of a star where neither electron or neutron degeneracy pressure is sufficient to prevent further collapse, is there a possibility that the star will become a quark star rather than a black hole? From what I understand, quarks are perpetually...

what if...Neutron stars I know likely its been answered but if two neutron stars collid, it wouldn't seem that there combined massess would forum a black hole...if I recall that any matter striking the surface of a neutron star impacts with such violence that there is a massive explosion. So I...

1. How fast are stars orbit speed in elliptical galaxies (from and to) 2. How big differences are there typical between Perigalacticon and Apogalacticon in a. elliptical galaxies and b. spiral galaxies?

If proton decay does not occur, will neutron stars just last for eternity unless something collides with them?

To a close time, i settled my interpretation of expansion of the SUn... When the H=fuel in the core is over, the helium atoms is now having more density. Hence, the pressure increases on the outer H-fuel which ultimately will fuse faster and faster making a great deal of energy casuing...

[FONT="Arial Black"]Question 1: http://i.minus.com/iOmQvqhasiXmx.png My reasoning is curves 3 and 4. These curves have the biggest relative brightness of orange. [FONT="Arial Black"]Question 2: Stars are called blackbody radiators because they a) never appear perfectly black...

After reading "The Five Ages of the Universe" by Greg Laughlin and Fred Adams, I wondered, if all matter composed of ordinary atoms (protons decay) decay, and black holes decay due to Hawking Radiation, do neutron stars decay in any way? They are composed entirely of neutrons that are kept...

If there were a star which was almost, but not quite massive enough to become a black hole it seems as though gravitational time dilation should make it appear very dim. If time dilation resulted in 1/1000 of the time passing within the star as passes for us, we should see a star emitting 1/1000...

Why are all stars not the same size? Given that the nuclear fusion within a star begins when the pressure/temperature in the core of a collapsing cloud reaches certain parameters, why are all stars not the same size?

what creates the "star points" in telescope pictures of stars? it's a basic question. e.g. see this hi-rez Hubble Deep Space pic: http://upload.wikimedia.org/wikipedia/commons/9/9b/Hs-2004-07-a-full_jpgNR.jpg i count about three bright objects with pointy cross-like projections from...

This topic is quite confusing.. In the first place, how can we classify for example all O class stars would be having the same spectrum with the same absorbtion lines... Secondly, i just need a clarification on what do these absorbtion line reprsent and upon that how can we decide whether a star...

Well, this topic is driving me crazy so any answers or replies should preferably be detailed and in an easy way.. My question is i want a sum up of the evolution of a low mass star... I will give my answer and tell me where are the dropouts.. Let me begin,With a protostar accreting hydrogen in...

I've been deep into this topic for a couple of days and it is becoming just more and more confusing. I am yet a beginner so i would like explanations to be detailed and easy. Moving directly, my doubt is.. We treat stars as black bodies which emit radiation... From where did the stars originally...

In my book, it is written that in an evolution of a star, specifically the sun, IT will run low on hydrogen fuel but will have produced so much energy that it will expand slightly... Once H- fuel is used, the star will start fusing helium nuclei. This complex process can cause an explosion that...

Hi dudes, My questions are: What does planet's revolution depends? If for example is there a planet 4 time the mass of the Earth at about its same distance from a star 4 time the mass of sun, could it be it has the same revolution period ot the eath?

Homework Statement Homework Equations L = M^3.5 The Attempt at a Solution Am I right in saying that this is the correct proportionality for luminosity and mass in a star? If it is, i am confused. In an example I have it states that when mass is doubled the luminosity...

I need so advise on SPH open source code to use to look at mergers and rotating objects... if anyone has some links or tutorials? Thank you!

Hi, has it really been proven that the process of fusion is REALLY enough to keep stars from imploding under their own gravitational force? I suspect that there might possibly be another factor involved, in keeping the stars inflated until they start to cool and hit that point of...