Star Definition and 1000 Threads

[SOLVED] Density of a star Homework Statement For a star of mass M and radius R, the density increases from the centre to the surface as a function of radial distance r, according to \rho = \rho_{c}[1-(\frac{r}{R})^2] where \rho_{c} is the central density constant. a) Find M(r). b)...

The Chandrasekhar limit (~1.4 Msolar) is an upper limit to the mass a white dwarf star. So this means we can not have a white dwarf star in nature that weighs more than this. But is it true that we can have a neutron star that weighs less than 1.4 Msolar? If so, this makes no sense to me...

Homework Statement Consider a double-star system with two stars, A and B, in circular orbits of the same period T about their center of mass. The Earth is in the plane defined by these orbits at a distance R of many light-years. Let the speed of A in its orbit be u; then at any instant it has...

Hello, several nights ago I was outside looking at the sky. I noticed this strange looking star near the horizon, and I swear to you, it kept flashing from red to blue and back. I vaguely remember reading something about this, but I don't quite remember what it was.

Hi all, I'm wondering why we see those horizontal and vertical stripes of lights when looking at a light source (see e.g. http://apod.nasa.gov/apod/image/0601/pleiades_gendler_big.jpg" ). Why are these lines of light present in the first place and why are they only horizontal and vertical in...

Wow, From current experiments and theory; the idea of a cloaking device may be a reality. This leads me to the question; is there research in other areas of the so called "Star trek Physics" i.e. force fields etc?

I was flipping through the channels this evening and came across an old Star Trek (original series) episode. Since I hadn't seen one in while (It is shown at 10pm, and lately I've had to get up early Sun AM, and I am in bed by then), I decided to watch it. I had just recently purchased a...

When a star explodes, does the shock wave move faster than the local speed of light? If it does, what effects would this have? A little explaining is in order... While the actual speed of light does not change (c in a vacuum) the overall progression of light is greatly slowed down due to...

http://www.nasa.gov/centers/goddard/news/topstory/2007/intergalatic_shot.html Solid proof that aliens are about, this must have been a warp core breach.

Homework Statement Two equal-mass stars maintain a constant distance apart of 8.0 x10^10 m and rotate about a point midway between them at a rate of one revolution every 12.6 yr (a) why don't the two stars crash into one another due to the gravitational force between them (b) what must be...

Neutron stars are extremely dense objects with a mass comparable to the mass of the sun but a radius of only several thousand meters. Consider a neutron star of mass M = 1.99e+030 kg and a radius of R = 10.8 km. What is the gravitational acceleration near the surface of the star? I tried...

I'm having trouble solving this question... If the epsilon ring of Uranus is 75 km wide, how long will it occult a star? Any help would be greatly appreciated.

If star clusters were all about the same physics size, how could one estimate their relative distances?

Homework Statement An empty bucket (mass M, area A) is launched with velocity v0 from a space station into a cloud of dust (density ρ). As the bucket moves through the dust it will collect dust in it until the bucket comes to a stop. Solve the place of the bucket x=x(t). 2. The attempt at a...

Hi! I have a project where I am supposed to model the s-process in a star in its Helium shell burning region, and i shall do this for a variation of neutron exposure, where neutron exposure are defined as: \tau = N* \Delta t , t is time. N is number density of neutrons. So I in...

Homework Statement Under some circumstances, a star can collapse into an extremely dense object made mostly of neutrons and called a neutron star. The density of a neutron star is roughly 10^{14} times as great as that of ordinary solid matter. Suppose we represent the star as a uniform...

Homework Statement Say you have a binary star sytem. Both stars have mass M and semimajor axis a. The orbits are extremely eccentric (e is approximately 1). How would you describe the energy of the system? Homework Equations SEE BELOW The Attempt at a Solution Basically I'm very...

Homework Statement Neutron stars, such as the one at the center of the Crab Nebula, have about the same mass as our sun but a much smaller diameter. If you weigh 675 N on the earth, what would be your weight on the surface of a neutron star that has the same mass as our sun and a diameter...

What is the estimated value of the local star formation rate (SFR) and how accurately do we know this number?

[b]1. After a collapsing star decreases its radius to half its initial size, predict what will happen to its angular velocity(Assume uniform density at all times)Your answer describes the high angular speed of neutron stars. Find the change in the rotational kinetic energy of the star. Where...

Homework Statement I need to know how to calculate the temperature of a star from it's B-V color Homework Equations B = -2.5log(F440)+C V = -2.5log(F550)+C B-V = -2.5log(F440/F550) The Attempt at a Solution Really no idea, all my textbooks say that B-V color is used to...

Homework Statement One of the most prominent spectral lines of hydrogen is H_\alpha line.A bright red light with wavelength of 656.1\times 10^{-9}m.What's the expected wavelength of the H_\alpha line from a star receding with a speed of 3000 km/s? The Attempt at a Solution Is...

A recent (dumb) question that came to mind. Perhaps I posted in the wrong place recently. Given the brightest known star. What is the maximum distance we would be able to see it given current technology. Is there a rule or something? Say the divergence of photons vs initial brightness...

Period of a Star...Please help! Homework Statement The mass of a star is 1.250×1031 kg and it performs one rotation in 36.30 day. Find its new period (in days) if the diameter suddenly shrinks to 0.590 times its present size. Assume a uniform mass distribution before and after. I don't...

A star has a mass approximately 100 times that of our sun. If a planet with the same mass as the Earth is oribiting at a radius similar to that of the Earth's radius around the sun, how long would it take the planet to revolve around the star once? Ok, the period of the Earth's rotation is...

Does anybody have any idea how to solve this problem: The extinction of light due to its passage through a partially opaque medium is given by Beer’s Law (known by most chemistry students and many physics students, I hope!): I = Io e^ T where (Io) is the intensity of the light...

iI was asked to find the mass of a star given the orbital distance and the period. my mass came out to be 2.31^30 kg. Its then asking me to express it in terms of our sun's mass. Really don't understand what it means by that

1. Homework Statement Determine the apparent magnitude difference between sirius and the sun,as seen from the Earth. How much more luminosity is sirius than the Sun ? 2. Homework Equations f=sigma*T^4(eff) m-n=2.5*log(f(m)/f(n)) 3. The Attempt at a Solution the apparent...

Homework Statement Determine the apparent magnitude difference between sirius and the sun,as seen from the Earth. How much more luminosity is sirius than the Sun ? Homework Equations f=sigma*T^4(eff) m-n=2.5*log(f(m)/f(n)) The Attempt at a Solution the apparent magnitude...

Homework Statement A variable star changes in brightness by a factor of 4. What is the change in magnitude?Homework Equations m and n represent two stars of magnitude m-n=2.5 log(f(n)/f(m)) log (f(n)/f(m))=.4*(m-n) The Attempt at a Solution I think m-n is suppose to represent a change in...

Field of Eschatology pertaining to the binary star "Wormwood" Doe sanyone have any information of the binary star "Wormwood" can they offer any insight as to how it coinsides with the book of Revelation chapter 8

http://science.nasa.gov/headlines/y2007/15aug_mira.htm?list213022 Audio http://science.nasa.gov/headlines/y2007/images/mira/audio/story.m3u

Sun is an "ordinary" star I've read in different books the Sun is an "ordinary" star, and an "atypical" star. Anyone know which description is the correct one?

Homework Statement An astronomer observes a hydrogen line in the spectrum of a star. The wavelength of hydrogen in the laboratory is 6.563 x 10-7m, but the wavelength in the star’s light is measured at 6.56186 x 10-7m. Which of the following explains this discrepancy? A) The star is...

Homework Statement The light from a star reflects from a concave mirror with a radius of curvature of 1.70 m. Determine how far the image of the star is from the surface of the mirror. Speed of light = 3.0 x 10^8 m/s r = 1.7 m f = 0.85 m 1/di + 1/do = 1/f... and then I'm stuck b/c...

Why doesn't a star collapse in the early stages of its life instead of the later. You would think that with less gas at the end stages gravity would weaken and not allow a black hole.

Is it possible to calculate the radii of a star knowing its mass, luminosity and effective temperature? Thanks

http://starwars.com/ I remember standing in line for hours to see this... and I don't think it was even opening day. wikipedia.org: Star Wars IMDB: Star Wars Stamps from USPS: http://www.uspsjedimaster.com/

Homework Statement In a star Trek episode, a space station orbiting a planet blows up. The chew of the Enterprise simultaneously hears and see the explosion; they realized that tehre is no chance for rescue. If you have been hired a consultant, what two physics errors would you have found and...

Hi guys - Here's the problem I am chewing on: A binary star system consists of two stars, each equal to the sun in mass. The distance between the two stars is 1.0 X 10^12m. A comet which is essentially at rest, begins to make its journey toward the binary star system as a result of...

Has there ever been an observed star collision? If there hasn't, what might occur?

If the universe is expanding, then the brightness of distant stars should gradually decrease. Did anyone observe this phenomena of fading star light ?

so much for trek being dead for a long long time... and staring matt daemon as Kirk! http://imdb.com/title/tt0796366/ http://movies.ign.com/articles/767/767783p1.html

Homework Statement Last part of MTW Gravitation exercise 23.7: Calculate in Newtonian theory the energy one would gain from gravity if one were to construct a star by adding one spherical shell of matter on top of another, working from the inside outward. Use Laplace's equation d(r^2 (d...

What an incredible story: An unpopular and short lived series refuses to die, and now, along with its offspring, Trek spans forty years that have inspired countless young minds. http://www.startrek.com/startrek/view/series/ [The History Channel is currently running a two-hour documentary...

This problem deals with two main sequence stars in an eclipsing binary star system. I need to determine the system's peiod and separation (P and a). Right now i know that the brightest star has an absolute magnitude of -1 (219 solar luminosity), is 17,000 degrees kelvin, has a radius of 1.74...

Has anyone ever been to one of these? I'm going to one for the first time this saturday and I'm just wondering what to expect. What exactly goes on? Do they just set up the telescopes pointing to different celestial objects and you go around looking through each one? I am majoring in...

Homework Statement A B0 star has a luminosity of ~ 16000 L(solar) and a mass of ~ 16 M(solar). Can you estimate the time on the main sequence for this star simply from considering the rest mass energy of the core of the star (~10% of the total, and fusion burns with an efficiency of about...

I am in Astr. 1020, and in my introductory Astronomy class I had last semester, we didnt learn anything. It was a "here's the study guide (aka the answers to the test)" kind of class so I didnt really learn that much. Now, my Astr. 1020 teacher is rather difficult due to what I didnt learn...

What would happen if Saturn had become a second Sun in the formation of our universe? Would Earth have ever come to the way it is now? What would happen if it all of a sudden became a sun this very instant? All comments are appreciated!