Star Definition and 1000 Threads

Gravity around star is often depicted as the curvature if spacetime or a 'dimple" in a flat sheet. What would happen to space-time around a star if the star were to instantly disapear? Would the fabric of space time snap back to flat space or would it reverberate, expanding then contracting...

What happens to the Schwarzschild metric for an isolated non-rotating body when the horizon radius is inside the body? As I remember from classical physics all of the gravitational pull on an object inside a shell cancels out so it would seem that the horizon radius can not include any mass...

Would a star that is too small to go supernova (Sol or Alpha Centauri) still go supernova if its core somehow instantly vanished? Wouldn't gravity collapse it and wouldn't that pressure be the same as the pressure that makes larger stars go supernova?

Hello everyone! I'm new here and I've checked this forums once in a while for physics information, mainly astrophysics stuff but I usually found all the answers I needed. Not this time though. A bit about me. I'm an Indie game developer and the game I'm working on takes place in a...

Is there any reason to expect both the star formation history and the angular diameter distance to peak at around the same value (redshift ~ 1.6)?

for visible interference, we should have coherent source. if we want to take spectrum of star, need coherent light. i don't know that star's light coherent or not!

i and my friend want to have spectrum of star. i need star light with high intensity to diffract this. unfortunately, we don't know how we can have a intense light? do you know how we can do this? or in general, how can we have spectrum of light star?

Hi, I'm attempting to determine the approximate pixel coordinates of cataloged stars within the field of view of a spacecraft camera. I'm given the right ascension and declination of the center of the camera field of view and its dimensions. I've used that information to filter a star...

How Iron is poison for a star. I have not read this thing in my course book. Today I was watching Discovery channel. there was a show on stars which describe this. I think this is related to binding energy per nucleon of Iron which is highest of all.(I am not sure it is just an Idea)

hi, heres' problem from an international olympiad "The Damavand Mountain is located at the North part of Iran, in south coast of Caspian Sea. Consider an observer standing on the Damavand mountaintop (latitude = 35° 57′ N; longitude = 52° 6' E; altitude 5.6 x 10^3m from the mean sea level)...

Hey all, I was watching a talk by Layrence Krauss on what might be possible from all the science fiction in star trek. One thing that he mentioned was that everyone comitted suicide in the show everytime they said engage! because of the massive G forces due to acceleration. The writers got...

Homework Statement 2 stars are separated by a distancce r, one star has mass 2/3M the other has mass 2M (M is a solar mass). The period of revolution is 5 years, calculate r. Homework Equations Fg=(GM1M2)/r^2 The Attempt at a Solution Ok so I know that the binary star...

Hi I'm studying strain analysis using Mohr's circle. I have some problem using a star rosette to construct the circle. My problem lies with trying to identify the points which indicate the planes the rosette act on. Besides that, what is meant by "strain rosette with gauge X (gauge X being...

Homework Statement Hey I have to create a six-pointed star and a hexagon with polar coordinates using MATLAB. I don't need help with using MATLAB, I just need help with the math. Note that I don't really need to know how the math sense this assignment is for a CSE course. I just don't...

A study, accepted for publication in the journal Astronomy & Astrophysics, says ESA’s Herschel Space Observatory has spotted a young sun-like star 750 light-years from Earth that is shooting water from its poles at about 124,000 miles per hour. I wonder, do all protostars do this? Is oxygen...

In an article in the NY Times http://www.nytimes.com/2011/06/21/science/space/21obhole.html" , it was written: “This is a singular event in the history of mankind,” Dr. Joshua Bloom, an associate professor of astronomy at UC Berkeley, said. “This black hole was otherwise sitting dormant, a star...

although observed about 3 months ago I only learned about it today -I hope it is not a double post http://chandra.harvard.edu/photo/2011/grb110328/ http://www.universetoday.com/84694/space-telescopes-observe-unprecedented-explosion/ and two arxiv papers...

A star is 40 light years from Earth. (a) How far would you measure this distance to be if you traveled it in a spaceship moving at 1.00X10^8 m/s (b) How long would the trip last (for you)? Can someone please help me out with this question and what equations I should use to solve this...

Hi all, I would love if someone could clarify these five questions for me: 1. Is it correctly understood that all stars are of a certain generation? 2. Which generation is the sun? 3. What is the highest generation star we know of? 4. In the Milky Way, what is the share of first...

Like the question says, would a neutrino be stopped by the very high density matter in a neutron star? IH

If a super-duper-hyper-energetic particle like the OMG particle (refer http://en.wikipedia.org/wiki/Oh-My-God_particle) were to impact the surface of a neutron star, could the tremendous impact density it creates lead to the beginnings of an embryonic black hole that would (slowly/quickly?)...

Black holes suck in everything around them. My 5 year old knows that one. It's all over TV, etc. But what about the original star? Wouldn't that have just as much gravity? Wouldn't it do the same thing with the strength? Is it just that black holes are more exciting to talk about?

Homework Statement People hoping to travel to other worlds are faced with huge challenges. One of the biggest is the time required for a journey. The nearest star is 4.1 x 10^16 m away. Suppose you had a spacecraft that could accelerate at 1.5g for half a year, then continue at a constant...

Hi, I don't know what is the generation number of our solar system. But it is certainly not the first generation of stars. Because the heavy elements that made up the planets must have been synthesized during the supernovae of earlier generation stars. Let's assume a star massive enough to...

Homework Statement What is the temperature of a star if the flux at 450 nm is measured to be 1.3 times the flux at 650 nm. Homework Equations I tried to use the equation Flux = 2πhv3/c2...

If a small black hole were to fall into a star or brown dwarf, presumably it would initiate accretion and fusion in a shell around it. Can such an object be stable over any decent timescale, or would it undergo variability/significant mass loss/supernova?

Hi, Is there a fairly even star (or galaxy) density in every direction we look, ignoring our own galaxy? Or are there some directions where our OU seem denser than others?

The Damavand Mountain is located at the North part of Iran, in south coast of Caspian Sea. Consider an observer standing on the Damavand mountaintop (latitude = 35° 57′ N; longitude = 52° 6' E; altitude 5.6 x10^3m from the mean sea level) and looking at the sky over the Caspian Sea. What...

So I know that we can use absorption or emission lines from a star or object emitting light to determine the composition of that object. But what methods are used to confirm that? We've been doing this in class and it seems rather primitive to eyeball the lines and compare them with example...

I have that \left( \frac{dR}{d \tau} \right)^2 = ( 1 - \epsilon)^2 ( \frac{R_{\text{max}}}{R}-1) describes the radius of the surface of a collapsing star in Schwarzschild geometry. I need to show it falls to R=0 in time \tau = \frac{\pi M}{(1-\epsilon)^{3/2}} So far I have rearranged to get...

i was wondering if there is a relationship between mass and temperature that would allow me to calculate the surface temperature of a blue super giant of 24 solar masses? or do i simply need more information to do this

why do we require delta and star load connection ? thanks.

What happens to regular matter that falls into a sun? Why is the sun made up primarily of light elements and the rest of the solar system isn't when a solar system evolves? (maybe with the gas giants it is but why isn't there a lot of heavy elements in the sun)

Are the absolute magnitude of stars relevant (calculated) with it's mass and rotational velocity? I understand that the mass of a star has a relation to it's size... regardless of this.. I need to know if mass and rotational velocity combined are used to determine anything for stars. Furthermore...

What do you think is the best type to find planets in the habitabel zone? What do you think of the suggetsion of white dwarfs? http://news.softpedia.com/news/White-Dwarfs-Are-Newest-Targets-for-Exoplanet-Research-192407.shtml any better suggestions?

in star connecting load why the phase current is equal to line current? advanced thanks.

http://arxiv.org/abs/1101.4298 The missing link: Merging neutron stars naturally produce jet-like structures and can power short Gamma-Ray Bursts Luciano Rezzolla, Bruno Giacomazzo, Luca Baiotti, Jonathan Granot, Chryssa Kouveliotou, Miguel A. Aloy (Submitted on 22 Jan 2011) "Short Gamma-Ray...

If gas has to be cooled below, say, 100 K, in order for stars to form, what is the highest redshift for star formation? What would be the necessary equations to solve this problem??

Because I was curious about this, I read here that, "Our own Sun is part of an open cluster than includes other nearby stars such as Alpha Centauri and Barnard's star." However, I cannot find any other pages claiming this, and the wikipedia entry on star clusters does not mention us being...

1. Question: In one region of a nebula the mean separation of atoms is 2.3x10^-3 m. What volume of the nebula contains enough atoms to make a star, similar to the sun, of radius 7.0x10^8 m within which the mean distance between atoms is 1.0x10^-10m? 2. Volume of sphere 4/3(pi(r^3 ))...

Neutrons have no charge, and in neutron stars we have matter that is only made of tightly packed neutrons. The mass is very great due to density. If I were to go fetch a baseball sized ball of neutron star matter from a neutron star and lay it on hard concrete ground... Other than making a...

In the first part of Brian Cox's documentary series 'Wonders of the Universe', he explains how the entropy of the universe always increases, and that we are therefore headed for a state of total 'disorder' where all is left of the universe is photons and dying black holes. But wasn't this...

Hello folks, this is my first post. I'm not quite sure that I fully understand the idea of a random walk of a photon that is generated at the core of a star. I've read this: http://www3.wooster.edu/physics/jrIS/Files/Walker_Web_article.pdf My understanding of the theory is this: A...

Homework Statement A star has a photospheric temperature of 5000 K, a radius of 0.9Ro, (Ro = radius of sun). If the star is 20 pc away, calculate the monochromatic flux (In Wm^2micron^-1) at 500 nm, measured at Earth. Calculated the surface area to be 1.6416*10^18 m^2.Homework Equations We...

Homework Statement Demonstrate that the temperature applicable to a stellar system is T = m < v2 (x) > ...3k where it is assumed that the stars have equal mass m, v(x) is the velocity of a star relative to the center-of-mass, and <> represents an average. Homework Equations...

*Please Help* Question related to Orbital speed of star, Keep getting *10^4 to high?? Homework Statement A star has a mass of 2.2*1030kg, there is a planet of mass 4.5*1027kg orbiting it at a distance of 3.1*1011m (also told that it has a "period of wobble" of 9.2*107s due to the orbiting...

Im trying to solve back for Jupiters effect on the suns orbital velocity. I've looked up the asnwer and its 12.7 m/s and the formula I have for this is http://en.wikipedia.org/wiki/Doppler_spectroscopy v = SQR (Gm*/r) where G is Grav constant M is the mass of the star (planets mass is...

How do I do this problem. I think you have to use this formula L1/L2 = 2.512^(M2-M1) and then see the relationship with the Stephan Boltzmann Law. I keep getting an answer of 0.1 based on the ratio, but it's not making any sense. Here's the question. Star P is a pulsating variable star. As...

Hello again, I've got a question about a star in a hydrostatic equilibrium. How do I derive an equation of motion for a pertubation in the full momentum equation? I'm attaching my solution (my_solution.jpg) , but I'm not quite sure about it. The full exercise is attached as...