Star Definition and 1000 Threads

Apparently, in the early universe, stars were massive - ranging up to about 500 solar masses. Furthermore the metallicity (elements other than H, He) in the early universe was effectively zero with only hydrogen, helium and trace amounts of lithium. Apparently, stars could reach large masses...

Is there such a thing as a black star? Not black hole. I read something from a national geographic magazine a few months back that was about an astronomical object. It was all black on the outside, emitted darkness instead of light, and it contained some water. It was some new discovery or...

Edit: nvm

Homework Statement There is no general analytical solution for the motion of a 3-body gravitational system. However, there do exist analytical solutions for very special initial conditions. The diagram below shows three stars, each of mass m, which move in the plane of the page along a circle...

Homework Statement Determine the dip in magnitudes and flux in the optical light curve caused by the planet in front of the star if the planet orbits at 0.1,1 and 5 AU: The star is a solar type star and the mass of both the planet and star are known as are their radii: The observer is 10pc...

I hear that large telescopes can resolve the Andromeda galaxy into individual stars. Is it possible to do the same for galaxies outside our local group? Also, have we observed any stars which sit in deep inter-galactic space, far from any galaxies?

Hi When I was a kid, the largest telescope was Mt Palomar, a little over 5 meter diameter mirror. In spite of its large size, I always read that stars appeared as points of light through the scope if it were used visually, i.e. stars are too small and too distant to appear as disks. However...

"Artificial Telekinesis" - The Star Wars Force Trainer Seems to be legit. I have been aware of work with this technology, but I think this is the first commercial product that I've seen. https://www.youtube.com/watch?v=LJbIGJrQK84 In fact the toy seems to have been around for a time...

Homework Statement An astronomer measures B and V for a large number of stars in a particular star cluster. (All stars in a given star cluster are at essentially the same distance from the Earth.) She then corrects B and V for interstellar absorption, and plots the resulting value of V for...

Homework Statement You wish to travel to the Pleiades (at a distance of 130 pc) in 10 years, according to the clock that you carry. How fast do you have to travel to accomplish this (express the velocity as a fraction of speed of light, v/c)? Homework Equations \Delta T...

A distant star has a single plante orbiting at a radius of 3.51X10^11m. The period of the planet's motion around the star is 853 days. What is the mass of the star? The universal gravitational constant is 6.67259X10^-11N m^2/kg^2. Answer in kg. Alrighty. So I tried to find the mass by using...

Think of a Star Trek dream team. Here's one that I made hastily. KIRK: Arnold Schwarzenegger SPOCK: Steven Seagal MCCOY: Peter Falk SCOTTY: Jim Carrey SULU: Bruce Lee CHEKOV: Brother Theodore UHURA: Whoppi Goldberg Wait! Whoppi was on the new ST. Jim Carrey would be funny being...

I need the % of stars in our galaxy, sorted by spectral classes and also by masses. Is there any such information somewhere ?

Please look this simple problem over. A star is composed of 91% H and 9% He. What energy is required to completely ionize this gas mixture? Energies of ionization are 13.6eV for H and 54.4eV and 24.5eV for the 1st and 2nd ionizations of He. My method: Let n be the total number of atoms...

How many generations of stars were required to make the elements found on Earth. In other words, does a star have to be born with heavier elements for some even heavier elements to form?

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 is the central density constant. a) Find M(r). b) Derive the relation between M and...

Homework Statement A star of mass 1.81×1031 kg and diameter 8.10E+9 m rotates with a period of 25.0 days. Suddenly the star changes size, and rotates with a new period of 18.0 days. Assuming a uniform density both before and after the size change, what is the new diameter of the star...

Homework Statement A star of mass 1.81×1031 kg and diameter 8.10E+9 m rotates with a period of 25.0 days. Suddenly the star changes size, and rotates with a new period of 18.0 days. Assuming a uniform density both before and after the size change, what is the new diameter of the star...

Hello all, First, since I'm just a physics teacher, and not an astrophysicist, my questions may sound "obscure" or badly formulated. Especially since I'm not an English native speaker. Sorry about that :shy: I need a mathematical relation which could give the mass of a "theoretical" star as...

I have, through general observation, theorized what I believe to be a logical explanation for the appearance of life on Earth. Although to me, this theory seems to provide a logical and rational explanation for the question of how life appeared on Earth, I have very little knowledge of Physics...

when two neutron stars collide, do they creat both a balck hole and release gamma rays or does it happen in stages?

Homework Statement Question 1 - If two stars A of luminosity 9000 and B of luminosity 90 (both relative to the Sun) appear equally bright from the Earth, how much further away is A from B? Question 2 - Star A is twice as bright as Star B, but B is twice as far away as A. Which star has...

Homework Statement Assuming a neutron star is made from an incompressible material, what is the hydraulic pressure 50m below the surface? Mass = 1.98x10^30kg Radius = 10km 2. The attempt at a solution g=GM/r^2 = (6.67x10^-11 x 1.98x10^30)/ 10000^2 = 1.32x10^12 m/s^2 P=P_{0} + \rhogh Pa...

Hi, I'm actually a Design Engineer but I find the topic of Relativity extremely interesting and I was wondering if somebody could give me some guidance on this. If Planets and Stars (due to their mass) 'warp' Space-Time then this means that our Sun distorts the fabric of space just like a...

I was listening to the regional NPR station yesterday and hear a brief discussion of two binary systems. http://stardate.org/radio/program.php?f=detail&id=2009-12-26 Is this common? Is it plausible? I presume that some how the velocity of Mu Columbae and the other star traveling 'north'...

Homework Statement The questions are about binary star system. Homework Equations Why the two stars in a binary star system are always diametrically opposite positions? Why the two stars have common period? Why the inner star is more massive? The Attempt at a Solution For the...

http://arxiv.org/abs/0912.3229

Homework Statement after subtracting the bias level from your count, you get a value of (N). to find the noise, you calculate sqrt(N) = noise. now the question, As above, your image has a noise of sqrt(N). What can you say about the presence of a faint star in the image that has a total...

Please could you let me know how to find out apparent magnitude of a star when you know the apparent magnitude of the binary star system? p.s. the distance between the observer and the system is'nt given. I have the luminosities of both the stars as well as absolute magnitudes of both the stars.

Homework Statement The spectral lines in a low mass main sequence star show sinusodal velocity variations with an amplitude of 500 km/s and a time period of 10 hours calculate a lower limit to the mass of the unseen binary companion Homework Equations M1 + M2 =...

Sorry no one was answering my question, and I just wanted to get this done: Homework Statement ...Hence show that the mass of the star is M = 4\pip_{c}\left(R^{3}/3 ) Homework Equations M(r) = 4 \pip_{c}\left(r^{3}/3 - r^{4}/4R) This is the mass within a radiusThe Attempt at a Solution I...

Homework Statement ...Hence show that the mass of the star is M = 4\pip_{c}\left(R^{3}/3 ) Homework Equations M(r) = 4 \pip_{c}\left(r^{3}/3 - r^{4}/4R) This is the shell massThe Attempt at a Solution I already found the shell mass via intergration, and I know that I have to build up an...

What is different about the photons from a star compared to something man-made which allows it to travel so far?

Orbital Speed of a Star - Please Help! Homework Statement Calculate \Omega(r) and v(r) for the following density models: (a) all the mass M is at the center of the galaxy; (b) a constant density adding up to a mass M(R0) at the Sun’s orbit and no mass beyond. Homework Equations...

I am having trouble understanding how stars orbit around a spiral galaxy. First off, my understanding of the Local Standard of Rest (LSR) is that it is a point which corresponds to the average velocity of all the stars in the defined local neighbourhood. This point moves around the centre of...

Homework Statement Let’s make an idealized star model with two parts: an isothermal helium core, and pure hydrogen layers outside the core. The core represents the part where hydrogen has already been burned. Mathematically this represents the simplest model that might resemble a...

I understand that a great number of star's we see are no longer there (now dead)we are just seeing the light traving from them over the vast distense of space, Question If I were looking into the sky at night and seeing start light from a now Dead star and someone else (you) at the same time...

A star's surface sends out energy in form of electromagnetic radiation and has an emissivity close to 1. Find the solar radius of Rigel that emits energy at a rate of 2,7 * 10^32W and has a surface temperature of 11000K. You may assume the star is spherical. Attempt at solution: Formula for...

it is known that there is considerable lag time when light travels from some place and reached us her on earth. is it possible that what we consider to be star formation actually nothing more than us receiving their light for the first time? thanks in advance.

The moment before a neutron star collapses matter is distributed across the whole volume of the neutron star? Can we say anything of the actual collapse, such as matter moves towards the center of the neutron star?

Say we slowly add mass to a neutron star till it collapses to a black hole. Just before it does has time in the neutron star almost come to a stop? Is the passage of time different for different locations in the neutron star just before it collapses? Would the strings of string theory come to a...

Homework Statement I'm to prove that the central pressure of a particular star is Pc = (15/16\pi)(GM2/R4) I am given the density as a function of r \rho(r) = \rho0[1 - (r/R)2] In part a I found the Mass by integrating the equation of hydrostatic equilibrium and found M =...

Homework Statement A binary star system has a period of 90 days. It consists of two equally massed stars each with a mass of twice that of the sun, that rotate like a dumbbell about the center of mass at the midpoint between them. How far apart are these stars? Homework Equations F =...

Is there a way to estimate the mass of a star using Spectral Class and absolute magnitude? If you can't then what info do I need in order to so. Thanks, Dan

Homework Statement f the Sun's atmosphere increased in temperature with radius at and above the photosphere, how would our observation of the solar spectrum be different? b) Consider a spherical hollow shell of gas around a star. If you observe this shell to produce a bright ring around the...

Homework Statement 2 stars rotating around the common centre of mass have masses m and 3m. What is the ratio of the force due to each star at the common centre of mass. Homework Equations None The Attempt at a Solution I tried to find the centre of mass and applied Newtons law of...

Homework Statement We observe a binary system in which the two stars are 1 and 2 arc sec, respectively, from the center of mass. The system is 10pc from us. The period is 33 yr. What are the masses of the two stars, assuming that i=90 degrees? Homework Equations The Attempt at a...

Im really trying to learn CFD since embry riddle does not have a good course for undergrads to learn some basics about viscous flow..Im really trying to learn CFD since aerodynamics in general interests me alot. Does anyone have good resources to learn some CFD software ( namely star design ...

Homework Statement Suppose I have a spherically symmetric static star. What is the total energy of (baryonic) matter inside the star? Homework Equations The metric is (parametrizing as in Weinberg): ds^2=-B(r)dt^2+A(r)dr^2+r^2d\Omega^2 I assume the energy-momentum tensor of a...

I am confused about this question: A giant star has a radius of 200 Rsun, with core of mass 0.6 Msun surrounded by an extended envelope of mass 0.2 Msun. (a) Estimate the gravitational potential energy of the envelope. When it says the envelope, does this mean the 'shell' surrounding...