All Questions
Tagged with binary-stars gravity
18
questions
2
votes
1
answer
50
views
How to relate a gravitational plane wave to the GW from a binary system?
I have two different forms of gravitational waves that I am trying to reconcile.
A monochromatic GW with angular frequency $\Omega$ propagating in the $\textbf{n}$-direction can be expressed as
$$ ...
- 1,751
1
vote
1
answer
92
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GENERAL RELATIVITY: gravitational time dilation outside 2 bodies [closed]
I know that gravitational time dilation near a single body is:
$$T_2=T_1\sqrt{1-\frac{2GM}{rc^2}} $$
Can you give gravitational time dilation formula when in proximity to multiple bodies?
- 81
1
vote
2
answers
139
views
Star with quadrupole in binary system violates Newton's 3th law?
Suppose that, in a binary system of two stars, the star A (and only the star A) has a non-zero quadrupole moment $Q_A$. Then, the star B feels the usual gravity force plus an additional force, ...
- 169
9
votes
3
answers
2k
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Does a double star system have more mass than its constituents?
According to Einstein, energy is equal to mass. Consider a planet that is in gravitational attraction to two stars. Normally I would say that the gravitational attraction is proportional to the masses ...
- 793
1
vote
1
answer
47
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If two black holes orbit around each other should their tidal forces cause a shrinking of the closer parts of their event horizons?
I recently asked a question about the influence of external gravitational fields on the stability of the geometry of a part or all the event horizon of a black hole. I understood the answer in a ...
- 2,255
6
votes
2
answers
711
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Can two relativistic black holes' event horizons overlap and separate again?
I have read this question:
What I have not seen is a purely classical argument for the non-separation of a black hole merger. One can obviously take the time reversed spacetime manifold of a merger ...
- 29k
5
votes
1
answer
423
views
Is there an approximate expression for the force between two black holes?
Just curious: is there an approximate expression for the gravitational attraction between two Schwarzschild black holes of masses $M$ and $m$, held without relative speed at some center to center ...
user85598
2
votes
3
answers
335
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Should the stars of a relativistic binary system have tangential acceleration?
Should the stars of a relativistic binary system have tangential acceleration?
- 1,815
2
votes
2
answers
142
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Would the 2 orbiting black holes emit gravitational waves?
Would the 2 orbiting black holes emit gravitational waves even if they are moving at a constant speed in orbits? Here, can we consider the changing direction of black holes in their orbits as ...
- 41
0
votes
0
answers
53
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Gravitational force between astronomical bodies in a binary system
If two celestial bodies of similar mass form a binary system and both have fairly relativistic velocities does in that case gravity act with delay and does the picture shown present the problem in the ...
- 2,255
7
votes
1
answer
282
views
Theoretical solution to binary black hole merger based on Hawking and Ellis
Following Hawking and Ellis, Chapter 9, Fig. 60, Pg. 322, the following figure is meant to illustrate the contrast between apparent horizons and event horizons in the case of a binary black hole ...
- 245
9
votes
2
answers
892
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Gravitational waves and chirp waveform
When two neutron stars collide emitting gravitational waves, what exactly does the chirp waveform represent and how is it used to infer the distance to the source?
- 928
2
votes
2
answers
216
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Time dilation, and curvature of space caused by two black holes of unequal masses
If you were to try to find the time dilation in a region of space near a black hole you would use the equation
$$t_r=\sqrt{1-\frac{2GM}{rc^2}}$$
Would the time dilation from two black holes be this?
...
- 780
0
votes
1
answer
124
views
When a star undergo collapse in a binary system what effect it has on its companion star? [closed]
when a star in its lifetime fuses up all its hydrogen and then collapse under gravitational force, till the temperature inside become high enough to restart the fusion of helium and radiation pressure ...
- 165
6
votes
2
answers
304
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Would two objects orbiting each other emit gravitational waves on every direction or only on their plane of rotation?
Imagine a system where two massive objects are orbiting each other, something like a binary black hole or neutron star system. Such a system should emit gravitational waves. I'm curious on the ...
- 161