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programming numerical algorithms for astrophysical applications.


Feb
9
revised Do stars have exactly sphere shape?
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Feb
9
answered If the earth stopped rotating, would we really fly inertially at 1000mph?
Feb
9
comment If the earth stopped rotating, would we really fly inertially at 1000mph?
You cannot stop earth rotating just like that. If you consider non-scientific non-sense (superman), then you shouldn't ask for a scientifically based answer either.
Feb
9
comment Do stars have exactly sphere shape?
nothing real is perfectly spherical.
Feb
9
answered Do stars have exactly sphere shape?
Jan
28
comment When we see half moon, why is it always the lower half?
The moon has no "lower" or "upper" half. Up and down are local coordinates and point in different directions for people at different places on Earth.
Jan
19
comment What if the black hole in the center of the galaxy grew faster?
@AlexeyBobrick Nope. The fact that these beasts grow to $10^{6-9}$ Solar masses shows that somehow they find a way to overcome the first problem. But eventually the feedback form the hole is so strong that it drives all the gas out of its host galaxy. This is thought to occur when all the energy of the wind is dumped into the galactic ISM, i.e. when the swept-up ISM cannot cool efficiently (if it can, only the wind momentum drives the outflow). Most efficient cooling is due to inverse Compton scattering off photons from the AGN itself (the shocked gas is much hotter than the accretion disc).
Jan
18
answered What is the difference between our time and space time?
Jan
18
answered What if the black hole in the center of the galaxy grew faster?
Jan
18
answered What happens to the energy from a GRB?
Jan
18
comment What happens to the energy from a GRB?
@AlexeyBobrick I think the precise formation mechanism of GRBs is still under debate, so your statement can only reflect a possible model, but is no definite widely accepted paradigm.
Jan
18
comment Is it possible that we see our solar system as a star?
perhaps you should read some more (and more reliable) sources. Did you look at wikipedia? No galaxy expands. The space between distant galaxies expands, though. Also, "expanding faster than light" makes no sense: light doesn't expand.
Jan
18
comment SPH simulations
There many different SPH codes around the astronomy community (I have one myself), but AFAIK none except gadget are publicly available for download (simply because these codes are very specific and easy to break if you don't know what you're doing). The problem with gadget is that it implements an out-of-date SPH algorithm (>10 years old) and was never really meant for planet collisions (I bet you would need a particular equation of state for planet collisions).
Jan
18
comment Do all moons orbit their planets on the ecliptic?
no moon is exactly in the eccliptic and no planet (except the one that defines the eccliptic) either. Why should they?
Jan
13
answered Are we made of the stuff of one star or more stars?
Jan
10
revised Does gravity slow or speed light up?
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Jan
10
answered Does gravity slow or speed light up?
Jan
10
revised How can the life time of a multiple star system, such as for example the trinary system PSR J0337+1715 be derived?
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Jan
10
answered How can the life time of a multiple star system, such as for example the trinary system PSR J0337+1715 be derived?
Jan
10
comment Heavy star and redshift
@frodeborli At cosmological red-shift 1000 there are no stars.