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seen Dec 12 at 17:37

programming numerical algorithms for astrophysical applications.


Dec
12
comment What is the most oblate astronomical object known?
The question is still ill-posed. Strictly speaking, there are no oblate spheroids. Oblate spheroid is a concept and real objects can only ever approximate such a concept. The question then is how well does the object have to satisfy this concept? There may be a pretty flat asteroid which happens to be near oblate (but not flattened by rotation, of course -- that was not required in the question).
Dec
11
comment What is the most oblate astronomical object known?
I think your question is ill-posed, as it uses the concepts of polar and equatorial diameter. However, for an irregular object these are not well-defined.
Dec
11
comment What is the most oblate astronomical object known?
Well, that's not what you've asked (originally). Perhaps you should qualify your answer then. IHMO, my suggestions are not trick answers, but honest and correct answers to your original question.
Dec
9
comment What is the most oblate astronomical object known?
What's an object? Would Saturn's rings qualify? -- they are pretty flat. Otherwise, what about the Galactic disc? or other astrophysical discs (accretion discs have aspect ratios 1:1000)? None of these are fully self-gravitating: there is always a round component contributing or even dominating gravity...
Dec
3
comment Why does the distance between Sun and Earth stay the same?
@StanLiou Do you have a www reference for that?
Dec
3
comment Why does the distance between Sun and Earth stay the same?
Being pushed some way doesn't imply that you're necessarily falling that way. See also the update to my answer.
Dec
2
comment Why does the distance between Sun and Earth stay the same?
did you mean to ask why the Earth-Sun distance remains unchanged?
Dec
1
comment Likelihood of a stable system with a dwarf planet's orbit inside that of a gas giant
The orbit of a dwarf planet in the inner planetary system is almost certainly chaotic and hence unstable, unless it is in orbital resonance with a major planet.
Nov
29
comment Why does the face of the moon 'sync' with the earth?
This is not a force, but radiation. Radiation also decays like $r^{-2}$, like gravitational forces (both is simple geometry).
Nov
28
comment How is the maximum density in a circumstellar disk determined?
If $r$ is the spherical radius (which is the usual convention for this symbol), then this is not a disc at all... If it is cylindrical radius, it is not a disc either, but a cylinder, since there is no $z$ dependence.
Nov
28
comment Why does the face of the moon 'sync' with the earth?
realitively weak forces such as gravitation lol. If you meant "gravity", that's the weakest force on small scales, but the only force on large scales. So it doesn't matter that it's "weak".
Nov
28
comment What is a low mass Black Hole?
That paper made the term "low-mass black holes" up. Moreover, it starts from a wrong premise, namely that the formation of supermassive BHs after $10^8$ years is a problem and hence requires some drastic solutions. All ideas that BHs can simply form from the direct collapse of gas are wrong, as they violate the Eddington limit by many orders of magnitude.
Nov
18
comment Is there enough hydrogen left after a star dies so another star will have enough to light up?
oops. yes, thanks.
Nov
17
comment Is broadcasting the location of Earth to potential extraterrestial civilization regulated?
If they were to watch the TV, they would soon find out (1) the coordinates and (2) that it's not worth to go there.
Nov
17
comment Is broadcasting the location of Earth to potential extraterrestial civilization regulated?
Hmm. don't think this is an astronomy question. Perhaps better at space?
Nov
17
comment Why Jupiter's Great Red Spot is Reddish?
@HDE226868 I accidentally copied (instead of edited) it. I then had to delete one of them.
Nov
16
comment Why Jupiter's Great Red Spot is Reddish?
@Deuterium I find it amazing that you ask this question just 3 days after this press release! What triggered the question?
Nov
9
comment Number density of stars on the Galactic plane
The stellar halo is definitely not appropriately described by a vertically exponential, but by a (galactocentric) radial power-law. Also, for most disc populations, $\mathrm{sech}^2(z/h)$ gives a better description than the exponential, but these are details.
Oct
6
comment Is there any way a meteor can hit at less than escape velocity?
@LDC3 clarified in answer, but this was already evident from the question. Did you vote this down??
Oct
5
comment What causes jets from newly born stars?
be honest upfront: "I/we don't know"