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programming numerical algorithms for astrophysical applications.


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 Red?
@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 Red?
@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"
Oct
5
comment What are the current observational limits on the existence of Dyson spheres/swarms/rings?
No serious astronomer does. Those who do, do only because they can market that well with the public and hence get some funding.
Oct
4
comment What causes jets from newly born stars?
It's not clear from your answer why the magnetic field would create jets.
Oct
4
comment What are the current observational limits on the existence of Dyson spheres/swarms/rings?
I think a Dyson sphere is impossible, because nothing can stabilise it against gravitational collapse into the star. A ring rotating at the right rate is better, but a completely different type of thing and can only capture a tiny fraction of the stars energy.
Sep
18
comment How fast is a comet moving when it crosses Earth's orbit?
who is Wolfram?
Sep
16
comment What are the biggest problems about the numerical, finite-element GR models?
Perhaps, this sort of calculation is not so interesting (compared to QCD). What has been done is the merging of two BHs (including the gravitational radiation and the resulting anisotropic effects)
Sep
15
comment What is the difference between Sphere of Influence and Hill sphere?
@HDE226868 Excellent spot! Unfortunately, this is on another stack exchange site, so we cannot close this as a duplicate. However, duplicating the answer is clearly not worth the effort.
Sep
15
comment Are there stars that don't emit visible light?
@jwenting Jupiter is not a star, but a planet. Stars are defined to undergo (or have undergone) hydrogen burning (H$\to$He fusion). This requires a minimum mass of about 0.08M$_\odot$. Objects smaller than that, but massive enough to have some fusion (Li) early on are brown dwarves. The mass limit here is about 10M$_{\mathrm{Jupiter}}$.
Sep
13
comment Are there sufficient observational data to measure non-Newtonian perihelion advances of any Asteroid and Comet orbits?
Use ADS to search for publications (via author names, title words, keywords, or words from the abstract) and even read their abstract for free. Almost all astronomy papers are also published on the arXiv (linked from ADS), where you can obtain (a preprint version) for free.
Sep
11
comment Are there sufficient observational data to measure non-Newtonian perihelion advances of any Asteroid and Comet orbits?
If you want to write a scientific publication, then search the published literature.
Sep
11
comment How many astronomers are there in the world today?
I didn't know your source, but I would have estimated the same number. However, there are many more (about the same number) with a PhD in astronomy who didn't follow it up with an academic career.
Sep
8
comment When will the Milky Way “arrive” at the Great Attractor, and what all happen then?
Given the accelerated expansion of the universe, is it at all clear that the MW will be arriving there (supposing it it indeed on course)? Note that the mysterious force (coined dark energy) driving the accelerated expansion is opposing the gravitational attractions.
Sep
7
comment Milky Way Formation
Neither, but both!