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Jun
10
awarded  Enlightened
Jun
10
awarded  Nice Answer
Jun
10
comment How do we know Milky Way is a 'barred' spiral galaxy?
@RobJeffries psst about that walter here.
Jun
10
comment How do we know Milky Way is a 'barred' spiral galaxy?
@RobJeffries Look at my article and any quoting it.
Jun
1
comment Why are all quasars so far away?
I disagree with you on the strangeness of creation of matter. With the big-bang, it's restricted to a single event with clear observational implications. With the steady state theory, it is required frequently and pervasively without any observational evidence.
May
31
comment Potential Re-Capture of Rogue Planets
Nice to see you quote Melvyn (et al). One thing all these studies (as well as my answer above) ignore, I think, it the possibility of tidal capture (or the aid of tidal dissipation in dynamical capture) and the role of tides in the orbital evolution of captured planets.
May
31
revised Potential Re-Capture of Rogue Planets
typo
May
31
comment Why are all quasars so far away?
There is still more than enough gas to make for a good quasar. The critical question is how much of that is funneled close enough to the black-hole binary (which will form) and then how much will actually accrete onto one of the holes (rather than being ejected via gravitational slingshot).
May
30
comment Why are all quasars so far away?
Okay, but the steade state theory requires strange physics (in the sense of my previous comment), namely generation of matter out of nothing as the universe keeps expanding. In fact, the steade state theory is just such a rubbish that I keep wondering how it ever could attract as much attention as it did.
May
30
comment Why are all quasars so far away?
Indeed, the collision of M31 with the Milky Way will most likely trigger some quasar activity. The black hole at the centre of M31 is $~100$ times as massive as that of our galaxy and can make for a pretty bright quasar.
May
30
comment Why are all quasars so far away?
I think Olber's paradox is the most obvious objection to the perfect cosmological principle. It can only be resolved if the universe is finite, either in space or in time (or both or some strange physics such as tiring light).
May
30
comment Why are all quasars so far away?
Nearby quasars would be even more interesting (since they allow detailed observations), but all of those are long known. Intermediate-redshift quasars (at $z\sim1-4$) are plenty and too distant for detailed investigations.
May
3
comment What is the most populated/numerous stellar system in which the orbits of all objects are known?
The Solar system is the only system for which all the major bodies and their orbits are known.
May
3
comment Why does the Solar System have no (natural) satellites of satellites?
Are you referring to the Kozai-Lidov effect? This only works for sufficiently inclined orbits, but orbits (around the moon) in the same plane as the Moon-Earth orbit should be stable (Solar tides are much weaker and the inclination is small).
May
3
comment Star versus Black Hole
@SwapnilRastogi As I said in the answer, some of the stellar matter [from the star ripped apart] forms an accretion disc around the BH. This is essentially all matter that is gravitationally bound to the BH. The remainder escapes. If the star was initially on a parabolic orbit (which to good approximation is the typical situation), half of the gas from the star will accrete and the other half escape.
Apr
29
revised How can a supernova affect black hole in a binary system?
typo
Apr
29
answered Star versus Black Hole
Apr
28
answered Could our Sun be a companion star of a massive black hole?
Apr
14
comment Can stars be observed from space by x-rays, near infrared and radio wavelengths?
No, "seen" implies the human eye, which is incapable of sensing in these wavelengths. Or didn't you mean that?
Apr
12
answered Can we know the orbital planes of extraterrestrial planetary bodies?