Listening to the Cries of Baby Stars

Re: # 55

The question about ellipse and circle is excellent and hard to answer. First of all, the orbit of the Earth and most of the planets are almost a circle (but not quite). When the Solar system formed, the planets and other bodies had much more chaotic orbits. However, after some time the orbits became more stabilized. Now, circle is the most stable orbit (or in physics term, a circlular orbit has the lowest energy). But its very hard to get to that level. In the Solar system, we already have giant planets like Jupiter and Saturn affecting the orbits of smaller bodies, perhaps preventing them from getting into a perfectly circular orbit.

There are few examples of circular orbits, and I think they are mostly confined to objects like binary neutron stars. These are the corpses of stars larger than the Sun. They are small but they have intense gravitational field, and perhaps these extreme conditions bring them into perfectly circular orbits. This is what I think, but the issue of orbits is very complex (especially with more than 3 bodies). Perhaps not too convincing, but I hope it helps a bit.

-Salman

#55:
I am not well versed with the geometrical facts about the orbits. Mr Hameed might be in a better position to explain it.

#59:
If the amount of matter falling in a black hole is very small, it may acheive relativistic velocity and it should not be surprising, because there are evidences about particles streaming out of their sources at speeds close to that of light. However if a black hole happens to be close to a star, there is an spectacular phnomenon. It is where a black hole shows its muscles. Because of its immense gravity, it starts to suck in the gases from the fateful star in tremendous amounts. Because of the extremely small radius, very little matter actually gets in the black hole...but the matter which escape this fate of falling in the black hole isn`t very lucky though. Because the amount of matter actually falling in the black hole is far far less than the amount dragged close by its gravity, there is a tremendous build-up of gases around the black hole, ``the accretion disc``. The pressure and temperature in the disc in so intense that the matter loses its integrity as atoms and molecules. There is a tremendous blast-off of matter and energy. The matter escapes on either sides of the accretion disc in the form of extremely fast particle jets. The energy escapes in the form high energy radiation. Cygnus X-1 is a classic example...The X-ray source in Cygnus X-1 is thought to be a black hole close to a massive star engulfing matter from it in the same manner.

#60:
Thanks for the compliment. I only try my best to convey to others what I know, in a simplified manner.


Dr. Muhammad Akbar Hussain Siddiqui
astronomer.bravehost.com

salman Hameed:

Thanks for this article. I particulary liked the poetic phrase `` cries of the baby stars``.
The questions in #60 are also for you. Please help.

thamks.

akbar260:

Am I glad that I opened this page! Akbar, allow me the privilege to add my name to the list of your admirers.

You not only have immense talent, but also a great ability to convey your ideas in a fresh, humorous, polite manner. Your expression of your love for your family is also very commendable.

You certainly are a bright star & likely to be a promising supernova for muslims & Pakistan.

Please continue to regale us laymen, the kind of stuff you wrote about Hydrogen, Helium Lithium etc.

From where & how the Universe gets & retains its balance? why the speed of heavenly bodies retain their chronometer-accuracy whereas man-made sattelites lose theirs & fall off. Also, why is the order not disturbed when meteorites , stars, & others collapse or burn out? Do the laws of entropy & enthalpy get ``suspended-in-balance``( my coinage) in a MACRO ( in universe terms) context?

As my questions might indicate, I know nothing--so please be kind to reply in laymen terms. Thanks.


P.S: You are my children`s age.

I really wonder what kind of speed, particles falling into a black hole achieve. Very close to speed of light I suppose?

If the radius of an average size black hole is just 3-4 kilometers then wouldn`t it take a lot of time to swallow a star? It would seem like a gigantic tank full of water emptying into a small drain!

Re: # 55

I think the answer is that circle is just a special case of ellipse. Therefore random state is ellipse and to get a perfect circular orbit would mean extraordinary circumstances. I hope I am correct.

Is there a limit to maximum temperature?

I mean what is temperature! It is the level of kinetic energy of particles ( this is what I was told in my physics class). Now speed of particles cannot exeed speed of light so the maximum temperture should also be limited........

Akbar sahib,

A very basic question, kindly explain if you have got some time to spare. Why are planets orbits elliptical and not exact circles. After all Kepler`s laws would be valid for perfect circles, no???

Regards

Re: # 53
1. Lorentz, in 1895, ten years before Albert Einstein formulated the Special Theory of Relativity in 1905, brought forward the idea of length contraction L = L0 Underroot 1-V2/C2, The Lorentz Contraction. He concluded that the Aether must have contracted their apparatus by that length calculated by the formula. Later on the conclusion was found to be wrong, but the calculation was found to be correct. The world had already entered into the age of relativity in 1895.

2. Hydrogen burns to form Helium, Helium burning produces Lithium, Lithium burning gives carbon, which in turn gives oxygen, Silicon, and so on. These processes are occuring in the Sun as well. In more massive stars, it goes upto Iron, when burning process halts suddenly, and there is no thermal expansion left to sustain the gravitational collapse. the star falls into itself!...and...rebounds!! The Supernova. I think this is the simplest way I can explain the mechanics of a Supernova. Deep inside Supernova, even Heavier elements like Gold, Platinum, and Uranium etc. are formed. The Sun and the Solar system are themselves formed from the remnants of a Supernova that happened billions of years ago. This explains the existence of heavier elements like Gold on Earth. This also explains why women sometimes burst into a Supernova...Gold is to be blamed which they wear!!

Dr. Muhammad Akbar Hussain Siddiqui
www.astronomer.zoomshare.com

Re: # 51

You mean to say that first discovery was made that speed of light is constant and then consequential theories like theory of relativity etc came about. Not the other way round i.e. first assumption was made that speed of light should be constant and then it was verified through experiments?

Can Helium also fuse into Helium and form heavier element?

Re: # 50
1. The speed of light is not `thought to be` but `is` constant, based on Michelson-Morley Experiment. The speed of light was measured in a fixed direction and six months later in the same direction, when, according to the Earth`s rotation around Sun, the apparatus was moving in the opposite direction than previously. But the speed of light was measured to be the same. One can read about this experiment in any good text book on physics.

2. The Moon`s rotation being exactly equal to its movement around its axis, is not a miracle. Since the moon is so small, and cooled so rapidly, the heavier core is not exactly in the centre, but is slightly shifted towards Earth, hence, the heavier part of the Moon keeps on `hanging` towards Earth, and this has `locked` and synchronized it revolution with its rotation. This is not only the case with Earth`s Moon, but with other moons like Io, Europa, Ganymede, Callisto, Triton, Charon etc. (I am not exactly sure about Titan).

3. All other elements in the Universe are thought to evolve from Hydrogen. Hydrogen fuses (`burns`) to form Helium, and its concentration is continuously increasing, though still, Hydrogen forms the overwhelmingly major fraction of all matter in the Universe.

4. The radius of an average black hole is expected to be something like 3-4 kilometers, may be less, may be more, but quite comparable to these dimensions.


Dr. Muhammad Akbar Hussain Siddiqui
www.astronomer.zoomshare.com

What would be the radius of event horizon of an average size black hole?

If stars burn hydrogen into helium then shouldn`t there be a lot of helium too in the universe?

Why doesn`t our moon spin or to be technically correct why is its period of orbit around earth exactly same as period of its rotation around its axis?