dear shahrzad
No problem you are free! and your exams are more important than this
& i will try to find this book and say you about it
dear shahrzad
No problem you are free! and your exams are more important than this
& i will try to find this book and say you about it
dear shahrzad
If you want to read this book free you can go to this page: [ برای مشاهده لینک ، با نام کاربری خود وارد شوید یا ثبت نام کنید ]
Hi Dears:
I ‘m a new member and… I’m interested in astronomy and I thought maybe you are interested in astronomy too so I choose this article for you (from Hubble site):
How can a star become a black hole?
A star shines because its center is so hot and dense that hydrogen nuclei fuse together, creating tremendous energy. It lives for millions or billions of years while the inward pull from its own gravity is balanced by the outward pressure from nuclear fusion. Its life ends when the nuclear fuel has been used up. First the star swells, brightens and cools to become a red giant. Then it collapses into a compact stellar remnant, much smaller than our Sun but of similar mass.
Stars less than eight times heavier than the Sun die relatively peacefully. The outer layers are shed in a stellar wind, making the star temporarily visible as a planetary nebulae. The remnant is about the size of the Earth and is called a white dwarf. Heavier stars die in a spectacular supernova explosion. If the star was moderately heavy, the remnant is a neutron star: a dense ball of neutral elementary particles, squeezed into a space little more than 10 miles across. Extremely heavy stars (more than 25 times heavier than the Sun) have no means to withstand their own gravity as they die. They collapse completely to a black hole.
We can see examples of the life cycle of stars all around us in the sky. Our own Sun is a fairly typical medium-sized middle-aged star. The star Betelgeuse is a well-known red giant. Planetary nebulae and supernova remnants can both be spectacular sights, even through a small telescope. Good examples are NGC 7027 and the Crab nebula, respectively. Albireo is an example of a binary star system in which two stars orbit around each other. More than half of all stars live in such systems. If one of the stars in such a binary system evolves into a black hole, then the system can sometimes be observed as a bright X-ray source. In our own Milky Way galaxy this is the case for example in Cygnus X-1. More examples can see in other nearby galaxies, such as in M33
Thank you dear parnyan it was great! you are welcome hear
we are enjoy it & i hope read more about it from you
hi again my friends
now i am going to put another poem for you.have fun.
TO THE RIVER --
by Edgar Allan Poe
Fair river! in thy bright, clear flow
Of crystal, wandering water,
Thou art an emblem of the glow
Of beauty- the unhidden heart-
The playful maziness of art
In old Alberto's daughter;
But when within thy wave she looks-
Which glistens then, and trembles-
Why, then, the prettiest of brooks
Her worshipper resembles;
For in his heart, as in thy stream,
Her image deeply lies-
His heart which trembles at the beam
Of her soul-searching eyes.
Dear shahrzad I know that this thing that i want to say has not any depends on English forums but i soddenly find out that you want to know more about Linux and Learning C++ so i want to say that if you want to have best "original" Linux you should choose Ubuntu if you want to have it for free! you can go to this address and register your name and address and number of cd and i promise you will get it free! and if you cant do this i can send you an original licensed Version free just send me your address because i am the ubuntu X developer
manager in Iran ..thanks
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Hi Dears
i found another article for you & i hope it was useful
Orion (astronomy)
Orion (astronomy), constellation located on the celestial equator east of Taurus. It is oblong, with three stars in line near its centre. It is represented on pictorial charts as the figure of Orion, the hunter in Greek mythology, standing with uplifted club. Three bright stars represent his belt and three fainter stars aligned south of the belt represent his sword. Alpha () Orionis, or Betelgeuse, is located in the left corner of the oblong, corresponding to Orion's shoulder. Beta (β) Orionis, or Rigel, is diagonally opposite Betelgeuse. A faint, misty patch surrounding the three stars marking Orion's sword is revealed in long-exposure photographs made with powerful telescopes as a spectacular mass of bright and dark gas and dust, many hundreds of light years across, in which stars are being born.
Hercules (astronomy)
Hercules (astronomy), large constellation of the northern hemisphere, lying between Lyra and Corona Borealis. Hercules is best seen during the summer. It is represented by the figure of the Greek hero Hercules in a kneeling position. The stars of the constellation are of third magnitude or dimmer. Hercules contains a globular cluster, called Messier 13, consisting of more than 50,000 stars. This cluster, about 34,000 light years from the Earth, can be seen by the naked eye
hi dear parnyan, I think the topic u should send post like these is here:
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Hi dears
next to this i will put VOA (Voice Of America) the Americas special English news! and the worlds most good known musics in English
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