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موضوع: Black Holes

  1. Top | #1
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    Post Black Holes

    hello my friends and dear astronomers

    we will speak about blackhole and its news in this topic

    if you have any question or any idea about the blackhole please share it


    ویرایش توسط stargazer : 02-17-2012 در ساعت 12:48 PM

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  3. Top | #2
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    of course i know that all of you are familier with blackhole's concept and its extraordinary traits
    but i have a question of you ?
    in your idea, a blackhole can has a distance ?!!
    for example you can measuring high and width of a thing !!!
    can you do it for a lovely blackhole ?

    ویرایش توسط stargazer : 02-17-2012 در ساعت 12:09 PM دلیل: Correcting Grammar points,replacing words

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  5. Top | #3
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    !!!!!!!!!!!Hi there
    Dear x-blackhole , I think u should give us some primary information about definition of blackholes at first
    But it doesn't matter I explain it & give an introduction of blackholes
    ویرایش توسط planetstruck : 04-11-2011 در ساعت 10:13 AM

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  7. Top | #4
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    ?What is a blackhole

    Most people think of a black hole
    as a voracious whirlpool in space, sucking down everything around it. But that’s not
    really true! A black hole is a place where gravity
    has gotten so strong that the escape velocity is faster
    than light. But what does that mean, exactly?

    A black hole is formed when a star of sufficient mass undergoes gravitational collapse, with most or all of its mass compressed into a ufficiently small area of space, causing infinite spacetime curvature at that point (a "singularity"). Such a massive spacetime curvature allows nothing, not even light, to escape from the "event horizon," or border.
    Black holes have never been directly observed, though predictions of their effects have matched observations.


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  9. Top | #5
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    How do black holes form


    The most common way for a black hole to form is
    probably in a supernova, an exploding star. When a star
    with about 25 times the mass of the Sun ends its life, it
    explodes. The outer part of the star screams outward
    at high speed, but the inner part of the star, its core,
    collapses down. If there is enough mass, the gravity of
    the collapsing core will compress it so much that it can
    become a black hole. When it’s all over, the black hole
    will have a few times the mass of the Sun. This is called
    a “stellar-mass black hole”, what many astronomers
    think of as a “regular” black hole.
    What happens when you fall into a black hole?
    If you fall into a black hole, you’re doomed. Sure, once you fall in you can never get
    back out, but it turns out you’ll probably be dead before you get there.
    The gravity you feel from an object gets stronger the closer you get. As you approach a
    stellar-mass black hole feet-first, the force of gravity on your feet can be thousands of times
    stronger than the force on your head! This has the effect of stretching you, pulling you apart like
    taffy. Tongue-in-cheek, scientists call this “spaghettification.” By the time you reach the black hole,
    you’ll be a thin stream of matter many miles long. It probably won’t hurt though: even falling from
    thousands of kilometers away, the entire gory episode will be over in a few milliseconds

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  11. Top | #6
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    نقل قول نوشته اصلی توسط planetstruck نمایش پست ها
    !!!!!!!!!!!Hi there
    Dear x-blackhole , I think u should give us some primary information about definition of blackholes at first
    But it doesn't matter I explain it & give an introduction of blackholes
    of course it's a resume of blackhole's definition
    A black hole is a region of space from which nothing, not even light, can escape. It is the result of the deformation of spacetime caused by a very compact mass. Around a black hole there is an undetectable surface which marks the point of no return. This surface is called an event horizon. It is called "black" because it absorbs all the light that hits it, reflecting nothing, just like a perfect black body in thermodynamics.[1] Quantum mechanics predicts that black holes also emit radiation like a black body with a finite temperature. This temperature decreases with the mass of the black hole, making it difficult to observe this radiation for black holes of stellar mass.

    Despite its invisible interior, a black hole can be observed through its interaction with other matter. A black hole can be inferred by tracking the movement of a group of stars that orbit a region in space. Alternatively, when gas falls into a stellar black hole from a companion star, the gas spirals inward, heating to very high temperatures and emitting large amounts of radiation that can be detected from earthbound and Earth-orbiting telescopes.

    Astronomers have identified numerous stellar black hole candidates, and have also found evidence of supermassive black holes at the center of galaxies. In 1998, astronomers found compelling evidence that a supermassive black hole of more than 2 million solar masses is located near the Sagittarius A* region in the center of the Milky Way galaxy. Recent results indicate that the supermassive black hole is more than 4 million solar masses.


    and if u want to catch more information go to :
    http://en.wikipedia.org/wiki/Black_hole
    ویرایش توسط planetstruck : 04-11-2011 در ساعت 10:14 AM دلیل: Correcting Grammar points,replacing words

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  13. Top | #7
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    U can open this file there are pics on it of blackholes..but u konw i think they aren't real
    فایل های پیوست شده فایل های پیوست شده

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  15. Top | #8
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    I want to take the first picture of a black hole

    07 February 2012 by Jon White

    __________________________________________________ ___________________________________

    Images of a black hole could test general relativity as well as prove they exist, says astronomer Dan Marrone *



    [Marrone and his team are hoping to take the first picture of a black hole in 2015 (Image: Jorge Vieira)]

    A black hole, by definition, is black. So how are you going to take a picture of one?


    If you look right at the black hole it should look quite dark, as very little light escapes. But just around the edge of it you see a bright ring, which is due to the photons that barely missed going into the black hole and skimmed around the edge of it a couple of times. This light is what we think we will be able to detect with the
    Event Horizon Telescope (EHT).

    The EHT is a "whole Earth telescope". How does it work?

    In radio astronomy, to get a higher resolution than you can from a single telescope, you record signals from many telescopes around the world and multiply them together with a special computer. It is as if you have a single telescope almost the size of the Earth.

    Which black holes are you targeting?

    Sagittarius A*, which is the supermassive black hole at the centre of our galaxy, and the black hole at the centre of M87, the biggest galaxy in the Virgo cluster of galaxies. With a telescope the size of the Earth and at the frequencies we are observing, we can just make out black holes of this size.

    Every image of a black hole so far has been an artist's impression. Will the real thing match expectations?

    The question of creating an image from what we measure is a tricky one. We will most likely represent it as a false colour image, using colours to represent how bright the light is. This image will not be as pretty as an artist's impression. The galaxy blurs the light between us and the black hole, so there are a lot of sharp features we can't possibly see. But any image we get shouldn't disappoint - we are looking at something no one has ever seen before.

    What about capturing a moving image - "black hole, the movie" as it were?

    We can, if there is something orbiting the black hole, as we expect there will be. If there is gas orbiting before it falls into the black hole, this takes between 4 and 27 minutes, depending on the spin of the black hole. If we look for several days and see changes in the structure, we can represent that as a movie as well.

    What are you hoping to learn from this image?

    Just being able to take a picture of a black hole, and show this shadow that we expect to be there because the light is not escaping, will be important. Beyond that we have a lot to learn about the structure of our galaxy's black hole, and what happens to a black hole when it is being starved of material, as Sagittarius A* appears to be.

    We also expect to be able to test
    general relativity, which tells us that the ring of light around the edge of the black hole needs to be perfectly circular. If general relativity is breaking in this very strong field regime, where gravity is at the limits of its power, then this ring of light won't be perfectly circular.

    *(Profile: Dan Marrone is an astronomer at the University of Arizona Steward Observatory. He is part of the Event Horizon Telescope programme, inaugurated last month, which aims to take the first picture of a black hole in 2015)

    From: NewScientist

    امضای ایشان
    برگ در انتهاي زوال مي افتد و ميوه در ابتداي کمال … بنگر که چگونه مي افتي ؟!

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  17. Top | #9
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    I think one of the best objects in the universe are black holes In the past I was afraid of the black hole but when I realized that After the death of stars, black hole is create I've changed my opinion because it's very exciting and I think imaginable
    this is link of short clip about black hole:
    http://www.faupload.com/upload/90/Ba...ing-a-star.flv

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  19. Top | #10
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    Black Holes         
    And there is another text by Clay Dillow which posted on 02.16.2012 , about :

    "How to take a picture of a black hole"


    ALMA Prototype Radio Antennas ALMA (ESO/NAOJ/NRAO)

    You can check it here too: http://www.popsci.com/technology/art...ure-black-hole
    امضای ایشان
    برگ در انتهاي زوال مي افتد و ميوه در ابتداي کمال … بنگر که چگونه مي افتي ؟!

  20. 5 کاربر مقابل از stargazer عزیز به خاطر این پست مفید تشکر کرده اند.


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