Astronomy A Closer look: Planetary Nebula

Discussion in 'Astronomy' started by Mizar, Dec 7, 2004.

  1. Mizar

    Mizar Premium Member

    When stars in the size range from 1- 12 times that of the sun Begin to "die" they begin to eject meterail and gas from themselves into space. They may continousily blow off as much as 1/4 of the stars entire mass in a constant expeling of gas. Over thousands of years the star slowly begins to decay. As is sheds off more and more gas a large cloud of gas begins to form around the star. Depending on what elements are in the gas the color of the cloud may vary. As the star releases more and more gas the shell/ cloud becomes more and more complex. As the star ages and sheds more mass it begins to shrink into geneally a white dwarf. The star is about the size of a large planet. There are so far 1,500 planetary nebulas to be cataloged today in our area of the MIlky Way galaxy

    The name planetary nebula has nothing to do with planets in all actuality. When viewed in a telescope most planetarys appear to be small circles of blue or green dim light. This description is similar to what William Herschel saw when veiwing Uranus and Neptune in a telescope. He named them planetary nebulas out of that idea.

    It is believed that most planetary nebulas visible are young by astronomical standards. One generally lasts about 1000 years. This is most likely so because as the gas shell expands into space it looses a light source and the gas can no longer be visible. It has even been seen over the course of a year or so a planetary nebula actually evolve. The typical planetary nebula gas cloud is about 1/4 to 1 light year wide.

    some famous planetary nebula are
    The ring nebula in Lyra (M57)
    The dumbell in Vulperula (M27)
    The helix (NGC7293)
    The snowball in Andromeda (NGC7662)
    The Eskimo in Gemini (NGC2392)
    (search the numbers ie M57 in a search engine to veiw a picture of each-or look at the above banner-they are in the order listed here left to right)

    Here is a captured evolution of a planetary nebula.