Banner
    Saturday in Space: Stellar Gas
    By Bente Lilja Bye | March 2nd 2013 01:40 PM | 7 comments | Print | E-mail | Track Comments
    About Bente Lilja

    Earth science expert and astrophysicist writes about Earth observation, geodesy, climate change, geohazards, water cycle and other science related...

    View Bente Lilja's Profile
    Gas looks so pretty in space, don't you agree?

    This particular stellar gas is named planetary nebula ESO 456-67 . Do not get the wrong idea reading 'planetary'. This celestial object has nothing to do with planets. Back in the days when telescopes provided less resolution than the ones we have today, it looked pretty small and hence was named planetary nebulae (as opposed to the bigger stars). What it really is, are shells with gas after stars fling them off towards the end of their lives. Check out the lives of stars here in the Hertzprung-Russell diagram. What is left after the star got rid of this gas is a small dense white dwarf.

    It is quite lovely, really.

    Planetary nebula ESO 456-67
    Planetary nebula ESO 456-67. Credit: ESA/Hubble&NASA. Acknowledgement: Jean-Christophe Lambry

    Comments

    MikeCrow
    The Helix Nebula


    The Crab Nebula


    M8 and M20
    Never is a long time.
    rholley
    Looking at M20 on the left, one sees the reddish emission nebula and the blue reflection nebula next to it.

    http://apod.nasa.gov/apod/ap090707.html
    Robert H. Olley / Quondam Physics Department / University of Reading / England
    MikeCrow
    They spent a lot more on their telescope and camera than I did on mine :)
    Never is a long time.
    MikeCrow
    Actually it's not the Helix Nebula, but the aptly named Dumbbell Nebula.
    Never is a long time.
    rholley
    The story of ‘Nebulium’ is quite interesting.

    Because the gas in the planetary nebulae is so rarefied, atoms can go minutes or more before colliding with another atoms.  This allows time for the ‘forbidden’ transitions to occur, so that the astronomers thought they were observing a new element.
    Robert H. Olley / Quondam Physics Department / University of Reading / England
    MikeCrow
    It's so rare, that if you were right there, your eyes would not see it as they appear in those images.
    Never is a long time.
    Atoms can go minutes or more before colliding with another atoms.  This allows time for the ‘forbidden’ transitions to occur, so that the astronomers thought they were observing a new element.


    Yes the forbidden line(O III) of O2+. I guess atoms are like people in that they can do odd things when going a long time without encounters. :)


    Other forbidden transitions occurring in low density plasmas include N II, SII and another one from oxygen,  OII.