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  1. #1
    canopus56's Avatar
    canopus56 Guest

    Default Evolution of globular clusters - new article in Astronomy magazine



    There is an interesting article in the May issue of Astronomy magazine
    that appeared on my local newstand yesterday:

    Reddy, Francis. May 2005. Stellar archaeology. Astronomy 33(5):34-39.


    Informal abstract: Reddy reviews current journal thinking about the
    formation and disintegration of globulars. As globulars pass through a
    galactic disk, stars are stripped off their outsides. After repeated
    orbits, this process eventually dissolves the globular. As a globular
    passes through a galactic disk, it propagates shock waves in gas in a
    galactic disk that can initiate creation of new open clusters.
    Globular clusters are created within galaxies by the same processes
    that makes open clusters, but are larger. The population of globular
    clusters in a galaxy also can be increased by galaxies merging and
    passing. One galaxy strips the globulars out of the spherical halo of
    the other galaxy. These process es of death, creation and accretion are
    one explanation for the bell shaped age distribution of old globulars
    in the Milky Way galaxy. Globulars in our Milky Way are older than 6
    billion years and may represent an older age and size continuum of
    younger and smaller open clusters.

    This issue and well-written article are worth checking out.

    - Canopus56


  2. #2
    Anthony Ayiomamitis's Avatar
    Anthony Ayiomamitis Guest

    Default Evolution of globular clusters - new article in Astronomy magazine

    I also REALLY enjoyed their article on M101. Now, if they could keep
    this up each and every month, I will be a very happy camper.

    Anthony.

    canopus56 wrote:



  3. #3
    Starlord's Avatar
    Starlord Guest

    Default Evolution of globular clusters - new article in Astronomy magazine

    It will not show up on the supermarket stand here until May 1st.

    "canopus56" <canopus56@yahoo.com> wrote in message
    news:1112913299.204945.78860@o13g2000cwo.googlegro ups.com...



  4. #4
    RichA's Avatar
    RichA Guest

    Default Evolution of globular clusters - new article in Astronomy magazine

    On 7 Apr 2005 15:34:59 -0700, "canopus56" <canopus56@yahoo.com> wrote:


    Does that mean that open clusters as they age somehow produce more
    stars and condense?
    -Rich

  5. #5
    canopus56's Avatar
    canopus56 Guest

    Default Evolution of globular clusters - new article in Astronomy magazine

    RichA wrote:

    The article doesn't say that; it's probably my poorly written summary.
    -

    Because globulars have several orders of magnitude more mass and more
    stars than open clusters, I do not know, but would suspect that the
    process by which globulars dissolve and open clusters disperse is
    fundamentally different.

    In globulars, gravitational tidal interactions tend to sift "heavier"
    binaries to the glob's center and relatively lighter single stars move
    to the outside. To use a poor analogy, the large peanuts in a can of
    Planters are sifted by gravity to the bottom of the can. At the edge of
    the globular sphere, these relatively lighter stars are then more
    likely to be "evaporated" into the galactic disk during gravitational
    interactions during the globular's transit of the disk on the next
    orbit.

    In smaller galactic open clusters, the graviational mass and attraction
    is lower. IMHO, stars on the exterior of the cluster would simply be
    more suspectible to being stripped away by encounters with nearby
    clouds and stars, without any sifting mechanism going on.

    - Canopus56


  6. #6
    canopus56's Avatar
    canopus56 Guest

    Default Evolution of globular clusters - new article in Astronomy magazine

    P.S. to RichA.

    No, because the shock wave mechanism that initiates the formation of
    new stars occurs when a large globular orbits out of the spherical halo
    and transits the gas rich galactic disk. The shock wave mechanism would
    be similar to high velocity molecular clouds.

    Open clusters travel inside the galactic disk and do not generate that
    kind of shock wave.

    - Peace - Canopus56


  7. #7
    canopus56's Avatar
    canopus56 Guest

    Default Evolution of globular clusters - new article in Astronomy magazine

    X-No-archive: yes
    Anthony Ayiomamitis wrote:

    Ditto. The M101 group is a very cool place. - Canopus56
    http://www.anzwers.org/free/universe/galgrps/m101.html


 

 

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