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  1. #1
    Magnificent Universe's Avatar
    Magnificent Universe Guest

    Default BREAKING NEWS: Andromeda X--Andromeda's Newest Satellite Galaxy



    The discovery of a new galaxy orbiting Andromeda gives a boost to the
    leading theory of galaxy formation, say astronomers in Europe and the United
    States. The new galaxy, named Andromeda X, is the dimmest satellite galaxy
    ever seen around Andromeda. For the full story, including a
    never-before-published color image of the new galaxy, see
    http://KenCroswell.com/AndromedaX.html .

    Other recent stories:
    Most Stars Are Single (January 19, 2006):
    http://KenCroswell.com/MostStarsAreSingle.html .
    The Cosmic Origin of Carbon (January 11, 2006):
    http://KenCroswell.com/OriginOfCarbon.html .
    The Tenth Planet's First Anniversary (January 5, 2006):
    http://KenCroswell.com/TenthPlanetFirstAnniversary.html .
    Pulsar at the Galactic Center? (January 3, 2006):
    http://KenCroswell.com/G359.html .
    The Three Moons of Pluto (December 21, 2005):
    http://KenCroswell.com/PlutoMoons.html .
    The First Direct Distance to Andromeda (November 4, 2005):
    http://KenCroswell.com/AndromedaDistance.html .

    Correct email: MagnificentUniverse "at" yahoo "dot" com.



  2. #2
    Rich's Avatar
    Rich Guest

    Default BREAKING NEWS: Andromeda X--Andromeda's Newest Satellite Galaxy

    On Sun, 29 Jan 2006 20:34:19 -0800, "Magnificent Universe"
    <MagnificentUniverse@yyyyy.com> wrote:


    I hate when they compare absolute magnitudes of stars to extended
    objects, it means NOTHING as far as visibility is concerned. Does
    anyone know what the dimmest absolute magnitude star is that can be
    seen with our current telescopes at the distance of the Andromeda
    galaxy? If stars need to be absolute magnitude -7 or something to be
    visible at all from Andromeda, it's no wonder there are possible
    invisilble companion galaxies there.
    -Rich

  3. #3
    Brian Tung's Avatar
    Brian Tung Guest

    Default BREAKING NEWS: Andromeda X--Andromeda's Newest Satellite Galaxy

    Rich wrote:

    The distance modulus for M31 is about 24.5, give or take. So if you're
    talking about actually seeing it visually through an amateur-class
    telescope, even a large one, you probably are limited to stars that are
    absolute magnitude -7 or brighter. But for detection in images, we
    can obviously see stars much dimmer than that. With something like a
    Hubble Deep Field, you could see stars down to around sixth magnitude
    or so, absolute magnitude.

    Now, for purposes of detecting a galaxy, you need not detect the stars
    to see the galaxy, especially if the galaxy is far enough away that you
    don't resolve the individual stars.

    --
    Brian Tung <brian@isi.edu>
    The Astronomy Corner at http://astro.isi.edu/
    Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
    The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
    My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.html

  4. #4
    Stupendous_Man's Avatar
    Stupendous_Man Guest

    Default BREAKING NEWS: Andromeda X--Andromeda's Newest Satellite Galaxy


    Brian Tung wrote:


    In this particular case, of course, the problem is that
    the galaxy IS so close that we can and do resolve the
    individual stars. That's one of the reasons it's so hard
    to find dwarf galaxies in the Local Group: they only
    appear when one looks in big catalogs of stars for
    small regions of slightly higher stellar density ....

    Michael Richmond


 

 

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