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  1. #21
    gswork's Avatar
    gswork Guest

    Default The Sun, in an Open Cluster



    "Thomas" <TMA1@yahoo.ca> wrote in message news:<48drc.2849$J02.1602@edtnps84>...

    That would make a nice target for an extrasolar probe. We'd need to
    figure on getting the probe capable of travelling up to around 50% of
    c thought, otherwise the travel period would be *sooo* long.

    Imagine a route that takes it to all three stars over a 10 year
    period, add the 4.5 years it takes to get signals back. I think that
    would be an amazing mission. not one for our lifetimes i guess...

    Some astronomers speculate that A & B may have rocky planets in their
    respective habitable zones, the calculations suggesting that the two
    stars wouldn't seriously peturb orbits closer to the star.

    As Star A is 1.1 times Sol's mass it's main sequence life time would
    be just around 8 billion years and star B has around 12 billion, if
    i'm following the mathematics right.

  2. #22
    Thomas's Avatar
    Thomas Guest

    Default The Sun, in an Open Cluster


    "> > My second goal when posting is to try not to embarrass myself when

    Sam is the judge of whether he should apologize NOT YOU.

    Apology accepted.

    Sam: Maybe you should have begun your answer with an introductory
    explanation of
    your idea. It makes for unambiguous communication. Something I strive for
    all
    the time.



  3. #23
    Ernie Wright's Avatar
    Ernie Wright Guest

    Default The Sun, in an Open Cluster

    Brian Tung wrote:


    You may already know this, but the Yale Bright Star Catalog lists both
    proper motion and radial velocity, along with position (of course) and
    parallax. It should be straightforward to get a cartesian vector from
    that.

    The initial position in spherical coordinates is

    P0 = (ra, dec, s)

    where s, the distance in parsecs, is 1 / parallax. The position after
    time t is

    P1 = (ra + pra, dec + pdec, s + v)

    where (pra, pdec) is the displacement due to proper motion and v is the
    displacement due to radial velocity. Convert P0 and P1 to rectangular
    coordinates and subtract to get the velocity vector (the displacement in
    rectangular coordinates over time t).

    - Ernie http://mywebpages.comcast.net/erniew


  4. #24
    Brian Tung's Avatar
    Brian Tung Guest

    Default The Sun, in an Open Cluster

    Ernie Wright wrote:

    Yes, but I was hoping not to have to do all that pesky work.

    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.txt

  5. #25
    Starry-Nite's Avatar
    Starry-Nite Guest

    Default The Sun, in an Open Cluster

    "Jeremiah J. Burton" <jburton@nospamhewittenergygroup.com> wrote in message news:<a51605754cd16be8707815112e416939@news.terane ws.com>...

    It is astronomically unlikely (sorry for the pun!) that ANY of our
    neighboring stars are kith and kin of the Sun. In the 4.7 billion
    years since the Sun's birth (current best estimate) the Sun has
    orbited the Galactic core ~20 times. Start with the initial stellar
    motions, factor in the gravitational doe-si-does that each member of
    the open cluster gives each of its neighbors as they are "born", add
    billions of years of being pushed by supernovas, include a few Milky
    Way / minor galaxy collisions, and consider the numerous huge gas
    clouds the Sun has sauntered through. The Sun may be surrounded by
    cousins, but its brothers and sisters are spread throughout the
    Galaxy.

    When considering the question of galactic motion, I recalled a ship in
    the Pacific that lost a container of tennis shoes in a storm. The
    rotation of the currents in the Pacific mimic the rotation of the
    stars about the galactic core. Many of the shoes washed up along the
    shores of the Pacific Northwest, where folks arranged swap meets to
    match shoes (color, size, style, L & R).

    Now consider the rotation of the Pacific over a century. Over a
    millennium. Over a million years. Islands have come and gone. The
    continents themselves have shifted. What is the chance a million
    years hence of finding two of the lost shoes on the same beach? After
    dozens of rotations the Pacific has done a pretty good job of
    shuffling the deck. Likewise, the Galaxy has thoroughly randomized
    the locations of the stars in the original open cluster of the Sun's
    birth.

    The European Southern Observatory (motto: "ESO. Astronomy made in
    Europe") recently released a study that investigated galactic motion.
    Here is the summary:

    "A team of astronomers from Denmark, Switzerland and Sweden [2] has
    achieved a major breakthrough in our understanding of the Milky Way,
    the galaxy in which we live.

    After more than 1,000 nights of observations spread over 15 years,
    they have determined the spatial motions of more than 14,000
    solar-like stars residing in the neighbourhood of the Sun.

    For the first time, the changing dynamics of the Milky Way since its
    birth can now be studied in detail and with a stellar sample
    sufficiently large to allow a sound analysis. The astronomers find
    that our home galaxy has led a much more turbulent and chaotic life
    than previously assumed."

    For a popular account, check out the CNN story at:
    http://www.cnn.com/2004/TECH/space/04/06/crazy.sun/

    The official press release, along with a WAY COOL animation
    demonstrating galactic rotation, is at:
    http://www.eso.org/outreach/press-re.../pr-08-04.html

    The full article, "The Geneva-Copenhagen survey of the Solar
    neighbourhood: Ages, metallicities and kinematic properties of ~14,000
    F and G dwarfs", by B. Nordström et al., is available in PDF format
    here:
    http://www.edpsciences.org/papers/aa...ses/aa0959.pdf

    The research is scheduled to be published in the European research
    journal Astronomy & Astrophysics:
    http://www.edpsciences.org/aa


    ¤ Clear skies & a star to steer by! >Michael ¤


  6. #26
    Jim's Avatar
    Jim Guest

    Default The Sun, in an Open Cluster

    Thomas <TMA1@yahoo.ca> wrote:


    Well, that's your opinion. Not mine however.

    Jim
    --
    Find me at http://www.ursaminorbeta.co.uk
    "Brace yourself, this might make your eyes water."

  7. #27
    Ernie Wright's Avatar
    Ernie Wright Guest

    Default The Sun, in an Open Cluster

    Starry-Nite wrote:


    Cool!

    The catalog based on the work described in this paper is also available
    for download:

    http://cdsweb.u-strasbg.fr/viz-bin/Cat?V/117

    - Ernie http://mywebpages.comcast.net/erniew


  8. #28
    Ernie Wright's Avatar
    Ernie Wright Guest

    Default The Sun, in an Open Cluster

    Brian Tung wrote:


    I was asked recently for a 3D model of the solar neighborhood, so I had
    most of the code I needed already.

    Comparing what I got today with the data Michael Foerster posted about,
    I got pretty good directions from the Yale data, but the magnitudes were
    off, by as much as a factor of 2, presumably because the parallaxes in
    Yale aren't as reliable. Pretty sure Yale predates Hipparcos.

    An interesting diversion, at least. UVW data is in fields 42-44 of the
    Nordstrom catalog. The summary page is

    http://cdsweb.u-strasbg.fr/viz-bin/Cat?V/117

    - Ernie http://mywebpages.comcast.net/erniew


  9. #29
    Starry-Nite's Avatar
    Starry-Nite Guest

    Default The Sun, in an Open Cluster

    > Start with the initial stellar motions, factor in the

    Serendipity... A few hours after my previous post I saw a new story in
    the journal Science on recent solar origin research , based on work at
    Arizona State by Jeff Hester.

    You can find the original news release at:
    http://www.asu.edu/asunews/research/...h_creation.htm

    It seems that the interstellar cloud that gave birth to the Sun was
    even more violent than expected. Using data from the Spitzer,
    Chandra, and Hubble space telescopes (Save The Hubble!), the team
    found that characteristics of the star forming nebula indicate that
    among our Sun?s brother and sister stars were a few giant stars.
    These giants first cooked the nebula with intense UV radiation, and
    then further shook up the neighborhood with supernova explosions.

    "People have long imagined that the Sun formed in (a) more quiescent
    type of environment," Hester noted, "but we believe that we have
    compelling evidence that this is not the case."

    It seems that we started in an even rougher neighborhood than first
    imagined. In regards to this thread, the original open cluster
    containing the Sun and its brethren was a short-lasting feature
    (relatively speaking).

    ¤ Clear skies & a star to steer by! >Michael ¤


  10. #30
    Starry-Nite's Avatar
    Starry-Nite Guest

    Default The Sun, in an Open Cluster

    > Start with the initial stellar motions, factor in the

    Serendipity... A few hours after my previous post I saw a new story in
    the journal Science on recent solar origin research , based on work at
    Arizona State by Jeff Hester.

    You can find the original news release at:
    http://www.asu.edu/asunews/research/...h_creation.htm

    It seems that the interstellar cloud that gave birth to the Sun was
    even more violent than expected. Using data from the Spitzer,
    Chandra, and Hubble space telescopes (Save The Hubble!), the team
    found that characteristics of the star forming nebula indicate that
    among our Sun?s brother and sister stars were a few giant stars.
    These giants first cooked the nebula with intense UV radiation, and
    then further shook up the neighborhood with supernova explosions.

    "People have long imagined that the Sun formed in (a) more quiescent
    type of environment," Hester noted, "but we believe that we have
    compelling evidence that this is not the case."

    It seems that we started in an even rougher neighborhood than first
    imagined. In regards to this thread, the original open cluster
    containing the Sun and its brethren was a short-lasting feature
    (relatively speaking).

    ¤ Clear skies & a star to steer by! >Michael ¤


 

 
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