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  1. #1
    Tristan Miller's Avatar
    Tristan Miller Guest

    Default Sun's rotational speed


    According to Wikipedia, the star Altair "is most notable for its extremely
    rapid rotation; by measuring the width of its spectral lines, it was
    determined that its equator does a complete rotation in about 6 1/2 hours.
    In comparison, our star, the Sun, requires a little more than 25 days for a
    complete rotation."

    I wonder, would there be any observable effects to us here on earth if our
    sun started rotating at this speed? Would a significantly faster rotation
    affect the sun's appearance, or the earth's temperature, or planetary


    _V.-o Tristan Miller [en,(fr,de,ia)] >< Space is limited
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  2. #2
    Gautam Majumdar's Avatar
    Gautam Majumdar Guest

    Default Sun's rotational speed

    On Mon, 22 Sep 2003 14:27:11 +0100, Tristan Miller wrote:

    A very fast rotating star would become fatter at the equator, i.e., get an
    oblate shape. This has been observed for Achermer (alpha Eridani) &
    Altair. See : MacRobert A, The flattest star, Sky & Telescope (September)
    2003; 106 (3): 20


    Gautam Majumdar

  3. #3
    Llanzlan Klazmon The 15th's Avatar
    Llanzlan Klazmon The 15th Guest

    Default Sun's rotational speed

    Tristan Miller <> wrote in

    The sun would be a lot more oblate if it was rotating at that speed. That
    would result in more enhanced advance of the perihelions of the planetary
    orbits, especially Mercury's. Other than that you would have to look at
    detailed models. e.g the solar activity cycle is thought to be driven in
    part by the sun's differential rotation (i.e it doesn't rotate as a solid
    body). If the overall rotation rate was much higher it would probably
    result in some differences to the activity cycle but that is just a

    The point is moot, since you have conservation of angular momentum, the
    sun isn't going to suddenly speed up. The stars with high rates of
    rotation would have formed that way.

    Rgds Llanzlan.

  4. #4
    onegod's Avatar
    onegod Guest

    Default Sun's rotational speed

    It may or may not be possible for OUR sun to spin that fast, it probably
    depends on mass.
    For example pulsar can spin once per second.

    I suspect any visibly noticable shape change (ie lets say 5%) would make sun
    unstable and perhaps planet can come out from it.

    Anyway, chances are faster spin create bigger solar flair as well as more
    magnitism. Also more nuclear reaction.

    "Tristan Miller" <> wrote in message

  5. #5
    Painius's Avatar
    Painius Guest

    Default Sun's rotational speed

    "Llanzlan Klazmon The 15th" wrote in message... news:Xns93FF6EC0732AFLlanzlanLlurdiaxorbn@203.97.3 7.6...

    Interesting thought arises here, Llanzlan... while some
    high rates of stellar rotation might be brought about by
    collisions, most by far would be, as you say, from when
    the star was formed.

    Now since our Sun, while possessing nearly all the
    mass of our Solar System, has given up nearly all of its
    original angular momentum to the planets and other
    bodies in orbit around it...

    and since due to sunspots on other stars (starspots),
    astronomers are learning that some previously found
    exoplanets don't exist, and that the spectral shifting
    was caused by the rotation of the star...

    i'm wondering if a connection has been found between
    the rotational period of a star and the presence of a
    system of planets around the star? It may be possible
    that a fast-spinning star that has a lot of angular
    momentum would be a poor suspect, while a relatively
    slow-spinning star would be more apt to possess a
    system of orbiting bodies?

    happy days and...
    starry starry nights!

    Gaia shadow come November,
    Does this bode well for December?
    Moon aglow as I remember,
    Tremble, tremble glowing ember,
    Seems my life's a severed member.

    Paine Ellsworth



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