Do all stars spin?

hi, excuse my ignorance and enlighten me as to:

Do all stars spin around their centre?
Do some stars . . . erm . . . wiggle around some off-centre spot?
What effect might such movement, if its possible, have on circling
bodies in its solar system?
What would be the effect, if any, if a star stopped spinning? (both to
itself and the circling bodies in its solar system?

Just curious and always willing to learn.
Thanks.

Yes, all stars rotate on their axes. Think of it as the residual angular
momentum of the nebula that formed them.

Whether a star spins or not generally has little affect on objects orbiting
it (the gravitation force between them is only dependent on their masses and
their separation). But lack of spin would mean no magnetic field and,
therefore, much less activity on the star's surface, in it's corona, and in
its solar wind. At least that's my guess.



"Bhads" wrote in message
...
hi, excuse my ignorance and enlighten me as to:

Do all stars spin around their centre?
Do some stars . . . erm . . . wiggle around some off-centre spot?
What effect might such movement, if its possible, have on circling
bodies in its solar system?
What would be the effect, if any, if a star stopped spinning? (both to
itself and the circling bodies in its solar system?

Just curious and always willing to learn.
Thanks.

To spin "off-center" as you put it, would require that the off-center spot
be the center of mass. For example, the lighter crust is a good deal thicker
on the far side. In effect, this places the center of mass somewhat
displaced from dead center. It is closer to earth. It remains that way
because the moon has cooled and semi-rigid. But in a star, there is not
rigidity. Even if you could reach in an yank the core over to one side, it
would drift back and it would be centered again.

If you had a rigid star with an off-center center of mass? The effects would
be very minimal. The planets rotate around the point that is the center of
mass of the star and the planet, which is still near the star's physical
center.

If it stopped spinning? That might be interesting. If we are correct, you
would no longer be generating the magnetic field, which affects quite a bit.
And, it would change some of convection, or mixing of different depths. This
would change the evolutionary sequence somewhat, but I'm not sure to what
degree.

Nice question

Clear Skies

Chuck Taylor
Do you observe the moon?
Try the Lunar Observing Group
http://groups.yahoo.com/group/lunar-observing/
************************************************** **********


"Bhads" wrote in message
...
hi, excuse my ignorance and enlighten me as to:

Do all stars spin around their centre?
Do some stars . . . erm . . . wiggle around some off-centre spot?
What effect might such movement, if its possible, have on circling
bodies in its solar system?
What would be the effect, if any, if a star stopped spinning? (both to
itself and the circling bodies in its solar system?

Just curious and always willing to learn.
Thanks.

On Sat, 17 Jan 2004 18:48:30 +0000, Bhads wrote:


Do all stars spin around their centre? Do some stars . . . erm . . .
wiggle around some off-centre spot? What effect might such movement, if

As far as I am aware, a wobbling star is one of the major hints
astronomers have of planets circling it.

"Bhads" wrote in message...
...

hi, excuse my ignorance and enlighten me as to:

Do all stars spin around their centre?
Do some stars . . . erm . . . wiggle around some off-centre spot?
What effect might such movement, if its possible, have on circling
bodies in its solar system?
What would be the effect, if any, if a star stopped spinning? (both to
itself and the circling bodies in its solar system?

Just curious and always willing to learn.
Thanks.

'Lo Bhads --

Scientists believe that stars can form by the condensing of
gases. As the gases come together and become more and
more dense, they tend to rotate faster and faster. This is a
conservation of angular momentum that is similar to when a
skater spins around and brings the arms closer and closer
to his or her body. This causes the skater to spin faster and
faster.

Now, suppose the condensing protostar (not yet a real star)
spins SO fast, that it starts throwing off great amounts of
materials mostly from its quickly moving equator. The more
material that is thrown off, the slower the protostar spins.
This would be because the momentum (angular) is being
imparted to the thrown off materials, which are spinning and
whirling around, bumping into each other and forming planets
and such.

These spinning planets grow and grow, and then one day the
protostar ignites. It becomes a "fusor," a true star. The new
star then starts blowing off a tremendous "stellar wind" made
of particles like protons and electrons. (We call this the "solar
wind" in our system.) This wind blows most of the smaller
materials in the equatorial disk far away, while the larger of
the materials remain behind and orbit the star.

These large materials can be big enough to cause the star to
wobble a bit depending upon how big they are compared to
the star. A planet like Jupiter would cause a large wobble
because the Sun and Jupiter revolve around a center of
gravity that is about 460,000 miles out from the center of the
Sun.

Each planet in our Solar System affects our Sun this way, but
to a lesser degree than Jupiter does. So the wobble or as
you call it, the wiggle, is *caused* by the planets orbiting the
star, and the movement is therefore very complex.

For a star to stop spinning is a difficult thing for me to see.
I have read that there are binary stars that are tidally locked
and spin around each other like Pluto and Charon do, always
with the same side facing each other. But they are still
rotating with the same period as they revolve around each
other. Our Sun doesn't rotate very fast because it gave up
nearly all of its spinning momentum to the planets and the
asteroids early on, possibly even before it actually became a
fusor.

So while a very slow-spinning and wobbling star would be a
good candidate to have a complex stellar system of planets,
it is hard for me to picture a star that has completely stopped
spinning. It seems to me to be a very unlikely state for a star
to be in. As some others have mentioned, the greatest
effects would be those on the star's magnetic field, and also
possibly a bad effect on any life that may have evolved in the
system.

happy days and...
starry starry nights!

--
Are you lonely?
Are you only one of many lonely ones?
We are only
Oh! so lonely for we tend the only suns.

Paine Ellsworth

Hi Bhads All objects spin in our universe. It is hypothesised some
blackholes don't spin(a weak theory) The word spin is best used for the
micro realm,and rotate for the macro. Mars rotates at a speed very close
to Earth. Jupiter is interesting for it rotates very fast. I wonder
why? Bert

Hey,
thanks for the replies, guys.

The reason I asked:
I was imagining a scenario where the distance between solid planets
and their sun might have enough gravitational variation to constantly
churn the geography of the circling planets; constant volcanic
eruptions, shifting land masses, rising and falling mountains, lava
flowing in fresh cracks, etc. Perhaps such a sight might exist in a
binary system, if planets could form and survive in a safe orbit in
such a place?

Cheers.

The reason I asked:
I was imagining a scenario where the distance between solid planets
and their sun might have enough gravitational variation to constantly
churn the geography of the circling planets; constant volcanic
eruptions, shifting land masses, rising and falling mountains, lava
flowing in fresh cracks, etc. Perhaps such a sight might exist in a
binary system, if planets could form and survive in a safe orbit in
such a place?

Take a look at Io to see this in action. To do this requires the planet be
very close so the difference in gravitational attraction differs from one
side of the planet to the other. Not quite Roche limit, but you get the
idea.

Clear Skies

Chuck Taylor
Do you observe the moon?
Try the Lunar Observing Group
http://groups.yahoo.com/group/lunar-observing/

************************************

In Io's case (and it is the most volcanically active object in the solar
system), I don't think it's so much the tidal action of Jupiter alone as the
continual tug of war between Jupiter on one side and the other Galilean
moons on the other.


"Chuck Taylor" wrote in message
...
The reason I asked:
I was imagining a scenario where the distance between solid planets
and their sun might have enough gravitational variation to constantly
churn the geography of the circling planets; constant volcanic
eruptions, shifting land masses, rising and falling mountains, lava
flowing in fresh cracks, etc. Perhaps such a sight might exist in a
binary system, if planets could form and survive in a safe orbit in
such a place?

Take a look at Io to see this in action. To do this requires the planet be
very close so the difference in gravitational attraction differs from one
side of the planet to the other. Not quite Roche limit, but you get the
idea.

Clear Skies

Chuck Taylor
Do you observe the moon?
Try the Lunar Observing Group
http://groups.yahoo.com/group/lunar-observing/

************************************

"Bhads" wrote in message
...
hi, excuse my ignorance and enlighten me as to:

Do all stars spin around their centre?

Of course, but center is very subjective term and can be defined as center
of spin.... And spin can be once every few billion years...


Do some stars . . . erm . . . wiggle around some off-centre spot?

All does that, i suspect most undetectably small though. Think of this way,
earth with all the mountains etc. are smoother than just about smoother than
any common man made things if you scale.

What effect might such movement, if its possible, have on circling
bodies in its solar system?

Depends on how big such wiggle is. I doubt it has much impact though since
wiggle is probably around center You can think of jupitor as part of
sun and even such huge wiggle has minimal impact. Remember that we can
barely detect planets outside of our solar system.

What would be the effect, if any, if a star stopped spinning? (both to
itself and the circling bodies in its solar system?

Anything.... Basically it take act of god so anything it wishes.
Remember, if it spins once per few billion years it is still spinning.
Also imagine basket ball dropped from 100 feet and keep on bouncing and
never move rather than slightly roll toward end.


Just curious and always willing to learn.
Thanks.