Sun's rotational speed

Greetings.

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
orbits?

Regards,
Tristan

--
_
_V.-o Tristan Miller [en,(fr,de,ia)] Space is limited
/ |`-' -=-=-=-=-=-=-=-=-=-=-=-=-=-=-= In a haiku, so it's hard
(7_\\ http://www.nothingisreal.com/ To finish what you

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

Greetings.

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 orbits?

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

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

Greetings.

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 orbits?

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

Tristan Miller wrote in
:

Greetings.

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 orbits?


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
guess.


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.



Regards,
Tristan

Tristan Miller wrote in
:

Greetings.

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 orbits?


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
guess.


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.



Regards,
Tristan

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
...
Greetings.

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
orbits?

Regards,
Tristan

--
_
_V.-o Tristan Miller [en,(fr,de,ia)] Space is limited
/ |`-' -=-=-=-=-=-=-=-=-=-=-=-=-=-=-= In a haiku, so it's hard
(7_\\ http://www.nothingisreal.com/ To finish what you

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
...
Greetings.

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
orbits?

Regards,
Tristan

--
_
_V.-o Tristan Miller [en,(fr,de,ia)] Space is limited
/ |`-' -=-=-=-=-=-=-=-=-=-=-=-=-=-=-= In a haiku, so it's hard
(7_\\ http://www.nothingisreal.com/ To finish what you