Freethought & Rationalism Archive

Quetzal · 12-30-2001, 09:48 PM

Quote:

Originally posted by RufusAtticus:
Morpho,
Very good post.
Except I think you mean centripetal force and not centrifugal force.
<a href="http://www.pbs.org/tal/racecars/petlfugl.html" target="_blank">http://www.pbs.org/tal/racecars/petlfugl.html</a>-RvFvS

Rufus: Thanks. You're absolutely right. Centripetal force is the correct term. I actually debated which term to use, then decided - since I was writing something "popular" (LOL) - that I would use a term that most people, including Peanut (my daughter's nickname), would be familiar with. Centrifugal is one of the most widely used (and misused) terms in physics...Probably guilty of perpetuating a error, but what can I do?

RufusAtticus · 12-30-2001, 10:52 PM

You could put a disclaimer on it next time.

-RvFvS

Tim Thompson · 12-31-2001, 11:36 AM

The key point of Morpho's model is that the theory of star formation produces two big observational details: (1) protostars are surrounded by dusty disks, and (2), protostar formation creates fast jets of ionized gas, along the rotation axis. This theory dates back to the 50's or so, but has been strongly supported since then by images from the <a href="http://hst.stsci.edu/" target="_blank">Hubble Space Telescope</a>.

<a href="http://oposite.stsci.edu/pubinfo/PR/95/45.html" target="_blank">Disks in the Orion Nebula</a>.
<a href="http://oposite.stsci.edu/pubinfo/PR/94/24.html" target="_blank">Proplyds in the Orion Nebula</a>.
These links will take you to images that clearly show the flattened dust disks, both face on & edge on, as previously predicted by the theory of star formation. Since star formation almost always produces such disks, it is commonly believed amongst astronomers that planetary systems must be fairly common.

<a href="http://oposite.stsci.edu/pubinfo/pr/95/24.html" target="_blank">The Fire and Fury of Stellar Birth</a>.
This link leads to images of what are called Herbig-Haro objects, dust clouds complete with the axial jets that theory also predicts. Perhaps most revealing is <a href="http://oposite.stsci.edu/pubinfo/jpeg/HH30.jpg" target="_blank">the image of HH30</a>, which shows that the jet is really moving, and shows the shape of the dust disk much better than other images. The curved shape of the disk edge can be calculated from theory, but the new HST images observe that shape more precisely than theory can as yet predict it. Hence, the theory can be calibrated by the observed shapes.

<a href="http://oposite.stsci.edu/pubinfo/PR/95/44.html" target="_blank">Star Birth in M16</a>.
The images here are not as revealing as the others, but have their own value. These images detail the environment where we expect star formation to occur. I like the illustration of "eggs". These dense dust knots hide protostars from visible (eye-ball) observing, but the protostars can be seen in infrared (which is more heat sensitive), and at longer sub-millimeter wavelengths.

The point here, at least for me, is that star formation & planetary system formation are not just simple guess work, as too many creationists have told me. Rather, they are the result of some pretty sophisticated science. That science strongly suggests that the universe is quite "old", in the evolutionary sense, and does not offer much wiggle room for the concept of a "young" universe.

Y'all manages to catch me on my way out. I'll be gone for a couple of weeks, and unable to respond to any queries until I get back. Cheers.

<a href="http://www.geocities.com/Tim_J_Thompson/hr.html" target="_blank">Hertzsprung Russell Diagram And Stellar Evolution.</a>
<a href="http://www.geocities.com/Tim_J_Thompson/fusion.html" target="_blank">Solar Fusion & Neutrinos.</a>
<a href="http://home.austarnet.com.au/stear/aig_on_star_formation.htm" target="_blank">Answers in Genesis Gets it Wrong on Star Formation.</a>

Kosh · 01-01-2002, 06:28 AM

Quote:

Originally posted by Tim Thompson:
 Since star formation almost always produces such disks, it is commonly believed amongst astronomers that planetary systems must be fairly common.

Someone should throw up numbers on probability
of a planet with Earth like conditions. If
practically every system has planets, given the
sheer size of the known universe, it
should blow the creationists "uniqueness" argument
right out of the water. YOu know, that bit
about the 1000 km variance in orbit...

You Betcha · 01-02-2002, 09:07 AM

Why does the sun, which has 99% of the mass of the solar system, not have hardly, if any, of the angular momentum?

Amen-Moses · 01-02-2002, 09:42 AM

Quote:

Originally posted by You Betcha:
Why does the sun, which has 99% of the mass of the solar system, not have hardly, if any, of the angular momentum?

It is my understanding that it has shed-loads of angular momentum (i.e it is spinning quite fast) but it will have lost a lot of it in the early fusion phase change when it blew out a huge amount of it's mass. (I've long since forgotten the technical term for this but do remember that it was responsible for stripping the inner solar system of gas and dust.)

Amen-Moses

RufusAtticus · 01-02-2002, 01:37 PM

Quote:

Originally posted by You Betcha:
Why does the sun, which has 99% of the mass of the solar system, not have hardly, if any, of the angular momentum?

Because it's in the center.

-RvFvS

Coragyps · 01-02-2002, 01:42 PM

The Sun is still losing angular momentum - it emits the solar wind, which is a varying-strength stream of charged particles going out radially. The Sun's magnetic field tries to rotate with the Sun's rotation, but is always being dragged back by the charged particles. This exerts a braking force on the Sun's rotation - a friction, if you will, analogous to air + floor friction on a spinning top. Newly formed stars spin rapidly. Middle-aged ones (with decent magnetic fields and winds) spin much more sedately.

12-31-2001, 11:36 AM	#23
Tim Thompson Regular Member Join Date: Sep 2000 Location: Pasadena, CA, USA Posts: 455	The key point of Morpho's model is that the theory of star formation produces two big observational details: (1) protostars are surrounded by dusty disks, and (2), protostar formation creates fast jets of ionized gas, along the rotation axis. This theory dates back to the 50's or so, but has been strongly supported since then by images from the <a href="http://hst.stsci.edu/" target="_blank">Hubble Space Telescope</a>. <a href="http://oposite.stsci.edu/pubinfo/PR/95/45.html" target="_blank">Disks in the Orion Nebula</a>. <a href="http://oposite.stsci.edu/pubinfo/PR/94/24.html" target="_blank">Proplyds in the Orion Nebula</a>. These links will take you to images that clearly show the flattened dust disks, both face on & edge on, as previously predicted by the theory of star formation. Since star formation almost always produces such disks, it is commonly believed amongst astronomers that planetary systems must be fairly common. <a href="http://oposite.stsci.edu/pubinfo/pr/95/24.html" target="_blank">The Fire and Fury of Stellar Birth</a>. This link leads to images of what are called Herbig-Haro objects, dust clouds complete with the axial jets that theory also predicts. Perhaps most revealing is <a href="http://oposite.stsci.edu/pubinfo/jpeg/HH30.jpg" target="_blank">the image of HH30</a>, which shows that the jet is really moving, and shows the shape of the dust disk much better than other images. The curved shape of the disk edge can be calculated from theory, but the new HST images observe that shape more precisely than theory can as yet predict it. Hence, the theory can be calibrated by the observed shapes. <a href="http://oposite.stsci.edu/pubinfo/PR/95/44.html" target="_blank">Star Birth in M16</a>. The images here are not as revealing as the others, but have their own value. These images detail the environment where we expect star formation to occur. I like the illustration of "eggs". These dense dust knots hide protostars from visible (eye-ball) observing, but the protostars can be seen in infrared (which is more heat sensitive), and at longer sub-millimeter wavelengths. The point here, at least for me, is that star formation & planetary system formation are not just simple guess work, as too many creationists have told me. Rather, they are the result of some pretty sophisticated science. That science strongly suggests that the universe is quite "old", in the evolutionary sense, and does not offer much wiggle room for the concept of a "young" universe. Y'all manages to catch me on my way out. I'll be gone for a couple of weeks, and unable to respond to any queries until I get back. Cheers. <a href="http://www.geocities.com/Tim_J_Thompson/hr.html" target="_blank">Hertzsprung Russell Diagram And Stellar Evolution.</a> <a href="http://www.geocities.com/Tim_J_Thompson/fusion.html" target="_blank">Solar Fusion & Neutrinos.</a> <a href="http://home.austarnet.com.au/stear/aig_on_star_formation.htm" target="_blank">Answers in Genesis Gets it Wrong on Star Formation.</a>

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12-30-2001, 10:52 PM	#22
RufusAtticus Veteran Member Join Date: Nov 2001 Location: NCSU Posts: 5,853	You could put a disclaimer on it next time. -RvFvS

01-02-2002, 09:07 AM	#25
You Betcha Junior Member Join Date: Oct 2001 Location: Dallas, TX Posts: 57	Why does the sun, which has 99% of the mass of the solar system, not have hardly, if any, of the angular momentum?

01-02-2002, 01:42 PM	#28
Coragyps Veteran Join Date: Aug 2001 Location: Snyder,Texas,USA Posts: 4,411	The Sun is still losing angular momentum - it emits the solar wind, which is a varying-strength stream of charged particles going out radially. The Sun's magnetic field tries to rotate with the Sun's rotation, but is always being dragged back by the charged particles. This exerts a braking force on the Sun's rotation - a friction, if you will, analogous to air + floor friction on a spinning top. Newly formed stars spin rapidly. Middle-aged ones (with decent magnetic fields and winds) spin much more sedately.

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