Pressure at the core

"I.N. Galidakis" wrote in message
news:1224602447.956577@athprx04...
OG wrote:
"I.N. Galidakis" wrote in message
news:1224581136.871203@athprx04...
Mike Dworetsky wrote:
"I.N. Galidakis" wrote in message
news:1224527030.287674@athprx03...
OG wrote:
[snip]

Page updated to include Mass distribution, Luminosity and Pressure,
Units for density updated to SI units.
http://www.astd60.dsl.pipex.com:80/structure_of_sun.htm

Sorry for nitpicking, but is your "Log(P)" meant to be base 10? We
(the
abominable mathematicians) usually denote by "Log(x)" the natural
logarithm
(base e).

If I use log base 10 for P as per the page, the polytrope n=3 model
seems
to
agree with the data fairly well. If I use the natural log, the results
are
awry.
--
I.N. Galidakis


Unless otherwise specified, in astrophysics log means base 10, and ln
means
base e. The Sun's basic structure isn't all that different (in order
of
magnitude terms) from an n=3 polytrope, as I recall from dim and
distant
stellar structure courses.

It looks like even the magnitudes can be adjusted to a pretty good
match.
I was
able to extract some results which agree fairly well with the data in
the
links
OG and Sam provided. For those interested:

http://ioannis.virtualcomposer2000.c...Polytrope.html

Many thanks to all who replied.
--

Can I nitpick in return and point out the lack of units in your
discussion
:-)

Hehe! Added now.

Well done otherwise.

Thanks.

Did you look at the detailed working in the QUB notes ?
http://star.pst.qub.ac.uk/~sjs/teach...ecture%208.pdf

No, but now that I looked, I see that my assumption to normalize the
radius with
respect to the point xi where the density falls to 0, was on the
reasonable
side.

I better collect all those links and add them as refs at the end of the
article.
I think it would look better that way.

I assume that since you changed the contents of ref [6], this web resource
is
yours, but I cannot find any other data except "Owen's Spare Webpages". If
you'd
like me to put something more meaningful there (for ref [6]), please tell
me so.

No need, I just use my webspace as a place where I can upload informal
collections of 'stuff'.
Feel free to take the data and make it your own - though I'm sure the
Athlone Press would appreciate it if the acknowledgement stayed :-).

What I have just noticed is the link on page 13 of the QUB document (your
ref #5) that takes you to this collection of 16 standard models dating
between 1982 and 2005
http://www.sns.ias.edu/~jnb/SNdata/solarmodels.html

One day astrophysicists will use SI units too!

[newsgroups snipped]

In article 1224507902.533497@athprx04,
"I.N. Galidakis" writes:
http://en.wikipedia.org/wiki/Polytrope
Wiki does not mention what the constants are in its expression for K.

Article edited.

There's some useful information about solutions at
http://www.scientificarts.com/laneemden/laneemden.html

Searching on "Lane Emden" equation (i.e., three words, the first two
in quotes) produced lots of hits, but I didn't examine them.

--
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA
(Please email your reply if you want to be sure I see it; include a
valid Reply-To address to receive an acknowledgement. Commercial
email may be sent to your ISP.)

In article ,
"Mike Dworetsky" wrote:

snip

Unless otherwise specified, in astrophysics log means base 10, and ln means
base e.

Not just in astrophysics IME; it seems to be the general convention in
North American science and math textbooks -- up to the undergraduate
level at least -- for "log" to mean the common logarithm and "ln" the
natural.

There's also "lg" for the base-2 logarithm (octaves), less often seen
than the other two.

--
Odysseus

"Odysseus" wrote in message
news
In article ,
"Mike Dworetsky" wrote:

snip

No he didn't. You wrote snip.
What's up, afraid to present his argument, chicken ****?