Editing
SSC/Structure/PolytropesEmbedded/n1
(section)
Jump to navigation
Jump to search
Warning:
You are not logged in. Your IP address will be publicly visible if you make any edits. If you
log in
or
create an account
, your edits will be attributed to your username, along with other benefits.
Anti-spam check. Do
not
fill this in!
====Overlap with Stahler's Presentation==== We can invert the above expression for <math>~P_e(K,M)</math> to obtain the following expression for <math>~M(K,P_e)</math>: <div align="center"> <math>~M= K \biggl[\frac{2}{\pi} \cdot \frac{P_e}{G^3} \biggr]^{1/2} \biggl[ \frac{\xi_e(\sin\xi_e - \xi_e \cos\xi_e )}{\sin\xi_e} \biggr]</math> . </div> If, following Stahler's lead, we normalize this expression by <math>~M_\mathrm{SWS}</math> (evaluated for <math>~n=1</math>) and we normalize the above expression for <math>~R_\mathrm{eq}</math> by <math>~R_\mathrm{SWS}</math> (evaluated for <math>~n=1</math>), we obtain, <div align="center"> <table border="0" cellpadding="3"> <tr> <td align="right"> <math> \frac{M}{M_\mathrm{SWS}} </math> </td> <td align="center"> <math>~=~</math> </td> <td align="left"> <math> K \biggl[\frac{2}{\pi} \cdot \frac{P_e}{G^3} \biggr]^{1/2} \biggl[ \frac{\xi_e(\sin\xi_e - \xi_e \cos\xi_e )}{\sin\xi_e} \biggr] \biggl[ \biggl( \frac{G}{2} \biggr)^{3/2} K^{-1} P_\mathrm{ex}^{-1/2} \biggr] </math> </td> </tr> <tr> <td align="right"> </td> <td align="center"> <math>~=~</math> </td> <td align="left"> <math> (4\pi)^{-1/2} \biggl[ \frac{\xi_e(\sin\xi_e - \xi_e \cos\xi_e )}{\sin\xi_e} \biggr] \, , </math> </td> </tr> <tr> <td align="right"> <math> \frac{R_\mathrm{eq}}{R_\mathrm{SWS}} </math> </td> <td align="center"> <math>~=~</math> </td> <td align="left"> <math> \biggl[ \frac{K}{2\pi G} \biggr]^{1/2} \xi_e \biggl[ \frac{G}{2K} \biggr]^{1/2} = (4\pi)^{-1/2} \xi_e \, . </math> </td> </tr> </table> </div> <span id="Stahler1983Fig17"> <div align="center"> <table border="2" cellpadding="8"> <tr> <td align="center" colspan="2"> '''Figure 2:''' <font color="darkblue">Equilibrium Mass-Radius Diagram </font> </td> </tr> <tr> <td align="center" bgcolor="white"> [[File:Stahler1983TitlePage0.png|300px|center|Stahler (1983) Title Page]] <!-- [[Image:AAAwaiting01.png|300px|center|Stahler (1983) Title Page]] --> </td> <td valign="top" width=350 rowspan="3"> ''Top:'' A slightly edited reproduction of Figure 17 in association with Appendix B of [http://adsabs.harvard.edu/abs/1983ApJ...268..165S Stahler] (1983, ApJ, 268, 165). Stahler's figure caption reads, in part, "Mass-radius relation for bounded polytropes (schematic). Each curve is labeled by the appropriate value or range" of {{Math/MP_PolytropicIndex}} … "As the cloud density increases from unity, all curves leave the origin with the same slope …" ''Bottom:'' Curves depict the exact, analytically derived mass-radius relationship for truncated <math>~n = 1</math> (purple squares) and <math>~n = 5</math> (blue diamonds) polytropes that are embedded in an external medium of pressure <math>~P_e</math>; the relevant mathematical expressions are presented to the immediate right of Stahler's name in, respectively, our [[SSC/Structure/PolytropesEmbedded#n1Summary|<math>~n=1</math> summary table]] and our [[SSC/Structure/PolytropesEmbedded#n5Summary|<math>~n=5</math> summary table]]. As the dimensionless truncation radius, <math>~\xi_e</math>, increases steadily from zero, both curves exhibit very similar behavior up to <math>~M_n \equiv M/M_\mathrm{SWS} \approx 0.5</math>; thereafter the normalized mass and normalized radius continue to steadily increase along the <math>~n = 1</math> sequence, but the <math>~n = 5</math> sequence eventually bends back on itself, returning to the origin as <math>~\xi_e \rightarrow \infty</math>. ''Comparison:'' The monotonic <math>P-R</math> behavior of the analytically derived solution for {{Math/MP_PolytropicIndex}} = 1 <math>(\gamma_g = 2)</math>, shown above, is consistent with the behavior of the numerically derived solutions presented by Whitworth for slightly lower values of <math>\gamma_g</math> = 5/3 and 4/3. The analytically derived solution for {{Math/MP_PolytropicIndex}} = 5 <math>(\gamma_g = 6/5)</math> shows that, above some limiting pressure, no equilibrium configuration exists; this is consistent with the behavior of the numerically derived solutions presented by Whitworth for all values of <math>\gamma_g < 4/3 \, .</math> </td> </tr> <tr> <td align="center" bgcolor="white"> [[File:Stahler_MRdiagram1.png|300px|center|Stahler (1983) Figure 17 (edited)]] <!-- [[Image:AAAwaiting01.png|300px|center|Stahler (1983) Figure 17 (edited)]] --> </td> </tr> <tr> <td align="center" bgcolor="white"> [[File:Stahler1983Comparison.png|300px|center|To be compared with Stahler (1983)]] </td> </tr> </table> </div> </span>
Summary:
Please note that all contributions to JETohlineWiki may be edited, altered, or removed by other contributors. If you do not want your writing to be edited mercilessly, then do not submit it here.
You are also promising us that you wrote this yourself, or copied it from a public domain or similar free resource (see
JETohlineWiki:Copyrights
for details).
Do not submit copyrighted work without permission!
Cancel
Editing help
(opens in new window)
Navigation menu
Personal tools
Not logged in
Talk
Contributions
Log in
Namespaces
Page
Discussion
English
Views
Read
Edit
View history
More
Search
Navigation
Main page
Tiled Menu
Table of Contents
Old (VisTrails) Cover
Appendices
Variables & Parameters
Key Equations
Special Functions
Permissions
Formats
References
lsuPhys
Ramblings
Uploaded Images
Originals
Recent changes
Random page
Help about MediaWiki
Tools
What links here
Related changes
Special pages
Page information