Register to reply

Mass radius relationship for SIRIUS B

by cooper607
Tags: mass, radius, relationship, sirius
Share this thread:
cooper607
#1
Jul14-14, 06:37 AM
P: 49
hi guys, I have been doing a research on white dwarf stars and chanrashekhar limit. I need to plot a graph for the mass-radius relationship of the dwarfs. from the equalization of the hydrostatic equilibrium pressure and the electron degeneracy pressure I found out the radius -mass relationship for non relativistic fermi gas.

my final result is

R=3.58*10^16 M^(-1/3)

but when I take relativistic fermi gas, pressure comes in order of 4/3 and the radius cancels out leaving the equation to be
M(limit)=1.44 M(sun)

Now for this maximum limit how can I plot a graph for radius vs mass. which values should i input for different masses? please help me
Phys.Org News Partner Astronomy news on Phys.org
Image: Chandra's view of the Tycho Supernova remnant
Bright like a diamond: lasers and compressed carbon recreate Jupiter's core
New mass map of a distant galaxy cluster is the most precise yet
Matterwave
#2
Jul14-14, 08:31 AM
Sci Advisor
Matterwave's Avatar
P: 2,671
What do you mean plot a graph of radius vs mass for a limit? The limit is one value. It's a dot. What is the radius at this mass? If your final result is correct, you need only input this M(limit) into M.
cooper607
#3
Jul14-14, 12:37 PM
P: 49
But the relativistic fermi gas plot is different than the non relativistic, i want to know how do they get this graph?
Attached Thumbnails
ChandrasekharLimitGraph.svg.png  

Chronos
#4
Jul14-14, 12:58 PM
Sci Advisor
PF Gold
Chronos's Avatar
P: 9,366
Mass radius relationship for SIRIUS B

The formula can be found here - http://burro.astr.cwru.edu/Academics...WDmassrad.html. It is interesting to note that the radius actually shrinks as mass increases.
cooper607
#5
Jul15-14, 01:06 AM
P: 49
dear Chronos, I actually visited that page earlier, for relativistic fermi gas they derived the relation to be 1=M^(-1/3) , so radius actually cancels out from both sides. so how do they plot that graph where radius is zero when mass goes to 1.44? i didnt get any expression for the graph..can you tell me if there is any radius -mass relation for the relativistic curve ?


Register to reply

Related Discussions
White dwarf mass-radius relationship Introductory Physics Homework 2
Problem with relationship of mass and radius with time in centripetal force Introductory Physics Homework 6
Relationship between Zeffective and Radius Chemistry 7
Clearance with centripetal force relationship to freq, radius, and mass. General Physics 0
Relationship of temperature and radius. Introductory Physics Homework 2