Hello, may I ask if PHOEBE can extract the surface potential of the primary and secondary stars in semi-detached and detached models? If so, how can it be done?

[ty406-cyber]

Calculate the degree of connection using the potential extracted from the connected model as shown in the figure.

[giammarc]

Hello,

The following example script will show you how to get the potential values from the requiv values (and vice-versa). The example is for a detached binary, but will work the same for semi-detached binary. *NOT WELL, Phoebe does volume conservation so when eccentricity is not zero the potential obtained will only be valid for one time. Also notice that in the call to requiv_to_pot(r2,sma,1/q,F2,d,component=2) for the secondary the mass ratio passed must be inverted.
Let us know if anything is unclear or you have follow-up questions.

# import phoebe and define a default binary.  We'll use a detached example, 
# this will work for semi detached as well
import phoebe

b = phoebe.Bundle.default_binary()

# let's set a non-default mass ratio so we can see some differences in the pot'ls
q = 0.6
b.set_value('q@binary',q)

# get the default values of  r1 requiv and  r2 requiv
r1 = b.get_value('requiv@primary@component')
r2 = b.get_value('requiv@secondary@component')
print('r1 = ',r1,'  r2 = ',r2)


# get the semi-major axis, set the values of the Synchronicity parameters and eccentricity
# they will be needed later
# N  O  T  E    W  E  L  L:  when Phoebe does volume  conservation so when ecc != 0 you will be getting the 
# initial values of the potential.
sma = b.get_value('sma@orbit')
sma
F1 = 1
F2 = 1
ecc = 0  # the time independent case
d = 1 - ecc

# get the potentials
potl1 = phoebe.distortions.roche.requiv_to_pot(r1, sma, q, F1, d, component=1)
# ***notice*** the inverting of q -> 1/q in the following call.  This give the secondary component's
# pot'l in the primary's frame of reference.
potl2 = phoebe.distortions.roche.requiv_to_pot(r2,sma,1/q,F2,d,component=2)
print('potl1 = ', potl1,'  potl2 = ',potl2)


# if you want to go the other direction and get rquiv from potl ....
r1 = phoebe.distortions.roche.pot_to_requiv(potl1,sma,q,F1,d,component=1)
# ***notice*** the  q  is **NOT** inverted in the following call
r2 = phoebe.distortions.roche.pot_to_requiv(potl2,sma,q,F2,d,component=2)
print('r1 = ', r1,'  r2 = ', r2)

[ty406-cyber]

Thank you very much for your answer. I still have one more question, that is, can the model of contact binary extract the potential and error of the inner and outer Roche lobes after the MCMC process?