# binary_controls¶

## specifications for starting model¶

### m1¶

Initial mass of star 1 in Msun units. Not used when loading a saved model. same caveats as initial_mass in star/defaults/controls.defaults apply

m1 = 1.0d0


### m2¶

Initial mass of star 2 in Msun units. Not used when loading a saved model. same caveats as initial_mass in star/defaults/controls.defaults apply

m2 = 0.8d0


### initial_period_in_days¶

Initial orbital period in days.

initial_period_in_days = 0.5d0


### initial_separation_in_Rsuns¶

Initial separation measured in Rsuns. Only used when initial_period_in_days < 0

initial_separation_in_Rsuns = 100


### initial_eccentricity¶

Initial eccentricity of the system

initial_eccentricity = 0.0d0


## controls for output¶

### history_name¶

Name of file for binary output

history_name = 'binary_history.data'


### history_interval¶

append an entry to the history.data file when mod(model_number, history_interval) = 0.

history_interval = 5


### append_to_star_history¶

If true, then the columns from the binary_history are also included in each of the stars history files. NOTE: if .false., then pgstar cannot access binary data

append_to_star_history = .true.


### log_directory¶

Directory for binary output

log_directory = '.'


### history_txt_format¶

Format for double, int and text in binary output

history_dbl_format = '(1pes32.16e3, 1x)'
history_int_format = '(i32, 1x)'
history_txt_format = '(a32, 1x)'


### photo_directory¶

These overwrite the values of photo_interval, photo_digits and photo_directory for each star, so that profiles are outputted simultaneously

photo_interval = 50
photo_digits = 3
photo_directory = 'photos'


### terminal_interval¶

write info to terminal when mod(model_number, terminal_interval) = 0.

terminal_interval = 1


output the log header info to the terminal when mod(model_number, write_header_frequency*terminal_interval) = 0.

write_header_frequency = 10


### extra_binary_terminal_output_file¶

if not empty, output terminal info to this file in addition to terminal. this does not capture all of the terminal output – just the common items. it is intended for use in situations where you cannot directly see the terminal output such as when running on a cluster. if you want to be able to monitor the progress for such cases, you can set extra_binary_terminal_output_file = 'log' and then do tail -f log to view the terminal output as it is recorded in the file.

extra_binary_terminal_output_file = ''


## timestep controls¶

The terminal output during evolution includes a short string for the ‘dt_limit’. This is to give you some indication of what is limiting the time steps. Here’s a dictionary mapping those terminal strings to the corresponding control parameters. These only include limits from binary, to see the limits from star refer to star/default/controls.defaults

 terminal output       related parameter
'b_companion'          timestep limited by companion
'b_RL'                 fr
'b_jorb'               fj
'b_envelope'           fm
'b_separation'         fa
'b_eccentricity'       fe
'b_deltam'             fdm


### fe_hard¶

Timestep controls based on relative changes. After each step an upper limit is set on the timestep based on changes on different quantities. If the quantity is X and the change in one timestep dX, then this limit is given by

dt_next_max = dt * fX*abs(X / dX)


each of these controls deals with the following:

• fm: envelope mass
• fa: binary separation
• fr: change in (r-rl)/rl
• fj: change in orbital angular momentum
• fe: change in orbital eccentricity

hard limits are strictly enforced, if a timestep exceeds that limit then a retry is made.

fm = 0.01d0
fm_hard = -1d0
fa = 0.01d0
fa_hard = 0.02d0
fr = 0.10d0
fr_hard = -1d0
fj = 0.001d0
fj_hard = 0.01d0
fe = 0.01d0
fe_hard = -1d0


### fe_limit¶

Limits to timestep controls give by fm, fr and fe. As these three quantities evolve naturally to zero, following strictly the timestep limit given by fX would reduce timesteps infinetely. These fX_limit avoid this problem by computing the limit to the timestep as

dt_next_max = dt * fX*abs(max(abs(X),fX_limit) / dX)


If any of these fX_limit is smaller than zero it is ignored.

fm_limit = 1d-3
fr_limit = 1d-2
fe_limit = 1d-1


### fr_dt_limit¶

Minimum timestep limit allowed for the fr control in years.

fr_dt_limit = 10d0


### fdm_hard¶

Limits the timestep based on the fractional mass change of either component.

fdm = 0.005d0
fdm_hard = 0.01d0


### dt_softening_factor¶

Weight factor to average max_timestep with old one (in log space) as in

dt_next_max = 10**(dt_softening_factor*log10(dt_next_max_old) + &
(1-dt_softening_factor)*log10(dt_next_max))


where dt_next_max_old is the limit used in the previous step. This is meant to avoid large changes in dt. Values must be < 1 and >= 0.

dt_softening_factor = 0.5d0


### varcontrol_{stage}¶

Allows binary to set varcontrol_target for each star depending on the stage of evolution. Ignored if < 0. Each one controls the following stages,

• varcontrol_case_a : varcontrol_target for both stars during mass transfer

from a core hydrogen burning star.

• varcontrol_case_b : varcontrol_target for both stars during mass transfer

from a core hydrogen depleted star.

• varcontrol_ms : varcontrol_target for a star that has not depleted core H.

• varcontrol_post_ms : varcontrol_target for a star that has depleted core H.

varcontrol_case_a = -1d0
varcontrol_case_b = -1d0
varcontrol_ms = -1d0
varcontrol_post_ms = -1d0


### dt_reduction_factor_for_j¶

When a retry happens due to the hard limit in angular momentum changes, or because the timestep produced a negative j, further multiply the timestep by this factor for the next step. This can avoid multiple retries and waste of time.

dt_reduction_factor_for_j = 0.1d0


## when to stop¶

### accretor_overflow_terminate¶

terminate evolution if (r-rl)/rl is bigger than this for accretor

accretor_overflow_terminate = 0.0d0


### terminate_if_initial_overflow¶

terminate evolution if first model of run is overflowing

terminate_if_initial_overflow = .true.


### terminate_if_L2_overflow¶

terminate evolution if there is overflow through the second Lagrangian point Amount of overflow needed to reach L2 implemented as in Marchant et al. (2016), A&A, 588, A50

terminate_if_L2_overflow = .false.


## mass transfer controls¶

### mass_transfer_*¶

Transfer efficiency controls. alpha, beta, delta and gamma parameters as described in Tauris & van den Heuvel 2006 section 16.4.1, transfer efficiency is given by 1-alpha-beta-delta.

These only affect mass that is lost from the donor due to mass transfer, winds from each star will carry away angular momentum from the vicinity of each even when transfer efficiency is unity. Each of these represent the following:

• alpha : fraction of mass lost from the vicinity of the donor as fast wind
• beta : fraction of mass lost from the vicinity of the accretor as fast wind
• delta : fraction of mass lost from circumbinary coplanar toroid
• gamma : radius of the circumbinary coplanar toroid is gamma**2 * orbital_separation
mass_transfer_alpha = 0.0d0
mass_transfer_beta = 0.0d0
mass_transfer_delta = 0.0d0
mass_transfer_gamma = 0.0d0


### limit_retention_by_mdot_edd¶

Limit accretion using mdot_edd. The current implementation is intended for use with black hole accretors, as in e.g. Podsiadlowski, Rappaport & Han (2003), MNRAS, 341, 385. For other accretors mdot_edd should be set with use_this_for_mdot_edd, the hook use_other_mdot_edd, or by appropriately setting use_this_for_mdot_edd_eta. Note: MESA versions equal or lower than 8118 used eta=1 and did not correct the accreted mass for the energy lost by radiation.

If accreted material radiates an amount of energy equal to L=eta*mtransfer_rate*clight**2, then accretion is assumed to be limited to the Eddington luminosity,

Ledd = 4*pi*cgrav*Mbh*clight/kappa


which results in the Eddington mass-accretion rate

mdot_edd = 4*pi*cgrav*Mbh/(kappa*clight*eta)


the efficiency eta is determined by the properties of the last stable circular orbit, and for a BH with no initial spin it can be expressed in terms of the initial BH mass Mbh0 and the current BH mass,

eta = 1-sqrt(1-(Mbh/(3*Mbh0))**2)


for Mbh < sqrt(6) Mbh0. For BHs with initial spins different from zero, an effective Mbh0 can be computed, corresponding to the mass the black hole would have needed to have with zero spin to reach the current mass and spin.

limit_retention_by_mdot_edd = .false.


### use_es_opacity_for_mdot_edd¶

If .true., then the opacity for mdot_edd is computed as 0.2*(1+X) If .false., the opacity of the outermost cell of the donor is used

use_es_opacity_for_mdot_edd = .true.


### use_this_for_mdot_edd_eta¶

Fixed mdot_edd_eta, if negative, eta will be computed consistently as material is accreted. Values should be between ~0.06-0.42, the minimum corresponding to a BH with spin parameter a=0, and the maximum to a=1.

use_this_for_mdot_edd_eta = -1


If true, then reduce the increase in mass of the BH to account for the radiated energy eta*mtransfer_rate_clight**2 so that in a timestep

delta_Mbh = (1-eta)*mass_transfer_rate*dt

use_radiation_corrected_transfer_rate = .true.


### initial_bh_spin¶

Initial spin parameter of the black hole “a”. Must be between 0 and 1. Evolution of BH spin is done with eq. (6) of King & Kolb (1999), MNRAS, 305, 654

initial_bh_spin = 0


### use_this_for_mdot_edd¶

Fixed mdot_edd in Msun/yr, ignored if negative

use_this_for_mdot_edd = -1


### mdot_scheme¶

How to compute mass transfer. Options are:

• “Ritter” : Ritter 1988, A&A, 202, 93
• “Kolb” : Optically thick overflow of Kolb & Ritter 1990, A&A, 236, 385
• “roche_lobe” : Set mass transfer rate such that the donor remains inside
its Roche lobe. Only works implicitly.
• “contact” : Extends the roche_lobe scheme to include contact systems as in
Marchant et al. (2016), A&A, 588, A50
mdot_scheme = 'Ritter'


#### explicit mass transfer computation.¶

MESA can compute mass transfer rates either explicitly (at the beggining of the step) or implicitly (iterating the solution until the mass transfer rate matches the value computed at the end of the step). The explicit method is used if max_tries_to_achieve <= 0.

### cur_mdot_frac¶

Average the explicit mass transfer rate computed with the old in order to smooth large changes.

mass_transfer = mass_transfer_old * cur_mdot_frac + (1-cur_mdot_frac) * mass_transfer

cur_mdot_frac = 0.5d0


### max_explicit_abs_mdot¶

Limit the explicit mass transfer rate to max_explicit_abs_mdot, in Msun/secyer

max_explicit_abs_mdot = 1d-7


### max_tries_to_achieve¶

The implicit method will modify the mass transfer rate and redo the step until it either finds a solution, or the number of tries goes above max_tries_to_achieve. if max_tries_to_achieve <= 0 the explicit method is used.

max_tries_to_achieve = 20


### solver_type¶

Method use to solve for mass transfer. The solver first attempts to increase or reduce the mass transfer rate used through the step until finding an upper and lower limit to it. This controls what is done after that point. Options are:

• “cubic” : Given an upper and lower limit, plus a new try in between,
the root of the equation is estimated by using a cubic matching the three points.
• “bisect” : Simply takes the average of the boundaries for the next try
• “both” : Alternates between cubic and bisect each iteration
solver_type = 'both'


### implicit_scheme_tolerance¶

Tolerance for which a solution is considered valid. For the Ritter and Kolb schemes if we call mdot the mass transfer rate used for the step, and mdot_end the one computed at the end of it, a solution is valid if

abs((mdot-mdot_end)/mdot_end) < b% implicit_scheme_tolerance


For the roche_lobe scheme, a solution will be considered valid if

-implicit_scheme_tolerance < (r-rl)/rl < 0

When using the roche_lobe scheme smaller values of order 1d-3 or smaller are recommended.

implicit_scheme_tolerance = 1d-2


### implicit_scheme_tiny_factor¶

During the implicit scheme the solution is bracketed between a minimum and a maximum value mdot_hi and mdot_lo. Even if the desired tolerance is not achieved, the solution is accepted if the difference between abs(mdot_hi-mdot_lo) is smaller than implicit_scheme_tiny_factor*min(abs(mdot_hi),abs(mdot_lo))

implicit_scheme_tiny_factor = 1d-6


### implicit_lambda¶

The implicit scheme works by adjusting the mass transfer rate from the previous step until it finds a solution. If the mass transfer needs to increase/reduce after a try, then it is multiplied/divided by change_factor. initial_change_factor provides the initial value for this parameter, however, since at certain points the mass transfer rate will increase steeply and at others remain mostly constant from step to step, MESA adjusts the value of the change factor to make it easier to find solutions. Whenever the mass transfer rate changes from the previous value, MESA will modify the change_factor according to:

if(mass_transfer_rate < mass_transfer_prev) then
change_factor = change_factor*(1.0-implicit_lambda) &
+ implicit_lambda*(1+change_factor_fraction*(mass_transfer_rate/mass_transfer_prev-1))
else
change_factor = change_factor*(1.0-implicit_lambda) &
+ implicit_lambda*(1+change_factor_fraction*(mass_transfer_prev/mass_transfer_rate-1))
change_factor = change_factor*(1.0-implicit_lambda) &
+ implicit_lambda*(1+change_factor_fraction*(mass_transfer_rate/mass_transfer_prev-1))
end if


Choosing implicit_lambda = 0 will keep the change factor constant.

initial_change_factor = 1.5d0
change_factor_fraction = 0.9d0
implicit_lambda = 0.25d0


### min_change_factor¶

Maximum and minimum values for the change_factor

max_change_factor = 1.5d0
min_change_factor = 1.05d0


### change_factor_increase¶

If after every num_tries_for_increase_change_factor iterations the implicit scheme does not have upper and lower bounds for the mass transfer rate, multiply change_factor by change_factor_increase. Ignored if num_tries_for_increase_change_factor < 1. Increase is limited to max_change_factor.

num_tries_for_increase_change_factor = 20
change_factor_increase = 1.1d0


### starting_mdot¶

When using the roche_lobe scheme, if the donor overflows for the first time use starting_mdot (in Msun/secyer) as an initial guess for the mass transfer rate.

starting_mdot = 1d-12


### roche_min_mdot¶

When using the roche_lobe scheme, if mass transfer rate is below roche_min_mdot (in Msun/secyer) and the donor is not overflowing its roche lobe, assume detachment and stop mass transfer.

roche_min_mdot = 1d-16


### min_mdot_for_implicit¶

For any choice except for the roche_lobe scheme mass transfer will be computed explicitly until the explicit computation of mdot is > min_mdot_for_implicit (in Msun/secyer), even if max_tries_to_achieve > 0. This is to avoid spending many iterations when the stars are detached and the explicit calculation gives very low values of mdot.

min_mdot_for_implicit = 1d-16


### max_implicit_abs_mdot¶

Limit the implicit mass transfer rate to max_implicit_abs_mdot, in Msun/secyer

max_implicit_abs_mdot = 1d99


### report_rlo_solver_progress¶

Set true to see info about the iterations to compute mass transfer from RLOF

report_rlo_solver_progress = .false.


### do_enhance_wind_*¶

Use the Tout & Eggleton mechanism to tidally enhance the wind mass loss from one or both components according to:

Mdot_w = Mdot_w * ( 1 + B_wind * min( (R/RL)^6, 0.5^6 ) )

Tout & Eggleton 1988,MNRAS,231,823 (eq. 2)

“_1” refers to first star, “_2” to the second one.

do_enhance_wind_1 = .false.
do_enhance_wind_2 = .false.


### tout_B_wind_*¶

The B_wind parameter from the previous equation. Default value is taken from Tout & Eggleton 1988,MNRAS,231,823

“_1” refers to first star, “_2” to the second one.

tout_B_wind_1 = 1d4
tout_B_wind_2 = 1d4


### do_wind_mass_transfer_*¶

transfer part of the mass lost due to stellar winds from the mass losing component to its companion. Using the Bondi-Hoyle mechanism. “_1” refers to first star, “_2” to the second one.

do_wind_mass_transfer_1 = .false.
do_wind_mass_transfer_2 = .false.


### wind_BH_alpha_*¶

Bondi-Hoyle accretion parameter for each star. The default is 3/2 taken from Hurley et al. 2002, MNRAS, 329, 897, in agreement with Boffin & Jorissen 1988, A&A, 205, 155 “_1” refers to first star, “_2” to the second one.

wind_BH_alpha_1 = 1.5d0
wind_BH_alpha_2 = 1.5d0


### max_wind_transfer_fraction_*¶

Upper limit on the wind transfer fraction for star * “_1” refers to first star, “_2” to the second one.

max_wind_transfer_fraction_1 = 0.5d0
max_wind_transfer_fraction_2 = 0.5d0


## orbital jdot controls¶

### do_jdot_gr¶

Include gravitational wave radiation in jdot

do_jdot_gr = .true.


### do_jdot_ml¶

Include loss of angular momentum via mass loss. The parameters mass_transfer_* determine the fractions of mass lost from the vincinity of the donor, the accretor, or a circumbinary coplanar toroid.

do_jdot_ml = .true.


### do_jdot_ls¶

Fix jdot such that the total angular momentum of the system is conserved, except for loses due to other jdot mechanisms, or angular momentum loss from winds. This is meant to take care of L-S coupling due to tides.

do_jdot_ls = .true.


### do_jdot_missing_wind¶

Usually MESA computes stellar AM loss due to winds by taking the angular momentum from the removed layers of the star. However, when mass transfer is included, wind mass loss and mass accretion are added up, and only the remainder, if corresponding to net mass loss, contributes to stellar AM loss. jdot_missing_wind compensates for this, by removing from the orbit an amount of angular momentum equal to the mass lost that does not contribute to stellar AM loss, times the specific angular momentum at the surface.

do_jdot_missing_wind = .false.


### do_jdot_mb¶

Include magnetic braking as in Rappaport, Verbunt, and Joss. apj, 275, 713-731. 1983.

do_jdot_mb = .true.


### include_accretor_mb¶

If true, the contribution to jdot from magnetic braking of the accretor is also taken into account.

include_accretor_mb = .false.


### magnetic_braking_gamma¶

gamma exponent for magnetic braking.

magnetic_braking_gamma = 3.0d0


### keep_mb_on¶

If true keep magnetic braking even when radiative core goes away.

keep_mb_on = .false.


### jdot_mb_qlim_for_check_conv_env¶

Conditions for magnetic braking to operate. Magnetic braking is turned off if any of these do not apply. The mass fraction of the convective envelope has to be > jdot_mb_min_qconv_env The mass fraction of the convective envelope has to be < jdot_mb_max_qconv_env The mass fraction of the radiative core has to be < jdot_mb_max_qrad_core Here by mass fraction we refer to the mass of the respective zone divided by the total mass of the star. To compute the mass in the envelope we add all convective layers down to jdot_mb_qlim_for_check_conv_env, and keep adding layers downwards until we reach a non-convective zone. This is because the very outermost cell is likely radiative. A simular thing is done for the core with jdot_mb_qlim_for_check_rad_core. For full details check binary_jdot.f90.

jdot_mb_min_qconv_env = 1d-6
jdot_mb_max_qconv_env = 0.99d0
jdot_mb_qlim_for_check_conv_env = 0.999d0


### jdot_mb_mass_frac_for_scale¶

If jdot_mb_scale_for_low_qconv_env is .true., scale down jdot_mb if mass fraction of the convective envelope is below jdot_mb_mass_frac_for_scale. (Podsiadlowski et al. 2002, The Astrophysical Journal, Volume 565, Issue 2, pp. 1107-1133)

jdot_mb_scale_for_low_qconv_env = .true.
jdot_mb_mass_frac_for_scale = 0.02d0


### jdot_multiplier¶

Multiply total jdot by this factor. NOTE: jdot_ls is not affected by this.

jdot_multiplier = 1d0


## rotation and sync controls¶

### do_j_accretion¶

If true, compute accretion of angular momentum following A.3.3 of de Mink et al. 2013, ApJ, 764, 166. Otherwise, incoming material is assumed to have the specific angular momentum of the surface of the accretor.

do_j_accretion = .false.


### do_tidal_sync¶

If true, apply tidal torque to the star

do_tidal_sync = .false.


### sync_type_*¶

Timescale for orbital synchronisation. “_1” refers to first star, “_2” to the second one. Options are:

• “Instantaneous” : Keep the star synced to the orbit.
• “Orb_period” : Sync in the timescale of the orbital period.
• “Hut_conv” : Sync timescale following Hurley et al. 2002, MNRAS, 329, 897
for convective envelopes.
• “Hut_rad” : Sync timescale following Hurley et al. 2002, MNRAS, 329, 897
• “None” : No sync for this star.
sync_type_1 = 'Hut_conv'
sync_type_2 = 'Hut_conv'


### sync_mode_*¶

Where angular momentum is deposited for synchronization. “_1” refers to first star, “_2” to the second one. Options are:

• “Uniform” : Each layer is synced independently given the sync timescale.
sync_mode_1 = 'Uniform'
sync_mode_2 = 'Uniform'


### Ftid_*¶

Tidal strength factor. Synchronisation and circularisation timescales are divided by this. “_1” refers to first star, “_2” to the second one.

Ftid_1 = 1d0
Ftid_2 = 1d0


### do_initial_orbit_sync_*¶

Relax rotation of star to orbital period at the beggining of evolution. “_1” refers to first star, “_2” to the second one.

do_initial_orbit_sync_1 = .false.
do_initial_orbit_sync_2 = .false.


### tidal_reduction¶

tidal_reduction accounts for the reduction in the effectiveness of convective damping of the equilibrium tide when the tidal forcing period is less than the convective turnover period of the largest eddies. It corresponds to the exponent in eq. (32) of Hurley et al. 2002, MNRAS, 329, 897

tidal_reduction = 1 follows Zahn(1966, 1989), while tidal_reduction = 2 follows Goldreich & Nicholson (1977).

tidal_reduction = 2.0d0


## eccentricity controls¶

### do_tidal_circ¶

If true, apply tidal circularisation

do_tidal_circ = .false.


### circ_type_*¶

Mechanism for circularisation. Options are: “_1” refers to first star, “_2” to the second one.

• “Hut_conv” : Circ timescale following Hurley et al. 2002, MNRAS, 329, 897
for convective envelopes.
• “Hut_rad” : Circ timescale following Hurley et al. 2002, MNRAS, 329, 897
• “None” : no tidal circularisation
circ_type_1 = 'Hut_conv'
circ_type_2 = 'Hut_conv'


### use_eccentricity_enhancement¶

Flag to turn on Soker eccentricity enhancement

use_eccentricity_enhancement = .false.


### max_abs_edot_tidal¶

Maximum absolute value for tidal edot (in 1/s). If the computed tidal edot goes above this, then it is fixed at this maximum

max_abs_edot_tidal = 1d-6


### max_abs_edot_enhance¶

Maximum absolute value for eccentricity enhancement (in 1/s). If the computed edot goes above this, then it is fixed at this maximum

max_abs_edot_enhance = 1d-6


### min_eccentricity¶

If after a step eccentricity < min_eccentricity, then fix it at this value

min_eccentricity = 0.0d0


### max_eccentricity¶

If after a step eccentricity > max_eccentricity, then fix it at this value

max_eccentricity = 0.99d0


### anomaly_steps¶

For phase dependent processes, the orbit is divided into this number of steps in the true anomaly, to integrate through a full orbit and obtain the secular changes

anomaly_steps = 500


Flag to turn on irradiation of the donor due to accretion onto a compact object.

accretion_powered_irradiation = .false.


### col_depth_for_eps_extra¶

Energy from irradiation will be deposited in the outer 4*Pi*R^2*col_depth_for_eps_extra grams of the star.

col_depth_for_eps_extra = -1


Flag to turn on irradiation based on the luminosity of the accretor and binary separation. Requires evolve_both_stars = .true. in binary_job inlist.

use_accretor_luminosity_for_irrad = .false.


If irrad_flux_at_std_distance > 0 then irradiation flux is computed as

s% irradiation_flux = b% irrad_flux_at_std_distance * &

irrad_flux_at_std_distance = -1


### max_F_irr¶

max_F_irr = 5d12


## common envelope controls (EXPERIMENTAL, DON’T USE)¶

### CE_alpha¶

Common envelope efficiency factor

CE_alpha = 1d0


### CE_alpha_th¶

Common envelope thermal efficiency factor

CE_alpha_th = 1d0


### CE_alpha_core¶

Efficiency at which the change of energy in the core of the star contributes to envelope ejection.

CE_alpha_core = 0d0


### CE_mass_loss_rate_high¶

Upper mass loss rate imposed during CE in Msun/yr

CE_mass_loss_rate_high = 1d-1


### CE_mass_loss_rate_low¶

Lower mass loss rate imposed during CE in Msun/yr

CE_mass_loss_rate_low = 1d-6


### CE_rel_rlo_for_detachment¶

Consider the CE phase terminated when (r-rl)/rl < -CE_rel_rlo_for_detachment Between (r-rl)/rl = 0d0 and (r-rl)/rl = -CE_rel_rlo_for_detachment the mass loss rate is adjusted between CE_mass_loss_rate_high and CE_mass_loss_rate_low.

CE_rel_rlo_for_detachment = 0.02d0


### CE_years_detached_to_terminate¶

During CE, if the star spends this amount of time detached, terminate CE even if CE_rel_rlo_for_detachment has not been reached. If set to a large number mass loss will only stop when the star definetely wants to detach. If set to a low number system will likely switch to stable mass transfer.

CE_years_detached_to_terminate = 1d-1


### CE_begin_at_max_implicit_abs_mdot¶

If true, initiate a common envelope phase when max_implicit_abs_mdot is reached

CE_begin_at_max_implicit_abs_mdot = .false.


### CE_xa_diff_to_terminate¶

If the absolute difference between central and surface mass fractions of H and He is below this, terminate the simulation. This is to stop the simulation once the entire envelope has been removed

CE_xa_diff_to_terminate = 0.01d0


### CE_terminate_when_core_overflows¶

Terminate if, for the current orbital separation, the radius at the point where CE_xa_diff_to_terminate applies would overflow its Roche lobe

CE_terminate_when_core_overflows = .true.


### CE_min_period_in_days¶

Terminate the simulation if the period is below this during CE used to terminate the simulation early in cases where a merger would be expected.

CE_min_period_in_minutes = 5d0


### CE_energy_factor_HII_toHI¶

Recombination energy for ionized hydrogen will be multiplied by this factor when computing the energy.

CE_energy_factor_HII_toHI = 1d0


### CE_energy_factor_HeII_toHeI¶

Recombination energy for singly ionized helium will be multiplied by this factor when computing the energy.

CE_energy_factor_HeII_toHeI = 1d0


### CE_energy_factor_HeIII_toHeII¶

Recombination energy for doubly ionized helium will be multiplied by this factor when computing the energy.

CE_energy_factor_HeIII_toHeII = 1d0


### CE_energy_factor_H2¶

Dissociation energy for molecular hydrogen will be multiplied by this factor when computing the energy.

CE_energy_factor_H2 = 0d0


### CE_fixed_lambda¶

For comparison to rapid-pop-synth, if this is larger than zero, then compute the binding energy from this value of lambda rather than by integrating through the envelope

CE_fixed_lambda = -1d0


## miscellaneous controls¶

### keep_donor_fixed¶

keep star 1 as donor, even if accretor is closer to filling roche lobe

keep_donor_fixed = .true.


### mdot_limit_donor_switch¶

Do not change donor if mass transfer is larger than this (given in Msun/secyer). Avoids erratic changes when both stars are filling their roche loches.

mdot_limit_donor_switch = 1d-20


### use_other_{hook}¶

Logicals to deploy the use_other routines.

use_other_rlo_mdot = .false.
use_other_check_implicit_rlo = .false.
use_other_implicit_function_to_solve = .false.
use_other_tsync = .false.
use_other_sync_spin_to_orbit = .false.
use_other_mdot_edd = .false.
use_other_accreted_material_j = .false.
use_other_jdot_gr = .false.
use_other_jdot_ml = .false.
use_other_jdot_ls = .false.
use_other_jdot_missing_wind = .false.
use_other_jdot_mb = .false.
use_other_extra_jdot = .false.
use_other_binary_wind_transfer = .false.
use_other_edot_tidal = .false.
use_other_edot_enhance = .false.
use_other_extra_edot = .false.
use_other_CE_init = .false.
use_other_CE_rlo_mdot = .false.
use_other_CE_binary_evolve_step = .false.
use_other_CE_binary_finish_step = .false.