[enhancement] HMS+HMS Mergers rejuvenation according to Schneider+2016 by ezapartas · Pull Request #788 · POSYDON-code/POSYDON

ezapartas · 2026-01-16T06:54:47Z

This PR is changing the default option in the POSYDON .ini file of HMS_HMS_merging_rejuvenation = True to stronger rejuvenation of MS+MS mergers (according to Glebbeek+2023, Schneider+2016, following the recent Wang+2025 too). So it should be considered a change in POSYDON results for few types mergers

-This PR includes already the changes in #785 and builds on it. If accepted, that PR becomes unnecessary

…d the possibility to match with total_mass_h1

for more information, see https://pre-commit.ci

…to 'Glebbeek+2013'

for more information, see https://pre-commit.ci

ezapartas · 2026-01-24T10:11:11Z

With @dimsour94 we tested it with various options run.

added the options and default values of of rel_mass_lost_HMS_HMS and HMS_HMS_merging_rejuvenation in the .ini file of the population.

sgossage · 2026-03-24T18:57:55Z

We should merge PR#785 into main, then main into v2.3, then into this branch to incorporate the latest changes from PR#785, main, and v2.3.

4/23/26: I went ahead and merged v2.3 (which contains PR#785) into this.

sgossage · 2026-03-24T19:00:03Z

We should update the docs here with these changes.

4/24/26: I added some updates to the docs

…ageX

for more information, see https://pre-commit.ci

… options in merger step

for more information, see https://pre-commit.ci

maxbriel · 2026-05-07T08:09:54Z

+
+                    merged_star.mass = (star_base.mass + comp.mass) * (1.-rel_mass_lost_HMS_HMS)
+
+                    X_average_merged = (star_base.total_mass_h1 + comp.total_mass_h1 - (1.-rel_mass_lost_HMS_HMS) * X_initial) / merged_star.mass


Are you sure these equations are correct?

$$ \left< X \right> = (M_{H,1} + M_{H,2} - (1-\phi)X_0)/M_\mathrm{merged} $$

The $(1-\phi)X_0$ part does not have any units, but is divided by mass... This is different than what's mentioned in Schneider+2016 on p2357:

$$ \left< X \right> = (M_{H,1} + M_{H,2} - \phi(M_1+M_2)X_0)/M_\mathrm{merged} $$

This is the same with the Y_average_merged.

Suggested change

X_average_merged = (star_base.total_mass_h1 + comp.total_mass_h1 - (1.-rel_mass_lost_HMS_HMS) * X_initial) / merged_star.mass

X_average_merged = (star_base.total_mass_h1 + comp.total_mass_h1 - (rel_mass_lost_HMS_HMS *(star_base.mass + comp.mass)* X_initial)) / merged_star.mass

@maxbriel I think you are right. Thanks for catching this! @dimsour94 can you confirm?

maxbriel · 2026-05-07T08:17:41Z

+                                                                                    mass_weight2='mass'))

                # The change of masses occurs after the calculation of weighted averages
                merged_star.mass = (star_base.mass + comp.mass) * (1.-self.rel_mass_lost_HMS_HMS)


This line needs to be edited. It uses self.rel_mass_lost_HMS_HMS, which is set to a string in the rejuvenated case. This will fail.

Either move this inside the else statement or make sure it's compatible with the rejuvenated case.

maxbriel · 2026-05-07T08:19:46Z

+                # first we calculate the mass loss percentage:
+                if self.rel_mass_lost_HMS_HMS == "Glebbeek+2013":
+                    # Eq. 4 of Glebbeek+2013
+                    rel_mass_lost_HMS_HMS = (0.3 * q) / ((1.0 + q) ** 2.0)


If rel_mass_lost_HMS_HMS is set to a string, self.rel_mass_lost_HMS_HMS will also become a string. Since you're using rel_mass_lost_HMS_HMS variable later without the self, it's okay, but the original code uses and expects self.rel_mass_lost_HMS_HMS as a float. This should be edited to account for!

maxbriel · 2026-05-07T08:20:05Z

+                    merged_star.mass = (star_base.mass + comp.mass) * (1.-rel_mass_lost_HMS_HMS)
+
+                    X_average_merged = (star_base.total_mass_h1 + comp.total_mass_h1 - (1.-rel_mass_lost_HMS_HMS) * X_initial) / merged_star.mass
+                    Y_average_merged = (star_base.total_mass_he4 + comp.total_mass_he4 - (1.-rel_mass_lost_HMS_HMS) * Y_initial) / merged_star.mass


Same issue as with X_average_merged

maxbriel · 2026-05-07T08:20:48Z

+                    merged_star.center_he4 = Y_average_merged
+                    merged_star.surface_he4 = Y_average_merged
+
+                    for key in STARPROPERTIES:


What would you like to happen to the surface abundances: " c12", "n14", and "o16"?

maxbriel · 2026-05-07T08:22:25Z


                # The change of masses occurs after the calculation of weighted averages
                merged_star.mass = (star_base.mass + comp.mass) * (1.-self.rel_mass_lost_HMS_HMS)
+                merged_star.total_mass_h1 = merged_star.center_h1 * merged_star.mass


You've already set the total_mass_h1 in the rejuvenated case. This will always overwrite that value here. Should this be moved inside the else block?

maxbriel · 2026-05-07T08:22:51Z

+                    # Not used?
+                    #X_average1 = star_base.total_mass_h1 / star_base.mass
+                    #X_average2 = comp.total_mass_h1 / comp.mass


Remove comments

maxbriel · 2026-05-07T08:23:27Z

+                    merged_star.surface_he4 = Y_average_merged
+
+                    for key in STARPROPERTIES:
+                    # these stellar attributes become np.nan


Shift comment to correct indentation

Suggested change

# these stellar attributes become np.nan

# these stellar attributes become np.nan

maxbriel · 2026-05-07T08:27:45Z

+                    #X_average1 = star_base.total_mass_h1 / star_base.mass
+                    #X_average2 = comp.total_mass_h1 / comp.mass
+
+                    Z_div_Zsun_init = star_base.metallicity


Are there other variables you want/need to check that they exists?

maxbriel · 2026-05-07T08:36:54Z

@ezapartas @dimsour94 I've reviewed the PR and you will need to verify a few things in the implementation, because it currently brakes some of the other evolution. Furthermore, it seems that the average abundances equations are not the same as in Schneider+2016.

We can probably work through it with/for you, if you're okay with the suggested changes.

Currently causes binary candidates to fail in our dev-tools suite.

maxbriel · 2026-05-07T08:56:26Z

In the old test suite, binary 4 fails. This is probably due to the change from float to a string for rel_mass_loss_HMS_HMS.
This PR:

🚨 Binary Evolution Failed!
Exception: TypeError
Message: unsupported operand type(s) for -: 'float' and 'str'

Evolution steps before failure (3 steps):
     step_names     state      event               S1_state  S1_mass               S2_state  S2_mass  orbital_period
0  initial_cond  detached       ZAMS  H-rich_Core_H_burning    9.846  H-rich_Core_H_burning    9.611           3.821
1  step_HMS_HMS      RLO2       oCE2  H-rich_Core_H_burning    4.213  H-rich_Core_H_burning   10.952           5.138
2       step_CE    merged  oMerging2  H-rich_Core_H_burning    4.213  H-rich_Core_H_burning   10.952           5.138



--------------------------------------------------------------------------------------------------------------------------------------------
No warning(s) raised during evolution

on v2.3:

     step_names     state      event               S1_state  S1_mass                S2_state  S2_mass  orbital_period
0  initial_cond  detached       ZAMS  H-rich_Core_H_burning    9.846   H-rich_Core_H_burning    9.611           3.821
1  step_HMS_HMS      RLO2       oCE2  H-rich_Core_H_burning    4.213   H-rich_Core_H_burning   10.952           5.138
2       step_CE    merged  oMerging2  H-rich_Core_H_burning    4.213   H-rich_Core_H_burning   10.952           5.138
3   step_merged    merged        CC2       massless_remnant    0.000  H-rich_Core_C_depleted    9.466             NaN
4       step_SN    merged       <NA>       massless_remnant    0.000                      NS    1.914             NaN
5      step_end    merged        END       massless_remnant    0.000                      NS    1.914             NaN





--------------------------------------------------------------------------------------------------------------------------------------------
No warning(s) raised during evolution

added the HMS+HMS merging according to Schneider+2016 rejuvenation an…

29ecda2

…d the possibility to match with total_mass_h1

ezapartas marked this pull request as draft January 16, 2026 06:55

pre-commit-ci Bot and others added 7 commits January 16, 2026 06:56

[pre-commit.ci] auto fixes from pre-commit.com hooks

b075c20

for more information, see https://pre-commit.ci

rewrite rel_mass_lost_HMS_HMS part and some comments. Option changed …

66fbf50

…to 'Glebbeek+2013'

[pre-commit.ci] auto fixes from pre-commit.com hooks

332a3a4

for more information, see https://pre-commit.ci

self.HMS_HMS*

8607b4a

total_h1_mass even for HMS_HMS_merging_rejuvenation = False

48d94d2

check that rel_mass_lost_HMS_HMS is [0,1) or the specific string

6e625ad

[pre-commit.ci] auto fixes from pre-commit.com hooks

4570259

for more information, see https://pre-commit.ci

ezapartas marked this pull request as ready for review January 24, 2026 10:11

Update population_params_default.ini

e8e142a

added the options and default values of of rel_mass_lost_HMS_HMS and HMS_HMS_merging_rejuvenation in the .ini file of the population.

astroJeff requested review from astro-abhishek, maxbriel and sgossage January 28, 2026 21:13

ezapartas added 2 commits January 31, 2026 12:36

"Glebbeek+2013" as default option

30e3a57

"Glebbeek+2013" as default in the .ini file too.

e45b7ab

maxbriel changed the base branch from main to v2.3 February 10, 2026 08:21

maxbriel changed the title ~~HMS+HMS Mergers rejuvenation according to Schneider+2016~~ [enhancement] HMS+HMS Mergers rejuvenation according to Schneider+2016 Feb 10, 2026

maxbriel added the enhancement New feature or request label Feb 10, 2026

ezapartas mentioned this pull request Feb 12, 2026

[fix] Corrected/enhanced merger process #785

Merged

maxbriel added this to the v2.3 milestone Feb 13, 2026

sgossage assigned ezapartas Mar 16, 2026

sgossage reviewed Mar 24, 2026

View reviewed changes

Comment thread posydon/popsyn/population_params_default.ini Outdated

sgossage and others added 4 commits April 23, 2026 13:31

Merge branch 'v2.3' into dimitris_masos_MSMSmergers_rejuvenation_aver…

8a4d95e

…ageX

[pre-commit.ci] auto fixes from pre-commit.com hooks

4667d53

for more information, see https://pre-commit.ci

ignore docs/_source/_build/ now and also updating docs to explain new…

72683da

… options in merger step

[pre-commit.ci] auto fixes from pre-commit.com hooks

a0e7f94

for more information, see https://pre-commit.ci

maxbriel requested changes May 7, 2026

View reviewed changes


		merged_star.mass = (star_base.mass + comp.mass) * (1.-rel_mass_lost_HMS_HMS)

		X_average_merged = (star_base.total_mass_h1 + comp.total_mass_h1 - (1.-rel_mass_lost_HMS_HMS) * X_initial) / merged_star.mass

	# these stellar attributes become np.nan
	# these stellar attributes become np.nan

Conversation

ezapartas commented Jan 16, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

ezapartas commented Jan 24, 2026

Uh oh!

Uh oh!

sgossage commented Mar 24, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

sgossage commented Mar 24, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

maxbriel May 7, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

maxbriel commented May 7, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

maxbriel commented May 7, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

ezapartas commented Jan 16, 2026 •

edited

Loading

sgossage commented Mar 24, 2026 •

edited

Loading

sgossage commented Mar 24, 2026 •

edited

Loading

maxbriel May 7, 2026 •

edited

Loading

maxbriel commented May 7, 2026 •

edited

Loading

maxbriel commented May 7, 2026 •

edited

Loading