The mass of the primary star #933
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When I used the command of ./COMPAS -n 10000 to generate 10000 binaries, I fond that the program produced 55 binaries, where the primary masses are less than 5 solar mass. Moreover, mass ratios of these binaries are all equal to one. Then, I tried to set the lower limit of the primary mass equal to 5 solar mass explicitly, but still found the same phenomenon. I wonder is there something wrong with the way I use COMPAS. Thanks a lot! |
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Replies: 1 comment 1 reply
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Hi @hulin-Lee , I think these are probably systems that are born with very small separations and RLOF at birth, leading them to have their masses equalised. There is a flag in the SystemParameters file (MASSES_EQUILIBRATED_AT_BIRTH, see here) that tells you if this has occurred. This step happens after the initial sampling, so if you draw a binary with a primary of 6 MSun and a secondary of 3 MSun, if the masses are equilibrated it would produce a binary with both components being 4.5Msun. You could just manually filter these out, or you could try disabling the model for chemically homogenous evolution. |
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Thanks again! |
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Hi @hulin-Lee , I think these are probably systems that are born with very small separations and RLOF at birth, leading them to have their masses equalised. There is a flag in the SystemParameters file (MASSES_EQUILIBRATED_AT_BIRTH, see here) that tells you if this has occurred. This step happens after the initial sampling, so if you draw a binary with a primary of 6 MSun and a secondary of 3 MSun, if the masses are equilibrated it would produce a binary with both components being 4.5Msun. You could just manually filter these out, or you could try disabling the model for chemically homogenous evolution.